Updated Search for Dijet Resonances in the Dijet Mass Distribution in pp Collisions at √s = 7 TeV

Abstract

We present a measurement o fthe dijet invariant mass spectrum and search for new particles decaying to dijets at CMS in pp collisions at √s =7 TeV using data corresponding to an integrated luminosity of 836 92 nb−1. The dijet mass distribution of the two leading jets is measured and compared to QCD predictions from PYTHIA propagated through the CMS detector simulation. We require the pseudorapidity separation of the two jets to satisfy |∆η| < 1.3 with each jet inside the region |η| < 2.5. The highest observed dijet mass is 1.92 TeV. We fit the observed dijet mass spectrum with a parameterization, search for dijet resonances, and set upper limits at 95% Confidence Level (C.L.) on the product of the resonance cross section, branching ratio into dijets, and acceptance. These generic cross section limits are compared with theoretical predictions for the cross section for several models of new particles: string resonances, axigluons, colorons, excitedquarks, E6 diquarks, Randall-Sundrum gravitons, W andZ. We exclude at 95% C.L. string resonances with mass less than 2.10 TeV, excited quarks with mass less than 1.14 TeV, axigluons and colorons with mass less than 1.06 TeV, and E6 diquarks with mass less than 0.58 TeV.

Approved Plots from EXO-10-010 ( click on plot to get .pdf )

Figure Abbreviated Caption
Figure_001.gif Trigger efficiency as a function of dijet mass for events with the two leading jets satisfying ∆η < 1.3 and η < 2.5.
Figure_002-a.gif Missing calorimeter ET divided by total calorimeter ET.
Figure_002-b.gif The phi difference of the two leading jets.
Figure_003.gif Expected signal shapes of dijet mass resonances for qq, qg and gg resonances of mass 1.2 TeV as predicted from PYTHIA v6 Monte Carlo propagated through the full CMS detector simulation and jet reconstruction.
Figure_004.gif The measured differential cross section data (points) in dijet mass are compared to a QCD MC prediction (black line). The histogram bin widths are approximately equal to the expected dijet mass resolution for narrow resonances measured with calorimeter jets and gradually increase with dijet mass. The yellow band shows the sensitivity to a 10% systematic uncertainty on the jet energy scale.
Figure_005-a.gif First highest mass dijet events. Lego display of calorimeter energies in ηφ coordinates.
Figure_005-b.gif First highest mass dijet events. Lego display of calorimeter energies in the transverse rφ plane.
Figure_005-c.gif Second highest mass dijet events. Lego display of calorimeter energies in ηφ coordinates.
Figure_005-d.gif Second highest mass dijet events. Lego display of calorimeter energies in the transverse rφ plane.
Figure_005-e.gif Third highest mass dijet events. Lego display of calorimeter energies in ηφ coordinates.
Figure_005-f.gif Third highest mass dijet events. Lego display of calorimeter energies in the transverse rφ plane.
Figure_006.gif The dijet mass distribution (points) compared to simulations of excited quarks (dot dashed red curves) and string resonance (green dashed curve) signals in the CMS detector.
Figure_007.gif The ratio between the dijet mass distribution (points) and a smooth background fit (dashed line) is compared to a CMS detector simulation of an excited quark signal (dashed red curve) and a string resonance signal (dashed green curve).
Figure_008.gif The measured total cross section for dijets accepted by this analysis as a function of run number.
Figure_009.gif Fractional systematic uncertainties on the signal cross section showing the individual and total contributions for qg resonances.
Figure_010.gif The 95% C.L. upper limits on the cross section times branching ratio times acceptance for dijet resonances (points) shown seperately for the three different parton pairs qq, qg and gg, is compared to predictions for several types of new particles decaying to dijets.
Figure_011.gif The observed 95% C.L. upper limits on the cross section times branching ratio times acceptance for quark-gluon resonances (blue points) is compared to the expected limits (green boxes) and to predictions for string resonances (dot-dashed blue curve) and excited quarks (dashed red curve) in the dijet channel.
Figure_012.gif The observed 95% C.L. upper limits on the cross section times branching ratio times acceptance for quark-quark resonances (blue points) is compared to the expected limits (red boxes) and to predictions for axigluons and colorons (dotted blue curve) and E6 Diquarks (dashed green curve) in the dijet channel.

Link to EXO-10-010 PAS in CDS

-- SungwonLee - 29-Aug-2010

Topic attachments
I Attachment History Action Size Date Who Comment
GIFgif Figure_001.gif r1 manage 37.2 K 2010-08-29 - 19:15 SungwonLee  
PDFpdf Figure_001.pdf r1 manage 5.7 K 2010-08-29 - 19:14 SungwonLee  
GIFgif Figure_002-a.gif r1 manage 38.1 K 2010-08-29 - 19:15 SungwonLee  
GIFgif Figure_002-b.gif r1 manage 35.3 K 2010-08-29 - 19:16 SungwonLee  
GIFgif Figure_003.gif r1 manage 41.3 K 2010-08-29 - 19:16 SungwonLee  
GIFgif Figure_004.gif r1 manage 57.2 K 2010-08-29 - 19:16 SungwonLee  
GIFgif Figure_005-a.gif r1 manage 150.0 K 2010-08-29 - 19:17 SungwonLee  
GIFgif Figure_005-b.gif r1 manage 65.0 K 2010-08-29 - 19:17 SungwonLee  
GIFgif Figure_005-c.gif r1 manage 143.7 K 2010-08-29 - 19:18 SungwonLee  
GIFgif Figure_005-d.gif r1 manage 68.8 K 2010-08-29 - 19:18 SungwonLee  
GIFgif Figure_005-e.gif r1 manage 141.7 K 2010-08-29 - 19:18 SungwonLee  
GIFgif Figure_005-f.gif r1 manage 66.3 K 2010-08-29 - 19:19 SungwonLee  
GIFgif Figure_006.gif r1 manage 53.4 K 2010-08-29 - 19:19 SungwonLee  
GIFgif Figure_007.gif r1 manage 31.5 K 2010-08-29 - 19:19 SungwonLee  
GIFgif Figure_008.gif r1 manage 38.9 K 2010-08-29 - 19:20 SungwonLee  
GIFgif Figure_009.gif r1 manage 53.8 K 2010-08-29 - 19:20 SungwonLee  
GIFgif Figure_010.gif r1 manage 72.6 K 2010-08-29 - 19:21 SungwonLee  
GIFgif Figure_011.gif r1 manage 56.2 K 2010-08-29 - 19:21 SungwonLee  
GIFgif Figure_012.gif r1 manage 57.8 K 2010-08-29 - 19:22 SungwonLee  
Edit | Attach | Watch | Print version | History: r4 < r3 < r2 < r1 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r4 - 2010-09-09 - ChristopherHill
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    CMSPublic All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2020 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback