Observation of Bs0→J/ψK*(892)0 and Bs0→J/ψKS0 decays
Physical Review D - Particles, Fields, Gravitation and Cosmology 83:5 (2011)
Abstract:
We report the first observation of two Cabibbo-suppressed decay modes of the Bs0 meson. Using a sample of pp̄ collisions at √s=1.96TeV corresponding to 5.9fb-1 of integrated luminosity collected with the CDF II, the collider detector at the Fermilab Tevatron, we search for new Bs0 decay modes in a sample of events containing J/ψ→μ+μ - decays. We reconstruct a Bs0→J/ψK*(892)0 signal with K*(892)0→K+π-, observing a yield of 151±25 events with a statistical significance of 8.0σ. We also reconstruct a Bs0→J/ψKS0 signal with KS0→π+π-, observing a yield of 64±14 events with a statistical significance of 7.2σ. From these yields, we extract the branching ratios B(Bs0→J/ψK*(892)0)=(8. 3±3.8)×10-5 and B(Bs0→J/ψK0)=(3.5±0.8) ×10-5, where statistical, systematic, and fragmentation- fraction uncertainties are included in the combined uncertainty. © 2011 American Physical Society.Search for a heavy gauge boson W' in the final state with an electron and large missing transverse energy in pp collisions at s=7 TeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 698:1 (2011) 21-39
Abstract:
A search for a heavy gauge boson W' has been conducted by the CMS experiment at the LHC in the decay channel with an electron and large transverse energy imbalance ETmiss, using proton-proton collision data corresponding to an integrated luminosity of 36 pb-1. No excess above standard model expectations is seen in the transverse mass distribution of the electron- ETmiss system. Assuming standard-model-like couplings and decay branching fractions, a W' boson with a mass less than 1.36 TeV/c2 is excluded at 95% confidence level. © 2011 CERN.Measurement of b hadron lifetimes in exclusive decays containing a J/ψ in pp collisions at √s=1.96 TeV.
Phys Rev Lett 106:12 (2011) 121804
Abstract:
We report on a measurement of b-hadron lifetimes in the fully reconstructed decay modes B(+)→J/ψK(+), B⁰→J/ψK*(892)⁰, B⁰→J/ψK(s)⁰, and Λ(b)⁰→J/ψΛ⁰ using data corresponding to an integrated luminosity of 4.3 fb⁻¹, collected by the CDF II detector at the Fermilab Tevatron. The measured lifetimes are τ(B(+))=[1.639±0.009(stat)±0.009(syst)] ps, τ(B⁰)=[1.507±0.010(stat)±0.008(syst)] ps, and τ(Λ(b)⁰)=[1.537±0.045(stat)±0.014(syst)] ps. The lifetime ratios are τ(B(+))/τ(B⁰)=[1.088±0.009(stat)±0.004(syst)] and τ(Λ(b)⁰)/τ(B⁰)=[1.020±0.030(stat)±0.008(syst)]. These are the most precise determinations of these quantities from a single experiment.Search for high mass resonances decaying to muon pairs in √s=1.96 TeV pp collisions.
Phys Rev Lett 106:12 (2011) 121801
Abstract:
We present a search for a new narrow, spin-1, high mass resonance decaying to μ(+)μ⁻+X, using a matrix-element-based likelihood and a simultaneous measurement of the resonance mass and production rate. In data with 4.6 fb⁻¹ of integrated luminosity collected by the CDF detector in pp collisions at √s=1960 GeV, the most likely signal cross section is consistent with zero at 16% confidence level. We therefore do not observe evidence for a high mass resonance and place limits on models predicting spin-1 resonances, including M>1071 GeV/c² at 95% confidence level for a Z' boson with the same couplings to fermions as the Z boson.Measurement of b hadron lifetimes in exclusive decays containing a J/ψ in pp̄ collisions at √s=1.96TeV
Physical Review Letters 106:12 (2011)