Sneha Malde

Abstract:

The suppressed decay Λb0 → pπ−μ+μ−, excluding the J/ψ and ψ(2S) → μ+μ− resonances, is observed for the first time with a significance of 5.5 standard deviations. The analysis is performed with proton-proton collision data corresponding to an integrated luminosity of 3 fb−1 collected with the LHCb experiment. The Λb0 → pπ−μ+μ− branching fraction is measured relative to the Λb0 → J/ψ(→μ+μ−)pπ− branching fraction giving $\frac{\mathrm{\mathcal{B}}\left({\Lambda}_b^0\to p{\pi}^{-}{\mu}^{+}{\mu}^{-}\right)}{\mathrm{\mathcal{B}}\left({\Lambda}_b^0\to \mathrm{J}/\psi \left(\to {\mu}^{+}{\mu}^{-}\right)p{\pi}^{-}\right)}=0.044\pm 0.012\pm 0.007,$ where the first uncertainty is statistical and the second is systematic. This is the first observation of a b → d transition in a baryonic decay.

Abstract:

A search for the rare two-body charmless baryonic decay B + → pΛ¯ is performed with pp collision data, corresponding to an integrated luminosity of 3 fb −1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of B + →pΛ¯ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the B + →K S 0 π + decay for normalisation,(Formula Presented.)where the first uncertainty is statistical and the second systematic.[Figure not available: see fulltext.].

Abstract:

Two new algorithms for use in the analysis of pp collision are developed to identify the flavour of B0 mesons at production using pions and protons from the hadronization process. The algorithms are optimized and calibrated on data, using B0→ D−π+ decays from pp collision data collected by LHCb at centre-of-mass energies of 7 and 8TeV. The tagging power of the new pion algorithm is 60% greater than the previously available one; the algorithm using protons to identify the flavour of a B0 meson is the first of its kind..