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Compact Muon Solenoid
LHC, CERN

CMS-PAS-EXO-15-009
Searches for quark contact interactions and extra spatial dimensions with dijet angular distributions in proton proton collisions at 13 TeV
Abstract: A search for quark contact interactions and extra spatial dimensions using measurements of dijet angular distributions in pp collisions at $ \sqrt{s} = $ 13 TeV is presented. The data was collected by the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 2.6 fb$^{-1}$. The distributions are found to be in good agreement with predictions from perturbative QCD that include electroweak corrections. Limits for different contact interaction models are obtained. In the benchmark scenario, where only left-handed quarks participate and which is evaluated to leading-order in QCD, quark contact interactions are excluded to a scale of 12.1 (16.3) TeV for destructive (constructive) interference at 95% confidence level. Also presented are lower limits on the scale of graviton exchange according to GRW and HLZ conventions. In the GRW convention, virtual graviton exchange is excluded up to a scale of 9.1 TeV.
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Figure 1:
Normalized $ \chi _{dijet} $ distributions for 2.6 fb$^{-1}$ of integrated luminosity. The corrected data distributions are compared to NLO predictions with non-perturbative corrections (black dotted line). The error bars represent statistical and experimental systematic uncertainties combined in quadrature. The ticks on the error bars represent experimental systematic uncertainties only. Theoretical uncertainties are indicated as a gray band. Also shown are the predictions for QCD+CI with $\Lambda _{LL}^+ \mathrm{(LO)}= $ 10 TeV (red solid line), and QCD+ADD with $\Lambda _{T} \mathrm{(GRW)} =$ 9 TeV (blue dashed line).
Compact Muon Solenoid
LHC, CERN