17728018
Charmonium Spectroscopy from Inclusive psi-prime and J/psi Radiative Decays
Results from a detailed study using the Crystal Ball detector at the SLAC e/sup +/e/sup -/ storage ring SPEAR of the inclusive photon spectra from 1.8 x 10/sup 6/ psi' and 2.2 x 10/sup 6/ J/psi decays are presented. Radiative transitions from the psi' to the chi/sub 2,1,0/ states are observed with photon energies of 126.0 +- 0.2 +- 4, 169.6 +- 0.3 +- 4, and 258.4 +- 0.4 +- 4 MeV and branching ratios B(psi'..--> gamma..chi/sub 2,1,0/) = (8.0 +- 0.5 +- 0.7)%, (9.0 +- 0.5 +- 0.7)%, and (9.9 +- 0.5 +- 0.8)%, respectively. Values for the natural linewidths of the chi states are obtained: GAMMA(chi/sub 2,1,0/) = 0.8--4.9, gamma..eta/sub c-italic/) = (0.28 +- 0.06)% and B-italic(J/psi..--> gamma..eta/sub c-italic/) = (1.27 +- 0.36)%, and for the natural width GAMMA(eta/sub c-italic/) = 11.5 +- 4.5 MeV.
181671081
Search for B ---> K lepton+ lepton- and B ---> K* lepton+ lepton- decays
12584275
Study of charmless hadronic B meson decays to pseudoscalar-vector final states.
We report results of searches for charmless hadronic B meson decays to pseudoscalar( pi(+/-), K+/-, pi(0), or K(0)(S))-vector( rho, K(*), or omega) final states. By using 9.7x10(6) BB pairs collected with the CLEO detector, we report the first observation of B(-)--->pi(-)rho(0), B(0)-->pi(+/-)rho(-/+), and B(-)-->pi(-)omega, which are expected to be dominated by hadronic b-->u transitions. The measured branching fractions are (10.4(+3.3)(-3.4)+/-2.1)x10(-6), (27.6(+8.4)(-7.4)+/-4.2)x10(-6), and (11.3(+3.3)(-2.9)+/-1. 4)x10(-6), respectively. Branching fraction upper limits are set for all of the other decay modes investigated.
16089528
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, we have studied tau radiative decays tau(-)-->nu(tau)&mgr;(-)nu;(&mgr;)gamma and tau(-)-->nu(tau)e(-)nu;(e)gamma. For a 10 MeV minimum photon energy in the tau rest frame, the branching fraction for radiative tau decay to a muon or electron is measured to be (3.61+/-0.16+/-0. 35)x10(-3) or (1.75+/-0.06+/-0.17)x10(-2), respectively. The branching fractions are in agreement with standard model theoretical predictions.
34604877
Measurement of Cabibbo-suppressed decays of the tau lepton.
Branching ratios for the dominant Cabibbo-suppressed decays of the [tau] lepton have been measured by CLEO II in [ital e][sup +][ital e][sup [minus]] annihilation at the Cornell Electron Storage Ring ([radical][ital s] [similar to]10.6 GeV) using kaons with momenta below 0.7 GeV/[ital c]. The inclusive branching ratio into one charged kaon is (1.60[plus minus]0.12[plus minus]0.19)%. For the exclusive decays, [ital B]([tau][sup [minus]][r arrow][ital K][sup [minus]][nu][sub [tau]])=(0.66[plus minus]0.07[plus minus]0.09)%, [ital B]([tau][sup [minus]][r arrow][ital K][sup [minus]][pi][sup 0][nu][sub [tau]])=(0.51 [plus minus]0.10[plus minus]0.07)%, and, based on three events, [ital B]([tau][sup [minus]][r arrow][ital K][sup [minus]]2[pi][sup 0][nu][sub [tau]])[lt]0.3% at the 90% confidence level. These represent significant improvements over previous results. [ital B]([tau][sup [minus]][r arrow][ital K][sup [minus]][pi][sup 0][nu][sub [tau]]) is measured for the first time with exclusive [pi][sup 0] reconstruction.
117035924
Measurement of B (tau- ---> tau-neutrino K- K0) and b (tau- ---> tau-neutrino K- K0 pi0)
125069023
Measurement of the $B^\pm \to \rho^\pm \pi^0$ branching fraction and direct CP asymmetry
An improved measurement of the process B+- --> rho+- pi0 is presented. The data sample of 211/fb comprises 232 million Y(4S) --> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. The yield and CP asymmetry are calculated using an extended maximum likelihood fitting method. The branching fraction and asymmetry are found to be BR(B+- --> rho+- pi0) = [10.0 +- 1.4 (stat) +- 0.9 (syst)]x 10^-6 and Acp(B+- --> rho+- pi0) = -0.01 +- 0.13 (stat) +- 0.02 (syst), superseding previous measurements. The statistical significance of the branching fraction is calculated to be 8.7sigma.
125769388
Measurement of Time-Dependent CP Asymmetries and Constraints on sin$(2\beta+\gamma)$ with Partial Reconstruction of $B^0 \to D^{*\mp} \pi^{\pm}$ Decays
We present a preliminary measurement of the time-dependent CP-violating asymmetry in decays of neutral B mesons to the final states D*-+ pi+- using approximately 178 million BB events recorded by the BaBar experiment at the PEP-II e+e- storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high-momentum pi+- from the B decay and the low-momentum pi-+ from the D*-+ decay are used. % We measure the amplitude of the asymmetry to be $-0.041 \pm 0.016 (stat.) \pm 0.010 (syst.)$ and determine bounds on $|\sin(2 \beta + \gamma)|$.
17735409
Evidence for long-term gamma-ray and x-ray variability from the unidentified TeV source HESS J0632+057
HESS J0632+057 is one of only two unidentified very-high-energy gamma-ray sources which appear to be point-like within experimental resolution. It is possibly associated with the massive Be star MWC 148 and has been suggested to resemble known TeV binary systems like LS I +61 303 or LS 5039. HESS J0632+057 was observed by VERITAS for 31 hr in 2006, 2008, and 2009. During these observations, no significant signal in gamma rays with energies above 1?TeV was detected from the direction of HESS J0632+057. A flux upper limit corresponding to 1.1% of the flux of the Crab Nebula has been derived from the VERITAS data. The nondetection by VERITAS excludes with a probability of 99.993% that HESS J0632+057 is a steady gamma-ray emitter. Contemporaneous X-ray observations with the Swift X-Ray Telescope reveal a factor of 1.8 ? 0.4 higher flux in the 1-10?keV range than earlier X-ray observations of HESS J0632+057. The variability in the gamma-ray and X-ray fluxes supports interpretation of the object as a gamma-ray emitting binary.
118937544
VERITAS: Status and Highlights
The VERITAS telescope array has been operating smoothly since 2007, and has detected gamma-ray emission above 100 GeV from 40 astrophysical sources. These include blazars, pulsar wind nebulae, supernova remnants, gamma- ray binary systems, a starburst galaxy, a radio galaxy, the Crab pulsar, and gamma-ray sources whose origin remains unidentified. In 2009, the array was reconfigured, greatly im proving the sensitivity. We summarize the current status of the observatory, describe some of the scientific highlights since 2009, and outline plans for the future.
17001801
Observation of Extended VHE Emission from the Supernova Remnant IC 443 with VERITAS
We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best-studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hours during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (sigma) before trials and 7.5 sigma after trials in a point-source search. The emission is centered at 06 16 51 +22 30 11 (J2000) +- 0.03_stat +- 0.08_sys degrees, with an intrinsic extension of 0.16 +- 0.03_stat +- 0.04_sys degrees. The VHE spectrum is well fit by a power law (dN/dE = N_0 * (E/TeV)^-Gamma) with a photon index of 2.99 +- 0.38_stat +- 0.3_sys and an integral flux above 300 GeV of (4.63 +- 0.90_stat +- 0.93_sys) * 10^-12 cm^-2 s^-1. These results are discussed in the context of existing models for gamma-ray production in IC 443.