Measurement of the differential cross-section of highly boosted top quarks as a function of their transverse momentum in $\sqrt{s}$ = 8 TeV proton-proton collisions using the ATLAS detector

TL;DR

This paper measures the differential cross-section of highly boosted top quarks as a function of their transverse momentum in 8 TeV proton-proton collisions, using advanced jet reconstruction and substructure techniques, and compares results with theoretical predictions.

Contribution

It provides the first detailed measurement of top quark production at high transverse momentum with corrections to particle and parton levels, validating various Monte Carlo models.

Findings

Measured cross-sections agree with most NLO and LO Monte Carlo predictions.

First detailed high-$p_T$ top quark differential cross-section measurement.

Provides data for testing QCD and top quark modeling at high energies.

Abstract

The differential cross-section for pair production of top quarks with high transverse momentum is measured in 20.3 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV. The measurement is performed for $t\bar{t}$ events in the lepton+jets channel. The cross-section is reported as a function of the hadronically decaying top quark transverse momentum for values above 300 GeV. The hadronically decaying top quark is reconstructed as an anti-$k_t$ jet with radius parameter $R=1.0$ and identified with jet substructure techniques. The observed yield is corrected for detector effects to obtain a cross-section at particle level in a fiducial region close to the event selection. A parton-level cross-section extrapolated to the full phase space is also reported for top quarks with transverse momentum above 300 GeV. The predictions of a majority of next-to-leading-order and leading-order matrix-element Monte Carlo generators are found to agree with the measured cross-sections.