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
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.
120882870
Veritas: Status summary 2009
VERITAS is a ground-based gamma-ray observatory that uses the imaging atmospheric Cherenkov technique and operates in the very-high energy (VHE) region of the gamma-ray spectrum from 100 GeV to 50 TeV. The observatory consists of an array of four 12 m-diameter imaging atmospheric Cherenkov telescopes located in southern Arizona, USA. The four-telescope array has been fully operational since September 2007, and over the last two years, VERITAS has been operating with high reliability and sensitivity. It is currently one of the most sensitive VHE observatories. This paper summarizes the status of VERITAS as of October 2009, and describes the detection of several new VHE gamma-ray sources.
125665211
Branching fractions in $B \to \phi$ h and search for direct CP violation in $B^\pm \to \phi K^\pm$
18988438
VERITAS Discovery of >200 GeV Gamma-Ray Emission from the Intermediate-Frequency-Peaked BL Lacertae Object W Comae
We report the detection of very high-energy -ray emission from the intermediate-frequencypeaked BLLacertae object WComae (z = 0.102) by VERITAS, an array of four imaging atmospheric-Cherenkov telescopes. The source was observed between January and April 2008. A strong outburst of -ray emission was measured in the middle of March, lasting for only four days. The energy spectrum measured during the two highest flare nights is fit by a power-law and is found to be very steep, with a differential photon spectral index of = 3 .81±0.35stat±0.34syst. The integral photon flux above 200GeV during those two nights corresponds to roughly 9% of the flux from the Crab Nebula. Quasi-simultaneous Swift observations at X-ray energies were triggered by the VERITAS observations. The spectral energy distribution of the flare data can be described by synchrotron-self-Compton (SSC) or external-Compton (EC) leptonic jet models, with the latter offering a more natural set of parameters to fit the data.
29318124
Discovery of Variability in the Very High Energy γ-Ray Emission of 1ES 1218+304 with VERITAS
We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ~6% of the Crab Nebula flux, the new VERITAS data reveal a prominent flare reaching ~20% of the Crab. While very high energy (VHE) flares are quite common in many nearby blazars, the case of 1ES 1218+304 (redshift z = 0.182) is particularly interesting since it belongs to a group of blazars that exhibit unusually hard VHE spectra considering their redshifts. When correcting the measured spectra for absorption by the extragalactic background light, 1ES 1218+304 and a number of other blazars are found to have differential photon indices Γ≤ 1.5. The difficulty in modeling these hard spectral energy distributions in blazar jets has led to a range of theoretical γ-ray emission scenarios, one of which is strongly constrained by these new VERITAS observations. We consider the implications of the observed light curve of 1ES 1218+304, which shows day scale flux variations, for shock acceleration scenarios in relativistic jets, and in particular for the viability of kiloparsec-scale jet emission scenarios.
122880000
Flavor-specific inclusive B decays to charm
We have measured the branching fractions for B → D X, B → DX, and B → D Xl^+ν. From these results and some previously measured branching fractions, we obtain B(b → cc s) = (21.9±3.7)%, B(b → sg)<6.8% at 90% C.L., and B(D^0 → K^-π^+) = (3.69±0.20)%. Implications for the “B semileptonic decay problem” (measured branching fraction being below theoretical expectations) are discussed. With the increase in the value of B(b → cc s) due to B → DX, the discrepancy is no longer statistically compelling.
18269472
Tau-charm factory design
2992264
Status of tau physics
We review, very briefly, many of the important results arising in the study of tau lepton production and decay, with emphasis on recent results. We discuss the studies of topological and exclusive branching fractions, inclusive semi-leptonic tau decay spectral functions, extraction of QCD parameters including α_S and the strange quark mass, exclusive semileptonic decays and low energy meson dynamics, and rare and forbidden (neutrinoless) decays. Special attention is paid to recent searches for CP non-conservation in tau pair production and tau decay.
6202742
Branching fraction and photon energy spectrum for b --> s gamma.
We have measured the branching fraction and photon energy spectrum for the radiative penguin process b-->s gamma. We find Beta(b-->s gamma) = (3.21+/-0.43+/-0.27(+0.18)(-0.10))x10(-4), where the errors are statistical, systematic, and from theory corrections. We obtain first and second moments of the photon energy spectrum above 2.0 GeV, = 2.346+/-0.032+/-0.011 GeV, and -(2) = 0.0226+/-0.0066+/-0.0020 GeV(2), where the errors are statistical and systematic. From the first moment, we obtain (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) the heavy quark effective theory parameter Lambda = 0.35+/-0.08+/-0.10 GeV.
15823008
Classical Theta Functions and Quantum Tori
The Schwartz kernel of the multiplication operation on a quantum torus is shown to be the distributional boundary value of a classical multivariate theta function. The kernel satisfies a Schrodinger equation in which the role of time is played by the deformation parameter 11 and the role of the hamiltonian by a Poisson structure. At least in some special cases, the kernel can be written as a sum of products of single variable theta functions. A quantum torus is, by definition, a "space" whose (noncommutative) algebra of functions is obtained by deformation of the (commutative) algebra of functions on a torus (R/Zy. In this note, we observe that the Schwartz kernels of the multiplication operators for a class of quantum tori are the (distributional) boundary values of classical theta functions, and we draw some conclusions from this observation. In particular, we show that each of these kernels satisfies a Schrodinger equation, in which the role of time is played by the deformation parameter h, and the role of the hamiltonian is played by the Poisson structure associated with the deformation. Thus, the "evolution in Plank's constant" of a torus is like the time evolution of a free particle, with the initial state (the Schwartz kernel of the operator of pointwise multiplication) being a delta function, like the initial state of a particle with certain position and totally uncertain momentum. This evolution equation suggests a possible answer to the question of how a deformed product must behave after the deformation parameter h has left the first infinitesimal neighborhood of zero. We note that our work seems to be quite different from Manin's study [2] of quantum theta functions, which are special functions on the quantum tori themselves. Communicated by T. Kawai, September 13, 1993. 1991 Mathematics Subject Classifications : 81S10, 33D10, 58B30. Department of Mathematics, University of California, Berkeley, CA 94720 USA. Research partially supported by NSF Grant DMS-93-09653.