Sneha Malde

Abstract:

The production of B± mesons in proton-proton collisions at √s = 7TeVis studied using 35 pb-1 of data collected by the LHCb detector. The B± mesons are reconstructed exclusively in the B± → J/ΨK± mode, with J/Ψ→μ+μ-. The differential production cross-section is measured as a function of the B± transverse momentum in the ducial region 0 < pT < 40 GeV=c and with rapidity 2:0 < y < 4:5. The total cross-section, summing up B+ and B -, is measured to be σ(pp → B±X; 0 < pT < 40 GeV=c; 2:0 < y < 4:5) = 41:4 ± 1:5 (stat:) ± 3:1 (syst:) μb. Copyright CERN.

Abstract:

The isospin asymmetries of B → K(*)μ +μ- decays and the partial branching fractions of B0 → K0μ+μ- and B +→ K*+μ+μ- are measured as a function of the di-muon mass squared q2 using an integrated luminosity of 1.0fb-1 collected with the LHCb detector. The B → Kμ+μ- isospin asymmetry integrated over q2 is negative, deviating from zero with over 4 σ significance. The B → K*μ+μ- decay measurements are consistent with the Standard Model prediction of negligible isospin asymmetry. The observation of the decay B0 → Ks0μ+μ- is reported with 5.7 σ significance. Assuming that the branching fraction of B0 → K0μ+μ- is twice that of B 0 → Ks0μ+μ-, the branching fractions of B0 → K0μ +μ- and B → K*+μ +μ- are found to be (0.31+0.07-0.06) × 10-6 and (1.16 ±0.19) × 10-6, respectively.

Abstract:

The decay mode Bs0 → Ds∓ K± allows for one of the theoretically cleanest measurements of the CKM angle γ through the study of time-dependent CP violation. This paper reports a measurement of its branching fraction relative to the Cabibbo-favoured mode Bs0 → Ds- π+ based on a data sample corresponding to 0.37 fb-1 of proton-proton collisions at √s = 7TeV collected in 2011 with the LHCb detector. In addition, the ratio of B meson production fractions fs=fd, determined from semileptonic decays, together with the known branching fraction of the control channel B0 → D-π+, is used to perform an absolute measurement of the branching fractions: B( Bs0 → D s- π+) = (2.95 ± 0.05 ± 0.17-0.22+0.18) × 10-3 ; B( B s0 → Ds∓ K ±) = (1.90 ± 0.12 ± 0.13-0.14+0.12) × 10-4 ; where the first uncertainty is statistical, the second the experimental systematic uncertainty, and the third the uncertainty due to fs=fd. Copyright CERN.

Abstract:

Using 34.7 pb−1of data collected with the LHCb detector, the inclusive production of the X(3872) meson in pp collisions at √s = 7 TeV is observed for the first time. Candidates are selected in the X(3872)→J/ψπ+π−decay mode, and used to measure σ(pp→X(3872)+anything)B(X(3872)→J/ψπ+π−) = 5.4 ± 1.3 (stat) ± 0.8 (syst) nb, where σ(pp →X(3872) + anything) is the inclusive production cross section of X(3872) mesons with rapidity in the range 2.5–4.5 and transverse momentum in the range 5–20 GeV/c. In addition the masses of both the X(3872) and ψ(2S) mesons, reconstructed in the J/ψπ+π−final state, are measured to be mX(3872) = 3871.95 ± 0.48 (stat) ± 0.12 (syst) MeV/c2and mψ(2S) = 3686.12± 0.06 (stat) ± 0.10 (syst) MeV/c2.

Abstract:

The production of J/Ψ mesons accompanied by open charm, and of pairs of open charm hadrons are observed in pp collisions at a centre-of-mass energy of 7TeV using an integrated luminosity of 355 pb-1 collected with the LHCb detector. Model independent measurements of absolute cross-sections are given together with ratios to the measured J/Ψ and open charm cross-sections. The properties of these events are studied and compared to theoretical predictions. Copyright CERN.