R. Stroynowski

The new detector for data recording by the CLEO collaboration at the Cornell Electron Storage Ring is described. This detector has been designed to optimize studying e+ e− annihilation into hadronic matter at a total energy of 10 GeV. It consists of high precesion charged particle tracking chambers and an electromagnetic calorimeter together with systems for particle identification. The design of the detector and its performance over the first year and a half of operation are presented.

We have measured the inclusive $b\ensuremath{\rightarrow}s\ensuremath{\gamma}$ branching ratio to be $(2.32\ifmmode\pm\else\textpm\fi{}0.57\ifmmode\pm\else\textpm\fi{}0.35)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, where the first error is statistical and the second is systematic. Upper and lower limits on the branching ratio, each at 95% C.L., are $B(b\ensuremath{\rightarrow}s\ensuremath{\gamma})<4.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $B(b\ensuremath{\rightarrow}s\ensuremath{\gamma})>1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. These limits restrict the parameters of extensions of the standard model.

Using 13.5 ${\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ annihilation data collected with the CLEO II detector, we have observed a narrow resonance decaying to ${D}_{s}^{*+}{\ensuremath{\pi}}^{0}$ with a mass near $2.46\mathrm{GeV}{/c}^{2}.$ The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at $2.32\mathrm{GeV}{/c}^{2},$ the ${D}_{\mathrm{sJ}}^{*}{(2317)}^{+},$ that decays to ${D}_{s}^{+}{\ensuremath{\pi}}^{0}.$ Reconstructing the ${D}_{s}^{+}{\ensuremath{\pi}}^{0}$ and ${D}_{s}^{*+}{\ensuremath{\pi}}^{0}$ final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, $\ensuremath{\Delta}{M(D}_{s}{\ensuremath{\pi}}^{0}{)=M(D}_{s}{\ensuremath{\pi}}^{0})\ensuremath{-}{M(D}_{s})$ and $\ensuremath{\Delta}{M(D}_{s}^{*}{\ensuremath{\pi}}^{0}{)=M(D}_{s}^{*}{\ensuremath{\pi}}^{0})\ensuremath{-}{M(D}_{s}^{*}),$ both of them at values near $350\mathrm{MeV}{/c}^{2}.$ We interpret these peaks as signatures of two distinct states, the ${D}_{\mathrm{sJ}}^{*}{(2317)}^{+}$ plus a new state, designated as the ${D}_{\mathrm{sJ}}{(2463)}^{+}.$ Because of the similar $\ensuremath{\Delta}M$ values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences $〈\ensuremath{\Delta}{M(D}_{s}{\ensuremath{\pi}}^{0})〉=350.0\ifmmode\pm\else\textpm\fi{}1.2(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{syst})\mathrm{MeV}{/c}^{2}$ for the ${D}_{\mathrm{sJ}}^{*}{(2317)}^{+}$ state, and $〈\ensuremath{\Delta}{M(D}_{s}^{*}{\ensuremath{\pi}}^{0})〉=351.2\ifmmode\pm\else\textpm\fi{}1.7(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{syst})\mathrm{MeV}{/c}^{2}$ for the new ${D}_{\mathrm{sJ}}{(2463)}^{+}$ state. We have also searched, but find no evidence, for decays of the two states via the channels ${D}_{s}^{*+}\ensuremath{\gamma},{D}_{s}^{+}\ensuremath{\gamma},$ and ${D}_{s}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}.$ The observations of the two states at 2.32 and $2.46\mathrm{GeV}{/c}^{2},$ in the ${D}_{s}^{+}{\ensuremath{\pi}}^{0}$ and ${D}_{s}^{*+}{\ensuremath{\pi}}^{0}$ decay channels, respectively, are consistent with their interpretations as $c\overline{s}$ mesons with an orbital angular momentum $L=1$ and spin and parity ${J}^{P}{=0}^{+}$ and ${1}^{+}.$

We have measured the branching fraction and photon energy spectrum for the radiative penguin process b-->s gamma. We find Beta(b-->s gamma) = (3.21+/-0.43+/-0.27(+0.18)(-0.10))x10(-4), where the errors are statistical, systematic, and from theory corrections. We obtain first and second moments of the photon energy spectrum above 2.0 GeV, <E( gamma)> = 2.346+/-0.032+/-0.011 GeV, and <E(2)(gamma)>-<E(gamma)>(2) = 0.0226+/-0.0066+/-0.0020 GeV(2), where the errors are statistical and systematic. From the first moment, we obtain (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) the heavy quark effective theory parameter Lambda = 0.35+/-0.08+/-0.10 GeV.

We have observed the decays ${\mathit{B}}^{0}$\ensuremath{\rightarrow}${\mathit{K}}^{\mathrm{*}}$(892${)}^{0}$\ensuremath{\gamma} and ${\mathit{B}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathit{K}}^{\mathrm{*}}$(892${)}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma}, which are evidence for the quark-level process b\ensuremath{\rightarrow}s\ensuremath{\gamma}. The average branching fraction is (4.5\ifmmode\pm\else\textpm\fi{}1.5\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$. This value is consistent with standard model predictions from electromagnetic penguin diagrams.

We present the first measurement of the D*+ width using 9/fb of e+ e- data collected near the Upsilon(4S) resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the CESR beam spot to measure the energy release distribution from the D*+ -> D0 pi+ decay. We find Gamma(D*+) = 96 +- 4 (Statistical) +- 22 (Systematic) keV. We also measure the energy release in the decay and compute Delta m = m(D*+) - m(D0) = 145.412 +- 0.002 (Statistical) +- 0.012 (Systematic) MeV/c^2

The vertical cavity surface emitting laser (VCSEL) is a relatively new semiconductor laser device, especially applicable to fiber-optic networks in the 21st century.About 25 years have passed since its invention, and devices for Gigabit Ethernet are now being mass-produced.It is expected that VCSELs will open up a new era of very-high-speed fiber-optic networks and a wide range of application areas.VCSEL have many advantages, such as: (i) monolithic and high-yield fabrication; (ii) extremely low threshold and small power consumption; (iii) highspeed modulation capability at low driving current levels; (iv) easy packaging, and so on.The emission spectra have been extended from 850 nm toward the visible and infrared regions.We can expect reasonably high-power output, enough for most applications, and extremely high powers in some engineered arrayed devices.This book project was initiated to provide important information on VCSELs, edited by Prof. Herbert Li.Very regrettably, while editing this book he passed away.After some time, the present editor succeeded him.

We have studied exclusive, radiative B meson decays to charmless mesons in 9.7x10(6) B&Bmacr; decays accumulated with the CLEO detector. We measure B(B0-->K(*0)(892)gamma) = (4.55(+0.72)(-0. 68)+/-0.34)x10(-5) and B(B+-->K(*+)(892)gamma) = (3.76(+0.89)(-0. 83)+/-0.28)x10(-5). We have searched for CP asymmetry in B-->K(*)(892)gamma decays and measure A(CP) = +0.08+/-0.13+/-0.03. We report the first observation of B-->K(*)(2)(1430)gamma decays with a branching fraction of (1.66(+0.59)(-0.53)+/-0.13)x10(-5). No evidence for the decays B-->rhogamma and B0-->omegagamma is found and we limit B(B-->(rho/omega)gamma)/B(B-->K(*)(892)gamma)<0.32 at 90% C.L.

We report on a study of the invariant mass spectrum of the hadronic system in the decay τ−→π−π0ντ. This study was performed with data obtained with the CLEO II detector operating at the CESR e+e− collider. We present fits to phenomenological models in which resonance parameters associated with the ρ(770) and ρ(1450) mesons are determined. The π−π0 spectral function inferred from the invariant mass spectrum is compared with data on e+e−→π+π− as a test of the conserved vector current theorem. We also discuss the implications of our data with regard to estimates of the hadronic contribution to the muon anomalous magnetic moment.Received 21 October 1999DOI:https://doi.org/10.1103/PhysRevD.61.112002©2000 American Physical Society

We have fully reconstructed decays of both B0 and B- Mesons into final states containing either D, D*, D**, Psi, Psi', or Chi_{c1} mesons. This allows us to obtain new results on many physics topics including branching ratios, tests of the factorization hypothesis, color suppression, resonant substructure, and the B- - B0 mass difference.

Using 13.5 inverse fb of e+e- annihilation data collected with the CLEO II detector we have observed a narrow resonance in the Ds*+pi0 final state, with a mass near 2.46 GeV. The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at 2.32 GeV, the DsJ*(2317)+ that decays to Ds+pi0. Reconstructing the Ds+pi0 and Ds*+pi0 final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, dM(Dspi0)=M(Dspi0)-M(Ds) and dM(Ds*pi0)=M(Ds*pi0)-M(Ds*), both of them at values near 350 MeV. We interpret these peaks as signatures of two distinct states, the DsJ*(2317)+ plus a new state, designated as the DsJ(2463)+. Because of the similar dM values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences <dM(Dspi0)> = 350.0 +/- 1.2 [stat] +/- 1.0 [syst] MeV for the DsJ*(2317) state, and <dM(Ds*pi0)> = 351.2 +/- 1.7 [stat] +/- 1.0 [syst] MeV for the new DsJ(2463)+ state. We have also searched, but find no evidence, for decays of the two states via the channels Ds*+gamma, Ds+gamma, and Ds+pi+pi-. The observations of the two states at 2.32 and 2.46 GeV, in the Ds+pi0 and Ds*+pi0 decay channels respectively, are consistent with their interpretations as (c anti-strange) mesons with orbital angular momentum L=1, and spin-parities of 0+ and 1+.

We present the first measurement of the D*(+) width using 9/fb of e(+)e(-) data collected near the Upsilon(4S) resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the Cornell Electron-positron Storage Ring beam spot to measure the energy release distribution from the D*(+)-->D(0)pi(+) decay. We find gamma(D*(+)) = 96+/-4 (stat)+/-22 (syst) keV. We also measure the energy release in the decay and compute Delta m identical with m(D*(+))-m(D(0)) = 145.412+/-0.002 (stat)+/-0.012 (syst) MeV/c(2).

In e(+)e(-) collisions using the CLEO detector, we have studied the decay of the D0 to the final state K(0)(S)pi(+)pi(-) with the initial flavor of the D0 tagged by the decay D(*+)-->D0pi(+). We use the Dalitz technique to measure the resonant substructure in this final state and clearly observe ten different contributions by fitting for their amplitudes and relative phases. We observe a K(*)(892)(+)pi(-) component which arises from doubly Cabibbo suppressed decays or D0-D0; mixing.

In a sample of 19 million produced B mesons, we have observed the decays B -> eta K* and improved our previous measurements of B -> eta'K. The branching fractions we measure for these decay modes are BR(B+ -> eta K*+) = (26.4 +9.6-8.2 +- 3.3) x $10^{-6}$, BR(B0 -> eta K*0) = (13.8 +5.5-4.6 +- 1.6) x $10^{-6}$, BR(B+ -> eta' K+) = (80 +10-9 +- 7) x $10^{-6}$ and BR(B0 -> eta' K0) = (89 +18-16 +- 9) x $10^{-6}$. We have searched with comparable sensitivity for related decays and report upper limits for these branching fractions.

We report a measurement of the ${\mathit{D}}^{\mathrm{*}+}$ and ${\mathit{D}}^{\mathrm{*}0}$ decay branching fractions based on 780 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ of data collected with the CLEO II detector. For radiative ${\mathit{D}}^{\mathrm{*}+}$ decay, we obtain an upper limit, scrB(${\mathit{D}}^{\mathrm{*}+}$\ensuremath{\rightarrow}${\mathit{D}}^{+}$\ensuremath{\gamma})4.2% (90% confidence level), which is substantially below previous results, and eliminates the need for an anomalously large charm quark magnetic moment.

We report on the observation of the ηc′(2S01), the radial excitation of the ηc(1S01) ground state of charmonium, in the two-photon fusion reaction γγ→ηc′→KS0K±π∓ in 13.6 fb−1 of CLEO II/II.V data and 13.1 fb−1 of CLEO III data. We obtain M(ηc′)=3642.9±3.1(stat)±1.5(syst) MeV and M(ηc)=2981.8±1.3(stat)±1.5(syst) MeV. The corresponding values of hyperfine splittings between S01 and S13 states are ΔMhf(1S)=115.1±2.0 MeV and ΔMhf(2S)=43.1±3.4 MeV. Assuming that the ηc and ηc′ have equal branching fractions to KSKπ, we obtain Γγγ(ηc′)=1.3±0.6 keV.Received 23 December 2003DOI:https://doi.org/10.1103/PhysRevLett.92.142001©2004 American Physical Society

The construction and assembly of the two half barrels of the ATLAS central electromagnetic calorimeter and their insertion into the barrel cryostat are described. The results of the qualification tests of the calorimeter before installation in the LHC ATLAS pit are given.

A module of the ATLAS electromagnetic barrel liquid argon calorimeter was exposed to the CERN electron test-beam at the H8 beam line upgraded for precision momentum measurement. The available energies of the electron beam ranged from 10 to 245 GeV. The electron beam impinged at one point corresponding to a pseudo-rapidity of η=0.687 and an azimuthal angle of φ=0.28 in the ATLAS coordinate system. A detailed study of several effects biasing the electron energy measurement allowed an energy reconstruction procedure to be developed that ensures a good linearity and a good resolution. Use is made of detailed Monte Carlo simulations based on GEANT4 which describe the longitudinal and transverse shower profiles as well as the energy distributions. For electron energies between 15 and 180 GeV the deviation of the measured incident electron energy over the beam energy is within 0.1%. The systematic uncertainty of the measurement is about 0.1% at low energies and negligible at high energies. The energy resolution is found to be about 10% ·E for the sampling term and about 0.2% for the local constant term.

A comprehensive review of the status of τ-lepton physics is presented. We include the knowledge on the properties of the tau, the decay branching fractions and tests of the standard model. Discussions of possible puzzles and an indication of the future possibilities in this field are a lso presented.

Invariant single-particle cross sections for pion and proton production in π±p interactions at 8 and 16 GeV/c are presented in terms of integrated distributions as functions of x, reduced rapidity ζ and p⊥2, and also in terms of double differential cross sections E d2σ/(dx dp⊥2) and dζ dp⊥2). A comparison of π± and π− induced reactions is made and the energy dependence is discussed. It is shown that the single-particle structure function cannot be factorized in its dependece on transverse and longitudinal momentum. For the beam-unlike pion, there is an indication for factorizability in terms of rapidity and transverse momentum in a small central region.

We search for CP-violating charge asymmetries (alpha(CP)) in the B meson decays to K(+/-)pi(-/+), K(+/-)pi(0), K(0)(S)pi(+/-), K(+/-)eta('), and omega pi(+/-). Using 9.66 million upsilon(4S) decays collected with the CLEO detector, the statistical precision on alpha(CP) is in the range of +/-0.12 to +/-0.25 depending on decay mode. While CP-violating asymmetries of up to +/-0.5 are possible within the standard model, the measured asymmetries are consistent with zero in all five decay modes studied.

We report results of searches for charmless hadronic B meson decays to pseudoscalar( pi(+/-), K+/-, pi(0), or K(0)(S))-vector( rho, K(*), or omega) final states. By using 9.7x10(6) BB pairs collected with the CLEO detector, we report the first observation of B(-)--->pi(-)rho(0), B(0)-->pi(+/-)rho(-/+), and B(-)-->pi(-)omega, which are expected to be dominated by hadronic b-->u transitions. The measured branching fractions are (10.4(+3.3)(-3.4)+/-2.1)x10(-6), (27.6(+8.4)(-7.4)+/-4.2)x10(-6), and (11.3(+3.3)(-2.9)+/-1. 4)x10(-6), respectively. Branching fraction upper limits are set for all of the other decay modes investigated.

Using data collected by the CLEO II detector, we have observed two states decaying to ${\ensuremath{\Lambda}}_{c}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. Relative to the ${\ensuremath{\Lambda}}_{c}^{+}$, their mass splittings are measured to be $+307.5\ifmmode\pm\else\textpm\fi{}0.4\ifmmode\pm\else\textpm\fi{}1.0$ and $+342.2\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\pm\else\textpm\fi{}0.5\mathrm{MeV}{/c}^{2}$, respectively; this represents the first measurement of the less massive state. These two states are consistent with being orbitally excited, isospin zero ${\ensuremath{\Lambda}}_{c}^{+}$ states.

We have studied charmless hadronic decays of $B$ mesons into two-body final states with kaons and pions and observe three new processes with the following branching fractions: $B(B\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({4.3}_{\ensuremath{-}1.4}^{+1.6}\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, $B(B\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{0})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({14.6}_{\ensuremath{-}5.1\ensuremath{-}3.3}^{+5.9+2.4})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, and $B(B\ensuremath{\rightarrow}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{0})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({11.6}_{\ensuremath{-}2.7\ensuremath{-}1.3}^{+3.0+1.4})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. We also update our previous measurements for the decays $B\ensuremath{\rightarrow}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}$ and ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$.

Using a sample of $2.6\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\Upsilon}(4\mathrm{S})\ensuremath{\rightarrow}B\overline{B}$ events collected with the CLEO II detector at the Cornell Electron Storage Ring, we have measured the form factors for ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{*+}{\ensuremath{\ell}}^{\ensuremath{-}}\overline{\ensuremath{\nu}}$. We perform a three-parameter fit with the joint distribution of four kinematic variables to obtain the form-factor ratios ${R}_{1}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.18\ifmmode\pm\else\textpm\fi{}0.30\ifmmode\pm\else\textpm\fi{}0.12$ and ${R}_{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.71\ifmmode\pm\else\textpm\fi{}0.22\ifmmode\pm\else\textpm\fi{}0.07,$ and the form-factor slope ${\ensuremath{\rho}}_{{A}_{1}}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.91\ifmmode\pm\else\textpm\fi{}0.15\ifmmode\pm\else\textpm\fi{}0.06,$ which is closely related to the slope of the Isgur-Wise function. The form-factor ratios are consistent with predicted corrections to the heavy-quark symmetry limit ${R}_{1}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}R}_{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$.

We have measured the first and second moments of the hadronic mass-squared distribution in B -> X_c l nu, for P(lepton) > 1.5 GeV/c. We find <M_X^2 - M_D[Bar]^2> = 0.251 +- 0.066 GeV^2, < (M_X^2 -<M_X^2>)^2 > = 0.576 +- 0.170 GeV^4, where M_D[Bar] is the spin-averaged D meson mass. From that first moment and the first moment of the photon energy spectrum in b -> s gamma, we find the HQET parameter lambda_1 (MS[Bar], to order 1/M^3 and beta_0 alpha_s^2) to be -0.24 +- 0.11 GeV^2. Using these first moments and the B semileptonic width, and assuming parton-hadron duality, we obtain |V_cb| = 0.0404 +- 0.0013.

We report on determinations of $|{V}_{\mathrm{ub}}|$ resulting from studies of the branching fraction and ${q}^{2}$ distributions in exclusive semileptonic B decays that proceed via the $\stackrel{\ensuremath{\rightarrow}}{b}u$ transition. Our data set consists of the $9.7\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ meson pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the CLEO II detector. We measure $\mathcal{B}{(B}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\mathcal{l}}^{+}\ensuremath{\nu})=(1.33\ifmmode\pm\else\textpm\fi{}0.18\ifmmode\pm\else\textpm\fi{}0.11\ifmmode\pm\else\textpm\fi{}0.01\ifmmode\pm\else\textpm\fi{}0.07)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\mathcal{B}{(B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ensuremath{-}}{\mathcal{l}}^{+}\ensuremath{\nu})=(2.17\ifmmode\pm\else\textpm\fi{}{0.34}_{\ensuremath{-}0.54}^{+0.47}\ifmmode\pm\else\textpm\fi{}0.41\ifmmode\pm\else\textpm\fi{}0.01)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4},$ where the errors are statistical, experimental systematic, systematic due to residual form-factor uncertainties in the signal, and systematic due to residual form-factor uncertainties in the cross-feed modes, respectively. We also find $\mathcal{B}{(B}^{+}\ensuremath{\rightarrow}\ensuremath{\eta}{\mathcal{l}}^{+}\ensuremath{\nu})=(0.84\ifmmode\pm\else\textpm\fi{}0.31\ifmmode\pm\else\textpm\fi{}0.16\ifmmode\pm\else\textpm\fi{}0.09)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4},$ consistent with what is expected from the $\stackrel{\ensuremath{\rightarrow}}{B}\ensuremath{\pi}\mathcal{l}\ensuremath{\nu}$ mode and quark model symmetries. We extract $|{V}_{\mathrm{ub}}|$ using light-cone sum rules for $0&lt;~{q}^{2}&lt;16{\mathrm{GeV}}^{2}$ and lattice QCD for $16{\mathrm{GeV}}^{2}&lt;~{q}^{2}&lt;{q}_{\mathrm{max}}^{2}.$ Combining both intervals yields $|{V}_{\mathrm{ub}}|=(3.24\ifmmode\pm\else\textpm\fi{}0.22\ifmmode\pm\else\textpm\fi{}{0.13}_{\ensuremath{-}0.39}^{+0.55}\ifmmode\pm\else\textpm\fi{}0.09)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ for $\ensuremath{\pi}\mathcal{l}\ensuremath{\nu},$ and $|{V}_{\mathrm{ub}}|=(3.00\ifmmode\pm\else\textpm\fi{}{0.21}_{\ensuremath{-}0.35\ensuremath{-}0.38}^{+0.29+0.49}\ifmmode\pm\else\textpm\fi{}0.28)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ for $\ensuremath{\rho}\mathcal{l}\ensuremath{\nu},$ where the errors are statistical, experimental systematic, theoretical, and \ensuremath{\rho}l\ensuremath{\nu} form-factor shape, respectively. Our combined value from both decay modes is $|{V}_{\mathrm{ub}}|=(3.17\ifmmode\pm\else\textpm\fi{}{0.17}_{\ensuremath{-}0.17\ensuremath{-}0.39}^{+0.16+0.53}\ifmmode\pm\else\textpm\fi{}0.03)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}.$

We present measurements of spectral moments extracted from the invariant mass distributions of the final states of hadronic τ decay products recorded in the CLEO detector. From a fit of theoretical predictions to the measurements of spectral moments and the total hadronic decay width of the τ, we determine the strong coupling constant and a set of non-perturbative QCD parameters. The strong coupling constant is measured to be αs(mτ) = 0.306 ± 0.024, which when extrapolated to the Z mass, yields αs(Mz) = 0.114 ± 0.003.

The resonant substructure in D0 --> K0S pi+ pi- decays is described by a combination of ten quasi two-body intermediate states which include both CP-even and CP-odd eigenstates and one doubly-Cabibbo suppressed channel. We present a formalism that connects the variation in D0 decay time over the Dalitz plot with the mixing parameters, x and y, that describe off-shell and on-shell D0-D0B mixing. We analyze the CLEO II.V data sample and find the parameters x and y are consistent with zero. We limit (-4.7 < x < 8.6)% and (-6.1 < y < 3.5)% at the 95\% confidence level

We report the results of a study of the three-prong decay mode of the $\ensuremath{\tau}$ in data taken with the DELCO detector at the SLAC ${e}^{+}{e}^{\ensuremath{-}}$ storage ring PEP. We determine the total three-prong branching ratio to be $B(3)=(12.1\ifmmode\pm\else\textpm\fi{}0.5\ifmmode\pm\else\textpm\fi{}1.2)%$ and the exclusive branching ratios $B(\ensuremath{\tau}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\nu})=(5.0\ifmmode\pm\else\textpm\fi{}0.1)%$ and $B(\ensuremath{\tau}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{0}\ensuremath{\nu})=(6.0\ifmmode\pm\else\textpm\fi{}1.2)%$, respectively. The data with three charged pions allow for the determination of the mass and width of the ${A}_{1}$ resonance as ${M}_{{A}_{1}}=1056\ifmmode\pm\else\textpm\fi{}20\ifmmode\pm\else\textpm\fi{}15$ MeV and ${\ensuremath{\Gamma}}_{{A}_{1}}={476}_{\ensuremath{-}120}^{+132}\ifmmode\pm\else\textpm\fi{}54$ MeV.

We review the constraints imposed by the spontaneously broken chiral symmetry of the QCD vacuum on the hadron properties at finite temperature T and baryon density ρB. A restoration of chiral symmetry is indicated by the dropping of the scalar quark condensate q̄q at finite T and ρB in various approaches. This suggests the hadrons to become approximately massless in hot and dense nuclear matter or the vector and axial vector currents to become equal. In this respect we study the properties of hadrons – as produced in relativistic nucleus–nucleus collisions – by means of a covariant hadronic transport approach where scalar and vector hadron self-energies are taken into account explicitly which are modelled in terms of effective ‘chiral’ Lagrangians. Within this transport approach we investigate the reaction dynamics of relativistic heavy-ion collisions and analyse experimental data on π,η,K+,K−,ρ,ω,φ,p̄ and charmonium production for proton–nucleus and nucleus–nucleus collisions from SIS to SPS energies (1–200A GeV). Whereas π,η and to some extent K+ mesons are found not to change their properties in the nuclear medium substantially, antiprotons and antikaons do show sizeable attractive self-energies as can be extracted from their experimental abundancies and spectra. The properties of the vector mesons ρ,ω and φ at finite baryon density are investigated by their dileptonic decay; the CERES and HELIOS-3 data at SPS energies are found to be incompatible with a ‘bare’ vector meson mass scenario. Here, a description by ‘dropping’ ρ and ω masses leads to a very good reproduction of the data, however, also approaches based on more conventional hadronic interactions as pion polarizations and meson–nucleon scattering amplitudes are compatible with the present dilepton spectra at SPS energies. Constraints from dilepton studies at BEVALAC/SIS energies are investigated in all decay schemes as well as a variety of further observables that allow to disentangle the different scenarios experimentally. Furthermore, the charmonium production and suppression in proton–nucleus and nucleus–nucleus collisions is investigated within the transport approach in order to probe a possible transition to a quark-gluon plasma (QGP) phase. We finally discuss ‘optimized’ observables for an experimental investigation of the restoration of chiral symmetry and/or the phase transition to a quark-gluon plasma.

Using data obtained with the CLEO III detector, running at the Cornell Electron Storage Ring (CESR), we report on a new study of exclusive radiative $\ensuremath{\Upsilon}(1\mathrm{S})$ decays into the final states $\ensuremath{\gamma}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\gamma}{K}^{+}{K}^{\ensuremath{-}}$, and $\ensuremath{\gamma}p\overline{p}$. We present branching ratio measurements for the decay modes $\ensuremath{\Upsilon}(1\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}{f}_{2}(1270)$, $\ensuremath{\Upsilon}(1\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}{f}_{2}^{\ensuremath{'}}(1525)$, and $\ensuremath{\Upsilon}(1\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}{K}^{+}{K}^{\ensuremath{-}}$; helicity production ratios for ${f}_{2}(1270)$ and ${f}_{2}^{\ensuremath{'}}(1525)$; upper limits for the decay $\ensuremath{\Upsilon}(1\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}{f}_{J}(2200)$, with ${f}_{J}(2220)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, ${K}^{+}{K}^{\ensuremath{-}}$, $p\overline{p}$; and an upper limit for the decay $\ensuremath{\Upsilon}(1\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}X(1860)$, with $X(1860)\ensuremath{\rightarrow}\ensuremath{\gamma}p\overline{p}$.

A new value of the upper limit for the branching ratio of the decay of K0S into e+e− has been experimentally obtained using a lead glass detector. The value is BR (K0S → e+e−) < 1.1 × 10−4 (90% CL).

The resonant structure of the four pion final state in the decay $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}3\ensuremath{\pi}{\ensuremath{\pi}}^{0}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ has been analyzed using 4.27 million ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ pairs collected by the CLEO II experiment at the Cornell Electron Storage Ring. A partial wave analysis of the resonant structure of the $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}3\ensuremath{\pi}{\ensuremath{\pi}}^{0}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ decay has been performed; the spectral decomposition of the four pion system is dominated by the $\ensuremath{\omega}\ensuremath{\pi}$ and ${a}_{1}\ensuremath{\pi}$ final states. The mass and width of the ${\ensuremath{\rho}}^{\ensuremath{'}}$ resonance have been extracted from a fit to the $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}\ensuremath{\omega}\ensuremath{\pi}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ spectral function. We have searched for second class currents in the decay $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}\ensuremath{\omega}\ensuremath{\pi}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ using spin-parity analysis and established an upper limit on the non-vector current contribution.

We present an update of the search for the lepton family number violating decay $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}\ensuremath{\mu}\ensuremath{\gamma}$ using 12.6 million ${\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ pairs collected with the CLEO detector. No evidence of a signal has been found and the corresponding upper limit is $\mathcal{B}(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}\ensuremath{\mu}\ensuremath{\gamma})&lt;1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ at 90% C.L., significantly smaller than previous experimental limits.

In a sample of 9.66x10(6)B&Bmacr; pairs collected with the CLEO detector we make the first observation of B decays to an eta(c) and a kaon. We measure branching fractions B(B+-->eta(c)K+) = (0.69(+0.26)(-0.21)+/-0.08+/-0.20)x10(-3) and B(B degrees -->eta(c)K degrees ) = (1.09(+0.55)(-0.42)+/-0.12+/-0.31)x10(-3), where the first error is statistical, the second is systematic, and the third is from the eta(c) branching fraction uncertainty. From these we extract the eta(c) decay constant in the factorization approximation, f(eta(c)) = 335+/-75 MeV. We also search for B decays to a chi(c0) and a kaon. No evidence for a signal is found and we set 90% C.L. upper limits: B(B+-->chi(c0)K+)<4.8x10(-4) and B(B degrees -->chi(c0)K degrees )<5.0x10(-4).

We have investigated $D^{+}\pi^{-}$ and $D^{*+}\pi^{-}$ final states and observed the two established $L=1$ charmed mesons, the $D_1(2420)^0$ with mass $2421^{+1+2}_{-2-2}$ MeV/c$^{2}$ and width $20^{+6+3}_{-5-3}$ MeV/c$^{2}$ and the $D_2^*(2460)^0$ with mass $2465 \pm 3 \pm 3$ MeV/c$^{2}$ and width $28^{+8+6}_{-7-6}$ MeV/c$^{2}$. Properties of these final states, including their decay angular distributions and spin-parity assignments, have been studied. We identify these two mesons as the $j_{light}=3/2$ doublet predicted by HQET. We also obtain constraints on {\footnotesize $\Gamma_S/(\Gamma_S + \Gamma_D)$} as a function of the cosine of the relative phase of the two amplitudes in the $D_1(2420)^0$ decay.

Recent developments in the field of large ${p}_{T}$ physics are reviewed. Special attention is paid to the explanation of the data offered by specific constituent models. Emphasis is placed on those data which tend to differentiate between the models. Prospects for better understanding of large ${p}_{T}$ events as the result of new experiments and further theoretical work are discussed.

Using the CLEO detector at the Cornell Electron Storage Ring, we have made a measurement of $R\ensuremath{\equiv}\ensuremath{\sigma}{(e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{hadrons})/\ensuremath{\sigma}{(e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})=3.56\ifmmode\pm\else\textpm\fi{}0.01\ifmmode\pm\else\textpm\fi{}0.07$ at $\sqrt{s}$=10.52 GeV. This implies a value for the strong coupling constant of ${\ensuremath{\alpha}}_{s}(10.52 \mathrm{GeV})=0.20\ifmmode\pm\else\textpm\fi{}0.01\ifmmode\pm\else\textpm\fi{}0.06$, or ${\ensuremath{\alpha}}_{s}{(M}_{Z})=0.13\ifmmode\pm\else\textpm\fi{}0.005\ifmmode\pm\else\textpm\fi{}0.03$.

Using data taken with the CLEO II detector at the Cornell Electron Storage Ring, we present the first full angular analysis in the color-suppressed modes B0→J/ψK*0 and B+→J/ψK*+. This leads to a complete determination of the decay amplitudes of these modes including the longitudinal polarization γL/γ=0.52±0.07±0.04 and the P wave component |P|2=0.16±0.08±0.04. In addition, we update the branching fractions for B→J/ψK and B→J/ψK∗.Received 24 February 1997DOI:https://doi.org/10.1103/PhysRevLett.79.4533©1997 American Physical Society

Using data recorded by the CLEO II detector at the Cornell Electron Storage Ring, we report the first observation of an excited charmed baryon decaying into ${\ensuremath{\Xi}}_{c}^{0}{\ensuremath{\pi}}^{+}$. The state has mass difference $M({\ensuremath{\Xi}}_{c}^{0}{\ensuremath{\pi}}^{+})\ensuremath{-}M({\ensuremath{\Xi}}_{c}^{0})$ of $174.3\ifmmode\pm\else\textpm\fi{}0.5\ifmmode\pm\else\textpm\fi{}1.0\mathrm{MeV}{/c}^{2}$, and a width of $&lt;3.1\mathrm{MeV}{/c}^{2}$ (90% confidence level limit). We identify the new state as the ${\ensuremath{\Xi}}_{c}^{*+}$, the isospin partner of the recently discovered ${\ensuremath{\Xi}}_{c}^{*0}$.

We have measured the CP asymmetry A(CP) identical with[gamma(b-->sgamma)-gammab-->sgamma)]/[gamma(b-->sgamma)+gamma(b-->sgamma)] to be A(CP) = (-0.079+/-0.108+/-0.022) (1.0+/-0.030), implying that, at 90% confidence level, A(CP) lies between -0.27 and +0.10. These limits rule out some extreme non-standard-model predictions, but are consistent with most, as well as with the standard model.

Using the CLEO II detector, we have measured the branching fractions for $\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\Upsilon}(1S)$, $\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\Upsilon}(2S)$, and the cascade $\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}\ensuremath{\Upsilon}(2S)+X$, $\ensuremath{\Upsilon}(2S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\Upsilon}(1S)$, analyzing the exclusive mode where the daughter $\ensuremath{\Upsilon}$ state decays to a ${e}^{+}{e}^{\ensuremath{-}}$ or ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ pair, as well as the inclusive ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ transitions where the final $\ensuremath{\Upsilon}$ state decays into hadrons. Properties of the $\ensuremath{\pi}\ensuremath{\pi}$ system are analyzed. Searches for the cascade decay $\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{h}_{b}$, ${h}_{b}\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\eta}}_{b}$ and $\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{h}_{b}$ were also performed.

We report results from a search for the decays ${\mathit{B}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$, ${\mathit{B}}^{0}$\ensuremath{\rightarrow}${\mathit{K}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$, and ${\mathit{B}}^{0}$\ensuremath{\rightarrow}${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{\ensuremath{-}}}$. We find 90% confidence level upper limits on the branching fractions, ${\mathit{B}}_{\mathrm{\ensuremath{\pi}}\mathrm{\ensuremath{\pi}}}$2.9\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$, ${\mathit{B}}_{\mathit{K}\mathrm{\ensuremath{\pi}}}$2.6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$, and ${\mathit{B}}_{\mathit{K}\mathit{K}}$0.7\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$. While there is no statistically significant signal in the individual modes, the sum of ${\mathit{B}}_{\mathrm{\ensuremath{\pi}}\mathrm{\ensuremath{\pi}}}$ and ${\mathit{B}}_{\mathit{K}\mathrm{\ensuremath{\pi}}}$ exceeds zero with a significance of more than 4 standard deviations, indicating that we have observed charmless hadronic B decays.

The construction of the ATLAS electromagnetic liquid argon calorimeter modules is completed and all the modules are assembled and inserted in the cryostats. During the production period four barrel and three endcap modules were exposed to test beams in order to assess their performance, ascertain the production quality and reproducibility, and to scrutinize the complete energy reconstruction chain from the readout and calibration electronics to the signal and energy reconstruction. It was also possible to check the full Monte Carlo simulation of the calorimeter. The analysis of the uniformity, resolution and extraction of constant term is presented. Typical non-uniformities of 5‰ and typical global constant terms of 6‰ are measured for the barrel and endcap modules.

We investigate the decays D(0)-->pi(-)l(+)nu and D(0)-->K(-)l(+)nu, where l is e or mu, using approximately 7 fb(-1) of data collected with the CLEO III detector. We find R(0) identical with B(D(0)-->pi(-)e(+)nu)/B(D(0)-->K(-)e(+)nu)=0.082+/-0.006+/-0.005. Fits to the kinematic distributions of the data provide parameters describing the form factor of each mode. Combining the form factor results and R(0) gives |f(pi)(+)(0)|(2)|V(cd)|(2)/|f(K)(+)(0)|(2)|V(cs)|(2)=0.038(+0.006+0.005)(-0.007-0.003).

We report a measurement of the branching ratios for two decay modes of the τ lepton: RB(τ±→K±K∓π±ντ)=(0.22−0.11+0.17)% and RB(τ±→K±π∓π±(π0)ντ)=(0.22−0.13+0.16)%. The separation of these channels is accomplished in the DELCO detector by use of a gas Čerenkov counter to identify fast kaons. The invariant-mass distribution of the K±K∓π± system has been used to set an upper bound on the τ neutrino mass of 157 MeV at 95% confidence limit.Received 13 November 1984DOI:https://doi.org/10.1103/PhysRevLett.54.624©1985 American Physical Society

Charged particle multiplicity cross sections for 100 GeV/c π−p inelastic interactions are presented and compared with results at other energies. The results for multiplicities n ⪖ 4 show a consistent trend in their energy dependence. The two-prong cross section curve differs as it tends to flatten off at the higher energies. The zero-prong cross section values decrease steeply as plab−1.1. The results for n ⩾ 2 for π−p and pp reactions appear to lie on a “universal” curve if nσn/σinel is plotted against 〈n〉/n. This “scaling” rule is equivalent to KNO scaling, but the plot suggested here is more useful in studying low multiplicities. An interpretation in terms of a two-component model and a possible extrapolation to higher energies are proposed.

Positive correlations are observed for pion pairs of equal charge and similar momentum vectors, produced in the reactions πp→p+5π and πp→p + 7π at 4 to 25 GeV/c. The results are consistent with being due to the second-order interference effects expected for pairs of identical bosons and lead to the determination of the average dimension of the “fire-ball’ from which the pions are emitted (〈R〉 = 1.0 ± −0.2+0.4 fm). Attempts are made to study the fire-ball shape by selecting pions pair emitted in various polar and azimuthal directions.

The ATLAS detector has been designed for operation at CERN's Large Hadron Collider. ATLAS includes a complex system of liquid argon calorimeters. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on the Front End Boards (FEBs). This paper describes the design, implementation and production of the FEBs and presents measurement results from testing performed at several stages during the production process.

The distributions in the Feynman variable x for the pions produced in the inclusive reactions (1) π+p → π− + anything and (2) π+p → π+ + anything are compared at 8 and 16 GeV/c. The distributions are similar in first approximation, but second order differences are observed. In particular, at x ≈ 0 the distributionsfor π+ overlap at the two energies for π− they are different, and at x ≈ −2 they are similar for π− but not for π+. Comparison of the lonigtudinal momentum spectra in the lab. (target) system gives results consistent with limiting fragmentation for reaction (1), but not for reaction (2). Since the combination (abc̄) is (π+pπ+), exotic, for reaction (1) and (π+pπ−), non exotic, for reaction (2), these results are consistent with the suggestion of Chan et al. that when (abc) is exotic, limiting fragmentation may set in already at moderate (accelerator) energies.

Results are presented for six reactions induced by K−p collisions at 10 GeV/c, where K∗(890) and K∗(1420) resonances are produced in association with a proton, a neutron, a Δ+(1236) or ΔO(1236) isobar. Partial and differential cross sections as well as density matrix elements are compared to one another and to previous results at lower energies. The following observations are made: (i) There is a first indication of a difference in the energy dependence of the pK∗− and nK∗O cross sections. (ii) In the pK∗−(890) channel the ratio of π to ω exchange decreases with increasing energy. (iii) The ratio of π to ω exchange increases with the mass produced, the pion exchange contribution to the pK∗−(1420) channel being larger than that to the pK∗−(890) channel. (iv) Natural spin-parity exchange dominates in the pK∗−(890) channel, but there are significant contributions of both natural and unnatural parity exchanges in the nK∗O(890) channel. (v) There exists a clear hierarchy of exchanges such that when ω or fO-exchanges are possible, they dominate over pion-exchange; pion exchange dominates over ϱ or A2-exchange in ΔQ = 1 or ΔI = 1 reactions, at least up to 10 GeV/c. (vi) Differential cross sections dσ/dt′ of reactions dominated by pion exchange are better fitted by a two-exponential formula of the type P[exp (−Qt′)+R exp (−St′)], than by the pion propagator. (vii) At least ≈ 25% of the unnatural exchange in the nK∗O(890) channel at 4–10 GeV/c must be due to mechanisms other than simple pion exchange.

We have searched for two-body charmless decays of B mesons to purely hadronic exclusive final states including $\omega$ or $\phi$ mesons using data collected with the CLEO II detector. With this sample of $6.6 \times 10^6$ B mesons we observe a signal for the $\omega K^+$ final state, and measure a branching fraction of B($B^+ \to \omega K^+$) = 1.5 +0.7 -0.6 +-0.2 $\times 10^{-5}$. We also observe some evidence for the $\phi K^*$ final state, and upper limits are given for 22 other decay modes. These results provide the opportunity for studies of theoretical models and physical parameters.

Using the CLEO-II detector, we have obtained evidence for a new meson decaying to $D^0 K^+$. Its mass is $2573.2^{+1.7}_{-1.6}\pm 0.8\pm 0.5$ {}~MeV/$c^2$ and its width is $16^{+5}_{-4}\pm 3$~MeV/$c^2$. Although we do not establish its spin and parity, the new meson is consistent with predictions for an $L=1$, $S=1$, $J_P=2^+$ charmed strange state.

We have studied the color-suppressed hadronic decays of neutral B mesons into the final states ${D}^{(*)0}{\ensuremath{\pi}}^{0}$. Using $9.67\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected with the CLEO detector, we observe the decays ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{0}$ and ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{*0}{\ensuremath{\pi}}^{0}$ with the branching fractions $B({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{0})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({2.74}_{\ensuremath{-}0.32}^{+0.36}\ifmmode\pm\else\textpm\fi{}0.55)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $B({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{*0}{\ensuremath{\pi}}^{0})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({2.20}_{\ensuremath{-}0.52}^{+0.59}\ifmmode\pm\else\textpm\fi{}0.79)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. The first error is statistical and the second systematic. The statistical significance of the ${D}^{0}{\ensuremath{\pi}}^{0}$ signal is $12.1\ensuremath{\sigma}$ ( $5.9\ensuremath{\sigma}$ for ${D}^{*0}{\ensuremath{\pi}}^{0}$). Utilizing the ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{(*)0}{\ensuremath{\pi}}^{0}$ branching fractions we determine the strong phases ${\ensuremath{\delta}}_{I,D(*)}$ between isospin $1/2$ and $3/2$ amplitudes in the $D\ensuremath{\pi}$ and ${D}^{*}\ensuremath{\pi}$ final states to be $\mathrm{cos}{\ensuremath{\delta}}_{I,D}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.89\ifmmode\pm\else\textpm\fi{}0.08$ and $\mathrm{cos}{\ensuremath{\delta}}_{I,D*}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.89\ifmmode\pm\else\textpm\fi{}0.08$, respectively.

A measurement of absolute integrated luminosity is presented using the CLEO II detector operating at the CESR e+e− storage ring. Independent analyses of three different final states (e+e−, γγ, and μ+μ−) at √s ⋍ 10 GeV normalize to the expected theoretical cross sections and correct for detection efficiencies. The resulting luminosities are measured with systematic errors of ±1.8%, ±1.6%, and ±2.2%, respectively, and are consistent with one another. The combined luminosity has a systematic error of ±1.0%.

We have studied light production and propagation in three different samplesof plastic scintillating fibers manufactured by Kyowa Gas Co.: SCSF-81, SCSF-38 and SCSF-38 with afquenching additive. The emissio time distribution is described phenomenologically by a fast two-step scintillation process and an additional slow component, the time constants of which are determined. The light yield from the fibers is measured as a function of distance for the two light components which propagate by total internal reflection from the core-clad interface and from the clad-air interface. We obtain the absolute light yield and attenuation lengths for the different fibers.

The momentum distributions of particles produced in K−p interactions at 10 and 16 GeV/c are studied. In particular the average transverse momentum is presented as a function of the reduced longitudinal momentum for six different secondary particles, namely: π+, π−, K−, K0, p and Λ. The average transverse momentum increases with increasing mass of the particle produced and tends to increase with increasing energy.

A partial-wave analysis has been made of the (3π) system produced in the reaction π+p → (π+π+π−)p at 8, 16 and 23 GeV/c using the Illinois partial-wave analysis program. The (3π) systems is in about 93% of the cases in the unnatural spin-parity states 0−, 1+, 2− and 3+ and is produced in about 100% of the cases by natural parity exchange. For all JP states, the differential cross section dσ/dt′ peaks at small tt′, except for 2+D which has a dip at t′ ≈ 0. The cross sections for JP = 1+, 2+ and 2− in the A1, A2 and A3 regions, respectively, all have similar energy dependence, plab−n, with n = 0.3 ± 0.2. The weak variation of the 1+S phase across the 1.0–1.2 GeV mass region, suggests that A1 cannot be considered as a single resonance, while the phase variation of 2+D (ϱπ) in the A2 mass region is consistent with resonance behaviour. In the A3 region, the behaviour of the 2−S and 2−P phases is complex and further work is needed to understand the mechanisms involved there.

The isospin I = 12 state of the nucleon pion system in π+p reactions leading to single pion production has been separated from the I = 32 state. The contribution of the former to the total ππN cross section is found to decrease much less with increasing energy than that of the latter. This is interpreted in terms of pomeron-exchange (or diffractive) processes responsible for at least 70% of the I = 12 contribution at 16 GeV/c and 50 % of the ππN cross section. For I = 12, the (Nπ) mass spectrum has a broad unresolved enhancement which reaches its maximum value at ≈ 1300 MeV, well below the first known I = 12 isobar. The production characteristics of this low mass (Nπ) system are different from those of the Δ (1236).

Results are presented on elastic scattering of 10.1 GeV/c K− mesons on protons, based on a sample of 16 261 kinematically-fitted bubble-chamber events. The differential cross section is given over the |t|- range of 0.06 to 2.5 GeV2 and is fitted with the expressions a ebt, A eBt+Ct2 and (P eQt+ReSt) over various intervals of t. The results are compared with those of other experiments at nearby energies. Upper limits of |α| < 0.28 and σB < 0.4 μb (both at a 90% confidence level) are given for the ratio of real to imaginary part of the forward-scattering amplitude and the backward-elastic-scattering cross section, respectively.

We report the first observation of two narrow charmed strange baryons decaying to $\Xi_c^+\gamma$ and $\Xi_c^0\gamma$, respectively, using data from the CLEO II detector at CESR. We interpret the observed signals as the $\Xi_c^{+\prime}(c{su})$ and $\Xi_c^{0\prime}(c{sd})$, the symmetric partners of the well-established antisymmetric $\Xi_c^+(c[su])$ and $\Xi_c^0(c[sd])$. The mass differences $M(\Xi_c^{+\prime})-M(\Xi_c^+)$ and $M(\Xi_c^{0\prime})-M(\Xi_c^0)$ are measured to be $107.8\pm 1.7\pm 2.5$ and $107.0\pm 1.4\pm 2.5 MeV/c^2$, respectively.

We have searched for the effective FCNC decays b->s l+l- using an inclusive method. We set upper limits on the branching ratios B(b->s e+e-) < 5.7 10^{-5}, B(b->s mu+mu-) < 5.8 10^{-5}, and B(b->s e+-mu-+) < 2.2 10^{-5} (at 90 %\ C.L.). Combining the di-electron and di-muon decay modes we find: B(b->s l+l-) < 4.2 10^{-5} (at 90 % C.L.).

Using the CLEO II data sample, with an integrated luminosity of 1.8 fb−1 at and near the Υ(4S) resonance, we have observed a signal for D0→K+π−, which could be due to either D0D¯0 mixing or doubly Cabibbo suppressed decay, or a combination of the two. We find scrB(D0→K+π−)/scrB(D0→K−π+)=0.0077±0 .0025(stat) ±0.0025(syst).Received 2 December 1993DOI:https://doi.org/10.1103/PhysRevLett.72.1406©1994 American Physical Society

We report the first observation of exclusive decays of the type B-->D(*)N_NX, where N is a nucleon. Using a sample of 9.7x10(6)B_B pairs collected with the CLEO detector operating at the Cornell Electron Storage Ring, we measure the branching fractions B(B0-->D(*-)p_p pi(+)) = (6.5(+1.3)(-1.2)+/-1.0)x10(-4) and B(B0-->D(*-)p_n) = (14.5(+3.4)(-3.0)+/-2.7)x10(-4). Antineutrons are identified by their annihilation in the CsI electromagnetic calorimeter.

We have studied inclusive D*± production using the DELCO detector at PEP. Our technique involved kaon identification in the momentum range above 3.2 GeV/c using a threshold gas Čerenkov counter. This leads to a model-independent upper limit on D0−D¯0 mixing of 8.1% (90% confidence level). We also have measured the charm fragmentation function, which peaks at x≡PD*(Ebeam2−MD*2)12 of 0.56±0.06(stat.), and the total cross section for D* production, σ(D*±)=0.140±0.021(stat.)±0.032(syst.) nb (x>0.3, with radiative correction).Received 5 November 1984DOI:https://doi.org/10.1103/PhysRevLett.54.522©1985 American Physical Society

Using 9.0 fb -1 of integrated luminosity in e + e -collisions near the Υ(4S) mass collected with the CLEO II.V detector we report the first observation of the decay D 0 → K 0 S ηπ 0 .We measure the ratio of branching fractions, BR(D 0 →K 0 S ηπ 0 ) BR(D 0 →K 0 S π 0 ) = 0.46 ± 0.07 ± 0.06.We perform a Dalitz analysis of 155 selected D 0 → K 0 S ηπ 0 candidates and find leading contributions from a 0 (980)K 0 S and K * (892)η intermediate states.

Using of data collected with the CLEO-c detector, we report on first observations and measurements of Cabibbo-suppressed decays of D mesons in the following six decay modes: pi+ pi- pi0 pi0, pi+ pi+ pi- pi- pi0, pi+ pi0 pi0, pi+ pi+ pi- pi0, eta pi0, and omega pi+ pi-. Improved branching fraction measurements in eight other multipion decay modes are also presented. The measured D --> pi pi rates allow us to extract the ratio of isospin amplitudes A(DeltaI = (3/2) / A(DeltaI = (1/2)) = 0.420 +/- 0.014(stat) +/- 0.016(syst) and the strong phase shift of delta1 = (86.4 +/- 2.8 +/- 3.3) degrees, which is quite large and now more precisely determined.

It is shown that helicity is conserved in the t-channel for A1 and Q-meson production by pions of 8 and 16 GeV/c and kaons of 10 GeV/c, respectively. This is in contrast to evidence for s-channel helicity conservation reported for elastic scattering and rho photoproduction. This difference in behaviour of diffractive processes may be due to the fact that there is a change in spin in the former reactions but not in the latter, or, alternatively, to different mechanisms operating in the two cases.

Lambda production is studied in K−p interactions at 10.1 GeV/c, where the dominant reaction is K−p → Λ + pions. General characteristics such as the distributions of the double differential cross section in the lab system, of the variable x = pL∗pmax∗, of p⊥2 and of the missing mass to the lambda are presented. Total cross sections for Λ production and for the various channels are given. Differential cross sections dσdt, dσdt′ and dσdu′ are presented. Forward and backward peaks are observed in the dσdt′ and dσdu′ distributions, respectively. It is found that the exponential slope of these distributions decreases with increasing missing mass to the lambda and, for dσdt′, also for increasing multiplicity in the final state. The polarization of the lambdas is studied as a function of multiplicity, pL∗, (Λπ±) effective mass, t′ and u′. The forward lambdas show

A search for the lepton-family-number-violating decays →e␥ and →␥ has been performed using CLEO II data.No evidence of a signal has been found and the corresponding upper limits are B(→e␥)Ͻ2.7ϫ10Ϫ6 and B(→␥)Ͻ3.0ϫ10Ϫ6 at 90% C.L. ͓S0556-2821͑97͒50207-4͔

Using data collected with the CLEO II detector at the Cornell Electron Storage Ring, we have studied the decays of leptons produced through e ϩ e Ϫ annihilation into final states containing K S 0 mesons, observed through their decays to ϩ Ϫ .We present branching fractions for decays to five final states: Ϫ →K 0 h Ϫ , Ϫ →K 0 h Ϫ 0 , Ϫ →K 0 K Ϫ , Ϫ →K 0 K Ϫ 0 , and Ϫ →K S 0 K S 0 h Ϫ , where K 0 h Ϫ denotes the sum of the processes involving K ¯0 Ϫ and K 0 K Ϫ particle combinations.Substructure and mass spectra in these final states are also addressed.

The construction and performance of the barrel pre-series module 0 of the future ATLAS electromagnetic calorimeter at the LHC is described. The signal reconstruction and performance of ATLAS-like electronics has been studied. The signal to noise ratio for muons has been found to be 7.11±0.07. An energy resolution of better than 9.5%GeV1/2/E (sampling term) has been obtained with electron beams of up to 245GeV. The uniformity of the response to electrons in an area of Δη×Δφ=1.2×0.075 has been measured to be better than 0.8%.

The angular distributions of the decay Λ+c→Λe+νe have been studied using the CLEO II detector. By performing a three-dimensional maximum likelihood fit, the form factor ratio R=f2/f1 is determined to be −0.25±0.14±0.08. The decay asymmetry parameter of the Λc averaged over q2 is calculated to be αΛc=−0.82+0.09+0.06−0.06−0.03.Received 13 January 1995DOI:https://doi.org/10.1103/PhysRevLett.75.624©1995 American Physical Society

Using the CLEO II detector at CESR, we observe 500 $\Lambda l^+$ pairs consistent with the semileptonic decay $\Lambda_c \to \Lambda l^+ \nu_{l}$. We measure $\sigma (e^+ e^- \to \Lambda_c X) \dot {cal B}(\Lambda_c^+ \to \Lambda l \nu_{l}) =4.77 \pm 0.25 \pm 0.66 $pb. Combining with the charm semileptonic width and the lifetime of the $\Lambda_c$, we also obtain ${\cal B}(\Lambda_c \to p K^- \pi^+)$. We find no evidence for $\Lambda l^+ \nu_{l}$ final states in which there are additional $\Lambda_c^+$ decay products. We measure the decay asymmetry parameter of $\Lambda_c \to \Lambda l^+ \nu_{l}$ to be $\alpha_{\Lambda_c} =-0.89\pm{^{0.17}_{0.11}}\pm{^{0.09}_{0.06}}.

two typographical errors in Table I of our Letter: In the ninth row of Table I for the K 2 1430, the phase should read 335 not 155.In the eleventh row of Table I for the nonresonant, the phase should read 340 not 160.

Using the decay modes, ${\mathit{D}}^{\mathrm{*}+}$\ensuremath{\rightarrow}${\mathit{D}}^{+}$${\mathrm{\ensuremath{\pi}}}^{0}$ and ${\mathit{D}}^{\mathrm{*}0}$\ensuremath{\rightarrow}${\mathit{D}}^{0}$${\mathrm{\ensuremath{\pi}}}^{0}$, we have measured the ${\mathit{D}}^{\mathrm{*}+\mathrm{\ensuremath{-}}}$${\mathit{D}}^{+}$ and ${\mathit{D}}^{\mathrm{*}0\mathrm{\ensuremath{-}}}$${\mathit{D}}^{0}$ mass differences to be 140\ifmmode\pm\else\textpm\fi{}0.08\ifmmode\pm\else\textpm\fi{}0.06 and 142.12\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.05 MeV, respectively. Combining these measurements with the Particle Data Group average for the ${\mathit{D}}^{\mathrm{*}+\mathrm{\ensuremath{-}}}$${\mathit{D}}^{0}$ mass difference, we obtain isospin mass splittings for ${\mathit{D}}^{\mathrm{*}+\mathrm{\ensuremath{-}}}$Dusp*0 and ${\mathit{D}}^{+\mathrm{\ensuremath{-}}}$${\mathit{D}}^{0}$ of 3.32\ifmmode\pm\else\textpm\fi{}0.08\ifmmode\pm\else\textpm\fi{}0.05 and 4.80\ifmmode\pm\else\textpm\fi{}0.10 \ifmmode\pm\else\textpm\fi{}0.06 MeV. We discuss the implications of these measurements for models of isospin mass differences and model-dependent estimates of ${\mathit{f}}_{\mathit{D}}$.

We present a measurement of the lepton decay asymmetry ${\mathit{A}}_{\mathrm{fb}}$ in the reaction B\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}}$${\mathit{l}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\nu}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}_{\mathit{l}}$ using data collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR). The value of ${\mathit{A}}_{\mathrm{fb}}$ confirms that the chirality of the weak interaction is predominantly left-handed in b\ensuremath{\rightarrow}c transitions as expected in the standard model, if it is assumed that the lepton current is also left-handed. Using ${\mathit{A}}_{\mathrm{fb}}$ and the previously determined branching ratio, ${\mathit{q}}^{2}$ distribution, and ${\mathit{D}}^{\mathrm{*}}$ polarization, we obtain the first measurement of the form-factor ratios that are used to describe this semileptonic decay.

Using the CLEO II detector at the Cornell Electron Storage Ring, we have determined the inclusive ${\mathit{B}}^{\mathrm{*}}$ cross section above the \ensuremath{\Upsilon}(4S) resonance in the energy range from 10.61 to 10.70 GeV. We also report a new measurement of the energy of the ${\mathit{B}}^{\mathrm{*}}$\ensuremath{\rightarrow}B\ensuremath{\gamma} transition photon of 46.2\ifmmode\pm\else\textpm\fi{}0.3\ifmmode\pm\else\textpm\fi{}0.8 MeV.

Using data collected by the CLEO detector in the Upsilon(4S) region, we report new measurements of the exclusive decays of B mesons into final states of the type Lambda_c^+ p-bar n(pi), where n=0,1,2,3. We find signals in modes with one, two and three pions and an upper limit for the two body decay Lambda_c^+ pbar. We also make the first measurements of exclusive decays of B mesons to Sigma_c p-bar n(pi), where n=0,1,2. We find signals in modes with one and two pions and an upper limit for the two body decay Sigma_c p-bar. Measurements of these modes shed light on the mechanisms involved in B decays to baryons.

Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay lambda(+)(c)lambda--> e(+)nu(e). By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R= f(2)/f(1) = -0.31 +/- 0.05(stat) +/- 0.04(syst), the pole mass, M(pole) = [2.21 +/- 0.08(stat) +/- 0.14(syst)] GeV/c(2), and the decay asymmetry parameter of the lambda(+)(c), alpha (lambda(c)) = -0.86 +/-0.03(stat) +/- 0.02(syst), for q(2) = 0.67 (GeV/c(2))(2). We compare the angular distributions of the lambda(+)(c) and lambda(-)(c) and find no evidence for CP violation: A(lambda(c)) = (alpha(lambda(c)) + alpha (lambda(c)))/(alpha(lambda(c))-alpha(lambda(c))) = 0.00 +/- 0.03(stat) +/- 0.01(syst) +/- 0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A(lambda), for ppi(-).

In e+e− collisions recorded using the CLEO II.V detector we have studied the Cabibbo suppressed decay of D0→π+π−π0 with the initial flavor of the D0 tagged by the decay D*+→D0π+. We use the Dalitz-plot analysis technique to measure the resonant substructure in this final state and observe ρπ and nonresonant contributions by fitting for their amplitudes and relative phases. We describe the ππ S wave with a K-matrix formalism and limit this contribution to the rate to be <2.5%@95% confidence level, in contrast to the large rate observed in D+→π+π−π+ decay. Using the amplitudes and phases from this analysis, we calculate an integrated CP asymmetry of 0.01+0.09−0.07±0.05.Received 29 March 2005Corrected 6 June 2007DOI:https://doi.org/10.1103/PhysRevD.72.031102©2005 American Physical Society

In the years between 2000 and 2002 several pre-series and series modules of the ATLAS EM barrel and end-cap calorimeter were exposed to electron, photon and pion beams. The performance of the calorimeter with respect to its finely segmented first sampling has been studied. The polar angle resolution has been found to be in the range 50–60 (mrad)/E(GeV). The π0 rejection has been measured to be about 3.5 for 90% photon selection efficiency at pT=50GeV/c. e–π separation studies have indicated that a pion fake rate of (0.07–0.5)% can be achieved while maintaining 90% electron identification efficiency for energies up to 40 GeV.

Using the CLEO II.V detector observing ${e}^{+}{e}^{\ensuremath{-}}$ collisions at around 10.6 GeV we search for neutral $D$ mixing in semileptonic ${D}^{0}$ decays tagged in charged ${D}^{*}$ decays. Combining the results from the $Ke\ensuremath{\nu}$ and ${K}^{*}e\ensuremath{\nu}$ channels we find that the rate for $D$ mixing is less than 0.0078 at $90%$ C.L.

Abstract The production of prompt electron-positron pairs in 16 GeV/c π−p collisions has been measured using the LASS spectrometer at SLAC. An excess of events is observed above the estimated contributions of direct and Dalitz decay of known resonances in the kinematic range defined by 0.1⩽x⩽0.45, 0⩽pT⩽0.8 GeV/c and 0.2⩽M(e+e−)⩽0.7 GeV/c2. The excess signal decreases slowly with increasing M, but exhibits very steep x and pT2 dependence. The contribution of this signal to the e+e− and γ/π ratios is discussed. Detailed comparisons are made between e+e− distributions and the corresponding low-mass μ+μ− distributions, and a simple production mechanism is proposed which describes the 16 GeV/c data well. The implications for direct photon production are presented, and it is shown that the model provides simultaneously a good description of the experimental data on the (e/π) and (μ/π) ratios for pT

A sample of events enriched with bb production is obtained with the DELCO detector at PEP and is used to measure the mean multiplicity and spectra of charged particles in bottom-quark jets. Bottom-quark jets are found to be significantly softer and more spherical than jets in general hadronic events.

Results are reported from a study of the impact parameters of electrons in hadronic events produced at the PEP ${e}^{+}{e}^{\ensuremath{-}}$ storage ring. Electrons in hadronic events are produced by bottom and charm decay and their impact parameters show hadrons containing bottom quarks to have a lifetime of ${1.16}_{\ensuremath{-}0.34}^{+0.37}$(stat.) \ifmmode\pm\else\textpm\fi{}0.23 (syst.) psec. This result is used to constrain elements of the Kobayashi-Maskawa mixing matrix.

Using data taken with the CLEO III detector at the Cornell Electron Storage Ring, we have investigated the direct photon spectrum in the decays $\ensuremath{\Upsilon}(1\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}gg$, $\ensuremath{\Upsilon}(2\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}gg$, $\ensuremath{\Upsilon}(3\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}gg$. The latter two of these are first measurements. Our analysis procedures differ from previous ones in the following ways: (a) background estimates (primarily from ${\ensuremath{\pi}}^{0}$ decays) are based on isospin symmetry rather than a determination of the ${\ensuremath{\pi}}^{0}$ spectrum, which permits measurement of the $\ensuremath{\Upsilon}(2\mathrm{S})$ and $\ensuremath{\Upsilon}(3\mathrm{S})$ direct photon spectra without explicit corrections for ${\ensuremath{\pi}}^{0}$ backgrounds from, e.g., ${\ensuremath{\chi}}_{bJ}$ states, (b) we estimate the branching fractions with a parametrized functional form (exponential) used for the background, and c) we use the high-statistics sample of $\ensuremath{\Upsilon}(2\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\Upsilon}(1\mathrm{S})$ to obtain a tagged sample of $\ensuremath{\Upsilon}(1\mathrm{S})\ensuremath{\rightarrow}\ensuremath{\gamma}+X$ events, for which there are no QED backgrounds. We determine values for the ratio of the inclusive direct photon decay rate to that of the dominant three-gluon decay $\ensuremath{\Upsilon}\ensuremath{\rightarrow}ggg\text{ }\text{ }({R}_{\ensuremath{\gamma}}=B(gg\ensuremath{\gamma})/B(ggg))$ to be ${R}_{\ensuremath{\gamma}}(1\mathrm{S})=(2.70\ifmmode\pm\else\textpm\fi{}0.01\ifmmode\pm\else\textpm\fi{}0.13\ifmmode\pm\else\textpm\fi{}0.24)%$, ${R}_{\ensuremath{\gamma}}(2\mathrm{S})=(3.18\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\pm\else\textpm\fi{}0.22\ifmmode\pm\else\textpm\fi{}0.41)%$, and ${R}_{\ensuremath{\gamma}}(3\mathrm{S})=(2.72\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\pm\else\textpm\fi{}0.32\ifmmode\pm\else\textpm\fi{}0.37)%$, where the errors shown are statistical, systematic, and theoretical model dependent, respectively. Given a value of ${Q}^{2}$, one can estimate a value for the strong coupling constant ${\ensuremath{\alpha}}_{s}({Q}^{2})$ from ${R}_{\ensuremath{\gamma}}$.

We evaluate the partial widths for internal conversions in the Higgs decays to two photons. For the Higgs masses of interest at the CERN LHC in the range of 100--150 GeV, the conversions to pairs of fermions represent a significant fraction of Higgs decays.

Using the current world's largest data sample of $\ensuremath{\psi}(3770)$ decays, we present results of a search for the non-$D\overline{D}$ decay $\ensuremath{\psi}(3770)\ensuremath{\rightarrow}{K}_{S}^{0}{K}_{L}^{0}$. We find no signal, and obtain an upper limit of $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\psi}(3770)\ensuremath{\rightarrow}{K}_{S}^{0}{K}_{L}^{0})&lt;0.07\text{ }\text{ }\mathrm{pb}$ at 90% confidence level (CL). Our result tests a theoretical prediction for the upper bound on $\mathcal{B}(\ensuremath{\psi}(3770)\ensuremath{\rightarrow}{K}_{S}^{0}{K}_{L}^{0})$ based on a charmonia-mixing model.

High statistics data for the reaction K−p→K−π+n have been obatined using the LASS spectrometer at SLAC. An energy independent partial wave analysis of these data yields unique K−π+ elastic scatering partila wave amplitudes in the Kπ invariant mass region from 0.7 GeV to 1.8 GeV, and two distinguishable sets of amplitudes between 1.8 GeV and 2.3 GeV. Besides the three “old” K∗ resonances [JP = 1−K∗(892), 2+K∗(1430), 3−K∗(1780)] these partial waves display evidence for a K∗ resonance with JP=4+ near 2.07 GeV. The energy dependence of the S wave amplitude confirms the existence of a resonant 0+ state in the 1.4 GeV region [the k(1500)], and provides evidence for a new high-mass S wave resonance [′'(1850)] near 1.85 GeV. Resonant behavior is also observed in the P wave amplitude around 1.7 GeV.

A comparison is made of the low-mass three-meson systems (πππ), (Kππ), (πKK) and (KKK) diffractively produced in the reaction meson + proton → three mesons + proton. Several striking similarities and a few important differences are observed: (i) the reactions are consistent with the assumption that the three mesons decay entirely into a 0− meson and a 0+, 1− or 2+ resonance; (ii) the three-meson mass spectra have a peak ≈ 250 MeV above the effective threshold Meff of the dominant decay mode and then fall off approximately as (mass)−3;(iii) the average spin 〈J〉 = 0.55 + 1.1 Qeff, where Qeff = M - Meff; (iv) the average orbital angular momentum 〈l〉 increases according to 〈l〉 = 0.75 Qeff; (v) the three-meson states are produced dominantly in unnatural spin-parity states and no evidence for their being resonant is found; (vi) the only natural spin-parity states found are the well-established 2+ resonances A2 and K∗ (1420); they have similar properties to the non-resonant unnatural parity states except for a dip at t = 0 in the dσ/dt distributions; (vii) both the unnatural and natural spin-parity states are produced mostly by an exchange of natural parity; (viii) there is evidence for two types of production mechanism with different polarization properties, one approximately conserving helicity in the t-channel and the other in the s-channel.

The ATLAS detector has been built to study the reactions produced by the Large Hadron Collider (LHC). ATLAS includes a system of liquid argon calorimeters for energy measurements. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on a set of front-end electronic boards. The front-end boards are installed in crates mounted between the calorimeters, where they will be subjected to significant levels of radiation during LHC operation. As a result, all components used on the front-end boards had to be subjected to an extensive set of radiation qualification tests. This paper describes radiation-tolerant designs, radiation testing, and radiation qualification of the front-end readout system for the ATLAS liquid argon calorimeters.

Using the CLEO II detector at CESR, we have observed two charmed states, where the higher mass state decays to D0π+ and to D∗0π+, while the lower mass state decays to D∗0π+, but not to D0π+. The masses and widths were measured to be 2425±2±2 MeV/c2 and 26−7−4+8+4 MeV/c2 for the lower mass state, and 2463±3±3 MeV/c2 and 27−8−5+11+5 MeV/c2 for the higher mass state. Properties of these states, including their decay angular distributions and spin-parity assignments have been studied. The results of this analysis support the identification of these states as the charged L = 1 D1 (2420)+ and D2∗ (2460)+, respectively. The isospin mass splittings between these states and their neutral partners have also been measured. This is the first full reconstruction of any decay mode of the D1 (2420)+ and the first observation of the decay of D2∗ (2460)+ to D∗0π+.

Branching ratios for the dominant Cabibbo-suppressed decays of the $\ensuremath{\tau}$ lepton have been measured by CLEO II in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation at the Cornell Electron Storage Ring ($\sqrt{s}\ensuremath{\sim}10.6$ GeV) using kaons with momenta below 0.7 GeV/c. The inclusive branching ratio into one charged kaon is (1.60 \ifmmode\pm\else\textpm\fi{} 0.12 \ifmmode\pm\else\textpm\fi{} 0.19)%. For the exclusive decays, $B({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\nu}}_{\ensuremath{\tau}})=(0.66\ifmmode\pm\else\textpm\fi{}0.07\ifmmode\pm\else\textpm\fi{}0.09)%$, $B({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\nu}}_{\ensuremath{\tau}})=(0.51\ifmmode\pm\else\textpm\fi{}0.10\ifmmode\pm\else\textpm\fi{}0.07)%$, and, based on three events, $B({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}2{\ensuremath{\pi}}^{0}{\ensuremath{\nu}}_{\ensuremath{\tau}})&lt;0.3%$ at the 90% confidence level. These represent significant improvements over previous results. $B({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\nu}}_{\ensuremath{\tau}})$ is measured for the first time with exclusive ${\ensuremath{\pi}}^{0}$ reconstruction.

The branching fractions for $\ensuremath{\tau}\ensuremath{\rightarrow}e\ensuremath{\nu}{\ensuremath{\nu}}_{\ensuremath{\tau}},$ $\ensuremath{\mu}\ensuremath{\nu}{\ensuremath{\nu}}_{\ensuremath{\tau}},$ and $h{\ensuremath{\nu}}_{\ensuremath{\tau}}$ are measured using data collected with the CLEO detector at the CESR ${e}^{+}{e}^{\ensuremath{-}}$ collider: ${\mathcal{B}}_{e}$=0.1776$\ifmmode\pm\else\textpm\fi{}$0.0006$\ifmmode\pm\else\textpm\fi{}$0.0017, ${\mathcal{B}}_{\ensuremath{\mu}}$=0.1737$\ifmmode\pm\else\textpm\fi{}$0.0008$\ifmmode\pm\else\textpm\fi{}$0.0018, and ${\mathcal{B}}_{h}$=0.1152$\ifmmode\pm\else\textpm\fi{}$0.0005$\ifmmode\pm\else\textpm\fi{}$0.0012, where the first error is statistical, the second systematic, and $h$ refers to either a charged $\ensuremath{\pi}$ or $K$. Also measured is the $\ensuremath{\tau}$ mass, ${m}_{\ensuremath{\tau}}$=(1778.2$\ifmmode\pm\else\textpm\fi{}$1.4) MeV. Lepton universality is affirmed by the relative branching fractions $({\mathcal{B}}_{\ensuremath{\mu}}$/${\mathcal{B}}_{e}$=0.9777$\ifmmode\pm\else\textpm\fi{}$0.0063$\ifmmode\pm\else\textpm\fi{}$0.0087, ${\mathcal{B}}_{h}$/${\mathcal{B}}_{e}$=0.6484$\ifmmode\pm\else\textpm\fi{}$0.0041$\ifmmode\pm\else\textpm\fi{}$0.0060) and the charged-current gauge coupling-constant ratios ${(g}_{\ensuremath{\mu}}{/g}_{e}$=1.0026$\ifmmode\pm\else\textpm\fi{}$0.0055, ${g}_{\ensuremath{\tau}}{/g}_{\ensuremath{\mu}}$=0.9990$\ifmmode\pm\else\textpm\fi{}$0.0098). The $\ensuremath{\tau}$ mass result may be recast as a $\ensuremath{\tau}$ neutrino mass limit, ${m}_{{\ensuremath{\nu}}_{\ensuremath{\tau}}}&lt;$60 MeV at 95% C.L.

We have observed five new decay modes of the charmed baryon ${\ensuremath{\Lambda}}_{c}^{+}$ using data collected with the CLEO II detector. Four decay modes, ${\ensuremath{\Lambda}}_{c}^{+}\ensuremath{\rightarrow}p{\overline{K}}^{0}\ensuremath{\eta}$, $\ensuremath{\Lambda}\ensuremath{\eta}{\ensuremath{\pi}}^{+}$, ${\ensuremath{\Sigma}}^{+}\ensuremath{\eta}$, and ${\ensuremath{\Sigma}}^{*+}\ensuremath{\eta}$, are first observations of final states with an $\ensuremath{\eta}$ meson, while the fifth mode, ${\ensuremath{\Lambda}}_{c}^{+}\ensuremath{\rightarrow}\ensuremath{\Lambda}{\overline{K}}^{0}{K}^{+}$, requires the creation of an $s\overline{s}$ quark pair. We measure the branching fractions of these modes relative to ${\ensuremath{\Lambda}}_{c}^{+}\ensuremath{\rightarrow}{\mathrm{pK}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ to be $0.25\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\pm\else\textpm\fi{}0.04$, $0.35\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.06$, $0.11\ifmmode\pm\else\textpm\fi{}0.03\ifmmode\pm\else\textpm\fi{}0.02$, $0.17\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\pm\else\textpm\fi{}0.03$, and $0.12\ifmmode\pm\else\textpm\fi{}0.02\ifmmode\pm\else\textpm\fi{}0.02$, respectively.

A limit on the tau neutrino mass Mντ is obtained from a study of tau decays in the reaction e+e−→τ+τ− at center-of-mass energies ∼10.6 GeV. The result is based on an end-point analysis of the invariant mass spectrum of the decay products in the decay modes τ−→3h−2h+ντ and τ−→2h−h+2π0ντ. The data sample used in this analysis contains 1.77×106 tau pairs, corresponding to an integrated luminosity of 1.92 fb−1, and is substantially larger than previous data samples used to place a limit on Mντ. The limit obtained for both five-hadron modes together is 32.6 MeV at 95% C.L.Received 1 March 1993DOI:https://doi.org/10.1103/PhysRevLett.70.3700©1993 American Physical Society

We report new measurements of the differential and total branching ratios for inclusive B decay to D^0, D^+ and D^{*+} and the first measurement of the same quantities for inclusive B decay to $D^{*0}$. Here B is the mixture of B_d and B_u from $\Upsilon(4S)$ decay. Furthermore, since more than one charm particle (or antiparticle) of the same kind can be produced in B decay, here ``inclusive B branching ratio'' is used to mean the average number of charm particles and their antiparticles of a certain species produced in B decay. We obtain the following results (the first error is statistical, the second systematic of this analysis, the third is propagated from other measurements): ${\cal B}(B\to D^0 X) = (0.636\pm 0.014\pm 0.019\pm 0.018), {\cal B}(B\to D^+ X) = (0.235\pm 0.009\pm 0.009\pm 0.024), {\cal B}(B\to D^{*0} X) = (0.247\pm 0.012\pm 0.018\pm 0.018), {\cal B}(B\to D^{*+} X) = (0.239\pm 0.011\pm 0.014\pm 0.009)$. The following ratio of branching ratios is not affected by most of the systematic errors: ${\cal B}(B\to D^{*0} X)/{\cal B}(B\to D^{*+} X) = (1.03\pm 0.07\pm 0.09\pm 0.08).$ We also report the first measurement of the momentum-dependent $D^{*0}$ polarization and a new measurement of the $D^{*+}$ polarization in inclusive B decay. Using these measurements and other CLEO results and making some additional assumptions, we calculate the average number of c and $\bar c$ quarks produced in B decay to be $< n_c > = 1.10\pm 0.05$.

We present an observation and time-integrated rate measurement of the decay ${D}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ produced in $9{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ collisions near the $\ensuremath{\Upsilon}(4S)$ resonance. The signal is inconsistent with an upward fluctuation of the background by 4.9 standard deviations. We measured the time-integrated rate of ${D}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ normalized to the rate of $\overline{{D}^{0}}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ to be ${0.0043}_{\ensuremath{-}0.0010}^{+0.0011}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.0007(\mathrm{syst})$. This decay can be produced by doubly Cabibbo-suppressed decays or by the ${D}^{0}$ evolving into a $\overline{{D}^{0}}$ through mixing, followed by a Cabibbo-favored decay to ${K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$. We also found the $\mathrm{CP}$ asymmetry $A\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({9}_{\ensuremath{-}22}^{+25})%$ be consistent with zero.