Measurement of the forward-backward asymmetry in low-mass bottom-quark pairs produced in proton-antiproton collisions

Abstract

We report a measurement of the forward-backward asymmetry, AFB, in bb pairs produced in protonantiproton collisions and identified by muons from semileptonic b-hadron decays. The event sample is collected at a center-of-mass energy of √ s =1.96 TeV with the CDF II detector and corresponds to 6.9 fb −1 of integrated luminosity. We obtain an integrated asymmetry of AFB(bb)= (1.2 ± 0.7)% at the particle level for b-quark pairs with invariant mass, m bb , down to 40 GeV/c 2 and measure the dependence of AFB(bb) on m bb . The results are compatible with expectations from the standard model.

Complementary constraints on $$ Zb\overline{b} $$ couplings at the LHC

“…On the other hand, an electron ion collider (EIC) at Brookhaven was approved and projections for its capability and that of other EIC proposals to probe these couplings was investigated in [19,20]. In the case of hadron colliders, neither the Tevatron [21,22] nor the large hadron collider (LHC) [23] have so far been able to provide competitive bounds, mostly due to large QCD backgrounds and large theory uncertainties; see also [24].…”

Charge Asymmetry in Top Quark Pair Production

“…For light quarks (u, d) when the initial and outgoing quark is the same, the t-channel qq → qq must be considered too [60]. The charge asymmetry in the pp → bb production was measured at the LHC by the LHCb experiment [61], while the forward-backward asymmetry in the pp → bb production was measured at the Tevatron by the CDF experiment [62,63] and by the D0 experiment in the production of B ± mesons [64]. At the Tevatron, the bb production is dominated by the gg fusion unlike the top quark pair production due to the much lower b-quark mass.…”

Asymmetric heavy-quark hadroproduction at LHCb: predictions and applications

“…With such kinematic requirements, the phase-space regions where the NLO fixed-order calculation receives large logarithmic corrections (for example, due to the presence of g → bb collinear enhancements) are avoided, and the effects of resumming these types of contributions is therefore typically small. 3 Another consideration is that the prediction of flavour-tagged anti-k t jets is only infrared (IR)-safe for the massive calculation. Due to the presence of wide-angle g → QQ splittings of soft gluons, the massless calculation is IR-unsafe [47].…”

“…Similar studies of the angular asymmetries in heavy-quark production have also been carried out at hadron colliders. In pp collisions at the Tevatron, a measurement of the asymmetry in b-quark pair production has been performed for B-hadrons by the DØ collaboration [2], and also for bottom-quark jet (b-jet) pairs by the CDF collaboration [3]. A measurement of the b-jet pair asymmetry has also been achieved by the LHCb collaboration in pp collisions at the LHC [4].…”