Guy Wilkinson

Abstract:

First observation of the decay B_s⁰ → K_S⁰K^∗(892)⁰ at LHCb

A search for B_(s)⁰ → K_S⁰K^∗(892)⁰ decays is performed using pp collision data, corresponding to an integrated luminosity of 1.0 fb⁻¹, collected with the LHCb detector at a centre-of-mass energy of 7 TeV. The B_s⁰ → K_S⁰K^∗(892)⁰ decay is observed for the first time, with a significance of 7.1 standard deviations. The branching fraction is measured to be
𝓑(B_s⁰ → K̅⁰K^∗(892)⁰) + 𝓑(B_s⁰ → K⁰K̅^∗(892)⁰)=(16.4 ± 3.4 ± 2.3) × 10⁻⁶,
where the first uncertainty is statistical and the second is systematic. No evidence is found for the decay B⁰ → K_S⁰K^∗(892)⁰ and an upper limit is set on the branching fraction, 𝓑(B⁰ → K̅⁰K^∗(892)⁰) + 𝓑(B⁰ → K⁰K̅^∗(892)⁰) < 0.96 × 10⁻⁶, at 90 % confidence level. All results are consistent with Standard Model predictions.

Abstract:

The Dalitz plot analysis technique is used to study the resonant substructures of B−→D+π−π− decays in a data sample corresponding to 3.0  fb−1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. A model-independent analysis of the angular moments demonstrates the presence of resonances with spins 1, 2 and 3 at high D+π− mass. The data are fitted with an amplitude model composed of a quasi-model-independent function to describe the D+π− S wave together with virtual contributions from the D∗(2007)0 and B*0 states, and components corresponding to the D∗2(2460)0, D∗1(2680)0, D∗3(2760)0 and D∗2(3000)0 resonances. The masses and widths of these resonances are determined together with the branching fractions for their production in B−→D+π−π− decays. The D+π− S wave has phase motion consistent with that expected due to the presence of the D∗0(2400)0 state. These results constitute the first observations of the D∗3(2760)0 and D∗2(3000)0 resonances, with significances of 10σ and 6.6σ, respectively.

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:

Quantum-correlated measurements of the decay D0 → KS0π+π−π0 are performed with a data sample corresponding to an integrated luminosity of 818 pb−1 collected at the ψ(3770) resonance by the CLEO-c detector. Preliminary results are presented for the CP-even fraction F+ and the strong-phase differences of this decay. The value of F+ is measured to be 0.246 ± 0.018. The strong-phase differences are measured in different regions of KS0π+π−π0 phase space by binning around the intermediate resonances present. The potential sensitivity of the results for determining the CKM angle γ from B± → D(KS0π+π−π0)K± decays using data collected by the Belle detector is also shown.