7637272
Improved measurement of B(D+ --> mu+nu) and the pseudoscalar decay constant fD+.
We extract a relatively precise value for the decay constant of the meson by measuring B(D+ --> mu+nu) = (4.40 +/-0.66(+0.09)(-0.12) x 10(-4) using 281 pb(-1) of data taken on phi(3770) the resonance with the CLEO-c detector. We find fD+ = (222.6 +/- 16.7(+2.8)(-3.4)) MeV, and compare with current theoretical calculations. We also set a 90% confidence upper limit on B(D+e+nu)< 2.4 x 10(-5) which constrains new physics models.
42582723
Measurement of the Ds+ - Ds- production asymmetry in 7 TeV pp collisions
Article history: Received 4 May 2012 Received in revised form 30 May 2012 Accepted 1 June 2012 Available online 6 June 2012 Editor: W.-D. Schlatter Heavy quark production in 7 TeV centre-of-mass energy pp collisions at the LHC is not necessarily flavour symmetric. The production asymmetry, AP, between D+s and D−s mesons is studied using the φπ± decay mode in a data sample of 1.0 fb−1 collected with the LHCb detector. The difference between π+ and π− detection efficiencies is determined using the ratios of fully reconstructed to partially reconstructed D∗± decays. The overall production asymmetry in the D±s rapidity region 2.0 to 4.5 with transverse momentum larger than 2 GeV is measured to be AP = (−0.33 ± 0.22 ± 0.10)%. This result can constrain models of heavy flavour production. © 2012 CERN. Published by Elsevier B.V. All rights reserved.
209963341
Measurement of B(Upsilon(5S) ---> B(*)(s) anti-B(*)(s)) Using phi Mesons
119287240
Searches for Majorana neutrinos in $B^-$ decays
Searches for heavy Majorana neutrinos in B- decays in final states containing hadrons plus a \mu- \mu- pair have been performed using 0.41/fb of data collected with the LHCb detector in proton-proton collisions at a center-of-mass energy of 7 TeV. The D+ \mu- \mu- and D*+ \mu- \mu- final states can arise from the presence of virtual Majorana neutrinos of any mass. Other final states containing \pi+, Ds+, or D0\pi+ can be mediated by an on-shell Majorana neutrino. No signals are found and upper limits are set on Majorana neutrino production as a function of mass, and also on the B- decay branching fractions.
14029193
Performance of the CLEO III LiF-TEA ring imaging Cherenkov detector in a high-energy muon beam
Abstract The CLEO III Ring Imaging Cherenkov detector uses LiF radiators to generate Cherenkov photons which are then detected by proportional wire chambers using a mixture of CH 4 and TEA gases. The first two photon detector modules which were constructed, were taken to the Fermilab and tested in a beam dump that provided high-momentum muons. We report on results using both plane and “sawtooth”–shaped radiators. Specifically, we discuss the number of photoelectrons observed per ring and the angular resolution. The particle separation ability is shown to be sufficient for the physics of CLEO III.
119969840
First spatial alignment of the LHCb VELO and analysis of beam absorber collision data
A first alignment of the LHCb Vertex Locator has been obtained from beam induced tracks at the LHC. A 450 GeV/c protons were collided on a beam absorber during the LHC synchronisation tests of the anti-clockwise beam in August and September 2008. The resulting particle tracks have been reconstructed by the Vertex Locator. This was the first full reconstruction of tracks induced by the LHC beam. The quality of the data obtained is discussed. A total of 2200 tracks were reconstructed from the full data sample, and a first spatial alignment was obtained. The detector is aligned to an accuracy of Slim in the sensor plane. The results confirm that all detector modules have not been displaced from their surveyed positions by more than 10 mm. (C) 2010 Elsevier B.V. All rights reserved.
119221336
Long-term X-Ray Monitoring of LS I +61°303: Analysis of Spectral Variability and Flares
We report on the full analysis of a Rossi X-ray Timing Explorer Proportional Counter Array monitoring of the γ-ray binary system LS I +61°303. The data set covers 42 contiguous cycles of the system orbital motion. Analyzing this X-ray monitoring data set, the largest to date for this source, we report on the variability of the orbital profile and the spectral distribution, and provide strong evidence for an anti-correlation between flux and spectral index (the higher the flux, the harder the spectral index). Furthermore, we present the analysis of two newly discovered kilosecond-timescale flares, which present significant variability also on shorter timescales and tend to occur at orbital phases between 0.6 and 0.9. However, a detailed timing analysis of the flares does not show any coherent or quasi-coherent (QPO) structure in their power spectra. We also investigated the possible appearance of the radio super-orbital modulation at X-ray energies, but we could not unambiguously detect such modulation in the system flux history nor in the evolution of its orbital modulation fraction.
119204233
Search for new physics in events with same-sign dileptons and b-tagged jets in pp collisions at $ \sqrt {s} = 7 $ TeV
A bstractA search for new physics is performed using isolated same-sign dileptons with at least two b-quark jets in the final state. Results are based on a 4.98 fb−1 sample of proton-proton collisions at a centre-of-mass energy of 7 TeV collected by the CMS detector. No excess above the standard model background is observed. Upper limits at 95% confidence level are set on the number of events from non-standard-model sources. These limits are used to set constraints on a number of new physics models. Information on acceptance and efficiencies are also provided so that the results can be used to confront additional models in an approximate way.
118033851
A Lattice Non-Perturbative Hamiltonian Construction of 1+1D Anomaly-Free Chiral Fermions and Bosons - on the equivalence of the anomaly matching conditions and the boundary fully gapping rules
A non-perturbative Hamiltonian construction of chiral fermions and bosons with anomaly-free symmetry $G$ in 1+1D spacetime is proposed. More precisely, we ask "whether there is a local short-range finite quantum Hamiltonian system realizing onsite symmetry $G$ defined on a 1D spatial lattice with a continuous time, such that its low energy physics produces a 1+1D anomaly-free chiral matter theory of symmetry $G$?" Our answer is "yes." In particular, we show that the 3$_L$-5$_R$-4$_L$-0$_R$ U(1) chiral fermion theory, with two left-moving fermions of charge-3 and charge-4, and two right-moving fermions of charge-5 and charge-0 at low energy, can be put on a 1D spatial lattice where the U(1) symmetry is realized as an onsite symmetry, if we include properly-designed interactions between fermions with intermediate strength. We show how to design such proper interactions by looking for interaction terms with extra symmetries. In general, we show that any 1+1D U(1)-anomaly-free chiral matter theory can be defined as a finite system on 1D lattice with onsite symmetry, by using a quantum Hamiltonian with a continuous time, if we include properly-designed interactions between matter fields. We comment on the new ingredients and the differences of ours comparing to Eichten-Preskill and Chen-Giedt-Poppitz models, and suggest modifying Chen-Giedt-Poppitz model to have successful mirror-decoupling. As an additional remark, we show a topological non-perturbative proof on the equivalence relation between 't Hooft anomaly matching conditions and the boundary fully gapping rules of U(1) symmetry.
117877472
Measurement of the Decay $K_L \to \pi^0 e^+ e^- \gamma$
We report on a new measurement of the branching ratio B(KL -> pi0 e+ e- gamma) using the KTeV detector. This analysis uses the full KTeV data set collected from 1997 to 2000. We reconstruct 139 events over a background of 14, which results in B(KL -> pi0 e+ e- gamma) = (1.62 +/- 0.14 (stat) +/- 0.09 (syst)) x 10^{-8}. This result supersedes the earlier KTeV measurement of this branching ratio.
56145316
Schrödinger Fermi liquids
A class of strongly interacting many-body fermionic systems in 2+1D non-relativistic conformal field theory is examined via the gauge-gravity duality correspondence. The 5D charged black hole with asymptotic Schrodinger isometry in the bulk gravity side introduces parameters of background density and finite particle number into the boundary field theory. We propose the holographic dictionary, and realize a quantum phase transition of this fermionic liquid with fixed particle number by tuning the background density $\beta$ at zero temperature. On the larger $\beta$ side, we find the signal of a sharp quasiparticle pole on the spectral function A(k,w), indicating a well-defined Fermi surface. On the smaller $\beta$ side, we find only a hump with no sharp peak for A(k,w), indicating the disappearance of Fermi surface. The dynamical exponent $z$ of quasiparticle dispersion goes from being Fermi-liquid-like $z\simeq1$ scaling at larger $\beta$ to a non-Fermi-liquid scaling $z\simeq 3/2$ at smaller $\beta$. By comparing the structure of Green's function with Landau Fermi liquid theory and Senthil's scaling ansatz, we further investigate the behavior of this quantum phase transition.