LHCb

Abstract:

We present a new measurement of the B+ meson differential cross section dσ/dpT at s=1960GeV. The data correspond to an integrated luminosity of 739pb-1 collected with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider. B+ candidates are reconstructed through the decay B+→J/ψK+, with J/ψ→μ+μ-. The integrated cross section for producing B+ mesons with pT≥6GeV/c and |y|≤1 is measured to be 2.78±0.24μb. © 2007 The American Physical Society.

Abstract:

The design, manufacture and testing of lightweight glass-coated beryllium spherical converging mirrors for the RICH1 detector of the LHCb experiment are described. The mirrors need to be lightweight to minimize the material budget and fluorocarbon-compatible to avoid degradation in the RICH1 C4F10 gas radiator. Results of the optical measurements for small-sized prototypes and for a full-sized prototype mirror are reported. © 2006 Elsevier B.V. All rights reserved.

Abstract:

We present measurements of the branching fractions for the charmless two-body decays B0→π+π- and B0→K+π-, and a search for the decay B0→K+K-. We include the effects of final-state radiation from the daughter mesons for the first time, and quote branching fractions for the inclusive processes B0→h+h′-nγ, where h and h′ are pions or kaons. The maximum value of the sum of the energies of the n undetected photons, Eγmax, is mode-dependent. Using a data sample of approximately 227×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we measure: B(B0→π+π-nγ;Eγmax =150MeV)=(5.1±0.4±0.2) ×10-6, B(B0→K+π-nγ;Eγmax =105MeV)=(18.1±0. 6±0.6)×10-6, B(B0→K+K-nγ;Eγmax =59MeV)<0.5×10-6(90%confidence level), where the first uncertainty is statistical and the second is systematic. Theoretical calculations can be used to extrapolate from the above measurements the nonradiative branching fractions, B0. Using one such calculation, we find: B0(B0→π+π-)=(5.5±0. 4±0.3)×10-6, B0(B0→K+π-)=(19.1±0.6±0.6) ×10-6, B0(B0→K+K-)<0.5×10-6(90%confidence level). Meaningful comparison between theory and experiment, as well as combination of measurements from different experiments, can be performed only in terms of these nonradiative quantities. © 2007 The American Physical Society.

Abstract:

A search for charmed baryons decaying to D0p reveals two states: the Λc(2880)+ baryon and a previously unobserved state at a mass of [2939.8±1.3(stat)±1.0(syst)]MeV/c2 and with an intrinsic width of [17.5±5.2(stat)±5.9(syst)]MeV. Consistent and significant signals are observed for the K-π+ and K-π+π-π+ decay modes of the D0 in 287fb-1 annihilation data recorded by the BABAR detector at a center-of-mass energy of 10.58 GeV. There is no evidence in the D+p spectrum of doubly charged partners. The mass and intrinsic width of the Λc(2880)+ baryon and relative yield of the two baryons are also measured. © 2007 The American Physical Society.

Abstract:

Measurements of Zγ* production are presented using data collected by the DELPHI detector at centre-of-mass energies ranging from 183 to 209 GeV, corresponding to an integrated luminosity of about 667 pb-1. The measurements cover a wide range of the possible final state four-fermion configurations: hadronic and leptonic (e+e-qq, μ+μ-qq̄, qqνν), fully leptonic (l +l-l'+l'-) and fully hadronic final states (qq̄, qq̄, with a low mass qq̄ pair). Measurements of the Zγ* cross-section for the various final states have been compared with the Standard Model expectations and found to be consistent within the errors. In addition, a total cross-section measurement of the l +l-l'+l'- cross-section is reported, and found to be in agreement with the prediction of the Standard Model. © 2007 Springer-Verlag / Società Italiana di Fisica.