Measurement of differential production cross-sections for a $Z$ boson in association with $b$-jets in 7 TeV proton-proton collisions with the ATLAS detector

TL;DR

This paper reports measurements of how often a Z boson is produced with b-jets in proton-proton collisions at 7 TeV, providing detailed differential cross-sections to test quantum chromodynamics predictions.

Contribution

It presents the first detailed differential cross-section measurements of Z boson production with b-jets at 7 TeV, comparing results with theoretical QCD calculations.

Findings

Measured cross-sections as functions of Z boson and b-jet kinematics.

Results generally agree with leading-order and next-to-leading-order QCD predictions.

Provides data to improve theoretical models of Z+b-jet production.

Abstract

Measurements of differential production cross-sections of a $Z$ boson in association with $b$-jets in $pp$ collisions at $\sqrt{s}=7$ TeV are reported. The data analysed correspond to an integrated luminosity of 4.6 fb$^{-1}$ recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a $Z$ boson decaying into an electron or muon pair, and containing $b$-jets. For events with at least one $b$-jet, the cross-section is presented as a function of the $Z$ boson transverse momentum and rapidity, together with the inclusive $b$-jet cross-section as a function of $b$-jet transverse momentum, rapidity and angular separations between the $b$-jet and the $Z$ boson. For events with at least two $b$-jets, the cross-section is determined as a function of the invariant mass and angular separation of the two highest transverse momentum $b$-jets, and as a function of the $Z$ boson transverse momentum and rapidity. Results are compared to leading-order and next-to-leading-order perturbative QCD calculations.