Measurement of the ATLAS di-muon trigger efficiency in proton-proton collisions at 7 TeV

TL;DR

This paper evaluates the efficiency of the ATLAS di-muon trigger system in proton-proton collisions at 7 TeV, crucial for B-physics analyses and new physics searches, using real and simulated data.

Contribution

It provides a detailed measurement and validation of the di-muon trigger efficiency in ATLAS at 7 TeV, including performance assessment of dedicated trigger algorithms.

Findings

High trigger efficiency achieved for low pT di-muon events

Validation of trigger performance with collision data and simulations

Effective discrimination between topological and non-topological triggers

Abstract

At the LHC, muons are produced in many final states and used in a variety of analysis, such as Standard Model precision measurements and searches for new physics. The B-physics programme in ATLAS includes the measurement of CP violating effects in B meson decays, the search for rare b decay signatures, as well as the study of the production cross sections. The ATLAS detector can identify muons with high purity in a transverse momentum ($p_{T}$) range from a few GeV to several TeV. In order to achieve a high trigger efficiency for low $p_{T}$ di-muon events and at the same time keep an acceptable trigger rate, dedicated trigger algorithms have been designed and implemented in the trigger menu since the 2010 data taking period. There are two categories of B-physics triggers, one topological and one non-topological. Both of these have been studied and their performance assessed using collision data at $\sqrt{s}$ = 7 TeV. The performance found with data has been verified with simulated events.