Malcolm John

Abstract:

Measurements of the total and differential cross sections dσ/dp(T)(B) and dσ/dy(B) for B(+) mesons produced in pp collisions at sqrt[s]=7  TeV are presented. The data correspond to an integrated luminosity of 5.8  pb(-1) collected by the CMS experiment operating at the LHC. The exclusive decay B(+)→J/ψK(+), with J/ψ→μ(+)μ(-), is used to detect B(+) mesons and to measure the production cross section as a function of p(T)(B) and y(B). The total cross section for p(T)(B)>5  GeV and |y(B)|<2.4 is measured to be 28.1±2.4±2.0±3.1  μb, where the first uncertainty is statistical, the second is systematic, and the last is from the luminosity measurement.

Abstract:

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays Bs -> Ds+ X mu nu and Bs -> D0 K+ X mu nu are detected. Two structures are observed in the D0 K+ mass spectrum at masses consistent with the known D^+_{s1}(2536) and $D^{*+}_{s2}(2573) mesons. The measured branching fractions relative to the total Bs semileptonic rate are B(Bs -> D_{s2}^{*+} X mu nu)/B(Bs -> X mu nu)= (3.3\pm 1.0\pm 0.4)%, and B(Bs -> D_{s1}^+ X munu)/B(Bs -> X mu nu)= (5.4\pm 1.2\pm 0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D_{s2}^{*+} state in Bs decays; we also measure its mass and width.

Abstract:

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay Bs -> J/psi f0(980) is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the B_s system. Using a fit to the pi+ pi- mass spectrum with interfering resonances gives R_{f0/phi} = [Gamma(Bs -> J/psi f0, f0 -> pi+ pi-)]/[Gamma(Bs -> J/psi phi, phi -> K+K-)] = 0.252^{+0.046+0.027}_{-0.032-0.033}, where the uncertainties are statistical and systematic, respectively.

Abstract:

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay Bs0→J/Ψf0(980) is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the Bs0 system. Using a fit to the Π+Π- mass spectrum with interfering resonances gives Rf0/Φ≡Γ(Bs0→J/Ψf0,f0→Π+Π -)Γ(Bs0→J/Ψφ,φ →K+K-)=0.252-0.032-0.033+ 0.046+0.027. In the interval ±90 MeV around 980 MeV, corresponding to approximately two full f0 widths we also find R' ≡ Γ(Bs0→J/Ψf0,f0→Π+Π-)-980 Mev < 90 Mev)/Γ(Bs0→J/Ψφ,φ→K +K-)=0.162±0.022±0.016, where in both cases the uncertainties are statistical and systematic, respectively. © 2011 CERN.

Abstract:

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays B0s→D+s+Xμν̄ and B0s→D0K+Xμν̄ are detected. Two structures are observed in the D0K+ mass spectrum at masses consistent with the known Ds1(2536)+ and Ds2*(2573)+ mesons. The measured branching fractions relative to the total B-s0 semileptonic rate are B(B0s→Ds2*+Xμν̄)/B(B0s→Xμν̄)=(3.3±1.0±0.4)%, and B(B0s→D+s1Xμν̄)/B(B0s→Xμν̄)=(5.4±1.2±0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D*+s2 state in B0s decays; we also measure its mass and width. © 2011 CERN.