Guy Wilkinson

Abstract:

A combination of three LHCb measurements of the CKM angle gamma is presented. The decays B->DK and B->Dpi are used, where D denotes an admixture of D0 and D0-bar mesons, decaying into K+K-, pi+pi-, K+-pi-+, K+-pi-+pi+-pi-+, KSpi+pi-, or KSK+K- final states. All measurements use a dataset corresponding to 1.0 fb-1 of integrated luminosity. Combining results from B->DK decays alone a best-fit value of gamma = 72.0 deg is found, and confidence intervals are set gamma in [56.4,86.7] deg at 68% CL, gamma in [42.6,99.6] deg at 95% CL. The best-fit value of gamma found from a combination of results from B->Dpi decays alone, is gamma = 18.9 deg, and the confidence intervals gamma in [7.4,99.2] deg or [167.9,176.4] deg at 68% CL, are set, without constraint at 95% CL. The combination of results from B->DK and B->Dpi decays gives a best-fit value of gamma = 72.6 deg and the confidence intervals gamma in [55.4,82.3] deg at 68% CL, gamma in [40.2,92.7] deg at 95% CL are set. All values are expressed modulo 180 deg, and are obtained taking into account the effect of D0-D0bar mixing.

Abstract:

Using proton-proton collision data collected by the LHCb experiment at √s=7 TeV, corresponding to an integrated luminosity of 1.0 fb -1, the ratio of branching fractions of the B0→D* -π+π-π+ decay relative to the B0→D*-π+ decay is measured to be B(B0→D*-π+π-π+) B(B0→D*-π+)=2.64±0.04(stat)±0. 13(syst). The Cabibbo-suppressed decay B0→D*-K +π-π+ is observed for the first time, and the measured ratio of branching fractions is B(B0→D* -K+π-π+)B(B0→D* -π+π-π+)=(6.47±0. 37(stat)±0.35(syst))×10-2. A search for orbital excitations of charm mesons contributing to the B0→D* -π+π-π+ final state is also performed, and the first observation of the B0→D̄1(2420)0π+π- decay is reported with the ratio of branching fractions B(B0→(D̄1(2420)0→D*-π+) π-π+)B(B0→D*-π +π-π+)=(2.04±0.42(stat)±0. 22(syst))×10-2, where the numerator represents a product of the branching fractions B(B0→D̄1(2420)0π -π+) and B(D̄1(2420)0→D*-π+). © 2013 CERN. Published by the American Physical Society under the terms of the.

Abstract:

Bottom baryons decaying to a J/ψ meson and a hyperon are reconstructed using 1.0 fb-1 of data collected in 2011 with the LHCb detector. Significant Λb0→J/ψΛ, Ξb-→J/ψΞ- and Ωb-→J/ψΩ- signals are observed and the corresponding masses are measured to be M(Λb0)=5619.53±0.13(stat.) ±0.45(syst.) MeV/c2, M(Ξb-)=5795.8±0.9(stat.)±0.4(syst.) MeV/c2, M(Ωb-)=6046.0±2.2(stat.)±0.5(syst.) MeV/c2, while the differences with respect to the Λb0 mass are M(Ξb-)-M(Λb0)= 176.2±0.9(stat.)±0.1(syst.) MeV/c2, M(Ωb-)-M(Λb0)= 426.4±2.2(stat.)±0.4(syst.) MeV/c2. These are the most precise mass measurements of the Λb0, Ξb- and Ωb- baryons to date. Averaging the above Λb0 mass measurement with that published by LHCb using 35 pb-1 of data collected in 2010 yields M(Λb0)=5619. 44±0.13(stat.)±0.38(syst.) MeV/c2. © 2013 CERN. Published by the American Physical Society under the terms of the.

Abstract:

During 2011 the LHCb experiment at CERN collected 1.0 fb−1 of √s = 7 TeV pp collisions. Due to the large heavy quark production cross-sections, these data provide unprecedented samples of heavy flavoured hadrons. The first results from LHCb have made a significant impact on the flavour physics landscape and have definitively proved the concept of a dedicated experiment in the forwardregion at a hadron collider. This document discusses the implications of these first measurements on classes of extensions to the Standard Model, bearing in mind the interplay with the results of searches for on-shell production of new particles at ATLAS and CMS. The physics potential of an upgrade to the LHCb detector, which would allow an order of magnitude more data to be collected, is emphasised.