Measurement of the CP Violating Asymmetry a^s_sl using Bs0-\u3e(Ds-\u3ephi pi) mu nu

The time-integrated measurement of the semileptonic CP violating asymmetry, assl, with data acquired at the Large Hadron Collider with the LHCb experiment is presented. This measurement can help physicists understand some peculiarities in the Standard Model, which is the fundamental framework of knowledge of the universe. Should this asymmetry diverge from zero, new physics may be a main motivator. Using 1 fb-1 of collected data in 2011 with proton-proton collisions at a center-of-mass energy of 7 TeV, the measured value of assl presented is (-0.06 ± 0.50 ± 0.36)%, where the first uncertainty is statistical and the second is systematic. This is in very good agreement with the Standard Model prediction of (0.0019±0.0003)%, however divergent from the d0 collaboration measurement of (-1.12 ± 0.74 ± 0.17)%

Search for the Lepton Number Violating Decays B+ → π- μ+μ+ and B+→ K-μ+ μ+

A search is performed for the lepton number violating decay B^{+}\rightarrow h^- \mu^+ \mu^+, where h^- represents a K^- or a \pi^-, using data from the LHCb detector corresponding to an integrated luminosity of 36pb^{-1}. The decay is forbidden in the Standard Model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B^{+} \rightarrow K^- \mu^+ \mu^+) \u3c 5.4\times 10^{-8} and B(B^{+} \rightarrow \pi^- \mu^+ \mu^+) \u3c 5.8\times 10^{-8} are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively

Measurement of Measurement of V 0 Production Ratios in pp Collisions at ps = 0.9 and 7TeV

The \bar{\Lambda} / \Lambda and \bar{\Lambda} / K^0_\mathrm{S} production ratios are measured by the LHCb detector from 0.3\,\mathrm{nb}^{-1} of pp collisions delivered by the LHC at \sqrt{s} = 0.9\,TeV and 1.8\,\mathrm{nb}^{-1} at \sqrt{s} = 7\,TeV. Both ratios are presented as a function of transverse momentum, p_\mathrm{T}, and rapidity, y, in the ranges {0.15 \u3c p_\mathrm{T} \u3c 2.50\,\mathrm{GeV}/c} and {2.0

First Observation of Bs -\u3e J/psi f0(980) Decays

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay Bs -\u3e J/psi f0(980) is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the B_s system. Using a fit to the pi+ pi- mass spectrum with interfering resonances gives R_{f0/phi} = [Gamma(Bs -\u3e J/psi f0, f0 -\u3e pi+ pi-)]/[Gamma(Bs -\u3e J/psi phi, phi -\u3e K+K-)] = 0.252^{+0.046+0.027}_{-0.032-0.033}, where the uncertainties are statistical and systematic, respectively

Measurements of the Branching Fractions for B_(s) -\u3e D_(s)πππ and Λ_b^0 -\u3e Λ_c^+πππ

Branching fractions of the decays H_b\to H_c\pi^-\pi^+\pi^- relative to H_b\to H_c\pi^- are presented, where H_b (H_c) represents B^0-bar(D^+), B^- (D^0), B_s^0-bar (D_s^+) and \Lambda_b^0 (\Lambda_c^+). The measurements are performed with the LHCb detector using 35{\rm pb^{-1}} of data collected at \sqrt{s}=7 TeV. The ratios of branching fractions are measured to be B(B^0-bar -\u3e D^+\pi^-\pi^+\pi^-)/ B(B^0-bar -\u3e D^+\pi^-) = 2.38\pm0.11\pm0.21 B(B^- -\u3e D^0\pi^-\pi^+\pi^-) / B(B^- -\u3e D^0\pi^-) = 1.27\pm0.06\pm0.11 B(B_s^0-bar -\u3e D_s^+\pi^-\pi^+\pi^-) / B(B_s^0-bar -\u3e D_s^+\pi^-) = 2.01\pm0.37\pm0.20 B(\Lambda_b^0-\u3e\Lambda_c^+\pi^-\pi^+\pi^-) / B(\Lambda_b^0 -\u3e \Lambda_c^+\pi^-) = 1.43\pm0.16\pm0.13. We also report measurements of partial decay rates of these decays to excited charm hadrons. These results are of comparable or higher precision than existing measurements

Measurements of the Branching Fractions for B(s) → D(s)πππ and Λb0 → Λc+πππ

Branching fractions of the decays H_b\to H_c\pi^-\pi^+\pi^- relative to H_b\to H_c\pi^- are presented, where H_b (H_c) represents B^0-bar(D^+), B^- (D^0), B_s^0-bar (D_s^+) and \Lambda_b^0 (\Lambda_c^+). The measurements are performed with the LHCb detector using 35{\rm pb^{-1}} of data collected at \sqrt{s}=7 TeV. The ratios of branching fractions are measured to be B(B^0-bar -\u3e D^+\pi^-\pi^+\pi^-)/ B(B^0-bar -\u3e D^+\pi^-) = 2.38\pm0.11\pm0.21 B(B^- -\u3e D^0\pi^-\pi^+\pi^-) / B(B^- -\u3e D^0\pi^-) = 1.27\pm0.06\pm0.11 B(B_s^0-bar -\u3e D_s^+\pi^-\pi^+\pi^-) / B(B_s^0-bar -\u3e D_s^+\pi^-) = 2.01\pm0.37\pm0.20 B(\Lambda_b^0-\u3e\Lambda_c^+\pi^-\pi^+\pi^-) / B(\Lambda_b^0 -\u3e \Lambda_c^+\pi^-) = 1.43\pm0.16\pm0.13. We also report measurements of partial decay rates of these decays to excited charm hadrons. These results are of comparable or higher precision than existing measurements

Measurement of the Inclusive phi Cross-Section in pp Collisions at Sqrt(s) = 7 TeV

The cross-section for inclusive phi meson production in pp collisions at a centre-of-mass energy of sqrt(s) = 7 TeV has been measured with the LHCb detector at the Large Hadron Collider. The differential cross-section is measured as a function of the phi transverse momentum p_T and rapidity y in the region 0.6 \u3c p_T \u3c 5.0 GeV/c and 2.44 \u3c y \u3c 4.06. The cross-section for inclusive phi production in this kinematic range is sigma(pp -\u3e phi X) = 1758 pm 19(stat) ^{+43}_{-14}(syst) pm 182(scale) microbarn, where the first systematic uncertainty depends on the p_T and y region and the second is related to the overall scale. Predictions based on the Pythia 6.4 generator underestimate the cross-section

Measurement of J/Ψ Production in pp Collisions at √s=7 TeV

The production of J/psi mesons in proton-proton collisions at sqrt(s)=7 TeV is studied with the LHCb detector at the LHC. The differential cross-section for prompt J/psi production is measured as a function of the J/psi transverse momentum pT and rapidity y in the fiducial region 0

Observation of J/ψ Pair Production in pp Collisions at √s=7 TeV

The production of J/\psi pairs in proton-proton collisions at a centre-of-mass energy of 7 TeV has been observed using an integrated luminosity of 37.5 pb^{-1} collected with the LHCb detector. The production cross-section for pairs with both \jpsi in the rapidity range

Determination of f_s/f_d for 7 TeV pp Collisions and a Measurement of the Branching Fraction of the Decay Bd-\u3eD-K+

The relative abundance of the three decay modes B_d \to D^- K^+, B_d \to D^- \pi^+ and B_s \to D_s^- \pi^+ produced in 7 TeV pp collisions at the LHC is determined from data corresponding to an integrated luminosity of 35 pb^{-1}. The branching fraction of B_d \to D^- K^+ is found to be \cal B (B_d \to D^- K^+) = (2.01 \pm 0.18^{\textrm{stat}} \pm 0.14^{\textrm{syst}})\times 10^{-4}. The ratio of fragmentation fractions \fsfdt is determined through the relative abundance of B_s \to D_s^- \pi^+ to B_d \to D^- K^+ and B_d \to D^-\pi^+, leading to f_s/f_d = 0.253 \pm 0.017 \pm 0.017 \pm 0.020, where the uncertainties are statistical, systematic, and theoretical respectively