# First measurement of the charge asymmetry in beauty-quark pair production

LHCb Collaboration; Bernet, R; Müller, K; Steinkamp, O; Straumann, U; Serra, N; Vollhardt, A; et al (2014). First measurement of the charge asymmetry in beauty-quark pair production. Physical Review Letters, 113(082003):online.

## Abstract

The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in bb¯ pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0fb−1 collected at 7TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the bb¯ system. The results obtained are:
Abb¯C(40<Mbb¯<75GeV/c2)Abb¯C(75<Mbb¯<105GeV/c2)Abb¯C(Mbb¯>105GeV/c2)===0.4±0.4(stat)±0.3(syst)%2.0±0.9(stat)±0.6(syst)%1.6±1.7(stat)±0.6(syst)%
where Abb¯C is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark. The beauty jets are required to satisfy 2<η<4, ET>20GeV, and have an opening angle in the transverse plane Δϕ>2.6rad. These measurements are consistent with the predictions of the Standard Model.

## Abstract

The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in bb¯ pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0fb−1 collected at 7TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the bb¯ system. The results obtained are:
Abb¯C(40<Mbb¯<75GeV/c2)Abb¯C(75<Mbb¯<105GeV/c2)Abb¯C(Mbb¯>105GeV/c2)===0.4±0.4(stat)±0.3(syst)%2.0±0.9(stat)±0.6(syst)%1.6±1.7(stat)±0.6(syst)%
where Abb¯C is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark. The beauty jets are required to satisfy 2<η<4, ET>20GeV, and have an opening angle in the transverse plane Δϕ>2.6rad. These measurements are consistent with the predictions of the Standard Model.

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