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

TL;DR

This paper measures the forward-backward asymmetry in low-mass bottom-quark pairs produced in proton-antiproton collisions, providing results consistent with the Standard Model predictions.

Contribution

First measurement of $A_{FB}$ in low-mass $b\bar{b}$ pairs at Tevatron energies using muon-tagged events.

Findings

Measured $A_{FB}(b\bar{b})$ = (1.2 ± 0.7)% at particle level.

Analyzed $A_{FB}$ dependence on invariant mass $m_{b\bar{b}}$.

Results agree with Standard Model expectations.

Abstract

We report a measurement of the forward-backward asymmetry, $A_{FB}$, in $b\bar{b}$ pairs produced in proton-antiproton collisions and identified by muons from semileptonic $b$-hadron decays. The event sample was collected at a center-of-mass energy of $\sqrt{s}=1.96$ TeV with the CDF II detector and corresponds to 6.9 fb$^{-1}$ of integrated luminosity. We obtain an integrated asymmetry of $A_{FB}(b\bar{b})=(1.2 \pm 0.7)$\% at the particle level for $b$-quark pairs with invariant mass, $m_{b\bar{b}}$, down to $40$ GeV/$c^2$ and measure the dependence of $A_{FB}(b\bar{b})$ on $m_{b\bar{b}}$. The results are compatible with expectations from the standard model.