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Search Results: 1 - 10 of 12270 matches for " for the LHCb Collaboration "
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Measurement of relative branching fractions of B decays to $ψ(2S)$ and $J/ψ$ mesons
LHCb Collaboration
Statistics , 2012, DOI: 10.1140/epjc/s10052-012-2118-7
Abstract: The relative rates of B-meson decays into $J/\psi$ and $\psi(2S)$ mesons are measured for the three decay modes in pp collisions recorded with the LHCb detector. The ratios of branching fractions ($\mathcal{B}$) are measured to be $\frac{\mathcal{B}(B^+ \to \psi(2S) K^+)}{\mathcal{B}(B^+ \to J/\psi K^+)} = 0.594 \pm 0.006 (stat) \pm 0.016 (syst) \pm 0.015 (R_{\psi})$, $\frac{\mathcal{B}(B^0 \to \psi(2S) K^{*0})}{\mathcal{B}(B^0 \to J/\psi K^{*0})} = 0.476 \pm 0.014 (stat) \pm 0.010 (syst) \pm 0.012\,(R_{\psi})$, $\frac{\mathcal{B}^{0}_{s}(B^0_s \to \psi(2S)\phi)}{\mathcal{B}(B^0_s \to J/\psi\phi)} = 0.489 \pm 0.026 (stat) \pm 0.021 (syst) \pm 0.012\,(R_{\psi})$ where the third uncertainty is from the ratio of the $\psi(2S)$ and $J/\psi$ branching fractions to $\mu\mu$.
Time-dependent CP asymmetries in Bs decays at LHCb
LHCb collaboration,Johan Blouw
Physics , 2007,
Abstract: The LHCb experiment will search for New Physics in Bs mixing. The Bs mixing phase will be extracted from the measurement of the time-dependent CP asymmetry in exclusive Bs decays governed by the b -> ccbar s quark-level transition. Large New Physics effects can be discovered or excluded with the data collected during the very first physics run of LHC. Based on Monte Carlo simulations of the LHCb detector, the expected sensitivity with 2 inverse fb on the CP-violation parameter phi_s is sigma(phi_s) = 0.022.
LHCb commissioning and readiness for first data
Helge Voss,for the LHCb Collaboration
Physics , 2009,
Abstract: LHCb has been installed by spring 2008, followed by intensive testing and commissioning of the system in order to be ready for first data taking. Despite the horizontal geometry of the LHCb detector it was possible to collect over one million useful cosmic events that allowed a first time alignment of the sub-detectors. Moreover events from beam dumps during the LHC synchronisation tests provided very useful data for further time and spacial alignment of the detector. Here we present an overview of our commissioning activities, the current status and an outlook on the startup in 2009.
Bd->K*MuMu as a lab for discovering new physics at LHCb
Hugh Skottowe,for the LHCb collaboration
Physics , 2010,
Abstract: The analysis of the penguin decay Bd->K*MuMu at LHCb can act as a laboratory for the discovery and understanding of new physics. Through the Operator Product Expansion, the decay kinematics are well understood in both the Standard Model and in a large range of new physics scenarios. The theoretical errors from QCD effects can be characterized and a set of observables have been derived which minimise their influence in measurements. We will describe how these measurements can be made in LHCb with special emphasis on what can be done with a first run of the LHC with a few hundred pb-1 of integrated luminosity.
Measurement of Bc Mass and Lifetime at LHCb
Jibo He,for the LHCb collaboration
Physics , 2010, DOI: 10.3360/dis.2009.147
Abstract: The $B_c^\pm$ mass and lifetime measurements using the decay $B_c^\pm \to J/\psi \pi^\pm$ at the LHCb experiment were studied. About 310 signal events are expected for a data set which corresponds to an integrated luminosity of 1 fb$^{-1}$, with a $B/S$ ratio equal to 2. Based on these data, the $B_c^\pm$ mass and lifetime can be measured with expected statistical errors below 2 MeV/$c^2$ and 30 fs, respectively.
B_s --> D_(s)h(h)(h) Decays in LHCb
Steven Blusk,for the LHCb Collaboration
Physics , 2011,
Abstract: We report recent measurements from LHCb on $B_{(s)}\to D_{(s)}h(h)(h)$ decays using $\sim$35 pb$^{-1}$ of data collected in 2010. In brief, we measure the following ratios of branching fractions: B(B^0-bar --> D^+K^-) / B(B0-bar --> D^+ pi^-) = 0.0752 +- 0.0064 +- 0.0026 B(B_s-bar --> D^0 K^{*0}) / B(B^0-bar --> D^0 rho^0) = 1.39 +- 0.31 +- 0.17 +- 0.18 B(B^0-bar --> D^+ K^- pi^+ pi^-) / B(B^0-bar --> D^+ pi^- pi^+ pi^-) = 0.052 +- 0.009 +- 0.005 B(B^- --> D^0 K^- pi^+ pi^-) / B(B^- --> D^0 pi^- pi^+ pi^-) = 0.096 +- 0.015 +- 0.008, where the uncertainties are statistical and systematic, respectively. The first of these measurements is the most precise to date, and the others are first observations.
LHCb time-dependent results
Marta Calvi,for the LHCb Collaboration
Physics , 2011,
Abstract: This review reports preliminary results of time-dependent measurements of decays of B^0 mesons and B^0_s mesons coming from the analysis of about 36 pb^-1 of data collected by the LHCb experiment during the 2010 run of the Large Hadron Collider at sqrt(s)=7 TeV.
Soft QCD measurements in the forward direction with the LHCb experiment
Alessandro Camboni,for the LHCB Collaboration
Physics , 2011,
Abstract: LHCb presents studies of particle production in minimum bias events in pp collisions at \sqrt{s} = 7 TeV. These studies include measurements of strangeness production, particle ratios, baryon-antibaryon ratios and charged particle production. The forward coverage and low pT acceptance of the experiment makes these measurements very complementary to those performed by the central detectors at the LHC. Further benefits arise from the powerful particle identification capabilities provided by the LHCb RICH system. The measurements are compared with theoretical predictions.
W and Z production in the forward region at LHCb
Jonathan Anderson,for the LHCb collaboration
Physics , 2011,
Abstract: Measurements of electroweak boson production in pp collisions at $\sqrt{s} = 7$ TeV are presented using the decays $W \rightarrow \mu\nu$, $Z \rightarrow \mu\mu$ and $Z \rightarrow \tau\tau$ recorded using the LHCb detector at the LHC. For muonic $W$ and $Z$ decays, the data sample corresponds to an integrated luminosity of 37.1 $\pm$ 1.3 pb$^{-1}$. Here the $W$ and $Z$ bosons are reconstructed from muons with transverse momenta, $p_{T}$, above 20 GeV and pseudorapidity, $\eta$, between 2 and 4.5, and, in the case of the $Z$, a dimuon invariant mass $M_{Z}$ between 60 GeV and 120 GeV. For $Z$ decays to tau lepton final states, 247 pb$^{-1}$ of data has been used. Here one tau is identified through its decay to a muon and neutrinos; the other through its decay to an electron or muon and neutrinos. The cross-sections are measured to be: $\sigma(W^{+}\rightarrow\mu^{+}\nu) = $ 808 $\pm$ 7 $\pm$ 28 $\pm$ 28 pb; $\sigma(W^{+}\rightarrow\mu^{+}\nu) = $ 634 $\pm$ 7 $\pm$ 21 $\pm$ 22 pb; $\sigma(Z\rightarrow\mu\mu) = $ 74.9 $\pm$ 1.6 $\pm$ 3.8 $\pm$ 2.6 pb; $\sigma(Z\rightarrow\tau\tau) = $ 82 $\pm$ 8 $\pm$ 7 $\pm$ 4 pb. Here the first error is statistical, the second is systematic and the third is due to the luminosity determination. For muonic final states, differential measurements, cross-section ratios and the $W$ charge asymmetry are also measured in the same kinematic region. The ratio of the $Z\rightarrow\tau\tau$ and $Z\rightarrow\mu\mu$ cross-sections has been measured to be 1.09 $\pm$ 0.17, consistent with lepton universality. Theoretical predictions, calculated at next-to-next-to-leading order (NNLO) in QCD using recent parton distribution functions, are found to be in agreement with the measurements.
Central exclusive J/ψ and χc production at LHCb
Scott Stevenson,for the LHCb collaboration
Physics , 2013,
Abstract: Central exclusive J/{\psi} and {\chi}c meson production has been measured in decays to dimuons with the LHCb detector, in data corresponding to 36 /pb of integrated luminosity from \sqrt{s} = 7 TeV proton-proton collisions. Cross-section measurements for J/{\psi}, {\psi}(2S) and {\chi}c0,c1,c2 production are presented, and the J/{\psi} photoproduction cross-section is measured as a function of the photon-proton centre-of-mass energy and compared to measurements made at HERA.
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