Abstract:

A measurement is presented of decay-time-dependent CP violation in the decays B 0 → J/ψ K S 0 and B 0 → ψ(2S)K S 0 , where the J/ψ is reconstructed from two electrons and the ψ(2S) from two muons. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb −1 . The CP -violation observables are measured to beC(B0→J/ψKS0)=0.12±0.07±0.02,S(B0→J/ψKS0)=0.83±0.08±0.01,C(B0→ψ(2S)KS0)=−0.05±0.10±0.01,S(B0→ψ(2S)KS0)=0.84±0.10±0.01,where C describes CP violation in the direct decay, and S describes CP violation in the interference between the amplitudes for the direct decay and for the decay after B 0 − B¯ 0 oscillation. The first uncertainties are statistical and the second are systematic. The two sets of results are compatible with the previous LHCb measurement using B 0 → J/ψ K S 0 decays, where the J/ψ meson was reconstructed from two muons. The averages of all three sets of LHCb results areC(B0→[cc¯]KS0)=−0.017±0.029,S(B0→[cc¯] KS0)=0.760±0.034,under the assumption that higher-order contributions to the decay amplitudes are negligible. The uncertainties include statistical and systematic contributions.[Figure not available: see fulltext.].

Abstract:

Measurements of CP observables in B± → DK*± decays are presented, where D denotes a superposition of D0 and D0 meson states. Decays of the D meson to K- Π+, K-K+, Π-Π+, K- Π+ Π- Π+ and Π- Π+ Π- Π+ are used and the K*± meson is reconstructed in the K0 S± Π final state. This analysis uses a data sample of pp collisions collected with the LHCb experiment, corresponding to integrated luminosities of 1 fb-1, 2 fb-1 and 1.8 fb-1 at centre-of-mass energies p s = 7TeV, 8TeV and 13TeV, respectively. The sensitivity of the results to the CKM angle is discussed.

Abstract:

The TORCH time-of-flight detector is designed for large-area coverage, up to 30m^2, to provide particle identification between 2-10 GeV/c momentum over a flight distance of 10 m. The arrival times from Cherenkov photons produced within a quartz radiator plate of 10mm thickness are combined to achieve a 15 ps time-of-flight resolution per incident particle. Micro-Channel Plate Photomultiplier Tube (MCP-PMT) detectors of 53 X 53mm^2 active area have been developed with industrial partners for the TORCH application. The MCP-PMT is read out using charge division to give a 128 X 8 effective granularity. Laboratory results of development MCP-PMTs will be described, and testbeam studies using a small-scale TORCH prototype module will be presented.

Abstract:

The B0, Bs0, B+ and Λb0 hadron production asymmetries are measured using a data sample corresponding to an integrated luminosity of 3.0 fb^−1 , collected by the LHCb experiment in proton–proton collisions at centre-of-mass energies of 7 and 8 TeV. The measurements are performed as a function of transverse momentum and rapidity of the b hadrons within the LHCb detector acceptance. The overall production asymmetries, integrated over transverse momentum and rapidity, are also determined.