Invariant mass distributions of B+pi- and B0pi+ combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to 3.0 fb-1 of pp collision data, recorded by the LHCb detector at centre-of-mass e
nergies of 7 and 8 TeV. Precise measurements of the masses and widths of the B_1(5721)^(0,+) and B_2*(5747)^(0,+) states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range 5850--6000 MeV in both B+pi- and B0pi+ combinations. The structures are consistent with the presence of four excited B mesons, labelled B_J(5840)^(0,+) and B_J(5960)^(0,+), whose masses and widths are obtained under different hypotheses for their quantum numbers.
The relative abundance of the three decay modes $B_d to D^- K^+$, $B_d to D^- pi^+$ and $B_s to D_s^- pi^+$ produced in 7 TeV $pp$ collisions at the LHC is determined from data corresponding to an integrated luminosity of 35 pb$^{-1}$. The branching
fraction of $B_d to D^- K^+$ is found to be $cal B (B_d to D^- K^+) = (2.01 pm 0.18^{textrm{stat}} pm 0.14^{textrm{syst}})times 10^{-4}$. The ratio of fragmentation fractions fsfdt is determined through the relative abundance of $B_s to D_s^- pi^+$ to $B_d to D^- K^+$ and $B_d to D^-pi^+$, leading to $f_s/f_d = 0.253 pm 0.017 pm 0.017 pm 0.020$, where the uncertainties are statistical, systematic, and theoretical respectively.
A prototype particle tracking telescope has been constructed using Timepix and Medipix ASIC hybrid pixel assemblies as the six sensing planes. Each telescope plane consisted of one 1.4 cm2 assembly, providing a 256x256 array of 55 micron square pixel
s. The telescope achieved a pointing resolution of 2.3 micron at the position of the device under test. During a beam test in 2009 the telescope was used to evaluate in detail the performance of two Timepix hybrid pixel assemblies; a standard planar 300 micron thick sensor, and 285 micron thick double sided 3D sensor. This paper describes a detailed charge calibration study of the pixel devices, which allows the true charge to be extracted, and reports on measurements of the charge collection characteristics and Landau distributions. The planar sensor achieved a best resolution of 4.0 micron for angled tracks, and resolutions of between 4.4 and 11 micron for perpendicular tracks, depending on the applied bias voltage. The double sided 3D sensor, which has significantly less charge sharing, was found to have an optimal resolution of 9.0 micron for angled tracks, and a resolution of 16.0 micron for perpendicular tracks. Based on these studies it is concluded that the Timepix ASIC shows an excellent performance when used as a device for charged particle tracking.
