Background dependence of dimuon asymmetry in $\bar p p$ interactions at $\sqrt{s} = 1.96$ TeV

TL;DR

This paper investigates how background processes, especially kaon misidentification, affect the observed dimuon charge asymmetry at the Tevatron, proposing impact parameter restrictions to improve the measurement's accuracy.

Contribution

It provides a detailed analysis of background asymmetries with impact parameter bounds, aiding future precise measurements of B meson decay asymmetries.

Findings

Background asymmetry predictions depend on impact parameter cuts.

Complementary impact parameter bounds can help isolate B decay signals.

Results support improved background control in asymmetry measurements.

Abstract

The D0 Collaboration has reported an anomalous charge asymmetry in the production of same-sign muon pairs at the Fermilab Tevatron. The magnitude of this effect depends on the subtraction of several backgrounds, the most notable of which is due to kaons being misidentified as muons either through decays in flight or punch-through. The present authors suggested a check on such backgrounds consisting of a tight restriction on the muon impact parameter $b$, to confirm that this excess was indeed due to $B_{(s)}$ meson decays. The D0 Collaboration has performed a related check applying transverse impact parameter (IP) restrictions, whose implications are discussed. We study background asymmetry predictions for events involving two muons with IP bounds which are complementary to each other. These predictions may be used in future measurements of the net charge asymmetry from $B_{(s)}$ decays.