Search for quark compositeness in dijet angular distributions from pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper searches for signs of quark substructure by analyzing dijet angular distributions in proton-proton collisions at 7 TeV, finding no deviations from standard QCD predictions and setting limits on contact interaction scales.

Contribution

First measurement of dijet angular distributions at high invariant masses at 7 TeV, testing quark compositeness models with NLO QCD corrections, and setting new limits on contact interaction scales.

Findings

Data agree with perturbative QCD predictions.

Lower limits on contact interaction scale range from 7.5 to 14.5 TeV.

No evidence of quark compositeness observed.

Abstract

A search for quark compositeness using dijet angular distributions from pp collisions at sqrt(s) = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95% confidence level.