Malcolm John

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.

Abstract:

© 2017, The Author(s). Measurements of CP observables in B± → DK*± decays are presented, where D denotes a superposition of D0 and D¯ 0 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 KS0π± 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 s=7 TeV, 8 TeV and 13 TeV, respectively. The sensitivity of the results to the CKM angle γ is discussed.

Abstract:

A search for baryon-number violating Ξ0b oscillations is performed with a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 3  fb^−1. The baryon number at the moment of production is identified by requiring that the Ξ0b come from the decay of a resonance Ξ*−b → Ξ0bπ− or Ξ'−b → Ξ0bπ−, and the baryon number at the moment of decay is identified from the final state using the decays Ξ0b → Ξ+cπ−,Ξ+c → pK−π+. No evidence of baryon-number violation is found, and an upper limit at the 95% confidence level is set on the oscillation rate of ω < 0.08  ps^−1, where ω is the associated angular frequency.

Abstract:

Kinematic correlations for pairs of beauty hadrons, produced in high energy proton-proton collisions, are studied. The data sample used was collected with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3 fb^−1 . The measurement is performed using inclusive b → J/ψX decays in the rapidity range 2 < y J/ψ < 4.5. The observed correlations are in good agreement with theoretical predictions.

Abstract:

A search is presented for long-lived particles with a mass between 25 and 50GeV/c2 and a lifetime between 2 and 500 ps, using proton–proton collision data corresponding to an integrated luminosity of 2.0fb-1, collected by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The particles are assumed to be pair-produced in the decay of a 125GeV/c2 Standard-Model-like Higgs boson. The experimental signature is a single long-lived particle, identified by a displaced vertex with two associated jets. No excess above background is observed and limits are set on the production cross-section as a function of the mass and lifetime of the long-lived particle.