Malcolm John

Abstract:

A model-dependent amplitude analysis of the decay B0 → D(KS0π+π−)K∗0 is performed using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb−1, recorded at √s=7 and 8 TeV by the LHCb experiment. The CP violation observables x± and y±, sensitive to the CKM angle γ, are measured to bex−=−0.15±0.14±0.03±0.01,y−=0.25±0.15±0.06±0.01,x+=0.05±0.24±0.04±0.01,y+=−0.65−0.23+0.24±0.08±0.01, where the first uncertainties are statistical, the second systematic and the third arise from the uncertainty on the D → KS0π+π− amplitude model. These are the most precise measurements of these observables. They correspond to γ = (80−22+21)° and rB0=0.39±0.13, where rB0 is the magnitude of the ratio of the suppressed and favoured B0 → DK+π− decay amplitudes, in a Kπ mass region of ±50 MeV around the K*(892)0 mass and for an absolute value of the cosine of the K*0 decay angle larger than 0.4.[Figure not available: see fulltext.]

Abstract:

The first observation of the Bs0→D0KS0 decay mode and evidence for the Bs0→D∗0KS0 decay mode are reported. The data sample corresponds to an integrated luminosity of 3.0 fb-1 collected in pp collisions by LHCb at center-of-mass energies of 7 and 8 TeV. The branching fractions are measured to be B(Bs0→D0K0)=[4.3±0.5(stat)±0.3(syst)±0.3(frag)±0.6(norm)]×10-4,B(Bs0→D∗0K0)=[2.8±1.0(stat)±0.3(syst)±0.2(frag)±0.4(norm)]×10-4,where the uncertainties are due to contributions coming from statistical precision, systematic effects, and the precision of two external inputs, the ratio fs/fd and the branching fraction of B0→D0KS0, which is used as a calibration channel.

Abstract:

A study of $B_c^+\to K^+K^-\pi^+$ decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 $\mathrm{fb}^{-1}$ collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of $7$ and $8$ TeV. Evidence for the decay $B_c^+\to\chi_{c0}(\to K^+K^-)\pi^+$ is reported with a significance of 4.0 standard deviations, resulting in the measurement of $\frac{\sigma(B_c^+)}{\sigma(B^+)}\times\mathcal{B}(B_c^+\to\chi_{c0}\pi^+)$ to be $(9.8^{+3.4}_{-3.0}(\mathrm{stat})\pm 0.8(\mathrm{syst}))\times 10^{-6}$. Here $\mathcal{B}$ denotes a branching fraction while $\sigma(B_c^+)$ and $\sigma(B^+)$ are the production cross-sections for $B_c^+$ and $B^+$ mesons. An indication of $\bar b c$ weak annihilation is found for the region $m(K^-\pi^+)<1.834\mathrm{\,Ge\kern -0.1em V\!/}c^2$, with a significance of 2.4 standard deviations.

Abstract:

The product of the Λ0b (B0) differential production cross-section and the branching fraction of the decay Λ0b → J/ψ pK− (B0 → J/ψ K*(892)0) is measured as a function of the beauty hadron transverse momentum, pT, and rapidity, y. The kinematic region of the measurements is pT < 20 GeV/c and 2.0 < y < 4.5. The measurements use a data sample corresponding to an integrated luminosity of 3 fb−1 collected by the LHCb detector in pp collisions at centre-of-mass energies √s = 7 TeV in 2011 and √s = 8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio, fΛ0b /fd, the branching fraction of the decay Λ0b → J/ψ pK− is measured to be B(Λ0b → J/ψ pK−) = (3.17 ± 0.04 ± 0.07 ± 0.34+0−04528) × 10−4, where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B0 → J/ψ K*(892)0, and the fourth is due to the knowledge of fΛ0b /fd. The sum of the asymmetries in the production and decay between Λ0b and Λ0b is also measured as a function of pT and y. The previously published branching fraction of Λ0b → J/ψ pπ−, relative to that of Λ0b → J/ψ pK−, is updated. The branching fractions of Λ0b → Pc+(→ J/ψ p)K− are determined.

Abstract:

These proceedings summarise new results shown at the 2016 CKM workshop in Working Group 5. Time-integrated charge asymmetry measurements in B → Dh and charmless b-hadron decays are core themes of the group but several ancillary topics are reported. Vital to understanding B → D0K charge asymmetries in multibody D0 decays is knowledge of the CP content of the D0 decay and two important developments are described. Also reported is a number of searches for new hadronic B decay signatures. Experimental results are dominated by LHCb at this time though, results from Belle are still forthcoming.