Alexey Buzykaev

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 x 10(6) Upsilon(4S)-->B(-)B decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B(0) or B(-0) from its decay products. The amplitude of the CP asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay-time distributions in such events. We measure sin2beta=0.741+/-0.067(stat)+/-0.034(syst) and |lambda|=0.948+/-0.051(stat)+/-0.030(syst). The magnitude of lambda is consistent with unity, in agreement with the standard model expectation of no direct CP violation in these modes.

A new type of ring-imaging Cherenkov detector is being used for hadronic particle identification in the BaBar experiment at the SLAC B Factory (PEP-II). This detector is called DIRC, an acronym for Detection of Internally Reflected Cherenkov (Light). This paper will discuss the construction, operation and performance of the BaBar DIRC in detail.

In a search for $B\ensuremath{\rightarrow}c\overline{c}\ensuremath{\gamma}K$ decays with the BABAR detector, where $c\overline{c}$ includes $J/\ensuremath{\psi}$ and $\ensuremath{\psi}(2S)$, and $K$ includes ${K}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}_{S}^{0}$, and ${K}^{*}(892)$, we find evidence for $X(3872)\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\gamma}$ and $X(3872)\ensuremath{\rightarrow}\ensuremath{\psi}(2S)\ensuremath{\gamma}$ with $3.6\ensuremath{\sigma}$ and $3.5\ensuremath{\sigma}$ significance, respectively. We measure the product of branching fractions $\mathcal{B}\mathbf{(}{B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}X(3872){K}^{\ifmmode\pm\else\textpm\fi{}}\mathbf{)}\ifmmode\times\else\texttimes\fi{}\mathcal{B}\mathbf{(}X(3872)\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\gamma}\mathbf{)}=[2.8\ifmmode\pm\else\textpm\fi{}0.8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.1(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and $\mathcal{B}\mathbf{(}{B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}X(3872){K}^{\ifmmode\pm\else\textpm\fi{}}\mathbf{)}\ifmmode\times\else\texttimes\fi{}\mathcal{B}\mathbf{(}X(3872)\ensuremath{\rightarrow}\ensuremath{\psi}(2S)\ensuremath{\gamma}\mathbf{)}=[9.5\ifmmode\pm\else\textpm\fi{}2.7(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.6(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$.

We report the results of a search for the bottomonium ground state eta_b(1S) in the photon energy spectrum with a sample of (109 +/- 1) million of Upsilon(3S) recorded at the Upsilon(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. We observe a peak in the photon energy spectrum at E_gamma = 921.2 {+2.1} {-2.8} (stat) +/- 2.4(syst) MeV with a significance of 10 standard deviations. We interpret the observed peak as being due to monochromatic photons from the radiative transition Upsilon(3S) -> gamma eta_b(1S). This photon energy corresponds to an eta_b(1S) mass of $9388.9 {+3.1} {-2.3} (stat) +/- 2.7(syst) MeV/c2. The hyperfine Upsilon(1S)-eta_b(1S) mass splitting is 71.4 {+2.3} {-3.1} (stat) +/- 2.7(syst) MeV/c2. The branching fraction for this radiative Upsilon(3S) decay is estimated to be (4.8 +/- 0.5(stat) +/- 1.2 (syst)) x 10^(-4).

We present a study of the decays B^{0,+} --> J/psi pi^+ pi^- pi^0 K^{0,+}, using 467 10^6 BBbar pairs recorded with the BABAR detector. We present evidence for the decay mode X(3872) --> J/psi omega, with product branching fractions B(B^+ --> X(3872)K^+) B(X(3872) --> J/psi omega) =[0.6\pm0.2\stat \pm 0.1\syst ] 10^{-5}, and B(B^0 --> X(3872)K^0) B(X(3872) --> J/psi omega) =[0.6\pm0.3\stat \pm 0.1\syst ] 10^{-5}. A detailed study of the pi^+ pi^- pi^0 mass distribution from X(3872) decay favors a negative-parity assignment.

We report the results of a search for $Z(4430)^-$ decay to $J/\psi\pi^-$ or $\psi(2S)\pi^-$ in $B^{-,0}\to \jpsi\pi^- K^{0,+}$ and $B^{-,0}\to \psitwos \pi^- K^{0,+}$ decays. The data were collected with the BABAR detector at the SLAC PEP-II asymmetric-energy $e^+e^-$ collider operating at center of mass energy 10.58 \gev, and the sample corresponds to an integrated luminosity of 413 fb$^{-1}$. Each $K\pi$ mass distribution exhibits clear $K^{\ast}(892)$ and $K^{\ast}_2(1430)$ signals, and the efficiency-corrected spectrum is well-described by a superposition of the associated Breit-Wigner intensity distributions, together with an $S$-wave contribution obtained from the LASS $I=1/2$ $K\pi$ scattering amplitude measurements. Each $K\pi$ angular distribution varies significantly in structure with $K\pi$ mass, and is represented in terms of low-order Legendre polynomial moments. We find that each $J/\psi\pi$ or $\psi(2S)\pi$ mass distribution is well-described by the reflection of the measured $K\pi$ mass and angular distribution structures. We see no significant evidence for a $Z(4430)^-$ signal for any of the processes investigated, neither in the total $J/\psi\pi$ or $\psi(2S)\pi$ mass distribution, nor in the corresponding distributions for the regions of $K\pi$ mass for which observation of the $Z(4430)^-$ signal was reported. We obtain branching fraction upper limits ${\cal{B}}(B^-\to Z^-\bar{K^0}, Z^-\to J/\psi\pi^-)<1.5\times 10^{-5}$, ${\cal{B}}(B^0\to Z^-K^+, Z^-\to J/\psi\pi^-)<0.4\times 10^{-5}$, ${\cal{B}}(B^-\to Z^-\bar{K^0}, Z^-\to \psi(2S)\pi^-)<4.7\times 10^{-5}$, and ${\cal{B}}(B^0\to Z^-K^+, Z^-\to \psi(2S)\pi^-)<3.1\times 10^{-5}$ at 95% confidence level, where the $Z(4430)^-$ mass and width have been fixed to the reported central values.

Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B(0) or B(0)), and J/ψK(L)(0) or ccK(S)(0) final states (referred to as B(+) or B(-)), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B(0) → B(-) and B(-) → B(0), as a function of the time difference between the two B decays. Using 468 × 10(6) BB pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS(T)(+) = -1.37 ± 0.14(stat) ± 0.06(syst) and ΔS(T)(-) = 1.17 ± 0.18(stat) ± 0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.

We search for the flavor-changing neutral-current decays $B\ensuremath{\rightarrow}{K}^{(*)}\ensuremath{\nu}\overline{\ensuremath{\nu}}$, and the invisible decays $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ and $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ via $B\ensuremath{\rightarrow}{K}^{(*)}J/\ensuremath{\psi}$ and $B\ensuremath{\rightarrow}{K}^{(*)}\ensuremath{\psi}(2S)$, respectively, using a data sample of $471\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected by the BABAR experiment. We fully reconstruct the hadronic decay of one of the $B$ mesons in the $\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}B\overline{B}$ decay, and search for the $B\ensuremath{\rightarrow}{K}^{(*)}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ decay in the rest of the event. We observe no significant excess of signal decays over background and report branching fraction upper limits of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;3.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{0}\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;8.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{*+}\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;11.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{*0}\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;9.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, and combined upper limits of $\mathcal{B}(B\ensuremath{\rightarrow}K\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;3.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ and $\mathcal{B}(B\ensuremath{\rightarrow}{K}^{*}\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;7.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, all at the 90% confidence level. For the invisible quarkonium decays, we report branching fraction upper limits of $\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;3.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and $\mathcal{B}(\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\nu}\overline{\ensuremath{\nu}})&lt;15.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ at the 90% confidence level. Using the improved kinematic resolution achieved from hadronic reconstruction, we also provide partial branching fraction limits for the $B\ensuremath{\rightarrow}{K}^{(*)}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ decays over the full kinematic spectrum.

We present an analysis of exclusive charmless semileptonic $B$-meson decays based on $377\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs recorded with the BABAR detector at the $\mathit{\ensuremath{\Upsilon}}(4S)$ resonance. We select four event samples corresponding to the decay modes ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, ${B}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, and ${B}^{+}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$ and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two $B\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\ell}\ensuremath{\nu}$ samples, and similarly the two $B\ensuremath{\rightarrow}\ensuremath{\rho}\ensuremath{\ell}\ensuremath{\nu}$ samples, and measure the branching fractions $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu})=(1.41\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.07)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu})=(1.75\ifmmode\pm\else\textpm\fi{}0.15\ifmmode\pm\else\textpm\fi{}0.27)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, where the errors are statistical and systematic. We compare the measured distribution in ${q}^{2}$, the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{ub}|$. Based on the measured partial branching fraction for $B\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\ell}\ensuremath{\nu}$ in the range ${q}^{2}&lt;12\text{ }\text{ }{\mathrm{GeV}}^{2}$ and the most recent QCD light-cone sum-rule calculations, we obtain $|{V}_{ub}|=(3.78\ifmmode\pm\else\textpm\fi{}{0.13}_{\ensuremath{-}0.40}^{+0.55})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full ${q}^{2}$ range and the FNAL/MILC lattice QCD results, we obtain $|{V}_{ub}|=(2.95\ifmmode\pm\else\textpm\fi{}0.31)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ from $B\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\ell}\ensuremath{\nu}$, where the error is the combined experimental and theoretical uncertainty.

We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider at the Stanford Linear Accelerator Center. The data sample consists of 29.7 ${\mathrm{fb}}^{\mathrm{\ensuremath{-}}1}$ recorded at the $\ensuremath{\Upsilon}(4S)$ resonance and 3.9 ${\mathrm{fb}}^{\mathrm{\ensuremath{-}}1}$ off resonance. One of the neutral B mesons, which are produced in pairs at the $\ensuremath{\Upsilon}(4S),$ is fully reconstructed in the CP decay modes $J/\ensuremath{\psi}{K}_{S}^{0},$ $\ensuremath{\psi}{(2S)K}_{S}^{0},$ ${\ensuremath{\chi}}_{c1}{K}_{S}^{0},$ $J/\ensuremath{\psi}{K}^{*0}$ ${(K}^{*0}\ensuremath{\rightarrow}{K}_{S}^{0}{\ensuremath{\pi}}^{0})$ and $J/\ensuremath{\psi}{K}_{L}^{0},$ or in flavor-eigenstate modes involving ${D}^{(*)}\ensuremath{\pi}/\ensuremath{\rho}{/a}_{1}$ and $J/\ensuremath{\psi}{K}^{*0}$ ${(K}^{*0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}).$ The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. A neural network tagging algorithm is used to recover events without a clear lepton or kaon tag. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. Wrong-tag probabilities, the time-difference resolution function, and the ${B}^{0}\ensuremath{-}{B}^{0}$ oscillation frequency $\ensuremath{\Delta}{m}_{d}$ are measured with a sample of about 6350 fully-reconstructed ${B}^{0}$ decays in hadronic flavor-eigenstate modes. A maximum-likelihood fit to this flavor eigenstate sample finds $\ensuremath{\Delta}{m}_{d}=0.516\ifmmode\pm\else\textpm\fi{}0.016(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.010(\mathrm{syst}){\mathrm{ps}}^{\ensuremath{-}1}.$ The value of the asymmetry amplitude $\mathrm{sin}2\ensuremath{\beta}$ is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged ${B}^{0}$ decays in the CP-eigenstate modes. We find $\mathrm{sin}2\ensuremath{\beta}=0.59\ifmmode\pm\else\textpm\fi{}0.14(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{syst}),$ demonstrating that CP violation exists in the neutral B meson system. We also determine the value of the CP violation parameter $|\ensuremath{\lambda}|=0.93\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{syst}),$ which is consistent with the expectation of $|\ensuremath{\lambda}|=1$ for no direct CP violation.

We observe the decays ${D}_{s1}^{*}(2710{)}^{+}\ensuremath{\rightarrow}{D}^{*}K$ and ${D}_{sJ}^{*}(2860{)}^{+}\ensuremath{\rightarrow}{D}^{*}K$ and measure their branching fractions relative to the $DK$ final state. We also observe, in the ${D}^{*}K$ mass spectrum, a new broad structure at a mass of $(3044\ifmmode\pm\else\textpm\fi{}{8}_{\mathrm{stat}}(\genfrac{}{}{0}{}{+30}{\ensuremath{-}5}{)}_{\mathrm{syst}})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ having a width $\ensuremath{\Gamma}=(239\ifmmode\pm\else\textpm\fi{}{35}_{\mathrm{stat}}(\genfrac{}{}{0}{}{+46}{\ensuremath{-}42}{)}_{\mathrm{syst}})\text{ }\text{ }\mathrm{MeV}$. To obtain this result we use $470\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data recorded by the BABAR detector at the PEP-II asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV.

We present measurements of the decays B+ -> X(3872) K+ and B0 -> X(3872) K0 with X(3872) -> Jpsi pi+ pi-. The data sample used, collected with the BABAR detector at the PEP-II e+e- asymmetric-energy storage ring, corresponds to 455 x 10^6 BBbar pairs. Branching fraction measurements of BF(B+ -> X(3872) K+) x BF(X(3872) -> Jpsi pi+ pi-) = (8.4 +/- 1.5 +/- 0.7) x 10^{-6} and BF(B0 -> X(3872) K0) x BF(X(3872) -> Jpsi pi+ pi- = (3.5 +/- 1.9 +/- 0.4) x 10^{-6} are obtained. We set an upper limit on the natural width of the X(3872) of Gamma < 3.3 MeV/c^2 at the 90% confidence level.

We report the results of a study of the exclusive charmless semileptonic decays, ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, ${B}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, and ${B}^{+}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$ ($\ensuremath{\ell}=e$ or $\ensuremath{\mu}$) undertaken with approximately $462\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the BABAR detector. The analysis uses events in which the signal $B$ decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of ${q}^{2}$, the square of the momentum transferred to the lepton-neutrino pair, for ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, ${B}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, and ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$. From these distributions, we extract the form-factor shapes ${f}_{+}({q}^{2})$ and the total branching fractions $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu})=(1.45\ifmmode\pm\else\textpm\fi{}{0.04}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.06}_{\mathrm{syst}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ (combined ${\ensuremath{\pi}}^{\ensuremath{-}}$ and ${\ensuremath{\pi}}^{0}$ decay channels assuming isospin symmetry), $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\ell}}^{+}\ensuremath{\nu})=(1.19\ifmmode\pm\else\textpm\fi{}{0.16}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.09}_{\mathrm{syst}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\ell}}^{+}\ensuremath{\nu})=(0.38\ifmmode\pm\else\textpm\fi{}{0.05}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.05}_{\mathrm{syst}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. We also measure $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{\ensuremath{\ell}}^{+}\ensuremath{\nu})=(0.24\ifmmode\pm\else\textpm\fi{}{0.08}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.03}_{\mathrm{syst}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. We obtain values for the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|{V}_{ub}|$ by direct comparison with three different QCD calculations in restricted ${q}^{2}$ ranges of $B\ensuremath{\rightarrow}\ensuremath{\pi}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$ decays. From a simultaneous fit to the experimental data over the full ${q}^{2}$ range and the FNAL/MILC lattice QCD predictions, we obtain $|{V}_{ub}|=(3.25\ifmmode\pm\else\textpm\fi{}0.31)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, where the error is the combined experimental and theoretical uncertainty.

We perform a study of the exclusive production of $D \bar D$, $D \bar D^*$, and $D^* \bar D^*$ in initial-state-radiation events, from $e^+ e^-$ annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium and possible new resonances. The data sample corresponds to an integrated luminosity of 384 $fb^{-1}$ and was recorded by the BaBar experiment at the PEP-II storage rings. The $D \bar D$, $D \bar D^*$, and $D^* \bar D^*$ mass spectra show clear evidence of several $\psi$ resonances. However, there is no evidence for $Y(4260) \to D \bar D^*$ or $Y(4260)\to D^* \bar D^*$.

We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{\mathrm{cb}}|$ and the form-factor slope ${\ensuremath{\rho}}^{2}$ in $\overline{B}\ensuremath{\rightarrow}D{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}}$ decays based on $460\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ events recorded at the $\ensuremath{\Upsilon}(4S)$ resonance with the BABAR detector. $\overline{B}\ensuremath{\rightarrow}D{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}}$ decays are selected in events in which a hadronic decay of the second $B$ meson is fully reconstructed. We measure $\mathcal{B}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\mathcal{B}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}X{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=(0.255\ifmmode\pm\else\textpm\fi{}0.009\ifmmode\pm\else\textpm\fi{}0.009)$ and $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}X{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=(0.230\ifmmode\pm\else\textpm\fi{}0.011\ifmmode\pm\else\textpm\fi{}0.011)$, along with the differential decay distribution in $\overline{B}\ensuremath{\rightarrow}D{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}}$ decays. We then determine $\mathcal{G}(1)|{V}_{\mathrm{cb}}|=(42.3\ifmmode\pm\else\textpm\fi{}1.9\ifmmode\pm\else\textpm\fi{}1.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and ${\ensuremath{\rho}}^{2}=1.20\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.04$, where $\mathcal{G}(1)$ is the hadronic form factor at the point of zero recoil.

We study the process $\gamma \gamma \to J/\psi \omega$ using a data sample of 519.2 $fb^{-1}$ recorded by the BaBar detector at SLAC at the PEP-II asymmetric-energy $e^+ e^-$ collider at center-of-mass energies near the $\Upsilon(nS)$ ($n = 2,3,4$) resonances. We confirm the existence of the charmonium-like resonance X(3915) decaying to $J/\psi \omega$ with a significance of 7.6 standard deviations, including systematic uncertainties, and measure its mass $(3919.4 \pm 2.2 \pm 1.6) MeV/c^2$ and width $(13 \pm 6 \pm 3) MeV$, where the first uncertainty is statistical and the second systematic. A spin-parity analysis supports the assignment $J^P=0^+$ and therefore the identification of the signal as due to the $\chi_{c0}(2P)$ resonance. In this hypothesis we determine the product between the two-photon width and the final state branching fraction to be $(52 \pm 10 \pm 3) eV$

We report e+e−→b¯b cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II e+e− collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Υ(10860) and Υ(11020) resonances. In particular we show that their widths may be smaller than previously measured.Received 26 September 2008DOI:https://doi.org/10.1103/PhysRevLett.102.012001©2009 American Physical Society

A search for the Z(3930) resonance in gamma gamma production of the DDbar system has been performed using a data sample corresponding to an integrated luminosity of 384 fb^-1 recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DDbar invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8 sigma. We determine mass and width values of (3926.7 +- 2.7 +- 1.1) MeV/c^2 and (21.3 +- 6.8 +- 3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C-parity (J^PC = 2^++); therefore we identify the Z(3930) state as the chi_c2(2P) meson. The value of the partial width Gamma_(gamma gamma)xB(Z(3930)-> DDbar) is found to be (0.24 +- 0.05 +- 0.04) keV.

We present improved measurements of $CP$-violation parameters in the decays ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, ${B}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$, and of the branching fractions for ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ and ${B}^{0}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{0}$. The results are obtained with the full data set collected at the $\ensuremath{\Upsilon}(4S)$ resonance by the BABAR experiment at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory, corresponding to $(467\ifmmode\pm\else\textpm\fi{}5)\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs. We find the $CP$-violation parameter values and branching fractions: ${S}_{{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}}=\ensuremath{-}0.68\ifmmode\pm\else\textpm\fi{}0.10\ifmmode\pm\else\textpm\fi{}0.03$, ${C}_{{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}}=\ensuremath{-}0.25\ifmmode\pm\else\textpm\fi{}0.08\ifmmode\pm\else\textpm\fi{}0.02$, ${\mathcal{A}}_{{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}}=\ensuremath{-}0.107\ifmmode\pm\else\textpm\fi{}{0.016}_{\ensuremath{-}0.004}^{+0.006}$, ${C}_{{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}}=\ensuremath{-}0.43\ifmmode\pm\else\textpm\fi{}0.26\ifmmode\pm\else\textpm\fi{}0.05$, $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0})=(1.83\ifmmode\pm\else\textpm\fi{}0.21\ifmmode\pm\else\textpm\fi{}0.13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, $\text{ }\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{0})=\phantom{\rule{0ex}{0ex}}(10.1\ifmmode\pm\else\textpm\fi{}0.6\ifmmode\pm\else\textpm\fi{}0.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, where in each case, the first uncertainties are statistical and the second are systematic. We observe $CP$ violation with a significance of 6.7 standard deviations for ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and 6.1 standard deviations for ${B}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, including systematic uncertainties. Constraints on the unitarity triangle angle $\ensuremath{\alpha}$ are determined from the isospin relations among the $B\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}$ rates and asymmetries. Considering only the solution preferred by the Standard Model, we find $\ensuremath{\alpha}$ to be in the range [71\ifmmode^\circ\else\textdegree\fi{},109\ifmmode^\circ\else\textdegree\fi{}] at the 68% confidence level.

We search for the rare flavor-changing neutral current process $B^{+}\rightarrow K^{+}τ^{+}τ^{-}$ using data from the BABAR experiment. The data sample, collected at the center-of-mass energy of the $Υ{(4S)}$ resonance, corresponds to a total integrated luminosity of 424 fb$^{-1}$ and to 471 million $B\overline{B}$ pairs. We reconstruct one $B$ meson, produced in the $Υ{(4S)}\rightarrow B^{+} B^{-}$ decay, in one of many hadronic decay modes and search for activity compatible with a $B^{+}\rightarrow K^{+} τ^{+}τ^{-}$ decay in the rest of the event. Each $τ$ lepton is required to decay leptonically into an electron or muon and neutrinos. Comparing the expected number of background events with the data sample after applying the selection criteria, we do not find evidence for a signal. The measured branching fraction is ($1.31^{+0.66}_{-0.61}$( stat.)$^{+0.35}_{-0.25}$( sys.)$) \times 10^{-3}$ with an upper limit, at the 90\% confidence level, of $\mathcal{B}(B^{+}\rightarrow K^{+}τ^{+}τ^{-})$$&lt; 2.25\times 10^{-3}$.

We search for the $Z_1(4050)^+$ and $Z_2(4250)^+$ states, reported by the Belle Collaboration, decaying to $\chi_{c1} \pi^+$ in the decays $\bar B^0 \to \chi_{c1} K^- \pi^+$ and $B^+ \to \chi_{c1} K^0_S \pi^+$ where $\chi_{c1} \to \jpsi \gamma$. The data were collected with the BaBar detector at the SLAC PEP-II asymmetric-energy $e^+e^-$ collider operating at center-of-mass energy 10.58 GeV, and correspond to an integrated luminosity of 429 fb$^{-1}$. In this analysis, we model the background-subtracted, efficiency-corrected $\chi_{c1}\pi$ mass distribution using the $K \pi$ mass distribution and the corresponding normalized $K \pi$ Legendre polynomial moments, and then test the need for the inclusion of resonant structures in the description of the $\chi_{c1}\pi$ mass distribution. No evidence is found for the $Z_1(4050)^+$ and $Z_2(4250)^+$ resonances, and 90% confidence level upper limits on the branching fractions are reported for the corresponding $B$-meson decay modes.

The inclusive production of charmonium mesons in B meson decay has been studied in a 20.3 ${\mathrm{fb}}^{\mathrm{\ensuremath{-}}1}$ data set collected by the BABAR experiment operating at the $\ensuremath{\Upsilon}(4S)$ resonance. Branching fractions have been measured for the inclusive production of the charmonium mesons $J/\ensuremath{\psi},$ $\ensuremath{\psi}(2S),$ ${\ensuremath{\chi}}_{c1},$ and ${\ensuremath{\chi}}_{c2}.$ The branching fractions are also presented as a function of the center-of-mass momentum of the mesons and of the helicity of the $J/\ensuremath{\psi}.$

We report branching fraction measurements for exclusive decays of charged and neutral B mesons into two-body final states containing a charmonium meson. We use a sample of $22.72\ifmmode\pm\else\textpm\fi{}0.36$ million $B\overline{B}$ events collected between October 1999 and October 2000 with the BABAR detector at the PEP-II storage rings at the Stanford Linear Accelerator Center. The charmonium mesons considered here are $J/\ensuremath{\psi},$ $\ensuremath{\psi}(2S),$ and ${\ensuremath{\chi}}_{c1},$ and the light meson in the decay is either a K, ${K}^{*},$ or ${\ensuremath{\pi}}^{0}.$

We search for invisible decays of the Υ(1S) meson using a sample of 91.4×106 Υ(3S) mesons collected at the BABAR/PEP-II B factory. We select events containing the decay Υ(3S)→π+π−Υ(1S) and search for evidence of an undetectable Υ(1S) decay recoiling against the dipion system. We set an upper limit on the branching fraction B(Υ(1S)→invisible)<3.0×10−4 at the 90% confidence level.Received 20 August 2009DOI:https://doi.org/10.1103/PhysRevLett.103.251801©2009 American Physical Society

A Dalitz plot analysis of approximately 13 000 D+s decays to π+π−π+ has been performed. The analysis uses a 384 fb−1 data sample recorded by the BABAR detector at the PEP-II asymmetric-energy e+e− storage ring running at center of mass energies near 10.6 GeV. Amplitudes and phases of the intermediate resonances which contribute to this final state are measured. A high precision measurement of the ratio of branching fractions is performed: B(D+s→π+π−π+)/B(D+s→K+K−π+)=0.199±0.004±0.009. Using a model-independent partial wave analysis, the amplitude and phase of the S wave have been measured.Received 9 December 2008DOI:https://doi.org/10.1103/PhysRevD.79.032003©2009 American Physical Society

We measure the rate of D0−¯¯¯D0 mixing with the observable yCP=(τKπ/τKK)−1, where τKK and τKπ are, respectively, the mean lifetimes of CP-even D0→K+K− and CP-mixed D0→K−π+ decays, using a data sample of 384 fb−1 collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B Factory. From a sample of D0 and ¯¯¯D0 decays where the initial flavor of the decaying meson is not determined, we obtain yCP=[1.12±0.26(stat)±0.22(syst)]%, which excludes the no-mixing hypothesis at 3.3σ, including both statistical and systematic uncertainties. This result is in good agreement with a previous BABAR measurement of yCP obtained from a sample of D*+→D0π+ events, where the D0 decays to K−π+, K+K−, and π+π−, which is disjoint with the untagged D0 events used here. Combining the two results taking into account statistical and systematic uncertainties, where the systematic uncertainties are assumed to be 100% correlated, we find yCP=[1.16±0.22(stat)±0.18(syst)]%, which excludes the no-mixing hypothesis at 4.1σ.Received 7 August 2009DOI:https://doi.org/10.1103/PhysRevD.80.071103©2009 American Physical Society

Received 5 December 2008DOI:https://doi.org/10.1103/PhysRevLett.102.029901©2009 American Physical Society

We study the reaction e+e- --> e+e- eta_c, eta_c --> K_S K+- pi-+ and obtain eta_c mass and width values 2982.2+-0.4+-1.6 MeV/c^2 and 31.7+-1.2+-0.8 MeV, respectively. We find Gamma(eta_c --> gamma gamma)B(eta_c --> K anti-K pi)=0.374+-0.009+-0.031 keV, and measure the gamma gamma* --> eta_c transition form factor in the momentum transfer range from 2 to 50 GeV^2. The analysis is based on 469 fb-1 of integrated luminosity collected at PEP-II with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV.

Using 347.5 fb-1 of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244*10^3 signal events for the D+ --> K- pi+ e+ nu_e decay channel are analyzed. This decay mode is dominated by the \bar{K}^*(892)^0 contribution. We determine the \bar{K}^*(892)^0 parameters: m_{K^*(892)^0}=(895.4 +- 0.2 +- 0.2) MeV/c^{2}, \Gamma^0_{K^*(892)^0}=(46.5 +- 0.3 +- 0.2) MeV/c^{2} and the Blatt-Weisskopf parameter $r_{BW}=2.1 +- 0.5 +- 0.5 (GeV/c)^{-1} where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q^{2}=0 (r_{V} = V(0) / A_{1}(0)=1.463 +- 0.017 +- 0.031, r_{2} = A_{2}(0) / A_{1}(0) = 0.801 +- 0.020 +- 0.020) and the value of the axial-vector pole mass parameterizing the q^2 variation of A_{1} and A_{2}: m_{A}=(2.63 +- 0.10 +- 0.13) GeV/c^{2}. The S-wave fraction is equal to (5.79 +- 0.16 +- 0.15)%. Other signal components correspond to fractions below 1%. Using the D+ --> K- pi+ pi+ channel as a normalization, we measure the D+ semileptonic branching fraction: BR(D+ --> K- pi+ e+ nu_e) = (4.04 +- 0.03 +- 0.04 +- 0.09) \times 10^{-2} where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A_1 at q^{2}=0: A_{1}(0) = 0.6226 +- 0.0056 +- 0.0065 +- 0.0074. Fixing the P-wave parameters we measure the phase of the S-wave for several values of the Kpi mass. These results confirm those obtained with Kpi production at small momentum transfer in fixed target experiments.

We present a measurement of the decay amplitudes in B-->J/psiK*(892) channels using 20.7 fb(-1) of data collected at the Upsilon(4S) resonance with the BABAR detector at PEP-II. We measure a P-wave fraction R(perpendicular) = (16.0 +/- 3.2 +/- 1.4)% and a longitudinal polarization fraction (59.7 +/- 2.8 +/- 2.4)%. The measurement of a relative phase that is neither 0 nor pi, phi = 2.50 +/- 0.20 +/-0.08 radians, favors a departure from the factorization hypothesis. Although the decay B-->/psiK(pi) proceeds mainly via K*(892), there is also evidence for K2*(1430) and K(pi) S-wave contributions.

The production of $J/\ensuremath{\psi}$ mesons in continuum ${e}^{+}{e}^{\ensuremath{-}}$ annihilations has been studied with the BABAR detector at energies near the $\ensuremath{\Upsilon}(4S)$ resonance. The mesons are distinguished from $J/\ensuremath{\psi}$ production in $B$ decays through their center-of-mass momentum and energy. We measure the cross section ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}X$ to be $2.52\ifmmode\pm\else\textpm\fi{}0.21\ifmmode\pm\else\textpm\fi{}0.21\mathrm{pb}$. We set a $90%$ C.L. upper limit on the branching fraction for direct $\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}J/\ensuremath{\psi}X$ decays at $4.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$.

We report searches for $B$-meson decays to the charmless final states $\ensuremath{\rho}{K}^{*}$ and ${f}_{0}(980){K}^{*}$ with a sample of $232\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ collider. We measure in units of ${10}^{\ensuremath{-}6}$ the following branching fractions, where the first error quoted is statistical and the second systematic, or upper limits are given at the 90% confidence level : $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}{K}^{*+})&lt;6.1$, $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}{K}^{*0})=9.6\ifmmode\pm\else\textpm\fi{}1.7\ifmmode\pm\else\textpm\fi{}1.5$, $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ensuremath{-}}{K}^{*+})&lt;12.0$, $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}{K}^{*0})=5.6\ifmmode\pm\else\textpm\fi{}0.9\ifmmode\pm\else\textpm\fi{}1.3$, $\mathcal{B}\mathbf{(}{B}^{+}\ensuremath{\rightarrow}{f}_{0}(980){K}^{*+}\mathbf{)}=5.2\ifmmode\pm\else\textpm\fi{}1.2\ifmmode\pm\else\textpm\fi{}0.5$, and $\mathcal{B}\mathbf{(}{B}^{0}\ensuremath{\rightarrow}{f}_{0}(980){K}^{*0}\mathbf{)}&lt;4.3$. For the significant modes, we also measure the fraction of longitudinal polarization and the charge asymmetry: ${f}_{L}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}{K}^{*0})=0.52\ifmmode\pm\else\textpm\fi{}0.10\ifmmode\pm\else\textpm\fi{}0.04$, ${f}_{L}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}{K}^{*0})=0.57\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.08$, ${\mathcal{A}}_{CP}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}{K}^{*0})=\ensuremath{-}0.01\ifmmode\pm\else\textpm\fi{}0.16\ifmmode\pm\else\textpm\fi{}0.02$, ${\mathcal{A}}_{CP}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}{K}^{*0})=0.09\ifmmode\pm\else\textpm\fi{}0.19\ifmmode\pm\else\textpm\fi{}0.02$, and ${\mathcal{A}}_{CP}\mathbf{(}{B}^{+}\ensuremath{\rightarrow}{f}_{0}(980){K}^{*+}\mathbf{)}=\ensuremath{-}0.34\ifmmode\pm\else\textpm\fi{}0.21\ifmmode\pm\else\textpm\fi{}0.03$.

We present a measurement of ${D}^{0}\mathrm{\text{\ensuremath{-}}}{\overline{D}}^{0}$ mixing parameters using the ratios of lifetimes extracted from a sample of ${D}^{0}$ mesons produced through the process ${D}^{*+}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{+}$, which decay to ${K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$, ${K}^{\ensuremath{-}}{K}^{+}$, or ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$. The lifetimes of the $CP$-even, Cabibbo-suppressed modes ${K}^{\ensuremath{-}}{K}^{+}$ and ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ are compared with that of the $CP$-mixed, Cabibbo-favored mode ${K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ to obtain a measurement of ${y}_{CP}$, which in the limit of $CP$ conservation corresponds to the mixing parameter $y$. The analysis is based on a data sample of $384\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected by the BABAR detector at the PEP-II asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. We obtain ${y}_{CP}=[1.24\ifmmode\pm\else\textpm\fi{}0.39(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.13(\mathrm{syst})]%$, which is evidence for ${D}^{0}\mathrm{\text{\ensuremath{-}}}{\overline{D}}^{0}$ mixing at the $3\ensuremath{\sigma}$ level, and $\ensuremath{\Delta}Y=[\ensuremath{-}0.26\ifmmode\pm\else\textpm\fi{}0.36(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.08(\mathrm{syst})]%$, where $\ensuremath{\Delta}Y$ constrains possible $CP$ violation. Combining this result with a previous BABAR measurement of ${y}_{CP}$ obtained from a separate sample of ${D}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{K}^{+}$ events, we obtain ${y}_{CP}=[1.03\ifmmode\pm\else\textpm\fi{}0.33(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.19(\mathrm{syst})]%$.

We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons Bbar --> X_c l- nubar. Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1.9 GeV/c are obtained from a sample of 232x10^{6} Y(4S) --> B Bbar events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a re-evaluation of the moments of electron-energy spectra and partial decay fractions BR(Bbar --> X_c e- nubar for minimum electron momenta between 0.6 and 1.5 GeV/c based on a sample of 51x10^{6} Y(4S) --> B Bbar events. The measurements are used for the extraction of the total decay fraction, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_cb|, the quark masses m_b and m_c, and four heavy-quark QCD parameters in the framework of a Heavy Quark Expansion (HQE). We find BR(Bbar --> X_c l- nubar) = (10.64 +/- 0.17 +/- 0.06)% and |V_cb| = (42.05 +/- 0.45 +/- 0.70) x 10^{-3}.

Using a sample of 471 million BBbar events collected with the BaBar detector, we study the sum of seven exclusive final states B->X_s(d) gamma, where X_s(d) is a strange (non-strange) hadronic system with a mass of up to 2.0GeV/c^2. After correcting for unobserved decay modes, we obtain a branching fraction for b->d gamma of (9.2 +/- 2.0(stat.) +/- 2.3(syst.))x10^-6 in this mass range, and a branching fraction for b->s gamma of (23.0 +/- 0.8(stat.) +/- 3.0(syst.))x10^-5 in the same mass range. We find BF(b->dgamma) / BF(b->sgamma) = 0.040 +/- 0.009(stat.) +/- 0.010(syst.), from which we determine |V_td/V_ts|=0.199 +/- 0.022(stat.) +/- 0.024(syst.) +/- 0.002(th.).

Many scenarios of physics beyond the Standard Model predict the existence of new gauge singlets, which might be substantially lighter than the weak scale. The experimental constraints on additional scalars with masses in the MeV to GeV range could be significantly weakened if they interact predominantly with leptons rather than quarks. At an $e^+e^-$ collider, such a leptophilic scalar ($\phi_L$) would be produced predominantly through radiation from a $\tau$ lepton. We report herein a search for $e^+e^- \to \tau^+\tau^- \phi_L$, $\phi_L \to \ell^+\ell^-$ ($\ell=e,\mu$) using data collected by the BABAR experiment at SLAC. No significant signal is observed, and we set limits on the $\phi_L$ coupling to leptons in the range 0.04 < m$_{\phi_L}$ < 7.0 GeV. These bounds significantly improve upon the current constraints, excluding almost entirely the parameter space favored by the observed discrepancy in the muon anomalous magnetic moment below 4 GeV at 90\% confidence level.

We present the results of searches for B decays to charmless two-body final states containing eta(') or omega mesons, based on 20.7 fb(-1) of data collected with the BABAR detector. We find the branching fractions Beta(B(+)-->eta(')K(+)) = (70+/-8+/-5) x 10(-6), Beta(B(0)-->eta(')K(0)) = (42(+13)(-11) +/- 4) x 10(-6), and Beta(B(+)-->omega pi(+)) = (6.6(+2.1)(-1.8) +/- 0.7) x 10(-6), where the first error quoted is statistical and the second is systematic. We give measurements of four additional modes for which the 90% confidence level upper limits are Beta(B(+)-->eta(')pi(+)) < 12 x 10(-6), Beta(B(+)-->omega K(+)) < 4 x 10(-6), Beta(B(0)-->omega K(0)) < 13 x 10(-6), and Beta(B(0)-->omega pi(0)) < 3 x 10(-6).

We report a measurement of the branching fractions of ¯¯¯B→D**ℓ−¯νℓ decays based on 417 fb−1 of data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e+e− storage rings. Events are selected by fully reconstructing one of the B mesons in a hadronic decay mode. A fit to the invariant mass differences m(D(*)π)−m(D(*)) is performed to extract the signal yields of the different D** states. We observe the ¯¯¯B→D**ℓ−¯νℓ decay modes corresponding to the four D** states predicted by heavy quark symmetry with a significance greater than 5 standard deviations including systematic uncertainties.Received 4 August 2008DOI:https://doi.org/10.1103/PhysRevLett.101.261802©2008 American Physical Society

We perform a study of exclusive production of$D^+_sD^-_s$, $D^{*+}_sD^-_s$, and $D^{*+}_sD^{*-}_s$ final states in initial-state-radiation events from $e^+ e^-$ annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium $1^{--}$ states. The data sample corresponds to an integrated luminosity of 525 $fb^{-1}$ and was recorded by the BaBar experiment at the PEP-II storage ring. The $D^+_sD^-_s$, $D^{*+}_sD^-_s$, and $D^{*+}_sD^{*-}_s$ mass spectra show evidence of the known $\psi$ resonances. Limits are extracted for the branching ratios of the decays $X(4260)\to D^{(*)+}_sD^{(*)-}_s$.

A high-precision determination of the main parameters of the ψ(2S) resonance has been performed with the KEDR detector at the VEPP-4M e+e− collider in three scans of the ψ(2S)–ψ(3770) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the ψ(2S) we obtained the mass valueM=3686.114±0.007±0.011−0.012+0.002 MeV and the product of the electron partial width by the branching fraction into hadronsΓee×Bh=2.233±0.015±0.037±0.020 keV. The first and second uncertainties are statistical and systematic, respectively. The third uncertainty quoted is an estimate of the model dependence of the result due to assumptions on the interference effects in the cross section of the single-photon e+e− annihilation to hadrons explicitly considered in this work. Implicitly, the same assumptions were employed to obtain the charmonium leptonic width and the absolute branching fractions in many experiments. Using the result presented and the world average values of the electron and hadron branching fractions, one obtains the electron partial width and the total width of the ψ(2S):Γee=2.282±0.015±0.038±0.021 keV,Γ=296±2±8±3 keV. These results are consistent with and more than two times more precise than any of the previous experiments.

We present results for B-meson decay modes involving a charm meson, protons, and pions using 455 x 10^6 BBbar pairs recorded by the BaBar detector at the SLAC PEP-II asymmetric-energy e+ e- collider. The branching fractions are measured for the following ten decays: B0bar to D0 p pbar, B0bar to D*0 p pbar, B0bar to D+ p pbar pi-, B0bar to D*+ p pbar pi-, B- to D0 p pbar pi-, B- to D*0 p pbar pi-, B0bar to D0 p pbar pi- pi+, B0bar to D*0 p pbar pi- pi+, B- to D+ p pbar pi- pi-, and B- to D*+ p pbar pi- pi-, The four B- and the two five-body B0bar modes are observed for the first time. The four-body modes are enhanced compared to the three- and the five-body modes. In the three-body modes, the M(p pbar) and M(D(*)0 p) invariant mass distributions show enhancements near threshold values. In the four-body mode B0bar to D+ p pbar pi-, the M(p pi-) distribution shows a narrow structure of unknown origin near 1.5 GeV/c^2. The distributions for the five-body modes, in contrast to the others, are similar to the expectations from uniform phase-space predictions.

We measure the time-dependent CP asymmetry in B0→KS0π0γ decays for two regions of KS0−π0 invariant mass, m(KS0π0), using the final BABAR data set of 467×106 BB¯ pairs collected at the PEP-II e+e− collider at SLAC. We find 339±24 B0→K*0γ candidates and measure SK*γ=−0.03±0.29±0.03 and CK*γ=−0.14±0.16±0.03. In the range 1.1<m(KS0π0)<1.8 GeV/c2 we find 133±20 B0→KS0π0γ candidates and measure SKS0π0γ=−0.78±0.59±0.09 and CKS0π0γ=−0.36±0.33±0.04. The uncertainties are statistical and systematic, respectively.Received 19 July 2008DOI:https://doi.org/10.1103/PhysRevD.78.071102©2008 American Physical Society

We report measurements of branching fractions for the decays $B\ensuremath{\rightarrow}P\ensuremath{\ell}{\ensuremath{\nu}}_{\ensuremath{\ell}}$, where $P$ are the pseudoscalar charmless mesons ${\ensuremath{\pi}}^{\ensuremath{-}}$, ${\ensuremath{\pi}}^{0}$, $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$, based on $348\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected with the BABAR detector, using ${B}^{0}$ and ${B}^{+}$ mesons found in the recoil of a second $B$ meson decaying as $B\ensuremath{\rightarrow}{D}^{(*)}\ensuremath{\ell}{\ensuremath{\nu}}_{\ensuremath{\ell}}$. Assuming isospin symmetry, we combine pionic branching fractions to obtain $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}})=(1.54\ifmmode\pm\else\textpm\fi{}{0.17}_{(\mathrm{stat})}\ifmmode\pm\else\textpm\fi{}{0.09}_{(\mathrm{syst})})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$; we find $3.2\ensuremath{\sigma}$ evidence of the decay ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ and measure its branching fraction to be $(0.64\ifmmode\pm\else\textpm\fi{}{0.20}_{(\mathrm{stat})}\ifmmode\pm\else\textpm\fi{}{0.03}_{(\mathrm{syst})})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, and determine $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}})&lt;0.47\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ to 90% confidence level. Using partial branching fractions for the pionic decays in ranges of the momentum transfer and a variety of form factor calculation, we obtain values of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{ub}|$ in ranging from $3.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ to $4.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$.

We report a measurement of the branching fractions for _B-->D(*)(pi)l- _nu(l) decays based on 341.1 fb(-1) of data collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II e+ e- storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We obtain B(B- -->D(0)l-_nu(l)=(2.33+/-0.09(stat)+/-0.09(syst)%, B(B- -->D(*0)l-_nu(l)=(5.83+/-0.15(stat) +/-0.30(syst) %, B(_B(0)-->D+l-_nu(l)=(2.21+/-0.11(stat) +/-0.12(syst)%, B(_B(0)-->D(*)l-_nu(l)=(5.49+/-0.16(stat)+/-0.25(syst)%, B(B- -->D+pi-l-_nu(l)=(0.42+/-0.06(stat)+/-0.03(syst)%, B(B- -->D(*)+pi-l-_nu(l)=(0.59+/-0.05(stat)+/-0.04(syst)%, B(_B(0)-->D(0)pi+l-_nu(l)=(0.43+/-0.08(stat)+/-0.03(syst)%, and B(_B(0)-->D(*0)pi+l-_nu(l)=(0.48+/-0.08(stat)+/-0.04(syst)%.

We study two-body B-meson decays to a charmonium state (ηc, ηc(2S) or hc) and a K+ or K*0(892) meson using a sample of 349 fb−1 of data collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. We measure B(B0→ηcK*0)=(5.7±0.6(stat)±0.9(syst))×10−4, B(B0→ηc(2S)K*0)<3.9×10−4, B(B+→hcK+)×B(hc→ηcγ)<4.8×10−5 and B(B0→hcK*0)×B(hc→ηcγ)<2.2×10−4 at the 90% C.L., and B(ηc(2S)→K¯¯¯¯Kπ)=(1.9±0.4(stat)±1.1(syst))%. We also measure the mass and width of the ηc meson to be m(ηc)=(2985.8±1.5(stat)±3.1(syst)) MeV/c2 and Γ(ηc)=(36.3+3.7−3.6(stat)±4.4(syst)) MeV.Received 8 April 2008DOI:https://doi.org/10.1103/PhysRevD.78.012006©2008 American Physical Society

We present improved measurements of the branching fraction B, the longitudinal polarization fraction f{L}, and the direct CP asymmetry A{CP} in the B meson decay channel B;{+}-->rho;{+}rho;{0}. The data sample was collected with the BABAR detector at SLAC. The results are B(B;{+}-->rho;{+}rho;{0})=(23.7+/-1.4+/-1.4) x 10;{-6}, f{L}=0.950+/-0.015+/-0.006, and A{CP}=-0.054+/-0.055+/-0.010, where the uncertainties are statistical and systematic, respectively. Based on these results, we perform an isospin analysis and determine the Cabibbo-Kobayashi-Maskawa phase angle alpha=arg(-V{td}V{tb};/V{ud}V{ub}) to be (92.4{-6.5};{+6.0}) degrees.

We present a measurement of the branching fractions of the 22 decay channels of the B0 and B+ mesons to Dbar(*)D(*)K, where the D(*) and Dbar(*) mesons are fully reconstructed. Summing the 10 neutral modes and the 12 charged modes, the branching fractions are found to be B(B0 -> Dbar(*)D(*)K) = (3.68 +- 0.10 +- 0.24)% and B(B+ -> Dbar(*)D(*)K) = (4.05 +- 0.11 +- 0.28)%, where the first uncertainties are statistical and the second systematic. The results are based on 429 fb^-1 of data containing 471.10^6 BBbar pairs collected at the Y(4S) resonance with the BaBar detector at the SLAC National Accelerator Laboratory.

Searches for $B$ mesons decaying to final states containing a baryon and a lepton are performed, where the baryon is either ${\ensuremath{\Lambda}}_{c}$ or $\ensuremath{\Lambda}$ and the lepton is a muon or an electron. These decays violate both baryon and lepton number and would be a signature of physics beyond the standard model. No significant signal is observed in any of the decay modes, and upper limits in the range $(3.2--520)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ are set on the branching fractions at the 90% confidence level.

We present a measurement of the asymmetry A_{CP} between same-sign inclusive dilepton samples ℓ^{+}ℓ^{+} and ℓ^{-}ℓ^{-} (ℓ=e, μ) from semileptonic B decays in ϒ(4S)→BB[over ¯] events, using the complete data set recorded by the BABAR experiment near the ϒ(4S) resonance, corresponding to 471×10^{6} BB[over ¯] pairs. The asymmetry A_{CP} allows comparison between the mixing probabilities P(B[over ¯]^{0}→B^{0}) and P(B^{0}→B[over ¯]^{0}), and therefore probes CP and T violation. The result, A_{CP}=[-3.9±3.5(stat)±1.9(syst)]×10^{-3}, is consistent with the standard model expectation.

The properties of the Ξ(1530) resonance are investigated in the Λ+c→Ξ−π+K+ decay process. The data sample was collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e+e− collider operating at center-of-mass energies 10.58 and 10.54 GeV. The corresponding integrated luminosity is approximately 230 fb−1. The spin of the Ξ(1530) is established to be 3/2. The existence of an S-wave amplitude in the Ξ−π+ system is inferred, and its interference with the Ξ(1530)0 amplitude provides the first clear demonstration of the Breit-Wigner phase motion expected for the Ξ(1530). The P1(cosθΞ−) Legendre polynomial moment indicates the presence of a significant S-wave amplitude for Ξ−π+ mass values above 1.6 GeV/c2, and a dip in the mass distribution at approximately 1.7 GeV/c2 is interpreted as due to the coherent addition of a Ξ(1690)0 contribution to this amplitude. This would imply JP=1/2− for the Ξ(1690). Attempts at fitting the Ξ(1530)0 line shape yield unsatisfactory results, and this failure is attributed to interference effects associated with the amplitudes describing the K+π+ and/or Ξ−K+ systems.5 MoreReceived 12 March 2008DOI:https://doi.org/10.1103/PhysRevD.78.034008©2008 American Physical Society

We present updated measurements of the branching fractions for B0 meson decays to etaK0, etaeta, etaphi, etaomega, eta'K0, eta'eta', eta'phi, and eta'omega, and branching fractions and CP-violating charge asymmetries for B+ decays to etapi+, etaK+, eta'pi+ and eta'K+. The data represent the full dataset of 467 10^{6} BB pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decay modes and for B0\to eta'K0, we find evidence for three B0 decay modes at greater than 3.0sigma significance. We find B(B0\to etaK0) = (1.15^{+0.43}_{-0.38} \pm0.09)x10^{-6}, B(B0\to etaomega) = (0.94^{+0.35}_{-0.30}\pm0.09)x10^{-6}, and B(B0\to eta'omega) = (1.01^{+0.46}_{-0.38}\pm0.09)x10^{-6}, where the first (second) uncertainty is statistical (systematic). For the B+\to etaK+ decay mode, we measure the charge asymmetry A_{ch}(B+\to etaK+) = -0.36 \pm 0.11 \pm 0.03.

We present measurements of $B$ meson decays to the final states $\ensuremath{\omega}{K}^{*}$, $\ensuremath{\omega}\ensuremath{\rho}$, and $\ensuremath{\omega}{f}_{0}$, where ${K}^{*}$ indicates a spin 0, 1, or 2 strange meson. The data sample corresponds to $465\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ collider at SLAC. $B$ meson decays involving vector-scalar, vector-vector, and vector-tensor final states are analyzed; the latter two shed new light on the polarization of these final states. We measure the branching fractions for nine of these decays; five are observed for the first time. For most decays we also measure the charge asymmetry and, where relevant, the longitudinal polarization ${f}_{L}$.

We report an analysis of the charmless hadronic decays of charged B meson to the final state K+pi0pi0, using a data sample of 470+/-2.8 million BBbar events collected at the Y(4S) resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the branching fraction and CP asymmetry to be B(B+->K+pi0pi0)=(16.2+/-1.2+/-1.5)x10^-6 and A_CP(B+->K+pi0pi0)=-0.06+/-0.06+/-0.04, where the uncertainties are statistical and systematic respectively. Additionally we study the contributions of the B+->K*(892)+pi0, B+->f0(980)K+ and B+->chic0K+ quasi-two body decays. We report the world's best measurements of the branching fractions and CP asymmetry of the B+->K+pi0pi0 and B+->K*(892)+pi0 channels.

We report a search for CP violation in the decay modes $D^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, $D_s^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, and $D_s^{\pm}\to K^0_{\scriptscriptstyle S} \pi^\pm$ using a data set corresponding to an integrated luminosity of $469\,{\,fb}^{-1}$ collected with the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the PEP-II asymmetric energy $e^+e^-$ storage rings. The decay rate CP asymmetries, $A_{CP}$, are determined to be $(+0.13 \pm 0.36 \stat \pm 0.25 \syst)%$, $(-0.05 \pm 0.23 \stat \pm 0.24 \syst)%$, and $(+0.6 \pm 2.0 \stat \pm 0.3 \syst)%$, respectively. These measurements are consistent with zero, and also with the standard model prediction ($(-0.332 \pm 0.006)%$ for the $D^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$ and $D_s^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$ modes, and $(+0.332 \pm 0.006)%$ for the $D_s^{\pm}\to K^0_{\scriptscriptstyle S} \pi^\pm$ mode). They are the most precise determinations to date.

We have observed the decays B--> phiK and phiK(*) in a sample of over 45 million B mesons collected with the BABAR detector at the PEP-II collider. The measured branching fractions are B(B+--> phiK+) = (7.7(+1.6)(-1.4)+/-0.8)x10(-6), B(B0--> phiK0) = (8.1(+3.1)(-2.5)+/-0.8)x10(-6), B(B+--> phiK(*+)) = (9.7(+4.2)(-3.4)+/-1.7)x10(-6), and B(B0--> phiK(*0)) = (8.7(+2.5)(-2.1)+/-1.1)x10(-6). We also report the upper limit B(B+--> phipi(+))<1.4x10(-6) ( 90% C.L.).

We report evidence for the decays B0-->D(+)(s)pi(-) and B0-->D(-)(s)K+ and the results of a search for B0-->D(*+)(s)pi(-) and B0-->D(*-)(s)K+ in a sample of 84 x 10(6) upsilon(4S) decays into BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) storage ring. We measure the branching fractions B(B0-->D(+)(s)pi(-))=[3.2+/-0.9(stat)+/-1.0(syst)] x 10(-5) and B(B0-->D(-)(s)K+)=[3.2+/-1.0(stat)+/-1.0(syst)] x 10(-5). We also set 90% C.L. limits B(B0-->D(*+)(s)pi(-))<4.1 x 10(-5) and B(B0-->D(*-)(s)K+)<2.5 x 10(-5).

We report a study of the B meson decays, B+ -> J/psi phi K+, B0 -> J/psi phi K0S, B0 -> J/psi phi, B0 -> J/psi eta and B0 -> J/psi eta' using 56 million BBbar events collected at the Y(4S) resonance with the BABAR detector at the PEP-II e+ e- asymmetric-energy storage ring. We measure the branching fractions B(B+ -> J/psi phi K+) = (4.4 +- 1.4(stat) +- 0.5(syst)) * 10-5 and B(B0 -> J/psi phi K0S) = (5.1 +- 1.9(stat) +- 0.5(syst)) * 10^-5, and set upper limits at 90% confidence level for the branching fractions B(B0 -> J/psi phi) < 9.2 * 10^-6, B(B0 -> J/psi eta)< 2.7 * 10^-5, and B(B0 -> J/psi eta')< 6.3 * 10-5.

We present updated results on time-dependent CP asymmetries in fully reconstructed B0->D(*)+-pi-+ and B0->D+-rho-+ decays in approximately 232 million Y(4S)->BBbar events collected with the BaBar detector at the PEP-II asymmetric-energy B factory at SLAC. From a time-dependent maximum likelihood fit we obtain for the parameters related to the CP violation angle 2beta+gamma: a^{D\pi} = -0.010 +/- 0.023 +/- 0.007, c_{\rm lep}^{D\pi} = -0.033 +/- 0.042 +/- 0.012, a^{D^*\pi} = -0.040 +/- 0.023 +/- 0.010, c_{\rm lep}^{D^*\pi} = 0.049 +/- 0.042 +/- 0.015, a^{D\rho} = -0.024 +/- 0.031 +/- 0.009, c_{\rm lep}^{D\rho} = -0.098 +/- 0.055 +/- 0.018, where the first error is statistical and the second is systematic. Using other measurements and theoretical assumptions, we interpret the results in terms of the angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle and find |sin(2beta+gamma)| > 0.64 (0.40) at 68% (90%) confidence level.

We present a study of the decays B0 -> D0 K*0 and B0 -> barD0 K*0 with K*0 -> K+pi-. The D0 and the barD0 mesons are reconstructed in the final states f=K+pi-, K+pi-pi0, K+pi-pi+pi- and their charge conjugates. Using a sample of 465 million BBbar pairs collected with the Babar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we measure the ratio R_{ADS}=[Gamma(barB0 -> [f]_D barK*0)+Gamma(B0 -> [bar{f}]_D K*0)]/ [Gamma(barB0 -> [bar{f}]_D barK*0)+Gamma(B0 -> [f]_D K*0)] for the three final states. We do not find significant evidence for a signal and set the following limits at 95% probability: R_{ADS}(Kpi)<0.244, R_{ADS}(Kpipi0)<0.181 and R_{ADS}(Kpipipi)<0.391. From the combination of these three results, we find that the ratio rS between the b -> u and the b -> c amplitudes lies in the range [0.07,0.41] at 95% probability.

We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BaBar detector in the center-of-mass (CM) energy region above the Upsilon(4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of CM energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s to l nu X)=9.5 (+2.5/-2.0)(stat)(+1.1/-1.9)(syst)%, where l indicates the average of e and mu.

Flavor oscillations of neutral B mesons have been studied in e+e- annihilation data collected with the BABAR detector at center-of-mass energies near the upsilon(4S) resonance. The data sample used for this purpose consists of events in which one B0 meson is reconstructed in a hadronic decay mode, while the flavor of the recoiling B0 is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. From the time development of the observed mixed and unmixed final states, we determine the B0-B-0 oscillation frequency deltamd to be 0.516+/-0.016(stat)+/-0.010(syst) ps-1.

A largely model-independent measurement of the inclusive electron momentum spectrum and branching fraction for semileptonic decays of B mesons is presented based on data recorded at the $\ensuremath{\Upsilon}(4S)$ resonance with the BABAR detector. Backgrounds from secondary charm decays are separated from prompt B decays using charge and angular correlations between the electron from one B meson and a high momentum electron tag from the second B meson. The resulting branching fraction is $\mathcal{B}(\stackrel{\ensuremath{\rightarrow}}{B}\mathrm{Xe}\ensuremath{\nu})=[10.87\ifmmode\pm\else\textpm\fi{}0.18(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.30(\mathrm{syst})]%.$ Based on this measurement we determine the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|{V}_{\mathrm{cb}}|.$

Silica aerogel blocks are being produced for use in Cherenkov detectors by a collaboration of Boreskov Institute of Catalysis and Budker Institute of Nuclear Physics since 1986. Novosibirsk aerogel is used in several detectors; among them are KEDR, SND (BINP, Novosibirsk), LHCb (CERN, Geneva), AMS (for International Space Station mission) and others. Currently our investigations are going on in two directions: multilayer aerogels for Focusing Aerogel RICH and aerogels with high index of refraction. We have synthesized two-, three- and four-layer aerogel tiles with dimensions of 115 mm×115 mm. We have modernized the method of pinhole drying for preparation of aerogels with refractive index in the range of 1.07–1.20.

Received 9 January 2013DOI:https://doi.org/10.1103/PhysRevD.87.039901© 2013 American Physical Society

The B0 and B+ meson lifetimes have been measured in e+e- annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the Upsilon(4S) resonance. Events are selected in which one B meson is fully reconstructed in a hadronic final state while the second B meson is reconstructed inclusively. A combined fit to the B0 and the B+ decay time difference distributions yields tau_{B0} = 1.546 +/- 0.032 (stat) +/- 0.022(syst) ps, tau_{B+} = 1.673 +/- 0.032 (stat) +/- 0.023 (syst) ps and tau_{B+} / tau_{B0} = 1.082 +/- 0.026 (stat) +/- 0.012 (syst).

We present the results of searches for decays of B mesons to final states with a b_1 meson and a neutral pion or kaon. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465 million BBbar pairs produced in e+e- annihilation. The results for the branching fractions are, in units of 1e-6, BR(B+ to b_1+K0) = 9.6+/-1.7+/-0.9, BR(B0 to b_10K0) = 5.1+/-1.8+/-0.5 (&lt;7.8), BR(B+ to b_1+pi0) = 1.8+/-0.9+/-0.2 (&lt;3.3), and BR(B0 to b_10pi0) = 0.4+/-0.8+/-0.2 (&lt;1.9), with the assumption that BR(B_1 to omega pi)=1. We also measure the charge asymmetry A_ch(B+ to b_1+K0) = -0.03+/-0.15+/-0.02. The first error quoted is statistical, the second systematic, and the upper limits in parentheses indicate the 90% confidence level.

We report an analysis of charmless hadronic decays of neutral B mesons to the final state KsK+/-pi-/+, using a data sample of (465 +/- 5) x 10^6 BB-bar events collected with the BABAR detector at the Y(4S) resonance. We observe an excess of signal events with a significance of 5.2 standard deviations including systematic uncertainties and measure the branching fraction to be BF(B0 --> KsK+/-pi-/+) = (3.2 +/- 0.5 +/- 0.3) x 10^-6, where the uncertainties are statistical and systematic, respectively.

We study the decay B−→DK*− using a sample of 379×106 Υ(4S)→BB¯ events collected with the BABAR detector at the PEP-II B factory. We perform a Gronau-London-Wyler analysis where the D meson decays into either a CP-even (CP+) eigenstate (K+K−, π+π−), CP-odd (CP−) eigenstate (KS0π0, KS0ϕ, KS0ω) or a non-CP state (K−π+). We also analyze D meson decays into K+π− from a Cabibbo-favored D¯0 decay or doubly suppressed D0 decay [Atwood-Dunietz-Soni (ADS) analysis]. We measure observables that are sensitive to the Cabibbo-Kobayashi-Maskawa angle γ: the partial-rate charge asymmetries ACP±, the ratios RCP± of the B-decay branching fractions in CP± and non-CP decay, the ratio RADS of the charge-averaged branching fractions, and the charge asymmetry AADS of the ADS decays: ACP+=0.09±0.13±0.06, ACP−=−0.23±0.21±0.07, RCP+=2.17±0.35±0.09, RCP−=1.03±0.27±0.13, RADS=0.066±0.031±0.010, and AADS=−0.34±0.43±0.16, where the first uncertainty is statistical and the second is systematic. Combining all the measurements and using a frequentist approach yields the magnitude of the ratio between the Cabibbo-suppressed and favored amplitudes, rB=0.31 with a one (two) sigma confidence level interval of [0.24, 0.38] ([0.17, 0.43]). The value rB=0 is excluded at the 3.3 sigma level. A similar analysis excludes values of γ in the intervals [0, 7]°, [55, 111]°, and [175, 180]° ([85, 99]°) at the one (two) sigma confidence level.1 MoreReceived 23 September 2009DOI:https://doi.org/10.1103/PhysRevD.80.092001©2009 American Physical Society

We present the observation of the decay B0 -> chi_c0K*0 as well as evidence of B+ -> chi_c0K*+, with an 8.9 and a 3.6 standard deviation significance, respectively, using a data sample of 454 million Y(4S) -> BB decays collected with the BaBar detector at the PEP-II B meson factory located at the Stanford Linear Accelerator Center (SLAC). The measured branching fractions are: B(B0 -> chi_c0K*0) = (1.7 +/- 0.3 +/- 0.2) * 10^{-4} and B(B+ -> chi_c0K^*+) = (1.4 +/- 0.5 +/- 0.2) * 10^{-4}, where the first quoted errors are statistical and the second are systematic. We obtain a branching fraction upper limit of B(B+ -> chi_c0K*+) < 2.1 * 10^{-4} at the 90% confidence level.

We report a study of B -> D*K decays with D* decaying to D pi0 or D gamma, using 383 * 10**6 B Bbar pairs collected at the Upsilon(4S) resonance with the BaBar detector at the SLAC PEP-II B-Factory. The D meson decays under study include a non-CP mode (Kpi), CP-even modes (K+K-, pi^+pi^-) and CP-odd modes (KS pi0, KS phi, KS omega). We measure ratios (R*_{CP+-}) of branching fractions of decays to CP eigenmode states and to flavor-specific states as well as CP asymmetries (A*_{CP+-}). These measurements are sensitive to the unitarity triangle angle gamma. We obtain A*_{CP+} = -0.11 pm 0.09 pm 0.01, R*_{CP+} = ~1.31 pm 0.13 pm 0.04, and A*_{CP-} = 0.06 pm 0.10 pm 0.02, R*_{CP-} = ~1.10 pm 0.12 pm 0.04, where the first error is statistical and the second error is systematic. Translating our results into an alternative parametrization, widely used for related measurements, we obtain x*_{+}=0.11 pm 0.06 pm 0.02 and x*_{-} = 0.00 pm 0.06 pm 0.02. No significant CP-violating charge asymmetry is found in either the flavor-specific mode D -> K pi or in B -> D* pi decays.

We report a measurement of the branching fraction of the exclusive charmless semileptonic decay ${B}^{+}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$, where $\ensuremath{\ell}$ is either an electron or a muon. We use samples of ${B}^{+}$ mesons tagged by a reconstructed charmed semileptonic decay of the other $B$ meson in the event. The measurement is based on a data set of $426.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ collisions at a center-of-mass energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ storage rings. We measure a branching fraction of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\ell}}^{+}\ensuremath{\nu})=(1.35\ifmmode\pm\else\textpm\fi{}0.21\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, where the uncertainties are statistical and systematic, respectively. We also present measurements of the partial branching fractions in three bins of ${q}^{2}$, the invariant-mass squared of the lepton-neutrino system, and we compare them to theoretical predictions of the form factors.

New measurements of Ds+ and Ds*+ meson production rates from B decays and from qq¯ continuum events near the Υ(4S) resonance are presented. Using 20.8 fb−1 of data on the Υ(4S) resonance and 2.6 fb−1 off-resonance, we find the inclusive branching fractions B(B→Ds+X)=(10.93±0.19±0.58±2.73)% and B(B→Ds*+X)=(7.9±0.8±0.7±2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+→φπ+ branching fraction uncertainty. The production cross sections σ(e+e−→Ds+X)×B(Ds+→φπ+)=7.55±0.20±0.34pb and σ(e+e−→Ds*±X)×B(Ds+→φπ+)=5.8±0.7±0.5pb are measured at center-of-mass energies about 40 MeV below the Υ(4S) mass. The branching fractions ΣB(B→Ds(*)+D(*))=(5.07±0.14±0.30±1.27)% and ΣB(B→Ds*+D(*))=(4.1±0.2±0.4±1.0)% are determined from the Ds(*)+ momentum spectra. The mass difference m(Ds+)−m(D+)=98.4±0.1±0.3MeV/c2 is also measured.Received 25 January 2002DOI:https://doi.org/10.1103/PhysRevD.65.091104©2002 American Physical Society

We describe searches for decays to two-body charmless final states η′η, η′π0 and ηπ0 of B0 mesons produced in e+e− annihilation. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 232×106 produced B¯¯¯B pairs. The results for branching fractions are, in units of 10−6 (upper limits at 90% C.L.): B(B0→η′η)=0.2+0.7−0.5±0.4(<1.7), B(B0→ηπ0)=0.6+0.5−0.4±0.1(<1.3), and B(B0→η′π0)=0.8+0.8−0.6±0.1(<2.1). The first error quoted is statistical and the second systematic.Received 7 March 2006DOI:https://doi.org/10.1103/PhysRevD.73.071102©2006 American Physical Society

We present measurements of the branching fraction B and the longitudinal polarization fraction fL for B0 -> a1(1260)+ a1(1260)- decays, with a1(1260)+/- -> \pi- \pi+ \pi+/-. The data sample, collected with the detector BaBar at the SLAC National Accelerator Laboratory, represents 465 10^6 produced BBbar pairs. We measure B(B0 -> a1(1260)+ a1(1260)-) x [B(a1(1260)+ -> \pi- \pi+ \pi+)]^2 = (11.8 \pm 2.6 \pm 1.6) 10^{-6} and fL = 0.31 \pm 0.22 \pm 0.10, where the first uncertainty is statistical and the second systematic. The decay mode is measured with a significance of 5.0 standard deviations including systematic uncertainties.

We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B+ -> rho0 K*+ and B+ -> f0(980) K*+ with a sample of 467+/-5 million BBbar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e^+e^- collider at the SLAC National Accelerator Laboratory. We observe B+ -> rho0 K*+ with a significance of 5.3 sigma and measure the branching fraction Br(B+ -> rho0 K*+) = (4.6+/-1.0+/-0.4) x 10^{-6}, the longitudinal polarization fL = 0.78+/-0.12+/-0.03, and the CP-violation asymmetry ACP = 0.31+/-0.13+/-0.03. We observe B+ -> f0(980) K*+ and measure the branching fraction Br(B+ -> f0(980) K*+) x Br(f0(980) -> pi+pi-) = (4.2+/-0.6+/-0.3) x 10^{-6} and the CP-violation asymmetry ACP = -0.15+/-0.12+/-0.03. The first uncertainty quoted is statistical and the second is systematic.

The processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{0}$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}\ensuremath{\eta}$ are studied over a continuum of energies from threshold to 4 GeV with the initial-state photon radiation method. Using $454\text{ }\text{ }{\text{fb}}^{\ensuremath{-}1}$ of data collected with the BABAR detector at the SLAC PEP-II storage ring, the first measurements of the cross sections for these processes are obtained. The intermediate resonance structures from ${K}^{*0}(K\ensuremath{\pi}{)}^{0}$, ${K}^{*}(892{)}^{\ifmmode\pm\else\textpm\fi{}}(K\ensuremath{\pi}{)}^{\ensuremath{\mp}}$, and ${K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\rho}}^{\ensuremath{\mp}}$ are studied. The $J/\ensuremath{\psi}$ is observed in all of these channels, and corresponding branching fractions are measured.

We present a measurement of the branching fraction for the decay of the neutral B meson into the final state J/psipi(+)pi(-). The data set contains approximately 56 x 10(6) BB pairs produced at the Upsilon(4S) resonance and recorded with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) storage ring. The result of this analysis is B(B0-->J/psipi(+)pi(-))=(4.6+/-0.7+/-0.6) x 10(-5), where the first error is statistical and the second is systematic. In addition, we measure B(B0-->J/psirho(0))=(1.6+/-0.6+/-0.4) x 10(-5).

We measure the ${B}^{0}$ lifetime ${\ensuremath{\tau}}_{{B}^{0}}$ and the ${B}^{0}\ensuremath{-}{B}^{0}$ oscillation frequency $\ensuremath{\Delta}{m}_{d}$ with a sample of approximately 14000 exclusively reconstructed ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\mathcal{l}}^{+}{\ensuremath{\nu}}_{\mathcal{l}}$ signal events, selected from 23 million $B\overline{B}$ pairs recorded at the $\ensuremath{\Upsilon}(4S)$ resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b quark and the charges of its decay products. The lifetime and oscillation frequencies are measured simultaneously with an unbinned maximum-likelihood fit that uses, for each event, the measured difference in decay times of the two B mesons $(\ensuremath{\Delta}t),$ the calculated uncertainty on $\ensuremath{\Delta}t,$ the signal and background probabilities, and b-quark tagging information for the other B. The results are ${\ensuremath{\tau}}_{{B}^{0}}{=(1.523}_{\ensuremath{-}0.023}^{+0.024}\ifmmode\pm\else\textpm\fi{}0.022)\mathrm{ps}$ and $\ensuremath{\Delta}{m}_{d}=(0.492\ifmmode\pm\else\textpm\fi{}0.018\ifmmode\pm\else\textpm\fi{}0.013){\mathrm{ps}}^{\ensuremath{-}1}.$ The statistical correlation coefficient between ${\ensuremath{\tau}}_{{B}^{0}}$ and $\ensuremath{\Delta}{m}_{d}$ is -0.22.

We present a search for decays of $B$ mesons to final states with a $b\_1$ meson and a $\rho$ or $K^*(892)$ meson. The search is based on a data sample consisting of 465 million $B\kern 0.18em{\kern -0.18em B}{}$ pairs collected by the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the SLAC National Accelerator Laboratory. We do not observe any statistically significant signal. The upper limits we set on the branching fractions range from 1.4 to $8.0 \times 10^{-6}$ at the 90% confidence level (C.L.), including systematic uncertainties.

We present a new measurement of the time-dependent $CP$ asymmetry of ${B}^{0}\ensuremath{\rightarrow}{D}^{*+}{D}^{*\ensuremath{-}}$ decays using ($471\ifmmode\pm\else\textpm\fi{}5$) million $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II $B$ Factory at the SLAC National Accelerator Laboratory. Using the technique of partial reconstruction, we measure the time-dependent $CP$ asymmetry parameters $S=\ensuremath{-}0.34\ifmmode\pm\else\textpm\fi{}0.12\ifmmode\pm\else\textpm\fi{}0.05$ and $C=+0.15\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.04$. Using the value for the $CP$-odd fraction ${R}_{\ensuremath{\perp}}=0.158\ifmmode\pm\else\textpm\fi{}0.028\ifmmode\pm\else\textpm\fi{}0.006$, previously measured by BABAR with fully reconstructed ${B}^{0}\ensuremath{\rightarrow}{D}^{*+}{D}^{*\ensuremath{-}}$ events, we extract the $CP$-even components ${S}_{+}=\ensuremath{-}0.49\ifmmode\pm\else\textpm\fi{}0.18\ifmmode\pm\else\textpm\fi{}0.07\ifmmode\pm\else\textpm\fi{}0.04$ and ${C}_{+}=+0.15\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.04$. In each case, the first uncertainty is statistical and the second is systematic; the third uncertainty on ${S}_{+}$ is the contribution from the uncertainty on ${R}_{\ensuremath{\perp}}$. The measured value of the $CP$-even component ${S}_{+}$ is consistent with the value of $\mathrm{sin}2\ensuremath{\beta}$ measured in $b\ensuremath{\rightarrow}(c\overline{c})s$ transitions, and with the Standard Model expectation of small penguin contributions.

The B(0) lifetime was measured with a sample of 23 million BB pairs collected by the BABAR detector at the PEP-II e(+)e(-) storage ring during 1999 and 2000. Events from the semileptonic decay B(0)-->D(*-)l(+)nu(l) have been selected with a partial reconstruction method in which only the charged lepton and the slow pi from the D*--->D(0)pi(-) decay are reconstructed. The result is tau(B(0)) = 1.529+/-0.012(stat)+/-0.029(syst) ps.

We present measurements of the branching fraction and fraction of longitudinal polarization for the decay ${B}^{+}\ensuremath{\rightarrow}{\overline{K}}^{*0}{K}^{*+}$ with a sample of $(467\ifmmode\pm\else\textpm\fi{}5)\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider at the SLAC National Accelerator Laboratory. We obtain the branching fraction $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\overline{K}}^{*0}{K}^{*+})=(1.2\ifmmode\pm\else\textpm\fi{}0.5\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ with a significance of 3.7 standard deviations including systematic uncertainties. We measure the fraction of longitudinal polarization ${f}_{L}={0.75}_{\ensuremath{-}0.26}^{+0.16}\ifmmode\pm\else\textpm\fi{}0.03$. The first error quoted is statistical and the second is systematic.

Using a sample of 471 million B{bar B} events collected with the BABAR detector, we study the sum of seven exclusive final states B {yields} X{sub s(d){gamma}}, where X{sub s(d)} is a strange (non-strange) hadronic system with a mass of up to 2.0 GeV/c{sup 2}. After correcting for unobserved decay modes, we obtain a branching fraction for b {yields} d{gamma} of (9.2 {+-} 2.0(stat.) {+-} 2.3(syst.)) x 10{sup -6} in this mass range, and a branching fraction for b {yields} s{gamma} of (23.0 {+-} 0.8(stat.) {+-} 3.0(syst.)) x 10{sup -5} in the same mass range. We find {Beta}(b{yields}d{gamma})/{Beta}(b{yields}s{gamma}) = 0.040 {+-} 0.009(stat.) {+-} 0.010(syst.), from which we determine |V{sub td}/V{sub ts}| = 0.199 {+-} 0.022(stat.) {+-} 0.024(syst.) {+-} 0.002(th.).

We present the preliminary result of a search for the decay B+- --> a1+-K*0. The data, collected with the BaBar detector at the Stanford Linear Accelerator Center, represent 465 million BB pairs produced in e+e- annihilation at the Y(4s) energy. The result for the branching fraction is: B(B+ --> a1+ K*0) * B(a1+ --> pi+pi-pi+) = (0.7 +0.5/-0.4 +/-0.7) x 10-6, corresponding to an upper limit at 90% confidence level of 1.6 x 10-6. The first error quoted is statistical, the second systematic.

Using the eight time dependences for the decays Upsilon(4S)-> B0 B0bar -> fj fk with the dacay into a flavor-specific state fj = ell+- X before or after the decay into a CP eigenstate fk = c cbar KS,KL, as measured by the BABAR experiment, we determine the three CPT-sensitive parameters Re(z) and Im(z) in B0-B0bar mixing and |Abar/A| in B0 -> c cbar K0 decays. We find Im(z) = 0.010 +- 0.030 +- 0.013, Re(z) = -0.065 +- 0.028 +- 0.014, and |Abar/A| = 0.999 +- 0.023 +- 0.017, in agreement with CPT symmetry.

Using 230×106 B¯¯¯B events recorded with the BABAR detector at the e+e− storage rings PEP-II, we reconstruct approximately 4100 B0→J/ψK+π− and 9930 B+→J/ψK+ decays with J/ψ→μ+μ− and e+e−. From the measured B-momentum distributions in the e+e− rest frame, we determine the mass difference m(B0)−m(B+)=(+0.33±0.05±0.03) MeV/c2.Received 6 May 2008DOI:https://doi.org/10.1103/PhysRevD.78.011103©2008 American Physical Society

We present measurements of partial branching fractions of $B \rightarrow K^+ X$, $B \rightarrow K^0 X$, and $B \rightarrow \pi^+ X$, where $X$ denotes any accessible final state above the endpoint for B decays to charmed mesons, specifically for momenta of the candidate hadron greater than 2.34 (2.36) GeV for kaons (pions) in the B rest frame. These measurements are sensitive to potential new-physics particles which could enter the $b \rightarrow s(d)$ loop transitions. The analysis is performed on a data sample consisting of $383 \times 10^6$ $B \bar{B}$ pairs collected with the BaBar detector at the PEP-II $e^+e^-$ asymmetric energy collider. Our results are in agreement with standard model predictions and exclude large enhancements of the inclusive branching fraction due to sources of new physics.

We report a search for the rare decays $B^+ \to D^+ K^0$ and $B^+ \to D^+ K^{*0}$ in an event sample of approximately 465 million $B\bar B$ pairs collected with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC. We find no significant evidence for either mode and we set 90\% probability upper limits on the branching fractions of $B(B^+ \to D^+ K^0) < 2.9\times 10^{-6}$ and $B(B^+ \to D^+ K^{*0}) < 3.0\times 10^{-6}$.

We report a measurement of the branching fraction of the decay B0-->D(*+)D(*-) and of the CP-odd component of its final state using the BABAR detector. With data corresponding to an integrated luminosity of 20.4 fb (-1) collected at the Upsilon(4S) resonance during 1999-2000, we have reconstructed 38 candidate signal events in the mode B0-->D(*+)D(*-) with an estimated background of 6.2+/-0.5 events. From these events, we determine the branching fraction to be B(B0-->D(*+)D(*-))=[8.3+/-1.6(stat)+/-1.2(syst)]x10(-4). The measured CP-odd fraction of the final state is 0.22+/-0.18(stat)+/-0.03(syst).

The status of the experiment on the precise τ lepton mass measurement running at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the τ+τ− cross section behavior around the production threshold. The preliminary result based on 15.2 pb−1 of data is mτ=1776.69−0.19+0.17±0.15 MeV.

We have studied the B±→J/ψπ± and B±→J/ψK± decays using a 20.7 fb−1 data set collected with the BABAR detector. We observe a signal of 51±10 B±→J/ψπ± events and determine the ratio B(B±→J/ψπ±)/B(B±→J/ψK±) to be [3.91±0.78(stat)±0.19(syst)]%. The CP-violating charge asymmetries for the B±→J/ψπ± and B±→J/ψK± decays are determined to be Aπ=0.01±0.22(stat)±0.01(syst) and AK=0.003±0.030(stat)±0.004(syst). Received 3 August 2001DOI:https://doi.org/10.1103/PhysRevD.65.091101©2002 American Physical Society

We measure the branching fractions of the ψ(2S) meson to the leptonic final states e+e− and μ+μ− relative to that for ψ(2S)→J/ψπ+π−. The method uses ψ(2S) mesons produced in the decay of B mesons at the Υ(4S) resonance in a data sample collected with the BABAR detector at the Stanford Linear Accelerator Center. Using previous measurements for the ψ(2S)→J/ψπ+π− branching fraction, we determine the e+e− and μ+μ− branching fractions to be 0.0078±0.0009±0.0008 and 0.0067±0.0008±0.0007, respectively.Received 7 September 2001DOI:https://doi.org/10.1103/PhysRevD.65.031101©2001 American Physical Society

Using a sample of 471×10^6 BB[overbar] events collected with the BABAR detector, we study the sum of seven exclusive final states B→X_(s(d))γ, where X_(s(d)) is a strange (nonstrange) hadronic system with a mass of up to 2.0  GeV/c^2. After correcting for unobserved decay modes, we obtain a branching fraction for b→dγ of (9.2±2.0(stat)±2.3(syst))×10^(-6) in this mass range, and a branching fraction for b→sγ of (23.0±0.8(stat)±3.0(syst))×10^(-5) in the same mass range. We find B[script](b→dγ)/B[script](b→sγ)=0.040±0.009(stat)±0.010(syst), from which we determine |V_(td)/V_(ts)|=0.199±0.022(stat)±0.024(syst)±0.002(th).

Using a sample of 383×106 B¯¯¯B events collected by the BABAR experiment, we measure sums of seven exclusive final states B→Xd(s)γ, where Xd(Xs) is a nonstrange (strange) charmless hadronic system in the mass range 0.6–1.8 GeV/c2. After correcting for unmeasured decay modes in this mass range, we obtain a branching fraction for b→dγ of (7.2±2.7(stat)±2.3(syst))×10−6. Taking the ratio of Xd to Xs we find Γ(b→dγ)/Γ(b→sγ)=0.033±0.013(stat)±0.009(syst), from which we determine |Vtd/Vts|=0.177±0.043.Received 1 August 2008DOI:https://doi.org/10.1103/PhysRevLett.102.161803©2009 American Physical Society

We present updated measurements of time-dependent CP asymmetries in fully reconstructed neutral B decays containing a charmonium meson. The measurements reported here use a data sample of (465±5)×106 Υ(4S)→BB decays collected with the BABAR detector at the PEP-II asymmetric energy e+e- storage rings operating at the SLAC National Accelerator Laboratory. The time-dependent CP asymmetry parameters measured from JψKS0, JψKL0, ψ(2S)KS0, ηcKS0, χc1KS0, and J/ψK*(892)0 decays are: Cf=0.024±0.020(stat)±0.016(syst) and -ηfSf=0.687±0.028(stat)±0.012(syst).

We report a Dalitz plot analysis of charmless hadronic decays of charged $B$ mesons to the final state $K_{\rm S}^{0}\pi^{+}\pi^{0}$ using the full BaBar dataset of $470.9\pm2.8$ million $B\bar{B}$ events collected at the $\Upsilon(4S)$ resonance. We measure the overall branching fraction and $CP$ asymmetry to be ${\cal B}\left(B^{+}\to K^{0}\pi^{+}\pi^{0}\right) = \left(45.9 \pm 2.6 \pm 3.0^{+8.6}_{-0.0}\right)\times10^{-6}$ and $A_{CP}\left(B^{+}\to K^{0}\pi^{+}\pi^{0}\right) = 0.07 \pm 0.05 \pm 0.03^{+0.02}_{-0.03}$, where the uncertainties are statistical, systematic, and due to the signal model, respectively. This is the first measurement of the branching fraction for $B^{+} \to K^{0}\pi^{+}\pi^{0}$. We find first evidence of a $CP$ asymmetry in $B^{+}\to K^{*}(892)^{+}\pi^{0}$ decays: $A_{CP}\left(B^{+}\to K^{*}(892)^{+}\pi^{0}\right)=-0.52 \pm 0.14 \pm 0.04^{+0.04}_{-0.02}$. The significance of this asymmetry, including systematic and model uncertainties, is $3.4$ standard deviations. We also measure the branching fractions and $CP$ asymmetries for three other intermediate decay modes.

Received 2 February 2012DOI:https://doi.org/10.1103/PhysRevD.85.039903© 2012 American Physical Society