Sneha Malde

Abstract:

The CP asymmetry in the mixing of B0s and B¯0s mesons is measured in proton-proton collision data corresponding to an integrated luminosity of 3.0 fb−1, recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV. Semileptonic B0s and B¯0s decays are studied in the inclusive mode D∓s μ± ν-μX with the D∓s mesons reconstructed in the K+K−π∓ final state. Correcting the observed charge asymmetry for detection and background effects, the CP asymmetry is found to be assl=(0.39 ± 0.26 ± 0.20)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of assl to date. It is consistent with the prediction from the standard model and will constrain new models of particle physics.

Abstract:

The data sample of Λb0 → J/ψpK- decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3  fb^-1, is inspected for the presence of J/ψp or J/ψK- contributions with minimal assumptions about K-p contributions. It is demonstrated at more than nine standard deviations that Λ0b → J/ψpK- decays cannot be described with K-p contributions alone, and that J/ψp contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P+c → J/ψp charmonium-pentaquark states in the same data sample.

Abstract:

Associated production of bottomonia and open charm hadrons in pp collisions at s=7 and 8 TeV is observed using data corresponding to an integrated luminosity of 3 fb−1 accumulated with the LHCb detector. The observation of five combinations, Y(1S)D0, Y(2S)D0, Y(1S)D+, Y(2S)D+ and Y(1S)Ds+, is reported. Production crosssections are measured for Y(1S)D0 and Y(1S)D+ pairs in the forward region. The measured cross-sections and the differential distributions indicate the dominance of double parton scattering as the main production mechanism.

Abstract:

The oscillation frequency, Δ md, of B0 mesons is measured using semileptonic decays with a D- or D∗- meson in the final state. The data sample corresponds to 3.0fb-1 of pp collisions, collected by the LHCb experiment at centre-of-mass energies √s = 7 and 8 TeV. A combination of the two decay modes gives Δmd = (505.0 ± 2.1 ± 1.0) ns-1, where the first uncertainty is statistical and the second is systematic. This is the most precise single measurement of this parameter. It is consistent with the current world average and has similar precision.

Abstract:

The first study is presented of CP violation with an amplitude analysis of the Dalitz plot of B0 → DK+π- decays, with D→K+π-, K+K-, and π+π-. The analysis is based on a data sample corresponding to 3.0 fb-1 of pp collisions collected with the LHCb detector. No significant CP violation effect is seen, and constraints are placed on the angle γ of the unitarity triangle formed from elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Hadronic parameters associated with the B0→DK∗(892)0 decay are determined for the first time. These measurements can be used to improve the sensitivity to γ of existing and future studies of the B0 → DK∗(892)0 decay.