119001999
Experimental tests of lepton universality in τ decay
J. P. Alexander, C. Bebek, B. E. Berger, K. Berkelman, K. Bloom, D. G. Cassel, H. A. Cho, D. M. Coffman, D. S. Crowcroft, M. Dickson, P. S. Drell, K. M. Ecklund, R. Ehrlich, R. Elia, A. D. Foland, P. Gaidarev, R. S. Galik, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, P. I. Hopman, J. Kandaswamy, N. Katayama, P. C. Kim, D. L. Kreinick, T. Lee, Y. Liu, G. S. Ludwig, J. Masui, J. Mevissen, N. B. Mistry, C. R. Ng, E. Nordberg, M. Ogg, J. R. Patterson, D. Peterson, D. Riley, A. Soffer, and C. Ward Cornell University, Ithaca, New York 14853
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.
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.
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.
117035924
Measurement of B (tau- ---> tau-neutrino K- K0) and b (tau- ---> tau-neutrino K- K0 pi0)
120622268
Status report from VERITAS
VERITAS is a ground-based gamma-ray observatory covering energies between 100 GeV and 50 TeV and will start operating by January 2007. We give a brief report of the construction status and performance characteristics of the telescopes.
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.
2236887
The VERITAS Trigger System
The VERITAS gamma-ray observatory, situated in southern Arizona, is an array of four 12m diameter imaging Cherenkov telescopes, each with a 499-pixel photomultiplier-tube camera. The instrument is designed to detect astrophysical gamma rays at energies above 100 GeV. At the low end of the VERITAS energy range, fluctuations in the night sky background light and single muons from cosmic-ray showers constitute significant backgrounds. VERITAS employs a three-tier trigger system to reduce the rate of these background events: an initial trigger which acts at the single pixel level, a pattern trigger which acts on the relative timing and pixel level, a pattern trigger which acts on the relative timing and distribution of pixel-level triggers within a single telescope camera, and an array-level trigger which requires simultaneous observation of an air-shower event in multiple telescopes. This final coincidence requirement significantly reduces the rate of background events, particularly those due to single muons. In this paper, the implementation of all levels of the VERITAS trigger system is discussed and their joint performance is characterized.
40603151
VERITAS deep observations of the dwarf spheroidal galaxy Segue 1
The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report on the results of nearly 48 hours of good quality selected data, taken between January 2010 and May 2011. No significant γ-ray emission is detected at the nominal position of Segue 1, and upper limits on the integrated flux are derived. According to recent studies, Segue 1 is the most dark matter-dominated dwarf spheroidal galaxy currently known. We derive stringent bounds on various annihilating and decaying dark matter particle models. The upper limits on the velocity-weighted annihilation cross-section are ⟨σv⟩95% CL≲10−23 cm3 s−1, improving our limits from previous observations of dwarf spheroidal galaxies by at least a factor of 2 for dark matter particle masses mχ≳300 GeV. The lower limits on the decay lifetime are at the level of τ95% CL≳1024 s. Finally, we address the interpretation of the cosmic ray lepton anomalies measured by ATIC and PAMELA in terms of dark matter annihilation, and show that the VERITAS observations of Segue 1 disfavor such a scenario.
160875766
VERITAS: STATUS AND EARLY RESULTS ∗
Department of Physics and Astronomy, University of California at Los Angeles430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547 USAfor the VERITAS CollaborationV.A. Acciari, G. Blaylock, S.M. Bradbury, J.H. Buckley, V. BugaevY. Butt, K.L. Byrum, D.A. Carter-Lewis, O. Celik, A. CesariniL. Ciupik, Y.C.K. Chow, P. Cogan, P. Colin, W. Cui, M.K. DanielC. Dowdall, P. Dowkontt, C. Duke, T. Ergin, A.D. FalconeD.J. Fegan, S.J. Fegan, J.P. Finley, P. Fortin, L.F. Fortson, D. GallK. Gibbs, G. Gillanders, J. Grube, R. Guenette, G. Gyuk, D. HannaE. Hays, J. Holder, D. Horan, S.B. Hughes, C.M. Hui, T.B. HumenskyA. Imran, P. Kaaret, G.E. Kenny, M. Kertzman, D. Kieda, J. KildeaA. Konopelko, H. Krawczynski, F. Krennrich, M.J. Lang, S. LebohecK. Lee, G. Maier, H. Manseri, A. McCann, M. McCutcheon, J. MillisP. Moriarty, R. Mukherjee, T. Nagai, J. Niemiec, P.A. OgdenR.A. Ong, D. Pandel, J.S. Perkins, F. Pizlo, M. Pohl, J. QuinnK. Ragan, P.T. Reynolds, E. Roache, H.J. Rose, M. SchroedterG.H. Sembroski, A.W. Smith, D. Steele, S.P. Swordy, A. SysonJ.A. Toner, L. Valcarcel, V.V. Vassiliev, R. Wagner, S.P. WakelyJ.E. Ward, T.C. Weekes, A. Weinstein, R.J. White, D.A. WilliamsS.A. Wissel, M. Wood, B. Zitzerhttp://veritas.sao.arizona.edu