Compact Muon Solenoid
LHC, CERN
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| CMS-QCD-10-016 ; CMS-EXO-10-009 ; CERN-PH-EP-2010-092 | ||
| Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at $\sqrt{s}$ = 7 TeV | ||
| CMS Collaboration | ||
| 9 February 2011 | ||
| Phys. Rev. Lett. 106 (2011) 201804 | ||
| 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 is obtained at the 95% confidence level. | ||
| Links: e-print arXiv:1102.2020 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; Public twiki page ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Normalized dijet angular distributions in several $M_{jj}$ ranges, shifted vertically by the additive amounts given in parentheses in the figure for clarity. The data points include statistical and systematic uncertainties. The results are compared with the predictions of pQCD at NLO (shaded band) and with the predictions including a contact interaction term of compositeness scale $\Lambda ^{+} = $ 5 TeV (dashed histogram) and $\Lambda ^{-} = $ 5 TeV (dotted histogram). The shaded band shows the effect on the NLO pQCD predictions due to $\mu _r$ and $\mu _f$ scale variations and PDF uncertainties, as well as the uncertainties from the non-perturbative corrections added in quadrature. |
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Figure 2:
Observed ${\rm CL}_{\rm s}$ (solid line) and expected ${\rm CL}_{\rm s}$ (dashed line) with one (two) standard deviation(s) indicated by the dark (light) band as a function of the contact interaction scale $\Lambda ^{+}$. The 95% confidence level limits on $\Lambda ^{+}$ are extracted from the intersections of the observed and expected ${\rm CL}_{\rm s}$ lines with the horizontal line at ${\rm CL}_{\rm s} = $ 0.05. |
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Compact Muon Solenoid LHC, CERN |
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