Search for Baryon and Lepton Number Violating Decays of the τ\tau Lepton

We have searched for five decay modes of the tau lepton that simultaneously violate lepton and baryon number: tau -> anti-proton gamma, tau -> anti-proton pi0, tau -> anti-proton eta, tau -> anti-proton 2pi0, and tau -> anti-proton pi0eta. The data used in the search were collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR). The integrated luminosity of the data sample is 4.7 fb^{-1}, corresponding to the production of 4.3 x 10^6 tau+tau- events. No evidence is found for any of the decays, resulting in much improved upper limits on the branching fractions for the two-body decays and first upper limits for the three-body decays.Comment: 8 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Observation of Two Narrow States Decaying into Ξc+γ\Xi_{c}^{+}\gamma and Ξc0γ\Xi_{c}^{0}\gamma

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.Comment: 11 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN

A Measurement of the Decay Asymmetry Parameters in \Xi_{c}^{0}\to \X^{-}\pi^{+}

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the $\Xi_c^{0}$ decay asymmetry parameter in the decay $\Xi_c^{0} \to \Xi^{-} \pi^+$. We find $\alpha_{\Xi_c^{0}} \alpha_{\Xi} = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}$, using the world average value of $\alpha_{\Xi} = -0.456 \pm 0.014$ we obtain $\alpha_{\Xi_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(syst)}$. The physically allowed range of a decay asymmetry parameter is $-1<\alpha<+1$. Our result prefers a negative value: $\alpha_{\Xi_c^{0}}$ is $<0.1$ at the 90% CL. The central value occupies the middle of the theoretically expected range but is not yet precise enough to choose between models.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Measurement of Charge Asymmetries in Charmless Hadronic in B Meson Decays

We search for CP-violating asymmetries (Acp) in the B meson decays to K+- pi-+, K+- pi0, Ks pi+-, K+- eta', and omega pi+-. Using 9.66 million Upsilon(4S) decays collected with the CLEO detector, the statistical precision on Acp is in the range of \pm 0.12 to \pm 0.25 depending on decay mode. While CP-violating asymmetries of up to \pm 0.5 are possible within the Standard Model, the measured asymmetries are consistent with zero in all five decay modes studied.Comment: 10 pages, 3 figure

Update of the Search for the Neutrinoless Decay τ→μγ\tau\to \mu\gamma

We present an update of the search for the lepton family number violating decay $\tau \to \mu\gamma$ using a complete CLEO II data sample of 12.6 million $\tau^+\tau^-$ pairs. No evidence of a signal has been found and the corresponding upper limit is \BR(\tau \to \mu\gamma) < 1.0 \times 10^{-6} at 90% CL, significantly smaller than previous limits. All quoted results are preliminary.Comment: 9 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Rare Decays of the η′\eta^{'}

We have searched for the rare decays of the eta prime meson to e+ e- eta, e+ e- pizero, e+ e- gamma, and e mu in hadronic events at the CLEO II detector. The search is conducted on 4.80 fb^-1 of e+ e- collisions at the Cornell Electron Storage Ring. We find no signal in any of these modes, and set 90% confidence level upper limits on their branching fractions of 2.4 X 10^-3, 1.4 X 10^-3, 0.9 X 10^-3, and 4.7 X 10^-4, respectively. We also investigate the Dalitz plot of the common decay of the eta prime to pi+ pi- eta. We fit the matrix element with the Particle Data Group parameterization and find Re(alpha) = -0.021 +- 0.025, where alpha is a linear function of the kinetic energy of the eta.Comment: 12 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Observation of Radiative Leptonic Decay of the Tau Lepton

Using 4.68 fb^{-1} of e^+e^- annihilation data collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR) we have studied tau radiative decays tau -> mu nu nu gamma and tau -> e nu nu gamma. For a 10 MeV minimum photon energy in the tau rest frame, the branching fraction of radiative tau decay to a muon or electron is measured to be (3.61+-0.16+-0.35)*10^{-3} or (1.75+-0.06+-0.17)*10^{-2}, respectively. The branching fractions are in agreement with the Standard Model theoretical predictions.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Limit on Tau Neutrino Mass from τ−→π−π+π−π0ντ\tau^{-}\to \pi^{-}\pi^{+}\pi^{-}\pi^{0}\nu_{\tau}

From a data sample of 29058 $\tau^\pm\to\pi^\pm\pi^+\pi^-\pi^0\nu_\tau$ decays observed in the CLEO detector we derive a 95% confidence upper limit on the tau neutrino mass of 28 MeV.Comment: 17 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Hadronic Structure in the Decay τ−→π−π0ντ\tau^{-}\to \pi^{-}\pi^{0}\nu_{\tau}

We report on a study of the invariant mass spectrum of the hadronic system in the decay tau- -> pi- pi0 nu_tau. 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 rho(770) and rho(1450) mesons are determined. The pi- pi0 spectral function inferred from the invariant mass spectrum is compared with data on e+ e- -> pi+ pi- 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.Comment: 39 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

Resonant Structure of τ→3ππ0ντ\tau\to 3\pi\pi^{0}\nu_{\tau} and τ→ωπντ\tau\to \omega\pi\nu_{\tau} Decays

The resonant structure of the four pion final state in the decay $\tau \to 3\pi\pi^0\nu_\tau$ is analyzed using 4.27 million $\tau^+\tau^-$ pairs collected by the CLEO II experiment. We search for second class currents in the decay $\tau \to \omega\pi\nu_\tau$ using spin-parity analysis and establish an upper limit on the non-vector current contribution. The mass and width of the $\rho'$ resonance are extracted from a fit to the $\tau \to \omega\pi\nu_\tau$ spectral function. A partial wave analysis of the resonant structure of the $\tau \to 3\pi\pi^0\nu_\tau$ decay is performed; the spectral decomposition of the four pion system is dominated by the $\omega\pi$ and $a_1 \pi$ final states.Comment: 34 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN