Measurement of the flavour composition of dijet events in pp collisions at root s=7 TeV with the ATLAS detector

G. Aad, T. Abajyan, B. Abbott, J. Abdallah, S.A. Khalek, Mogens Dam, Jørgen Beck Hansen, Peter Henrik Hansen, John Renner Hansen, Jørn Dines Hansen, Simon Johann Franz Heisterkamp, Morten Dam Jørgensen, Nele Maria Philomena Boelaert, Esben Bryndt Klinkby, Ask Emil Løvschall-Jensen, Sascha Mehlhase, Björn Stefan Nilsson, Troels Christian Petersen, Stefania Xella

18 Citationer (Scopus)

Abstract

This paper describes a measurement of the flavour composition of dijet events produced in pp collisions at √s = 7 TeV using the ATLAS detector. The measurement uses the full 2010 data sample, corresponding to an integrated luminosity of 39 pb−1. Six possible combinations of light, charm and bottom jets are identified in the dijet events, where the jet flavour is defined by the presence of bottom, charm or solely light flavour hadrons in the jet. Kinematic variables, based on the properties of displaced decay vertices and optimised for jet flavour identification, are used in a multidimensional template fit to measure the fractions of these dijet flavour states as functions of the leading jet transverse momentum in the range 40 GeV to 500 GeV and jet rapidity |y| < 2.1. The fit results agree with the predictions of leading- and next-to-leading-order calculations, with the exception of the dijet fraction composed of bottom and light flavour jets, which is underestimated by all models at large transverse jet momenta. The ability to identify jets containing two b-hadrons, originating from e.g. gluon splitting, is demonstrated. The difference between bottom jet production rates in leading and subleading jets is consistent with the next-to-leading-order predictions.

OriginalsprogEngelsk
Artikelnummer2301
TidsskriftEuropean Physical Journal C
Vol/bind73
Udgave nummer2
ISSN1434-6044
DOI
StatusUdgivet - 12 feb. 2013

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