ATLAS b-jet identification performance and efficiency measurement with 𝑡𝑡¯ t t ¯ events in pp collisions at 𝑠√=13 s = 13 TeV

G. OTERO Y GARZON, ET. AL., THE ATLAS COLLABORATION

JOURNAL OF HIGH ENERGY PHYSICS

SPRINGER

Lugar: Berlin; Año: 2019

1126-6708

The algorithms used by the ATLAS Collaboration during Run 2 of the Large Hadron Collider to identify jets containing b-hadrons are presented. The performance of the algorithms is evaluated in the simulation and the efficiency with which these algorithms identify jets containing b-hadrons is measured in collision data. The measurement uses a likelihood-based method in a sample highly enriched in 𝑡𝑡¯tt¯ events. The topology of the 𝑡→𝑊𝑏t→Wb decays is exploited to simultaneously measure both the jet flavour composition of the sample and the efficiency in a transverse momentum range from 20 to 600 GeV. The efficiency measurement is subsequently compared with that predicted by the simulation. The data used in this measurement, corresponding to a total integrated luminosity of 80.5 fb−1fb−1, were collected in proton?proton collisions during the years 2015?2017 at a centre-of-mass energy 𝑠√=s= 13 TeV. By simultaneously extracting both the efficiency and jet flavour composition, this measurement significantly improves the precision compared to previous results, with uncertainties ranging from 1 to 8% depending on the jet transverse momentum.