Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at 7 TeV

TL;DR

This paper measures dijet angular distributions at 7 TeV in proton-proton collisions to test for quark compositeness, finding results consistent with QCD and setting new limits on contact interaction scales.

Contribution

First measurement of dijet angular distributions at 7 TeV with CMS, providing new constraints on quark compositeness and contact interaction scales.

Findings

Data agree with perturbative QCD predictions.

No evidence of quark compositeness found.

Lower limits on contact interaction scale set at 5.6 and 6.7 TeV.

Abstract

Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at sqrt(s) = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV (6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level.