Measurement of Kμ 3 0 form factors
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 647:5-6 (2007) 341-350
Abstract:
This Letter reports on a new high precision measurement of the form factors of the KL → π± μ∓ νμ decay. The data sample of about 2.3 × 106 events was recorded in 1999 by the NA48 experiment at CERN. Studying the Dalitz plot density we measured a linear, λ+′ = (20.5 ± 2.2stat ± 2.4syst) × 10-3, and a quadratic, λ+″ = (2.6 ± 0.9stat ± 1.0syst) × 10-3 term in the power expansion of the vector form factor. No evidence was found for a second order term for the scalar form factor; the linear slope was determined to be λ0 = (9.5 ± 1.1stat ± 0.8syst) × 10-3. Using a linear fit our results were: λ+ = (26.7 ± 0.6stat ± 0.8syst) × 10-3 and λ0 = (11.7 ± 0.7stat ± 1.0syst) × 10-3. A pole fit of the form factors yields: mV = (905 ± 9stat ± 17syst) MeV / c2 and mS = (1400 ± 46stat ± 53syst) MeV / c2. © 2007 Elsevier B.V. All rights reserved.Observation of WZ production
Physical Review Letters 98:16 (2007)
Abstract:
We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1fb-1 of integrated luminosity from pp̄ collisions at s=1.96TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7±0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to 6 standard deviations. The measured cross section is σ(pp̄→WZ)=5.0-1.6+1.8pb, consistent with the standard model expectation. © 2007 The American Physical Society.Measurement of the charge asymmetry in semileptonic Bs0 decays.
Phys Rev Lett 98:15 (2007) 151801
Abstract:
We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic Bs0 decays ASLs,unt by comparing the decay rate of Bs0-->micro+Ds-nuX, where Ds- -->phipi- and phi-->K+K-, with the charge-conjugate Bs0 decay rate. This sample was selected from 1.3 fb-1 of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain ASLs,unt=[1.23+/-0.97(stat)+/-0.17(syst)]x10(-2). Assuming that Deltam(s)/Gamma(s)>>1, this result can be translated into a measurement of the CP-violating phase in Bs0 mixing: DeltaGamma(s)/Deltam(s)tanphi(s)=[2.45+/-1.93(stat)+/-0.35(syst)]x10(-2).Measurement of the charge asymmetry in semileptonic Bs0 decays
Physical Review Letters 98:15 (2007)
Abstract:
We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic Bs0 decays ASLs,unt by comparing the decay rate of Bs0→μ+Ds-νX, where Ds- π- and →K+K-, with the charge-conjugate B̄s0 decay rate. This sample was selected from 1.3fb-1 of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain ASLs,unt=[1.23±0.97(stat)±0. 17(syst)]×10-2. Assuming that Δms/Γ̄s 1, this result can be translated into a measurement of the CP-violating phase in Bs0 mixing: ΔΓs/Δmstan s=[2.45±1.93(stat)±0.35(syst)] ×10-2. © 2007 The American Physical Society.Measurement of the top quark mass in pp̄ collisions at s=1.96TeV using the decay length technique
Physical Review D - Particles, Fields, Gravitation and Cosmology 75:7 (2007)