Measurement of top quark pair differential cross-sections in the dilepton channel in $pp$ collisions at $\sqrt{s} =$ 7 and 8\,TeV with ATLAS

TL;DR

This paper reports measurements of normalized differential cross-sections of top quark pair production in dilepton final states at 7 and 8 TeV, comparing results with theoretical models and Monte Carlo simulations to test the Standard Model predictions.

Contribution

It provides the first detailed differential cross-section measurements of $t\bar t$ production at 7 and 8 TeV in the dilepton channel, with corrections to parton level and comparison to various models.

Findings

Results are consistent with most theoretical predictions.

Differential cross-sections agree with Monte Carlo simulations within uncertainties.

Data constrains models of top quark production at LHC energies.

Abstract

Measurements of normalized differential cross-sections of top quark pair ($t\bar t$) production are presented as a function of the mass, the transverse momentum and the rapidity of the $t\bar t$ system in proton-proton collisions at center-of-mass energies of $\sqrt{s}$ = 7 TeV and 8 TeV. The dataset corresponds to an integrated luminosity of 4.6 fb$^{-1}$ at 7 TeV and 20.2 fb$^{-1}$ at 8 TeV, recorded with the ATLAS detector at the Large Hadron Collider. Events with top quark pair signatures are selected in the dilepton final state, requiring exactly two charged leptons and at least two jets with at least one of the jets identified as likely to contain a $b$-hadron. The measured distributions are corrected for detector effects and selection efficiency to cross-sections at the parton level. The differential cross-sections are compared with different Monte Carlo generators and theoretical calculations of $t\bar t$ production. The results are consistent with the majority of predictions in a wide kinematic range.