Sneha Malde

Abstract:

A study of $B_c^+\to K^+K^-\pi^+$ decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 $\mathrm{fb}^{-1}$ collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of $7$ and $8$ TeV. Evidence for the decay $B_c^+\to\chi_{c0}(\to K^+K^-)\pi^+$ is reported with a significance of 4.0 standard deviations, resulting in the measurement of $\frac{\sigma(B_c^+)}{\sigma(B^+)}\times\mathcal{B}(B_c^+\to\chi_{c0}\pi^+)$ to be $(9.8^{+3.4}_{-3.0}(\mathrm{stat})\pm 0.8(\mathrm{syst}))\times 10^{-6}$. Here $\mathcal{B}$ denotes a branching fraction while $\sigma(B_c^+)$ and $\sigma(B^+)$ are the production cross-sections for $B_c^+$ and $B^+$ mesons. An indication of $\bar b c$ weak annihilation is found for the region $m(K^-\pi^+)<1.834\mathrm{\,Ge\kern -0.1em V\!/}c^2$, with a significance of 2.4 standard deviations.

Abstract:

The product of the Λ0b (B0) differential production cross-section and the branching fraction of the decay Λ0b → J/ψ pK− (B0 → J/ψ K*(892)0) is measured as a function of the beauty hadron transverse momentum, pT, and rapidity, y. The kinematic region of the measurements is pT < 20 GeV/c and 2.0 < y < 4.5. The measurements use a data sample corresponding to an integrated luminosity of 3 fb−1 collected by the LHCb detector in pp collisions at centre-of-mass energies √s = 7 TeV in 2011 and √s = 8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio, fΛ0b /fd, the branching fraction of the decay Λ0b → J/ψ pK− is measured to be B(Λ0b → J/ψ pK−) = (3.17 ± 0.04 ± 0.07 ± 0.34+0−04528) × 10−4, where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B0 → J/ψ K*(892)0, and the fourth is due to the knowledge of fΛ0b /fd. The sum of the asymmetries in the production and decay between Λ0b and Λ0b is also measured as a function of pT and y. The previously published branching fraction of Λ0b → J/ψ pπ−, relative to that of Λ0b → J/ψ pK−, is updated. The branching fractions of Λ0b → Pc+(→ J/ψ p)K− are determined.

Abstract:

The decay B0→ψ(2S)K+π- is analyzed using 3 fb-1 of pp collision data collected with the LHCb detector. A model-independent description of the ψ(2S)π mass spectrum is obtained, using as input the Kπ mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the ψ(2S)π mass spectrum can be described in terms of Kπ reflections alone is rejected with more than 8σ significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the Z(4430)- exotic state.