Alain Bellerive

The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) 8B solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27(stat)+/-0.38(syst) x 10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Deltam(2)=7.1(+1.2)(-0.6) x 10(-5) eV(2) and theta=32.5(+2.4)(-2.3) degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.

Using the CLEO II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons ${\ensuremath{\pi}}^{0},$ \ensuremath{\eta}, and ${\ensuremath{\eta}}^{\ensuremath{'}}.$ From our measurements we have obtained the form factors associated with the electromagnetic transitions ${\ensuremath{\gamma}}^{*}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}\mathrm{meson}.$ We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and $30{\mathrm{GeV}}^{2}$ for ${\ensuremath{\pi}}^{0},$ \ensuremath{\eta}, and ${\ensuremath{\eta}}^{\ensuremath{'}},$ respectively, and have made comparisons to various theoretical predictions.

We report results from a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory. By exploiting particle identification information obtained from the proportional counters installed during the third phase, this analysis improved background rejection in that phase of the experiment. The combined analysis resulted in a total flux of active neutrino flavors from 8B decays in the Sun of (5.25 \pm 0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5} eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino oscillation analysis combining this result with results of all other solar neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} = (7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} = 0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} = (2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.).

The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) 8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54_-0.31;+0.33(stat)-0.34+0.36(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Deltam2=7.59_-0.21;+0.19x10(-5) eV2 and theta=34.4_-1.2;+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.

Results are reported from a joint analysis of Phase I and Phase II data from the Sudbury Neutrino Observatory. The effective electron kinetic energy threshold used is T_eff=3.5 MeV, the lowest analysis threshold yet achieved with water Cherenkov detector data. In units of 10^6 cm^{-2} s^{-1}, the total flux of active-flavor neutrinos from 8B decay in the Sun measured using the neutral current (NC) reaction of neutrinos on deuterons, with no constraint on the 8B neutrino energy spectrum, is found to be Phi_NC = 5.140 ^{+0.160}_{-0.158} (stat) ^{+0.132}_{-0.117} (syst). These uncertainties are more than a factor of two smaller than previously published results. Also presented are the spectra of recoil electrons from the charged current reaction of neutrinos on deuterons and the elastic scattering of electrons. A fit to the SNO data in which the free parameters directly describe the total 8B neutrino flux and the energy-dependent nu_e survival probability provides a measure of the total 8B neutrino flux Phi_8B = 5.046 ^{+0.159}_{-0.152} (stat) ^{+0.107}_{-0.123} (syst). Combining these new results with results of all other solar experiments and the KamLAND reactor experiment yields best-fit values of the mixing parameters of theta_{12}=34.06 ^{+1.16}_{-0.84} degrees and Delta m^2_{21}=7.59 ^{+0.20}_{-0.21} x 10^{-5} eV^2. The global value of Phi_8B is extracted to a precision of ^{+2.38}_{-2.95} %. In a three-flavor analysis the best fit value of sin^2\theta_{13} is 2.00 ^{+2.09}_{-1.63} x 10^{-2}. Interpreting this as a limit implies an upper bound of sin^2\theta_{13} < 0.057 (95% C. L.).

The Enriched Xenon Observatory (EXO) will search for double beta decays of 136Xe. We report the results of a systematic study of trace concentrations of radioactive impurities in a wide range of raw materials and finished parts considered for use in the construction of EXO-200, the first stage of the EXO experimental program. Analysis techniques employed, and described here, include direct gamma counting, alpha counting, neutron activation analysis, and high-sensitivity mass spectrometry.

CLEO has studied B decays to πℓν, ρℓν, and ωℓν, where ℓ=eorμ, by incorporating the missing momentum into full B reconstruction. With the B0 and B+ modes combined according to isospin predictions for the relative partial widths, we obtain B(B0→π−ℓ+ν)=(1.8±0.4±0.3±0.2)×10−4 and B(B0→ρ−ℓ+ν)=(2.5±0.4+0.5−0.7±0.5)×10−4, where the errors are statistical, systematic, and the estimated model dependence. We also estimate |Vub|=(3.3±0.2+0.3−0.4±0.7)×10−3.Received 1 July 1996DOI:https://doi.org/10.1103/PhysRevLett.77.5000©1996 American Physical Society

Based on a sample corresponding to 4.3 million produced tau-pair events, we have studied hadronic dynamics in the decay tau- --> nu_tau pi- pi0 pi0 in data recorded by the CLEO II detector operating at the CESR e+e- collider. The decay is dominated by the process tau --> nu_tau a_1(1260), with the a_1 meson decaying to three pions predominantly via the lowest dimensional (mainly S-wave) a_1 --> rho pi Born amplitude. From fits to the Dalitz plot and angular observables, we find significant additional contributions from amplitudes for a_1 decay to sigma pi, f_0(1370) pi and f_2(1270) pi, as well as higher dimensional a_1 --> rho pi and rho' pi amplitudes. The squared sigma pi amplitude accounts for ~15% of the total tau- --> nu_tau pi- pi0 pi0 rate in the models considered. We have searched for additional contributions from tau --> nu_tau pi'(1300). We place 90% confidence level upper limits on the branching fraction for this channel of between 1.0*10^{-4} and 1.9*10^{-4}, depending on the pi' decay mode. The pi- pi0 pi0 mass spectrum is parametrized by a Breit-Wigner form with a mass-dependent width which is specified according to the results of the Dalitz plot fits plus a coupling to an a_1 --> K* K amplitude. From a chi^2 fit, we extract the pole mass and width of the a_1, as well as the magnitude of the K* K coupling. We have also investigated the impact of a possible contribution from the a_1'(1700) meson on this spectrum. Finally, exploiting the parity-violating angular asymmetry in a_1 --> 3pi decay, we determine the signed value of the tau neutrino helicity to be h_{\nu_\tau} = -1.02 +- 0.13(stat.) +- 0.03(syst.+model), confirming the left-handedness of the tau neutrino.

We have searched for two-body charmless hadronic decays of $B$ mesons. Final states include $ππ$, $K π$, and $KK$ with both charged and neutral kaons and pions; $πρ$, $K ρ$, and $K^*π$; and $Kϕ$, $ K^*ϕ$, and $ϕϕ$. The data used in this analysis consist of 2.6~million $B\bar{B}$~pairs produced at the $Υ(4S)$ taken with the CLEO-II detector at the Cornell Electron Storage Ring (CESR). We measure the branching fraction of the sum of $B^0 \rightarrow π^+π^-$ and $B^0 \rightarrow K^+π^-$ to be $(1.8^{+0.6+0.2}_{-0.5-0.3}\pm0.2) \times 10^{-5}$. In addition, we place upper limits on individual branching fractions in the range from $10^{-4}$ to $10^{-6}$.

We study the exclusive semileptonic B meson decays ${\mathit{B}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}0}$${\mathit{l}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{} and B${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}+}$${\mathit{l}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{} using data collected with the CLEO II detector at the Cornell Electron-positron Storage Ring (CESR). We present measurements of the branching fractions scrB(B${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}+}$${\mathit{l}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{})= (0.5/${\mathit{f}}_{00}$)[4.49\ifmmode\pm\else\textpm\fi{}0.32(stat.)\ifmmode\pm\else\textpm\fi{}0.39 (syst.)]% and scrB(${\mathit{B}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}0}$${\mathit{l}}^{\mathrm{\ensuremath{-}}}$(\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{})= (0.5/${\mathit{f}}_{+\mathrm{\ensuremath{-}}}$)[5.13\ifmmode\pm\else\textpm\fi{}0.54 (stat) \ifmmode\pm\else\textpm\fi{}0.64 (syst)]%, where ${\mathit{f}}_{00}$ and ${\mathit{f}}_{+\mathrm{\ensuremath{-}}}$ are the neutral and charged B meson production fractions at the \ensuremath{\Upsilon}(4S) resonance, respectively. Assuming isospin invariance and taking the ratio of charged to neutral B meson lifetimes measured at higher energy machines, we determine the ratio ${\mathit{f}}_{+\mathrm{\ensuremath{-}}}$/${\mathit{f}}_{00}$=1.04\ifmmode\pm\else\textpm\fi{}0.13 (stat) \ifmmode\pm\else\textpm\fi{}0.12 (syst) \ifmmode\pm\else\textpm\fi{}0.10 (lifetime); further assuming ${\mathit{f}}_{+\mathrm{\ensuremath{-}}}$+${\mathit{f}}_{00}$=1 we also determine the partial width \ensuremath{\Gamma}(B\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}}$l\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{})=[29.9\ifmmode\pm\else\textpm\fi{}1.9 (stat) \ifmmode\pm\else\textpm\fi{}2.7 (syst.) \ifmmode\pm\else\textpm\fi{}2.0 (lifetime)] ${\mathrm{ns}}^{\mathrm{\ensuremath{-}}1}$ (independent of ${\mathit{f}}_{+\mathrm{\ensuremath{-}}}$/${\mathit{f}}_{00}$).From this partial width we calculate B\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}}$l\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{} branching fractions that do not depend on ${\mathit{f}}_{+\mathrm{\ensuremath{-}}}$/${\mathit{f}}_{00}$ or the individual B lifetimes, but only on the charged to neutral B lifetime ratio. The product of the CKM matrix element \ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{b}}$\ensuremath{\Vert} times the normalization of the decay form factor at the point of no recoil of the ${\mathit{D}}^{\mathrm{*}}$ meson, scrF(y=1), is determined from a linear fit to the combined differential decay rate of the exclusive B\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}}$l\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{} decays: \ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{b}}$\ensuremath{\Vert}scrF(1)=0.0351\ifmmode\pm\else\textpm\fi{}0.0019 (stat) \ifmmode\pm\else\textpm\fi{}0.0018 (syst) \ifmmode\pm\else\textpm\fi{}0.0008 (lifetime). The value for \ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{b}}$\ensuremath{\Vert} is extracted using theoretical calculations of the form factor normalization.

A study of b quark hadronisation is presented using inclusively reconstructed B hadrons in about four million hadronic Z decays recorded in 1992-2000 with the OPAL detector at LEP. The data are compared to different theoretical models, and fragmentation function parameters of these models are fitted. The average scaled energy of weakly decaying B hadrons is determined to be <xe>=0.7193+-0.0016(stat)+0.0036-0.0031(syst)

This paper details the solar neutrino analysis of the 385.17-day Phase-III data set acquired by the Sudbury Neutrino Observatory (SNO). An array of $^3$He proportional counters was installed in the heavy-water target to measure precisely the rate of neutrino-deuteron neutral-current interactions. This technique to determine the total active $^8$B solar neutrino flux was largely independent of the methods employed in previous phases. The total flux of active neutrinos was measured to be $5.54^{+0.33}_{-0.31}(stat.)^{+0.36}_{-0.34}(syst.)\times 10^{6}$ cm$^{-2}$ s$^{-1}$, consistent with previous measurements and standard solar models. A global analysis of solar and reactor neutrino mixing parameters yielded the best-fit values of $\Delta m^2 = 7.59^{+0.19}_{-0.21}\times 10^{-5}{eV}^2$ and $\theta = 34.4^{+1.3}_{-1.2}$ degrees.

This review paper provides a summary of the published results of the Sudbury Neutrino Observatory (SNO) experiment that was carried out by an international scientific collaboration with data collected during the period from 1999 to 2006. By using heavy water as a detection medium, the SNO experiment demonstrated clearly that solar electron neutrinos from $^8$B decay in the solar core change into other active neutrino flavors in transit to Earth. The reaction on deuterium that has equal sensitivity to all active neutrino flavors also provides a very accurate measure of the initial solar flux for comparison with solar models. This review summarizes the results from three phases of solar neutrino detection as well as other physics results obtained from analyses of the SNO data.

The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This document brings the story of the ILC up to date, emphasizing its strong physics motivation, its readiness for construction, and the opportunity it presents to the US and the global particle physics community.

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.

In a sample of $6.6\ifmmode\times\else\texttimes\fi{}{10}^{6}$ produced $B$ mesons we have observed decays $B\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}K$, with branching fractions $B({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{K}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({6.5}_{\ensuremath{-}1.4}^{+1.5}\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ and $B({B}^{0}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{K}^{0})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({4.7}_{\ensuremath{-}2.0}^{+2.7}\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. We have searched with comparable sensitivity for 17 related decays to final states containing an $\ensuremath{\eta}$ or ${\ensuremath{\eta}}^{\ensuremath{'}}$ meson accompanied by a single particle or low-lying resonance. Our upper limits for these constrain theoretical interpretations of the $B\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}K$ signal.

Photonic events with large missing energy have been observed in $\rm e^+e^-$ collisions at a centre-of-mass energy of 189 GeV using the OPAL detector at LEP. Results are presented for event topologies consistent with a single photon or with an acoplanar photon pair. Cross-section measurements are performed within the kinematic acceptance of each selection, and the number of light neutrino species is measured. Cross-section results are compared with the expectations from the Standard Model process $\mathrme^+\mathrme^-\to \nu\overline{\nu}$ + photon(s). No evidence is observed for new physics contributions to these final states. Upper limits on $\sigma(\mathrme^+\mathrme^-\to\mathrm{X}\mathrm{Y})\cdot\mathrm{BR}(\mathrm{X}\to\mathrm{Y}\gamma)$ and $\sigma(\mathrme^+\mathrme^-\to\mathrm{XX})\cdot\mathrm{BR}^2(\mathrm{X}\to\mathrm{Y}\gamma)$ are derived for the case of stable and invisible $\mathrm{Y}$ . These limits apply to single and pair production of excited neutrinos ( $\mathrm{X} = \nu^*, \mathrm{Y} = \nu$ ), to neutralino production ( $\mathrm{X}={{{\tilde{\chi}}^{0}}_{2}}, \mathrm{Y}={{{\tilde{\chi}}^{0}}_{1}}$ ) and to supersymmetric models in which $\mathrm{X} ={{{\tilde{\chi}}^{0}}_{1}}$ and $\mathrm{Y}={\tilde{\mathrm{G}}}$ is a light gravitino. The case of macroscopic decay lengths of particle X is considered for $\mathrme^+\mathrme^- \to \mathrm{XX}$ , $\rm X \to Y \gamma$ , when $M_{\mathrm Y}\approx 0$ . The single-photon results are also used to place upper limits on superlight gravitino pair production as well as graviton-photon production in the context of theories with additional space dimensions.

We have used the CLEO II detector and $2.06{\mathrm{fb}}^{\ensuremath{-}1}$ of $\ensuremath{\Upsilon}(4S)$ data to measure the $B$-meson semileptonic branching fraction. The $B\ensuremath{\rightarrow}\mathrm{Xe}\ensuremath{\nu}$ momentum spectrum was obtained over nearly the full momentum range by using charge and kinematic correlations in events with a high-momentum lepton tag and an additional electron. We find $B(B\ensuremath{\rightarrow}\mathrm{Xe}\ensuremath{\nu})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(10.49\ifmmode\pm\else\textpm\fi{}0.17\ifmmode\pm\else\textpm\fi{}0.43)%$, with overall systematic uncertainties less than those of untagged single-lepton measurements. We use this result to calculate the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element ${V}_{\mathrm{cb}}$ and to set an upper limit on the fraction of $\ensuremath{\Upsilon}(4S)$ decays to final states other than $B\overline{B}$.

A search has been made for neutrinos from the hep reaction in the Sun and from the diffuse supernova neutrino background (DSNB) using data collected during the first operational phase of the Sudbury Neutrino Observatory, with an exposure of 0.65 kilotonne-years. For the hep neutrino search, two events are observed in the effective electron energy range of 14.3 MeV

Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between $-1 \le \cos{\theta}_{\rm zenith} \le 0.4$ in a total exposure of 2.30\times 10^{14}$ cm$^{2}$ s. The measured flux normalization is $1.22 \pm 0.09$ times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle $\cos{\theta}_{\rm zenith} > 0.4$ is measured to be $(3.31 \pm 0.01 {\rm (stat.)} \pm 0.09 {\rm (sys.)}) \times 10^{-10}~\mu$/s/cm$^{2}$.

Neutron-antineutron oscillations in nature would violate baryon number and indicate a potential underlying mechanism for the observed matter-antimatter asymmetry. Sudbury Neutrino Observatory reports limits on neutron-antineutron oscillations for the first time in deuteron. These limits establish important constraints on beyond-the-Standard-Model scenarios that involve baryon-number violation.

We have used the CLEO-II detector at the Cornell Electron Storage Ringe (CESR) to study the inclusive production of charmonium mesons in a sample of 2.15 million BB¯ events. We find inclusive branching fractions of (1.12±0.04±0.06)% for B→J/ψX, (0.34±0.04±0.03)% for B→ψ′X, and (0.40±0.06±0.04)% for B→χc1X. We also find some evidence for the inclusive production of χc2, and set an upper limit for the branching fraction of the inclusive decay B→ηcX of 0.9% at 90% confidence level. Momentum spectra for inclusive J/ψ, ψ′, and χc1 production are presented. These measurements are compared to theoretical calculations.Received 13 December 1994DOI:https://doi.org/10.1103/PhysRevD.52.2661©1995 American Physical Society

A search for the Standard Model Higgs boson has been performed with the OPAL detector at LEP based on the full data sample collected at s≈192–209 GeV in 1999 and 2000, corresponding to an integrated luminosity of approximately 426 pb−1. The data are examined for their consistency with the background-only hypothesis and various Higgs boson mass hypotheses. A lower bound of 109.7 GeV is obtained on the Higgs boson mass at the 95% confidence level. At higher masses, the data are consistent with both the background and the signal-plus-background hypotheses.

A search for single top quark production via flavour changing neutral currents (FCNC) was performed with data collected by the OPAL detector at the e+e− collider LEP. Approximately 600 pb−1 of data collected at s=189–209 GeV were used to search for the FCNC process e+e−→tc(u)→bWc(u). This analysis is sensitive to the leptonic and the hadronic decay modes of the W boson. No evidence for a FCNC process is observed. Upper limits at the 95% confidence level on the single top production cross-section as a function of the centre-of-mass energy are derived. Limits on the anomalous coupling parameters κγ and κZ are determined from these results.

A search for stable and long-lived massive particles of electric charge |Q/e|=1 or fractional charges of 2/3, 4/3, and 5/3 is reported using data collected by the OPAL detector at LEP, at centre-of-mass energies from 130 to 209 GeV. These particles are assumed to be pair-produced in e+e− collisions and not to interact strongly. No evidence for the production of these particles was observed. Model-independent upper limits on the production cross-section between 0.005 and 0.028 pb have been derived for scalar and spin-1/2 particles with charge ±1. Within the framework of the Constrained Minimal Supersymmetric Standard Model (CMSSM), this implies a lower limit of 98.0 (98.5) GeV on the mass of long-lived right- (left-)handed scalar muons and scalar taus. Long-lived charged heavy leptons and charginos are excluded for masses below 102.0 GeV. For particles with fractional charge ±2/3, ±4/3 and ±5/3, the upper limit on the production cross-section varies between 0.005 and 0.020 pb. All mass and cross-section limits are derived at the 95% confidence level and are valid for particles with lifetimes longer than 10−6 s.

A search for pair-produced doubly charged Higgs bosons has been performed using data samples corresponding to an integrated luminosity of about 614 pb−1 collected with the OPAL detector at LEP at centre-of-mass energies between 189 GeV and 209 GeV. No evidence for a signal has been observed. A mass limit of 98.5 GeV/c2 at the 95% confidence level has been set for the doubly charged Higgs particle in left–right symmetric models. This is the first search for doubly charged Higgs bosons at centre-of-mass energies larger than 91 GeV.

Using data recorded by the CLEO-II detector at Cornell Electron Storage Ring (CESR), we report the first observation of a narrow state decaying into Ξ+cπ−. The state has mass difference M(Ξ+cπ−)−M(Ξ+c) of 178.2 ± 0.5 ± 1.0 MeV/c2, and a width of <5.5 MeV/c2 (90% confidence level limit). The most likely explanation of this new state is that it is the Ξ*0c, the JP=32+ spin excitation of the Ξ0c charmed baryon.Received 15 August 1995DOI:https://doi.org/10.1103/PhysRevLett.75.4364©1995 American Physical Society

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.

Hadronic event shape distributions from e+e- annihilation measured by the OPAL experiment at centre-of-mass energies between 91 GeV and 209 GeV are used to determine the strong coupling {\alpha}S. The results are based on QCD predictions complete to the next-to- next-to-leading order (NNLO), and on NNLO calculations matched to the resummed next-to-leading-log-approximation terms (NNLO+NLLA). The combined NNLO result from all variables and centre-of-mass energies is {\alpha}S(mZ0) = 0.1201 {\pm} 0.0008(stat.) {\pm} 0.0013(exp.) {\pm} 0.0010(had.) {\pm} 0.0024(theo.). while the combined NNLO+NLLA result is {\alpha}S(mZ0) = 0.1189 {\pm} 0.0008(stat.) {\pm} 0.0016(exp.) {\pm} 0.0010(had.) {\pm} 0.0036(theo.). The completeness of the NNLO and NNLO+NLLA results with respect to missing higher order contributions, studied by varying the renormalization scale, is improved compared to previous results based on NLO or NLO+NLLA predictions only. The observed energy dependence of {\alpha}S agrees with the QCD prediction of asymptotic freedom and excludes the absence of running.

The instantaneous luminosity of the Large Hadron Collider at CERN will be increased up to a factor of five with respect to the present design value by undergoing an extensive upgrade program over the coming decade. The most important upgrade project for the ATLAS Muon System is the replacement of the present first station in the forward regions with the so-called New Small Wheels (NSWs). The NSWs will be installed during the LHC long shutdown in 2018/19. Small-Strip Thin Gap Chamber (sTGC) detectors are designed to provide fast trigger and high precision muon tracking under the high luminosity LHC conditions. To validate the design, a full-size prototype sTGC detector of approximately 1.2 $\times$ $1.0\, \mathrm{m}^2$ consisting of four gaps has been constructed. Each gap provides pad, strip and wire readouts. The sTGC intrinsic spatial resolution has been measured in a $32\, \mathrm{GeV}$ pion beam test at Fermilab. At perpendicular incidence angle, single gap position resolutions of about $50\,\mathrm{\mu m}$ have been obtained, uniform along the sTGC strip and perpendicular wire directions, well within design requirements. Pad readout measurements have been performed in a $130\, \mathrm{GeV}$ muon beam test at CERN. The transition region between readout pads has been found to be $4\,\mathrm{mm}$, and the pads have been found to be fully efficient.

The long baseline between the Earth and the Sun makes solar neutrinos an excellent test beam for exploring possible neutrino decay. The signature of such decay would be an energy-dependent distortion of the traditional survival probability which can be fit for using well-developed and high precision analysis methods. Here a model including neutrino decay is fit to all three phases of $^8$B solar neutrino data taken by the Sudbury Neutrino Observatory. This fit constrains the lifetime of neutrino mass state $\nu_2$ to be ${>8.08\times10^{-5}}$ s/eV at $90\%$ confidence. An analysis combining this SNO result with those from other solar neutrino experiments results in a combined limit for the lifetime of mass state $\nu_2$ of ${>1.04\times10^{-3}}$ s/eV at $99\%$ confidence.

The ILD detector is proposed for an electron-positron collider with collision centre-of-mass energies from 90~\GeV~to about 1~\TeV. It has been developed over the last 10 years by an international team of scientists with the goal to design and eventually propose a fully integrated detector, primarily for the International Linear Collider, ILC. In this report the fundamental ideas and concepts behind the ILD detector are discussed and the technologies needed for the realisation of the detector are reviewed. The document starts with a short review of the science goals of the ILC, and how the goals can be achieved today with the detector technologies at hand. After a discussion of the ILC and the environment in which the experiment will take place, the detector is described in more detail, including the status of the development of the technologies foreseen for each subdetector. The integration of the different sub-systems into an integrated detector is discussed, as is the interface between the detector and the collider. This is followed by a concise summary of the benchmarking which has been performed in order to find an optimal balance between performance and cost. To the end the costing methodology used by ILD is presented, and an updated cost estimate for the detector is presented. The report closes with a summary of the current status and of planned future actions.

Using a sample of 3.3×106 Υ(4S)→B¯B events collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we measure B(→Bρlν), |Vub|, and the partial rate (ΔΓ) in three bins of q2≡(pB−pρ)2. We find B(B0→ρ−l+ν)=(2.69±0.41+0.35−0.40±0.50)×10−4, |Vub|=(3.23±0.24+0.23−0.26±0.58)×10−3, ΔΓ(0<q2<7GeV2/c4)=(7.6±3.0+0.9−1.2±3.0)×10−2ns−1, ΔΓ(7<q2<14GeV2/c4)=(4.8±2.9+0.7−0.8±0.7)×10−2ns−1, and ΔΓ(14<q2<21GeV2/c4)=(7.1±2.1+0.9−1.1±0.6)×10−2ns−1. Here, l=e or μ, but not both, and the errors are statistical, systematic, and theoretical. The method is sensitive primarily to →Bρlν decays with leptons in the energy range above 2.3 GeV. Averaging with the previously published CLEO results for →Bρlν, we obtain B(B0→ρ−l+ν)=(2.57±0.29+0.33−0.46±0.41)×10−4 and |Vub|=(3.25±0.14+0.21−0.29±0.55)×10−3. Received 24 May 1999DOI:https://doi.org/10.1103/PhysRevD.61.052001©2000 American Physical Society

Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to ''invisible'' modes, such as n ! 3. The analysis was based on a search for rays from the deexcitation of the residual nucleus that would result from the disappearance of either a proton or neutron from 16 O.A limit of inv > 2 10 29 yr is obtained at 90% confidence for either neutron-or proton-decay modes.This is about an order of magnitude more stringent than previous constraints on invisible proton-decay modes and 400 times more stringent than similar neutron modes.

We consider the decay of \ensuremath{\Upsilon}(1S) particles produced at CESR into a photon which is observed by the CLEO detector plus particles which are not seen. These could be real particles which fall outside of our acceptance, or particles which are noninteracting. We report the results of our search fo the process \ensuremath{\Upsilon}(1S)\ensuremath{\rightarrow}\ensuremath{\gamma}+``unseen'' for photon energies &gt;1 GeV, obtaining limits for the case where ``unseen'' is either a single particle or a particle-antiparticle pair. Our upper limits represent the highest sensitivity measurements for such decays to date.

Author(s): Aharmim, B.; Ahmed, S.N.; Anthony, A.E.; Beier, E.W.; Bellerive, A.; Bergevin, M.; Biller, S.D.; Boger, J.; Boulay, M.G.; Bowler, M.G.; Bullard, T.V.; Chan, Y.D.; Chen, M.; Chen, X.; Cleveland, B.T.; Cox, G.A.; Currat, C.A.; Dai, X.; Dalnoki-Veress, F.; Deng, H.; Doe, P.J.; Dosanjh, R.S.; Doucas, G.; Duba, C.A.; Duncan, F.A.; Dunford, M.; Dunmore, J.A.; Earle, E.D.; Elliott, S.R.; Evans, H.C.; Ewan, G.T.; Farine, J.; Fergani, H.; Fleurot, F.; Formaggio, J.A.; Frame, K.; Frati, W.; Fulsom, B.G.; Gagnon, N.; Graham, K.; Grant, D.R.; Hahn, R.L.; Hall, J.C.; Hallin, A.L.; Hallman, E.D.; Handler, W.B.; Hargrove, C.K.; Harvey, P.J.; Hazama, R.; Heeger, K.M.; Heelan, L.; Heintzelman, W.J.; Heise, J.; Helmer, R.L.; Hemingway, R.J.; Hime, A.; Howard, C.; Howe, M.A.; Huang, M.; Jagam, P.; Jelley, N.A.; Klein, J.R.; Kormos, L.L.; Kos, M.S.; Kruger, A.; Kraus, C.; Krauss, C.B.; Krumins, A.V.; Kutter, T.; Kyba, C.C.M.; Labranche, H.; Lange, R.; Law, J.; Lawson, I.T.; Lesko, K.T.; Leslie, J.R.; Levine, I.; Loach, J.C.; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H.B.; Maneira, J.; Marino, A.D.; McCauley, N. | Abstract: Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the D_2O target. The addition of salt enhanced the signal from neutron capture, as compared to the pure D_2O detector. By making a statistical separation of charged-current events from other types based on event-isotropy criteria, the effective electron recoil energy spectrum has been extracted. In units of 106 cm-2 s-1, the total flux of active-flavor neutrinos from 8B decay in the Sun is found to be 4.94+0.21_-0.21(stat)+0.38_-0.34(syst) and the integral flux of electron neutrinos for an undistorted 8B spectrum is 1.68+0.06_-0.06(stat)+0.08_-0.09(syst); the signal from (nu_x,e) elastic scattering is equivalent to an electron-neutrino flux of 2.35+0.22-0.22(stat)+0.15_-0.15(syst). These results are consistent with those expected for neutrino oscillations with the so-called Large Mixing Angle parameters, and also with an undistorted spectrum. A search for matter-enhancement effects in the Earth through a possible day-night asymmetry in the charged-current integral rate is consistent with no asymmetry. Including results from other experiments, the best-fit values for two-neutrino mixing parameters are Delta m2 = (8.0+0.6_-0.4) x 10-5 eV2 and theta = 33.9 +2.4_-2.2 degrees.

For the International Large Detector concept at the planned International Linear Collider, the use of time projection chambers (TPC) with micro-pattern gas detector readout as the main tracking detector is investigated. In this paper, results from a prototype TPC, placed in a 1 T solenoidal field and read out with three independent Gas Electron Multiplier (GEM) based readout modules, are reported. The TPC was exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for reconstructing hits, the measurement of the drift velocity, the space point resolution and the control of field inhomogeneities are presented.

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 data recorded by the CLEO-II detector at CESR, we report evidence of a pair of excited charmed baryons, one decaying into Λ+cπ+ and the other into Λ+cπ−. The doubly charged state has a measured mass difference M(Λ+cπ+)−M(Λ+c) of 234.5±1.1±0.8 MeV/c2 and a width of 17.9+3.8−3.2±4.0MeV/c2, and the neutral state has a measured mass difference M(Λ+cπ−)−M(Λ+c) of 232.6±1.0±0.8 MeV/c2 and a width of 13.0+3.7−3.0±4.0MeV/c2. We interpret these data as evidence of the Σ*++c and Σ*0c, the spin 32+ excitations of the Σc baryons.Received 26 September 1996DOI:https://doi.org/10.1103/PhysRevLett.78.2304©1997 American Physical Society

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%.

A search for the single production of doubly-charged Higgs bosons is performed using e+e− collision data collected by the OPAL experiment at centre-of-mass energies between 189 GeV and 209 GeV. No evidence for the existence of H±± is observed. Upper limits are derived on hee, the Yukawa coupling of the H±± to like-signed electron pairs. A 95% confidence level upper limit of hee< 0.071 is inferred for M(H±±)<160 GeV assuming that the sum of the branching fractions of the H±± to all lepton flavour combinations is 100%. Additionally, indirect constraints on hee from Bhabha scattering at centre-of-mass energies between 183 GeV and 209 GeV, where the H±± would contribute via t-channel exchange, are derived for M(H±±)<2 TeV. These are the first results both from a single production search and on constraints from Bhabha scattering reported from LEP.

Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 438 pb−1 at centre-of-mass energies of s=192–209 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level lower limit on the scalar top quark mass is 97.6 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is zero. When the scalar top quark decouples from the Z0 boson, the lower limit is 95.7 GeV. These limits were obtained assuming that the scalar top quark decays into a charm quark and the lightest neutralino, and that the mass difference between the scalar top quark and the lightest neutralino is larger than 10 GeV. The complementary decay mode of the scalar top quark decaying into a bottom quark, a charged lepton and a scalar neutrino has also been studied. The lower limit on the scalar top quark mass is 96.0 GeV for this decay mode, if the mass difference between the scalar top quark and the scalar neutrino is greater than 10 GeV and if the mixing angle of the scalar top quark is zero. From a search for the scalar bottom quark, a mass limit of 96.9 GeV was obtained if the mass difference between the scalar bottom quark and the lightest neutralino is larger than 10 GeV.

Anomalous quartic couplings between the electroweak gauge bosons may contribute to the $\ensuremath{\nu}\overline{\ensuremath{\nu}}\ensuremath{\gamma}\ensuremath{\gamma}$ and $q\overline{q}\ensuremath{\gamma}\ensuremath{\gamma}$ final states produced in ${e}^{+}{e}^{\ensuremath{-}}$ collisions. This analysis uses the LEP2 OPAL data sample at center-of-mass energies up to 209 GeV. Event selections identify $\ensuremath{\nu}\overline{\ensuremath{\nu}}\ensuremath{\gamma}\ensuremath{\gamma}$ and $q\overline{q}\ensuremath{\gamma}\ensuremath{\gamma}$ events in which the two photons are reconstructed within the detector acceptance. The cross section for the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}q\overline{q}\ensuremath{\gamma}\ensuremath{\gamma}$ is measured. Averaging over all energies, the ratio of the observed ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}q\overline{q}\ensuremath{\gamma}\ensuremath{\gamma}$ cross section to the standard model expectation is $\mathrm{R}(\mathrm{data}/\mathrm{SM})=0.92\ifmmode\pm\else\textpm\fi{}0.07\ifmmode\pm\else\textpm\fi{}0.04,$ where the errors represent the statistical and systematic uncertainties respectively. The $\ensuremath{\nu}\overline{\ensuremath{\nu}}\ensuremath{\gamma}\ensuremath{\gamma}$ and $q\overline{q}\ensuremath{\gamma}\ensuremath{\gamma}$ data are used to constrain possible anomalous ${W}^{+}{W}^{\ensuremath{-}}\ensuremath{\gamma}\ensuremath{\gamma}$ and $\mathrm{ZZ}\ensuremath{\gamma}\ensuremath{\gamma}$ couplings. Combining with previous OPAL results from the ${W}^{+}{W}^{\ensuremath{-}}\ensuremath{\gamma}$ final state, the 95% confidence level limits on the anomalous coupling parameters ${a}_{0}^{\mathrm{Z}},$ ${a}_{\mathrm{c}}^{\mathrm{Z}},$ ${a}_{0}^{\mathrm{W}}$ and ${a}_{\mathrm{c}}^{\mathrm{W}}$ are found to be $\ensuremath{-}0.007 {\mathrm{GeV}}^{\ensuremath{-}2}&lt;{a}_{0}^{\mathrm{Z}}/{\ensuremath{\Lambda}}^{2}&lt;0.023 {\mathrm{GeV}}^{\ensuremath{-}2},$ $\ensuremath{-}0.029 {\mathrm{GeV}}^{\ensuremath{-}2}&lt;{a}_{\mathrm{c}}^{\mathrm{Z}}/{\ensuremath{\Lambda}}^{2}&lt;0.029 {\mathrm{GeV}}^{\ensuremath{-}2},$ $\ensuremath{-}0.020 {\mathrm{GeV}}^{\ensuremath{-}2}&lt;{a}_{0}^{\mathrm{W}}/{\ensuremath{\Lambda}}^{2}&lt;0.020 {\mathrm{GeV}}^{\ensuremath{-}2},$ $\ensuremath{-}0.052 {\mathrm{GeV}}^{\ensuremath{-}2}&lt;{a}_{\mathrm{c}}^{\mathrm{W}}/{\ensuremath{\Lambda}}^{2}&lt;0.037 {\mathrm{GeV}}^{\ensuremath{-}2},$ where $\ensuremath{\Lambda}$ is the energy scale of the new physics. Limits found when allowing two or more parameters to vary are also presented.

.Using the OPAL detector at LEP, the running of the effective QED coupling α(t) is measured for space-like momentum transfer from the angular distribution of small-angle Bhabha scattering. In an almost ideal QED framework, with very favourable experimental conditions, we obtain: \( \Delta \alpha {\left( { - 6.07\;{\text{GeV}}^{2} } \right)} - \Delta \alpha {\left( { - 1.81\;{\text{GeV}}^{2} } \right)} = {\left( {440 \pm 58 \pm 43 \pm 30} \right)} \times 10^{{ - 5}} ,\) where the first error is statistical, the second is the experimental systematic and the third is the theoretical uncertainty. This agrees with current evaluations of α(t). The null hypothesis that α remains constant within the above interval of -t is excluded with a significance above 5σ. Similarly, our results are inconsistent at the level of 3σ with the hypothesis that only leptonic loops contribute to the running. This is currently the most significant direct measurement where the running α(t) is probed differentially within the measured t range.

Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 182 pb−1 at a centre-of-mass energy of s=189 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level (C.L.) lower limit on the scalar top quark mass is 90.3 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is zero. In the worst case, when the scalar top quark decouples from the Z0 boson, the lower limit is 87.2 GeV. These limits were obtained assuming that the scalar top quark decays into a charm quark and the lightest neutralino, and that the mass difference between the scalar top quark and the lightest neutralino is larger than 10 GeV. The complementary decay mode of the scalar top quark decaying into a bottom quark, a charged lepton and a scalar neutrino has also been studied. From a search for the scalar bottom quark, a mass limit of 88.6 GeV was obtained if the mass difference between the scalar bottom quark and the lightest neutralino is larger than 7 GeV. These limits significantly improve the previous OPAL limits.

We present a new determination of ${f}_{{D}_{s}}$ using 5 million ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}c\overline{c}$ events obtained with the CLEO II detector. Our value is derived from our new measured ratio $\ensuremath{\Gamma}{(D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}\ensuremath{\nu})/\ensuremath{\Gamma}{(D}_{s}^{+}\ensuremath{\rightarrow}\ensuremath{\varphi}{\ensuremath{\pi}}^{+})=0.173\ifmmode\pm\else\textpm\fi{}0.023\ifmmode\pm\else\textpm\fi{}0.035$. Using $\mathcal{B}{(D}_{s}^{+}\ensuremath{\rightarrow}\ensuremath{\varphi}{\ensuremath{\pi}}^{+})=(3.6\ifmmode\pm\else\textpm\fi{}0.9)$%, we extract ${f}_{{D}_{s}}=(280\ifmmode\pm\else\textpm\fi{}19\ifmmode\pm\else\textpm\fi{}28\ifmmode\pm\else\textpm\fi{}34) \mathrm{MeV}$. We compare this result with various model calculations.

We measure the mass of the τ to be 1775.1±1.6(mcnstat.)±1.0(mcnsys.) MeV using τ from Z0 decays. To test CPT invariance we compare the masses of the positively and negatively charged τ. The relative mass difference is found to be smaller than 3.0×10−3 at the 90% confidence level.

The magnitude of the Cabibbo-Kobayashi-Maskawa matrix element Vcb has been measured using B̄0→D∗+ℓ−ν̄ decays recorded on the Z0 peak using the OPAL detector at LEP. The D∗+→D0π+ decays were reconstructed both in the particular decay modes D0→K−π+ and D0→K−π+π0 and via an inclusive technique. The product of |Vcb| and the decay form factor of the B̄0→D∗+ℓ−ν̄ transition at zero recoil F(1) was measured to be F(1)|Vcb|=(37.1±1.0±2.0)×10−3, where the uncertainties are statistical and systematic respectively. By using Heavy Quark Effective Theory calculations for F(1), a value of|Vcb|=(40.7±1.1±2.2±1.6)×10−3was obtained, where the third error is due to theoretical uncertainties in the value of F(1). The branching ratio Br(B̄0→D∗+ℓ−ν̄) was also measured to be (5.26±0.20±0.46)%.

Upper limits on the ¯νe flux at the Sudbury Neutrino Observatory have been set based on the ¯νe charged-current reaction on deuterium. The reaction produces a positron and two neutrons in coincidence. This distinctive signature allows a search with very low background for ¯νe's from the Sun and other potential sources. Both differential and integral limits on the ¯νe flux have been placed in the energy range from 4–14.8 MeV. For an energy-independent νe→¯νe conversion mechanism, the integral limit on the flux of solar ¯νe's in the energy range from 4–14.8 MeV is found to be Φ¯νe≤3.4×104 cm−2 s−1 (90% C.L.), which corresponds to 0.81% of the standard solar model 8B νe flux of 5.05×106 cm−2 s−1, and is consistent with the more sensitive limit from KamLAND in the 8.3–14.8 MeV range of 3.7×102 cm−2 s−1 (90% C.L.). In the energy range from 4–8 MeV, a search for ¯νe's is conducted using coincidences in which only the two neutrons are detected. Assuming a ¯νe spectrum for the neutron induced fission of naturally occurring elements, a flux limit of Φ¯νe≤2.0×106 cm−2 s−1 (90% C.L.) is obtained.Received 15 July 2004DOI:https://doi.org/10.1103/PhysRevD.70.093014©2004 American Physical Society

From a data sample of 183 pb−1 recorded at a center-of-mass energy of s=189 GeV with the OPAL detector at LEP, 3068 W-pair candidate events are selected. Assuming Standard Model W boson decay branching fractions, the W-pair production cross section is measured to be σWW=16.30±0.34(stat.)±0.18(syst.) pb. When combined with previous OPAL measurements, the W boson branching fraction to hadrons is determined to be 68.32±0.61(stat.)±0.28(syst.)% assuming lepton universality. These results are consistent with Standard Model expectations.

The light yield of a water-based Cherenkov detector can be significantly improved by adding a wavelength shifter (WLS). WLS molecules absorb ultraviolet photons and re-emit them at longer wavelengths where typical photomultiplier tubes are more sensitive. In this study, several WLS compounds are tested for possible deployment in the Sudbury Neutrino Observatory (SNO). Test results on optical properties and chemical compatibility for a few WLS candidates are reported; together with timing and gain measurements. A Monte Carlo simulation of the SNO detector response is used to estimate the total light gain with WLS. Finally, a cosmic ray Cherenkov detector was built to investigate the optical properties of WLS.

This Letter describes a direct search for pair produced magnetic monopoles in e+e− collisions. The analysis is based on 62.7 pb−1 of data collected with the OPAL detector at an average centre-of-mass energy of s=206.3GeV. The monopole signal was assumed to be characterized by two back-to-back particles with an anomalously high ionization energy loss dE/dx in the tracking chambers. No evidence for production of monopoles was observed. Upper limits were obtained on the magnetic monopole pair-production cross-section (σ) in the mass range 45GeV/c2<mM<102GeV/c2. The average limit is σ<0.05pb and is essentially independent of the magnetic monopole mass. The cross-section limit is derived at the 95% confidence level and is valid for spin-1/2 magnetic monopoles.

The Sudbury Neutrino Observatory (SNO) has confirmed the standard solar model and neutrino oscillations through the observation of neutrinos from the solar core. In this paper we present a search for neutrinos associated with sources other than the solar core, such as gamma-ray bursts and solar flares. We present a new method for looking for temporal coincidences between neutrino events and astrophysical bursts of widely varying intensity. No correlations were found between neutrinos detected in SNO and such astrophysical sources.

Experimental tests of Lorentz symmetry in systems of all types are critical for ensuring that the basic assumptions of physics are well-founded. Data from all phases of the Sudbury Neutrino Observatory, a kiloton-scale heavy water Cherenkov detector, are analyzed for possible violations of Lorentz symmetry in the neutrino sector. Such violations would appear as one of eight possible signal types in the detector: six seasonal variations in the solar electron neutrino survival probability differing in energy and time dependence, and two shape changes to the oscillated solar neutrino energy spectrum. No evidence for such signals is observed, and limits on the size of such effects are established in the framework of the Standard Model Extension, including 40 limits on perviously unconstrained operators and improved limits on 15 additional operators. This makes limits on all minimal, Dirac-type Lorentz violating operators in the neutrino sector available for the first time.

A search has been performed for neutrinos from two sources, the $hep$ reaction in the solar $pp$ fusion chain and the $\nu_e$ component of the diffuse supernova neutrino background (DSNB), using the full dataset of the Sudbury Neutrino Observatory with a total exposure of 2.47 kton-years after fiducialization. The $hep$ search is performed using both a single-bin counting analysis and a likelihood fit. We find a best-fit flux that is compatible with solar model predictions while remaining consistent with zero flux, and set a one-sided upper limit of $\Phi_{hep} < 30\times10^{3}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$ [90% credible interval (CI)]. No events are observed in the DSNB search region, and we set an improved upper bound on the $\nu_e$ component of the DSNB flux of $\Phi^\mathrm{DSNB}_{\nu_e} < 19~\textrm{cm}^{-2}~\textrm{s}^{-1}$ (90% CI) in the energy range $22.9 < E_\nu < 36.9$~MeV.

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

A search was performed for charginos with masses close to the mass of the lightest neutralino in e+e- collisions at centre-of-mass energies of 189-209 GeV recorded by the OPAL detector at LEP. Events were selected if they had an observed high-energy photon from initial state radiation, reducing the dominant background from two-photon scattering to a negligible level. No significant excess over Standard Model expectations has been observed in the analysed data set corresponding to an integrated luminosity of 570pb-1. Upper limits were derived on the chargino pair-productin cross-section, and lower limits on the chargino mass were derived in the context of the Minimal Supersymmetric Extension of the Standard Model for the gravity and anomaly mediated Supersymmetry breaking scenarios.

Non-commutative QED would lead to deviations from the Standard Model depending on a new energy scale ΛNC and a unique direction in space defined by two angles η and ξ. In this analysis, η is defined as the angle between the unique direction and the rotation axis of the earth. The predictions of a tree level calculation for the process e+e−→γγ are evaluated for the specific orientation of the OPAL detector and compared to the measurements. Distributions of the polar and azimuthal photon angles are used to extract limits on the energy scale ΛNC depending on the model parameter η. It is shown that the time dependence of the total cross-section could be used to determine the model parameter ξ if there were a detectable signal. This is the first experimental study of non-commutative QED at an e+e− collider.

Flavour inclusive, udsc and b fragmentation functions in unbiased jets, and flavour inclusive, udsc, b and gluon fragmentation functions in biased jets are measured in e+e- annihilations from data collected at centre-of-mass energies of 91.2, and 183-209 GeV with the OPAL detector at LEP. The unbiased jets are defined by hemispheres of inclusive hadronic events, while the biased jet measurements are based on three-jet events selected with jet algorithms. Several methods are employed to extract the fragmentation functions over a wide range of scales. Possible biases are studied in the results are obtained. The fragmentation functions are compared to results from lower energy e+e- experiments and with earlier LEP measurements and are found to be consistent. Scaling violations are observed and are found to be stronger for the fragmentation functions of gluon jets than for those of quarks. The measured fragmentation functions are compared to three recent theoretical next-to-leading order calculations and to the predictions of three Monte Carlo event generators. While the Monte Carlo models are in good agreement with the data, the theoretical predictions fail to describe the full set of results, in particular the b and gluon jet measurements.

The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of about 31 km and is designed for a peak luminosity of 2x10^34 cm^-2 s^-1. The complex includes a polarized electron source, an undulator-based positron source, two 6.7 km circumference damping rings, two-stage bunch compressors, two 11 km long main linacs and a 4.5 km long beam delivery system. This report is Volume III (Accelerator) of the four volume Reference Design Report, which describes the design and cost of the ILC.

The International Linear Collider (ILC) Time Projection Chamber (TPC) transverse space-point resolution goal is 100 microns for all tracks including stiff 90 degree tracks with the full 2 meter drift. A Micro Pattern Gas Detector (MPGD) readout TPC can achieve the target resolution with existing techniques using 1 mm or narrower pads at the expense of increased detector cost and complexity. The new MPGD readout technique of charge dispersion can achieve good resolution without resorting to narrow pads. This has been demonstrated previously for 2 mm x 6 mm pads with GEMs and Micromegas in cosmic ray tests and in a KEK beam test in a 1 Tesla magnet. We have recently tested a Micromegas-TPC using the charge dispersion readout concept in a high field super-conducting magnet at DESY. The measured Micromegas gain was found to be constant within 0.5% for magnetic fields up to 5 Tesla. With the strong suppression of transverse diffusion at high magnetic fields, we measure a flat 50 micron resolution at 5 Tesla over the full 15 cm drift length of our prototype TPC.

A search is performed for Higgs bosons decaying into invisible final states, produced in association with a Z0 boson in e+e− collisions at energies between 183 and 209 GeV. The search is based on data samples collected by the OPAL detector at LEP corresponding to an integrated luminosity of about 660 pb−1. The analysis aims to select events containing the hadronic decay products of the Z0 boson and large missing momentum, as expected from Higgs boson decay into a pair of stable weakly interacting neutral particles, such as the lightest neutralino in the Minimal Supersymmetric Standard Model. The same analysis is applied to a search for nearly invisible Higgs boson cascade decays into stable weakly interacting neutral particles. No excess over the expected background from Standard Model processes is observed. Limits on the production of invisibly decaying Higgs bosons produced in association with a Z0 boson are derived. Assuming a branching ratio BR(h0→invisible)=1, a lower limit of 108.2 GeV is placed on the Higgs boson mass at the 95% confidence level. Limits on the production of nearly invisibly decaying Higgs bosons are also obtained.

We have performed three searches for high-frequency signals in the solar neutrino flux measured by the Sudbury Neutrino Observatory (SNO), motivated by the possibility that solar $g$-mode oscillations could affect the production or propagation of solar $^8$B neutrinos. The first search looked for any significant peak in the frequency range 1/day to 144/day, with a sensitivity to sinusoidal signals with amplitudes of 12% or greater. The second search focused on regions in which $g$-mode signals have been claimed by experiments aboard the SoHO satellite, and was sensitive to signals with amplitudes of 10% or greater. The third search looked for extra power across the entire frequency band. No statistically significant signal was detected in any of the three searches.

We use a data sample of 2.8 \ifmmode\times\else\texttimes\fi{} ${10}^{6}$ produced $\ensuremath{\tau}$-pair events, obtained with the CLEO II detector, to measure $\mathcal{B}({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{h}^{\ensuremath{-}}{h}^{+}{h}^{\ensuremath{-}}({\ensuremath{\pi}}^{0}){\ensuremath{\nu}}_{\ensuremath{\tau}})$, where $h$ refers to either a charged $\ensuremath{\pi}$ or $K$. These branching fractions are measured with samples of lepton-tagged and 3 vs 3 events. We find $\mathcal{B}({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{h}^{\ensuremath{-}}{h}^{+}{h}^{\ensuremath{-}}{\ensuremath{\nu}}_{\ensuremath{\tau}})=0.0951\ifmmode\pm\else\textpm\fi{}0.0007\ifmmode\pm\else\textpm\fi{}0.0020$ and $\mathcal{B}({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}{h}^{\ensuremath{-}}{h}^{+}{h}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\nu}}_{\ensuremath{\tau}})=0.0423\ifmmode\pm\else\textpm\fi{}0.0006\ifmmode\pm\else\textpm\fi{}0.0022$. We also measure $\mathcal{B}({\ensuremath{\tau}}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\omega}{h}^{\ensuremath{-}}{\ensuremath{\nu}}_{\ensuremath{\tau}})=0.0195\ifmmode\pm\else\textpm\fi{}0.0007\ifmmode\pm\else\textpm\fi{}0.0011$.

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+.

We have observed the decay ${B}^{+}\ensuremath{\rightarrow}{\overline{D}}^{0}{K}^{+}$, using $3.3\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected with the CLEO II detector at the Cornell Electron Storage Ring. We find the ratio of branching fractions $R\ensuremath{\equiv}B({B}^{+}\ensuremath{\rightarrow}{\overline{D}}^{0}{K}^{+})/B({B}^{+}\ensuremath{\rightarrow}{\overline{D}}^{0}{\ensuremath{\pi}}^{+})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.055\ifmmode\pm\else\textpm\fi{}0.014\ifmmode\pm\else\textpm\fi{}0.005$.

Neutrinoless 3-prong tau lepton decays into a charged lepton and either two charged particles or one neutral meson have been searched for using $4.79{\mathrm{fb}}^{\mathrm{\ensuremath{-}}1}$ of data collected with the CLEO II detector at Cornell Electron Storage Ring. This analysis represents an update of a previous study and the addition of six decay channels. In all channels the numbers of events found are compatible with background estimates and branching fraction upper limits are set for 28 different decay modes. These limits are either more stringent than those set previously or represent the first attempt to find these decays.

We have observed new channels for τ decays with an η in the final state. We study 3-prong tau decays, using the η→γγ and η→3π0 decay modes and 1-prong decays with two π0's using the η→γγ channel. The measured branching fractions are B(τ−→π−π−π+ηντ)=(3.4−0.5+0.6±0.6)×10−4 and B(τ−→π−2π0ηντ)=(1.4±0.6±0.3)×10−4. We observe clear evidence for f1→ηππ substructure and measure B(τ−→f1π−ντ)=(5.8−1.3+1.4±1.8)×10−4. We have also searched for η′(958) production and obtain 90% C.L. upper limits B(τ−→π−η′ντ)<7.4×10−5 and B(τ−→π−π0η′ντ)<8.0×10−5.Received 25 June 1997DOI:https://doi.org/10.1103/PhysRevLett.79.2406©1997 American Physical Society

A study of W+W− events accompanied by hard photon radiation, Eγ>2.5 GeV, produced in e+e− collisions at LEP is presented. Events consistent with being two on-shell W-bosons and an isolated photon are selected from 681 pb−1 of data recorded at 180 GeV<s<209 GeV. From the sample of 187 selected W+W−γ candidates with photon energies greater than 2.5 GeV, the W+W−γ cross-section is determined at five values of s. The results are consistent with the Standard Model expectation. Averaging over all energies, the ratio of the observed cross-section to the Standard Model expectation is R(data/SM)=0.99±0.09±0.04, where the errors represent the statistical and systematic uncertainties respectively. These data provide constraints on the related O(α) systematic uncertainties on the measurement of the W-boson mass at LEP. Finally, the data are used to derive 95% confidence level upper limits on possible anomalous contributions to the W+W−γγ and W+W−Z0γ vertices: −0.020 GeV−2<a0Λ2<0.020 GeV−2,−0.053 GeV−2<acΛ2<0.037 GeV−2,−0.16 GeV−2<anΛ2<0.15 GeV−2, where Λ represents the energy scale for new physics and a0, ac and an are dimensionless coupling constants.

Results are reported from a search for low-multiplicity neutrino bursts in the Sudbury Neutrino Observatory (SNO). Such bursts could indicate detection of a nearby core-collapse supernova explosion. The data were taken from Phase I (November 1999 - May 2001), when the detector was filled with heavy water, and Phase II (July 2001 - August 2003), when NaCl was added to the target. The search was a blind analysis in which the potential backgrounds were estimated and analysis cuts were developed to eliminate such backgrounds with 90% confidence before the data were examined. The search maintained a greater than 50% detection probability for standard supernovae occurring at a distance of up to 60 kpc for Phase I and up to 70 kpc for Phase II. No low-multiplicity bursts were observed during the data-taking period.

A study of W+W− events accompanied by hard photon radiation produced in e+e− collisions at LEP is presented. Events consistent with two on-shell W-bosons and an isolated photon are selected from 183 pb−1 of data recorded at s=189 GeV. From these data, 17 W+W−γ candidates are selected with photon energy greater than 10 GeV, consistent with the Standard Model expectation. These events are used to measure the e+e−→W+W−γ cross-section within a set of geometric and kinematic cuts, σ̂WWγ=136±37±8 fb, where the first error is statistical and the second systematic. The photon energy spectrum is used to set the first direct, albeit weak, limits on possible anomalous contributions to the W+W−γγ and W+W−γZ0 vertices:−0.070GeV−2<a0/Λ2<0.070GeV−2,−0.13GeV−2<ac/Λ2<0.19GeV−2,−0.61GeV−2<an/Λ2<0.57GeV−2,where Λ represents the energy scale for new physics.

Using data collected with the CLEO~II detector, we have observed the isospin-violating decay $D_s^{*+}\to D_s^+π^0$. The decay rate for this mode, relative to the dominant radiative decay, is found to be $Γ(D_s^{*+}\to D_s^+π^0)/Γ(D_s^{*+}\to D_s^+γ)= 0.062^{+0.020}_{-0.018}\pm0.022$.

The branching fractions for the five-charged-particle decays of the \ensuremath{\tau} lepton have been measured in ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ annihilations using the CLEO II detector at the Cornell Electron Storage Ring. Assuming all charged particles to be pions, the results are B(3${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$2${\mathrm{\ensuremath{\pi}}}^{+}$\ensuremath{\ge}0 neutrals ${\ensuremath{\nu}}_{\mathrm{\ensuremath{\tau}}}$)=(0.097\ifmmode\pm\else\textpm\fi{}0.005\ifmmode\pm\else\textpm\fi{}0.011)%, B(3${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$2${\mathrm{\ensuremath{\pi}}}^{+}$${\ensuremath{\nu}}_{\mathrm{\ensuremath{\tau}}}$)=(0.077\ifmmode\pm\else\textpm\fi{}0.005 \ifmmode\pm\else\textpm\fi{}0.009)%, B(3${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$2${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{0}$${\ensuremath{\nu}}_{\mathrm{\ensuremath{\tau}}}$)=(0.019\ifmmode\pm\else\textpm\fi{}0.004\ifmmode\pm\else\textpm\fi{}0.004)%, and B(3${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$2${\mathrm{\ensuremath{\pi}}}^{+}$2${\mathrm{\ensuremath{\pi}}}^{0}$${\ensuremath{\nu}}_{\mathrm{\ensuremath{\tau}}}$)0.011% at the 90% C.L. B(3${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$2${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{0}$${\ensuremath{\nu}}_{\mathrm{\ensuremath{\tau}}}$) is measured for the first time by exclusive ${\mathrm{\ensuremath{\pi}}}^{0}$ reconstruction. The results are compared with the predictions from the partially conserved-axial-current and conserved-vector-current hypotheses assuming isospin invariance.

Measurements of the $\tau$ lepton polarization and forward-backward polarization asymmetry near the Z $^0$ resonance using the OPAL detector are described. The measurements are based on analyses of $\tau \rightarrow{\rm e} \nu_e\nu_{\tau}, \tau\rightarrow \mu\nu_{\mu}\nu_{\tau}, \tau\rightarrow \pi\nu_{\tau}, \tau \rightarrow \rho\nu_{\tau}$ and $\tau\rightarrow{\rm a}_1\nu_{\tau}$ decays from a sample of 144,810 $\rm e^+e^-\rightarrow \tau^+\tau^-$ candidates corresponding to an integrated luminosity of 151 pb $^{-1}$ . Assuming that the $\tau$ lepton decays according to V–A theory, we measure the average $\tau$ polarization near $\sqrt{s} ={\rm M}_{\mathrm{Z}}$ to be $\langle P_{\tau}\rangle= (-14.10 \pm 0.73 \pm 0.55)\%$ and the $\tau$ polarization forward-backward asymmetry to be $\rm A_{\mathrm{pol}}^{\mathrm{FB}} = (-10.55 \pm 0.76 \pm 0.25)\%$ , where the first error is statistical and the second systematic. Taking into account the small effects of the photon propagator, photon-Z $^0$ interference and photonic radiative corrections, these results can be expressed in terms of the lepton neutral current asymmetry parameters: \begin{eqnarray} {\cal A}_{\tau} & = & 0.1456 \pm 0.0076 \pm 0.0057, \nonumber {\cal A}_{\mathrm e}& = & 0.1454 \pm 0.0108 \pm 0.0036. \nonumber \end{eqnarray} These measurements are consistent with the hypothesis of lepton universality and combine to give ${\cal A}_{\ell} = 0.1455 \pm 0.0073$ . Within the context of the Standard Model this combined result corresponds to $=0.23172 \pm 0.00092$ . Combing these results with those from the other OPAL neutral current measurements yields a value of $=0.23211 \pm 0.00068$ .

.Gluon jets with a mean energy of 22 GeV and purity of 95% are selected from hadronic Z0 decay events produced in e + e- annihilations. A subsample of these jets is identified which exhibits a large gap in the rapidity distribution of particles within the jet. After imposing the requirement of a rapidity gap, the gluon jet purity is 86%. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We use our data to test three QCD models which include a simulation of color reconnection: one in the Ariadne Monte Carlo, one in the Herwig Monte Carlo, and the other by Rathsman in the Pythia Monte Carlo. We find the Rathsman and Ariadne color reconnection models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and that the description of inclusive Z0 data is significantly degraded in this case. We conclude that color reconnection as implemented by these two models is disfavored. The signal from the Herwig color reconnection model is less clear and we do not obtain a definite conclusion concerning this model. In a separate study, we follow recent theoretical suggestions and search for glueball-like objects in the leading part of the gluon jets. No clear evidence is observed for these objects.

A search is performed for production of short-lived particles in e+e−→XY, with X→γγ and Y→ff̄, for scalar X and scalar or vector Y. Model-independent limits in the range of 25–60 femtobarns are presented on σ(e+e−→XY)×B(X→γγ)×B(Y→ff̄) for centre-of-mass energies in the range 205–207 GeV. The data from all LEP centre-of-mass energies 88–209 GeV are also interpreted in the context of fermiophobic Higgs boson models, for which a lower mass limit of 105.5 GeV is obtained for a “benchmark” fermiophobic Higgs boson.

This paper reviews the constraints on the solar neutrino mixing parameters with data collected by the Homestake, SAGE, GALLEX, Kamiokande, SuperKamiokande, and SNO experiments. An emphasis will be given to the global solar neutrino analyses in terms of matter-enhanced oscillation of two active flavors. The results to-date, including both solar model dependent and independent measurements, indicate that electron neutrinos are changing to other active types on route to the Earth from the Sun. The total flux of solar neutrinos is found to be in very good agreement with solar model calculations. Future measurements will focus on greater accuracy for mixing parameters and on better sensitivity to low neutrino energies.

In the Standard Model, b quarks produced in e+e− annihilation at the Z0 peak have a large average longitudinal polarization of −0.94. Some fraction of this polarization is expected to be transferred to b-flavored baryons during hadronization. The average longitudinal polarization of weakly decaying b baryons, 〈PLΛb〉, is measured in approximately 4.3 million hadronic Z0 decays collected with the OPAL detector between 1990 and 1995 at LEP. Those b baryons that decay semileptonically and produce a Λ baryon are identified through the correlation of the baryon number of the Λ and the electric charge of the lepton. In this semileptonic decay, the ratio of the neutrino energy to the lepton energy is a sensitive polarization observable. The neutrino energy is estimated using missing energy measurements. From a fit to the distribution of this ratio, the value 〈PLΛb〉=−0.56+0.20−0.13±0.09 is obtained, where the first error is statistical and the second systematic.

Using about 3.9 million hadronic Z decays from e+e− collisions recorded by the OPAL detector at LEP at centre-of-mass energies s≈MZ, the branching ratio for the decay D−s→τ−ν̄τ has been measured to be BR(D−s→τ−ν̄τ)=(7.0±2.1(stat)±2.0(syst))%. This result can be used to derive the decay constant of the D−s meson: fDs=(286±44(stat)±41(syst))MeV.

Elements of the spin density matrix for W bosons in e+e−→W+W−→qq̄′ℓνℓ events are measured from data recorded by the OPAL detector at LEP. This information is used to calculate polarised differential cross-sections and to search for CP-violating effects. Results are presented for W bosons produced in e+e− Collisions with centre-of-mass energies between 183 GeV and 209 GeV. The average fraction of W bosons that are longitudinally polarised is found to be (23.9±2.1±1.1)% compared to a Standard Model prediction of (23.9±0.1)%. All results are consistent with CP conservation.

Using a data sample of $\Upsilon(2S)$ events collected with the CLEO II detector at the Cornell Electron Storage Ring, we have investigated the hadronic transitions between the $\Upsilon(2S)$ and the $\Upsilon(1S)$. The charged dipion transition $\Upsilon(2S)\to \Upsilon(1S)\pi^+\pi^-$ was studied using two different analysis techniques. Selecting events in which $\Upsilon(1S)$ decays into a $\mu\mu$ or $ee$ lepton pair(``exclusive'' analysis), we measured the branching fraction of B=0.189+-0.004+-0.009, while using a method allowing $\Upsilon(1S)$ to decay into anything (``inclusive'' analysis) we found B=0.0196+-0.002+-0.010. The appropriate average of the two measurements gives B=0.0192+-0.002+-0.010. Combining the exclusive and inclusive results we derive the $\Upsilon(1S)$ leptonic branching ratios B_{ee}=0.0229+-0.0008+-0.0011 and B_{\mu\mu}=0.0249+-0.0008+-0.0013 We also studied $\Upsilon(2S)\to \Upsilon(1S)\pi^0\pi^0$ and obtained the branching fraction of B=0.092+-0.006+-0.007. Parameters of the $\pi\pi$ system (dipion invariant mass spectra, angular distributions) were analyzed and found to be consistent with current theoretical models. Lastly, we searched for the $\eta$ and single $\pi^0$ transitions and obtained the upper limits of 0.0028 and 0.0011 respectively.

Using the CLEO II detector we measure $\frac{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}\ensuremath{\eta}{e}^{+}\ensuremath{\nu})}{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}\ensuremath{\varphi}{e}^{+}\ensuremath{\nu})}=1.24\ifmmode\pm\else\textpm\fi{}0.12\ifmmode\pm\else\textpm\fi{}0.15$, $\frac{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{e}^{+}\ensuremath{\nu})}{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}\ensuremath{\varphi}{e}^{+}\ensuremath{\nu})}=0.43\ifmmode\pm\else\textpm\fi{}0.11\ifmmode\pm\else\textpm\fi{}0.07$, and $\frac{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{e}^{+}\ensuremath{\nu})}{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}\ensuremath{\eta}{e}^{+}\ensuremath{\nu})}=0.35\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.07$. We find the ratio of vector to pseudoscalar final states, $\frac{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}\ensuremath{\varphi}{e}^{+}\ensuremath{\nu})}{\mathcal{B}({D}_{s}^{+}\ensuremath{\rightarrow}(\ensuremath{\eta}+{\ensuremath{\eta}}^{\ensuremath{'}}){e}^{+}\ensuremath{\nu})}=0.60\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\pm\else\textpm\fi{}0.06$, which is similar to the ratio found in nonstrange $D$ decays.

We search for lepton flavour violating events (eμ, eτ and μτ) that could be directly produced in e+e− annihilations, using the full available data sample collected with the OPAL detector at centre-of-mass energies between 189 GeV and 209 GeV. In general, the Standard Model expectations describe the data well for all the channels and at each s. A single eμ event is observed where according to our Monte Carlo simulations only 0.019 events are expected from Standard Model processes. We obtain the first limits on the cross-sections σ(e+e−→eμ, eτ and μτ) as a function of s at LEP2 energies.

A search for charged excited leptons decaying into a lepton and photon has been performed using approximately 680 pb-1 of e+e- collision data collected by the OPAL detector at LEP at centre-of-mass energies between 183 GeV and 209 GeV. No evidence for their existence was found. Upper limits on the product of the cross-section and the branching fraction are inferred. Using results from the search for singly produced excited leptons, upper limits on the ratio of the excited lepton coupling constant to the compositeness scale are calculated. From pair production searches, 95% confidence level lower limits on the masses of excited electrons, muons and taus are determined to be 103.2 GeV.

We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in ${e}^{+}{e}^{\ensuremath{-}}$ annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic ${Z}^{0}$ decays observed with the OPAL detector at the LEP ${e}^{+}{e}^{\ensuremath{-}}$ collider at CERN. First, we test the boost algorithm through studies with HERWIG Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the energy evolution of the distributions, specifically the mean and first two nontrivial normalized factorial moments of the multiplicity distribution, and the fragmentation function. The theoretical results are found to be in global agreement with the data, although the factorial moments are not well described for jet energies below about 14 GeV.

The hadronic structure function of the photon F2γ(x,Q2) is measured as a function of Bjorken x and of the photon virtuality Q2 using deep-inelastic scattering data taken by the OPAL detector at LEP at e+e− centre-of-mass energies from 183 to 209 GeV. Previous OPAL measurements of the x dependence of F2γ are extended to an average Q2 of 〈Q2〉=780 GeV2 using data in the kinematic range 0.15<x<0.98. The Q2 evolution of F2γ is studied for 12.1<〈Q2〉<780 GeV2 using three ranges of x. As predicted by QCD, the data show positive scaling violations in F2γ with F2γ(Q2)/α=(0.08±0.02+0.05−0.03)+(0.13±0.01+0.01−0.01)lnQ2, where Q2 is in GeV2, for the central x region 0.10–0.60. Several parameterisations of F2γ are in qualitative agreement with the measurements whereas the quark-parton model prediction fails to describe the data.

From a total data sample of 701.1 pb-1 recorded with e+e- centre-of-mass energies of $\sqrt{s} =$ 161–209 GeV with the OPAL detector at LEP, 11693 W-pair candidate events are selected. These data are used to obtain measurements of the W-pair production cross sections at 10 different centre-of-mass energies. The ratio of the measured cross sections to the standard model expectation is found to be: ${\text{data}}/{{\text{SM}}} = 1.002\pm0.011 ({\text{stat.}}) \pm0.007 ({\text{syst.}}) \pm0.005 ({\text{theory}})$ , where the uncertainties are statistical, experimental systematics and theory systematics respectively. The data are used to determine the W boson branching fractions, which are found to be consistent with lepton universality of the charged current interaction. Assuming lepton universality, the branching ratio to hadrons is determined to be 67.41±0.37(stat.)±0.23(syst.)%, from which the CKM matrix element |Vcs| is determined to be 0.969±0.017(stat.)±0.012(syst.). The differential cross section as a function of the W- production angle is measured for the qqeν and qqμν final states. The results described in this paper are consistent with the expectations from the standard model.

Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass of the Z boson with the OPAL detector at LEP. The strong coupling αs is extracted by comparing data and QCD predictions for event shape observables at average reduced centre-of-mass energies ranging from 24 GeV to 78 GeV, and the energy dependence of αs is studied. Our results are consistent with the running of αs as predicted by QCD and show that within the uncertainties of our analysis event shapes in hadronic Z decays with hard and isolated photon radiation can be described by QCD at reduced centre-of-mass energies. Combining all values from different event shape observables and energies gives αs(MZ)=0.1182±0.0015(stat.)±0.0101(syst.).

A study of Bose–Einstein correlations in pairs of identically charged pions produced in e+e- annihilations at the Z0 peak has been performed for the first time assuming a non-static emitting source. The results are based on the high statistics data obtained with the OPAL detector at LEP. The correlation functions have been analyzed in intervals of the average pair transverse momentum and of the pair rapidity, in order to study possible correlations between the pion production points and their momenta (position–momentum correlations). The Yano–Koonin and the Bertsch–Pratt parameterizations have been fitted to the measured correlation functions to estimate the geometrical parameters of the source as well as the velocity of the source elements with respect to the overall centre-of-mass frame. The source rapidity is found to scale approximately with the pair rapidity, and both the longitudinal and transverse source dimensions are found to decrease for increasing average pair transverse momenta.

Using the CLEO II detector at the Cornell Electron Storage Ring we have observed the decay modes Ξc+→Ξ0e+νe and Ξc0→Ξ−e+νe by the detection of a Ξ-positron pair of appropriate invariant mass. We find B(Ξc+→Ξ0e+νe)σ(e+e−→Ξc+X)=1.55±0.33±0.25 pb, B(Ξc0→Ξ−e+νe)σ(e+e−→Ξc0X)=0.63±0.12±0.10 pb, B(Ξc+→Ξ−π+π+)/B(Ξc+→Ξ0e+νe)=0.44±0.11−0.06+0.11, and B(Ξc0→Ξ−π+)/B(Ξc0→Ξ−e+νe)=0.32±0.10−0.03+0.05. Assuming the Ξc+ and Ξc0 are equally produced in e+e− annihilation events at 10 GeV, the lifetime ratio of Ξc+/Ξc0 is measured to be 2.46±0.70−0.23+0.33.Received 12 October 1994DOI:https://doi.org/10.1103/PhysRevLett.74.3113©1995 American Physical Society

We measure the τ lepton lifetime with τ+τ− pairs in which one or both of the τ's decays to three charged particles. The data were collected with the CLEO II detector operating at the electron-positron collider CESR at energies on and near the Y(4S). We use displacements of the three-track vertices to determine the τ lifetime. The results is ττ = 289.0±2.8±4.0 fs.

Using the CLEO II detector operating at the e+e− Cornell Electron Storage Ring (CESR), we present evidence for new decay modes of the Ξc+ into Ξ0π+, Ξ0π+π0, and Ξ0π+π−π+. The branching ratios of these decay modes, relative to Ξc+→Ξ−π+π+, have been measured to be 0.55±0.13±0.09, 2.34±0.57±0.37, and 1.74±0.42±0.27, respectively.

Using a data sample of 57 pb−1 recorded at a centre-of-mass energy of 183 GeV with the OPAL detector at LEP, 282 W+W−→qqqq and 300 W+W−→qqℓνℓ candidate events are used to obtain a measurement of the mass of the W boson, MW=80.39±0.13(stat.)±0.05(syst.) GeV, assuming the Standard Model relation between MW and ΓW. A second fit provides a direct measure of the width of the W boson and gives ΓW=1.96±0.34(stat.)±0.20(syst.) GeV. These results are combined with previous OPAL results to obtain MW=80.38±0.12(stat.)±0.05(syst.) GeV and ΓW=1.84±0.32(stat.)±0.20(syst.) GeV.

Correlations among hadrons with the same electric charge produced in Z0 decays are studied using the high statistics data collected from 1991 through 1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth order are used to measure genuine particle correlations as a function of the size of phase space domains in rapidity, azimuthal angle and transverse momentum. Both all-charge and like-sign particle combinations show strong positive genuine correlations. One-dimensional cumulants initially increase rapidly with decreasing size of the phase space cells but saturate quickly. In contrast, cumulants in two- and three-dimensional domains continue to increase. The strong rise of the cumulants for all-charge multiplets is increasingly driven by that of like-sign multiplets. This points to the likely influence of Bose–Einstein correlations. Some of the recently proposed algorithms to simulate Bose–Einstein effects, implemented in the Monte Carlo model Pythia, are found to reproduce reasonably well the measured second- and higher-order correlations between particles with the same charge as well as those in all-charge particle multiplets.

We present an observation at LEP of the production of χc2 mesons in the collisions of two quasi-real photons using the OPAL detector. The χc2 mesons are reconstructed in the decay channel χc2→J/ψγ→ℓ+ℓ−γ (with ℓ = e,μ) using all data taken at e+e− centre-of-mass energies of 91 and 183 GeV, corresponding to integrated luminosities of 167 and 55 pb−1 respectively. The two-photon width of the χc2 is determined to be Γ(χc2→γγ)=1.76±0.47±0.37±0.15 keV, where the first error is statistical, the second is systematic and the third comes from branching ratio uncertainties.

The magnitude of the CKM matrix element Vub is determined by measuring the inclusive charmless semileptonic branching fraction of beauty hadrons at OPAL based on b -> Xu l nu event topology and kinematics. This analysis uses OPAL data collected between 1991 and 1995, which correspond to about four million hadronic Z decays. We measure Br(b -> Xu l) to be (1.63 +/- 0.53 +0.55/-0.62) x 10^(-3). The first uncertainty is the statistical error and the second is the systematic error. From this analysis, Vub is determined to be: |Vub| = (4.00 +/- 0.65(stat) +0.67/-0.76(sys) +/- 0.19(HQE)) x 10^(-3). The last error represents the theoretical uncertainties related to the extraction of |Vub| from Br(b -> Xu l) using the Heavy Quark Expansion.

The mass and width of the W boson are determined in e+e− collisions at LEP using 183 pb−1 of data recorded at a centre-of-mass energy s=189 GeV with the OPAL detector. The invariant mass distributions from 970 W+W−→qqqq and 1118 W+W−→qqℓνℓ candidate events are used to measure the mass of the W boson, MW=80.451±0.076 (stat.)±0.049 (syst.) GeV. A direct measurement of the width of the W boson gives ΓW=2.09±0.18 (stat.)±0.09 (syst.) GeV. The results are combined with previous OPAL results from 78 pb−1 of data recorded with s from 161 to 183 GeV, to obtain: MW=80.432±0.066 (stat.)±0.045 (syst.) GeV, ΓW=2.04±0.16 (stat.)±0.09 (syst.) GeV. The consistency of the direct measurement of MW with that inferred from other measurements of electroweak parameters provides an important test of the Standard Model of electroweak interactions.

Searches for first generation scalar and vector leptoquarks, and for squarks in R-parity violating SUSY models with the direct decay of the squark into Standard Model particles, have been performed using e+e− collisions collected with the OPAL detector at LEP at e+e− centre-of-mass energies between 189 and 209 GeV. No excess of events is found over the expectation from Standard Model background processes. Limits are computed on the leptoquark couplings for different values of the branching ratio to electron–quark final states.

We use data collected by the CLEO II detector at the Cornell Electron Storage Ring (CESR) to search for ${B}^{+}\ensuremath{\rightarrow}{h}^{+}{h}^{\ensuremath{-}}{h}^{+}$ (nonresonant) decays, where ${h}^{\ifmmode\pm\else\textpm\fi{}}$ can be either ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{,K}^{\ifmmode\pm\else\textpm\fi{}}$, or $p(\overline{p})$. We see no evidence for signals and set upper limits on the branching fractions in the range $(2.8--8.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. If observed, these decays may display CP violating asymmetries.