Study of multi-muon events produced in p-pbar collisions at sqrt(s)=1.96 TeV

TL;DR

This study investigates multi-muon events at the Fermilab Tevatron, revealing unexplained events with muons produced outside the beam pipe, which may resolve longstanding issues in b-bbar production understanding.

Contribution

It presents the first detailed analysis of muons produced outside the beam pipe, highlighting discrepancies with known QCD models and suggesting potential new physics or detector effects.

Findings

Known QCD processes model inside-beam muon events well

Unexplained excess of outside-beam muon events observed

Potential implications for b-bbar production and decay understanding

Abstract

We report a study of multi-muon events produced at the Fermilab Tevatron collider and recorded by the CDFII detector. In a data set acquired with a dedicated dimuon trigger and corresponding to an integrated luminosity of 2100 pb^-1, we isolate a significant sample of events in which at least one of the muon candidates is produced outside of the beam pipe of radius 1.5cm. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe are successfully modeled by known QCD processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDFII detector, trigger, and event reconstruction. Several topological and kinematic properties of these events are presented in this paper. These events offer a plausible resolution to long-standing inconsistencies related to b-bbar production and decay.