Studying the Underlying Event in Drell-Yan and High Transverse Momentum Jet Production at the Tevatron
ArXiv 1003.3146 (2010)
Abstract:
We study the underlying event in proton-antiproton collisions by examining the behavior of charged particles (transverse momentum pT > 0.5 GeV/c, pseudorapidity |\eta| < 1) produced in association with large transverse momentum jets (~2.2 fb-1) or with Drell-Yan lepton-pairs (~2.7 fb-1) in the Z-boson mass region (70 < M(pair) < 110 GeV/c2) as measured by CDF at 1.96 TeV center-of-mass energy. We use the direction of the lepton-pair (in Drell-Yan production) or the leading jet (in high-pT jet production) in each event to define three regions of \eta-\phi space; toward, away, and transverse, where \phi is the azimuthal scattering angle. For Drell-Yan production (excluding the leptons) both the toward and transverse regions are very sensitive to the underlying event. In high-pT jet production the transverse region is very sensitive to the underlying event and is separated into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The data are corrected to the particle level to remove detector effects and are then compared with several QCD Monte-Carlo models. The goal of this analysis is to provide data that can be used to test and improve the QCD Monte-Carlo models of the underlying event that are used to simulate hadron-hadron collisions.Study of the associated production of photons and b-quark jets in pp̄ collisions at √s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 81:5 (2010)
Abstract:
The cross section for photon production in association with at least one jet containing a b quark has been measured in proton antiproton collisions at √s=1.96TeV. The data sample used corresponds to an integrated luminosity of 340pb-1 collected with the CDF II detector. Both the differential cross section as a function of photon transverse energy ETγ and the total cross section are measured and compared to a next-to-leading order prediction for the process. © 2010 The American Physical Society.Measurement of the WW + WZ production cross section using the lepton + jets final state at CDF II.
Phys Rev Lett 104:10 (2010) 101801
Abstract:
We report two complementary measurements of the WW + WZ cross section in the final state consisting of an electron or muon, missing transverse energy, and jets, performed using pp collision data at square root of s = 1.96 TeV collected by the CDF II detector. The first method uses the dijet invariant mass distribution while the second more sensitive method uses matrix-element calculations. The result from the second method has a signal significance of 5.4sigma and is the first observation of WW + WZ production using this signature. Combining the results gives sigma(WW + WZ) = 16.0 +/- 3.3 pb, in agreement with the standard model prediction.Measurement of the Λb0 lifetime in Λb0→Λc+π - decays in pp̄ collisions at √s=1.96TeV
Physical Review Letters 104:10 (2010)
Abstract:
We report a measurement of the lifetime of the Λb0 baryon in decays to the Λc+π- final state in a sample corresponding to 1.1fb-1 collected in pp̄ collisions at √s=1.96TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Λb0 events we measure τ(Λb0)=1.401±0. 046(stat)±0.035(syst)ps (corresponding to cτ(Λb0)=420. 1±13.7(stat)±10.6(syst)μm, where c is the speed of light). The ratio of this result and the world average B0 lifetime yields τ(Λb0)/τ(B0)=0.918±0.038 (stat) and (syst), in good agreement with recent theoretical predictions. © 2010 The American Physical Society.Search for new bottomlike quark pair decays QQ̄→(tW) (t̄W±) in same-charge dilepton events
Physical Review Letters 104:9 (2010)