Search for Resonances in the Dijet Mass Spectrum from 7 TeV pp Collisions at CMS : EXO-11-015


Physics Letters B704, 123 (2011) also available at ArXiv 1107.4771.


A search for narrow resonances with a mass of at least 1 TeV in the dijet mass spectrum is performed using pp collisions at √s = 7 TeV corresponding to an integrated luminosity of 1fb-1, collected by the CMS experiment at the LHC. No resonances are observed. Upper limits at the 95%, confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, and gluon-gluon pairs. The data exclude new particles predicted in th following models at 95% confidence level: string resonances with mass less than 4.00 TeV, E6 diquarks with mass less than 3.52 TeV, excited quarks with mass less than 2.49 TeV, axigluons and colorons with mass less than 2.47 TeV, and W' bosons with mass less than 1.51 TeV.

Approved Plots from EXO-11-015 ( click on plot to get .pdf )

Figure Abbreviated Caption
c_DijetMass_calo_pf_fat_log.pdf The number of events observed versus dijet mass for wide jets(solid circles), particle flow AK7 jets(open boxes), and calorimeter AK7 jets(X symbols). png
DijetMass_Cross_Section_with_fit_signal_and_pull.pdf Dijet Mass spectrum from wide jets (points) compared to a smooth fit (solid) and to predictions including detector simulation of QCD (short-dashed), excited quark signals(dot-dashed), and string resonance signals(long-dashed). The QCD prediction has been normalized to the data. The error bars are statistical only. The dashed band shows the systematic uncertainty in the jet energy scale (JES). The bin by bin significance of the data-fit difference is shown at bottom. png
data_over_fit.pdf Ratio(points) between the dijet mass data from wide jets and the smotth fit, compared to the simulated ratios for excited quark signals (dot-dashed) in the CMS detector. The error bars represent statistical uncertainties only. png
c_resoncnace.pdf Simulation of the expected dijet mass distributions in the CMS detector from a narrow 2.0 TeV resonance of type quark-quark (solid), quark-gluon (dashed), and gluon-gluon (dotted) using wide jet reconstruction, and of type gluon-gluon using anti- kT jet reconstruction with distance parameter R = 0.7 (dot-dash). png
c_xs_sys.pdf The 95% CL upper limits on σ × B × A for dijet resonances of type gluon-gluon (open circles), quark-gluon (solid circle), and quark-quark (open boxes), compared to theoretical predictions for string resonances, E6 diquarks, excited quarks, axigluons, colorons, new gauage bosons W' and Z', Randall-Sundrum gratvitons. png
expected_qg.pdf The observed 95% CL upper limits on σ × B × A for quark-gluon dijet resonances (points) are compared to the expected limits (dot-dash) and their expected statistical variation at the 1 σ and 2 σ levels (shaded bands) and are also compared to the theoretical predictions for string resonances and excited quarks. png
limittable.pdf For each model we list the observed and expected upper values of the excluded mass range at 95% CL. The lower value of the excluded mass range from this search is 1 TeV. png
EventDisplay_1st_lego.pdf The lego display of event with highest dijet mass. png
EventDisplay_1st_rhophi.pdf The ρ-φ display of event with highest dijet mass. png
EventDisplay_10th_lego.pdf The lego display of event with the 10th highest dijet mass which is a good example of how wide jets recombine radiation. png
EventDisplay_10th_rhophi.pdf The ρ-φ display of event with the 10th highest dijet mass which is a good example of how wide jets recombine radiation. png
An example slide which shows the 10th higest dijet mass event and illusrates the recombination of radiation done by wide jets. png

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf DijetMass_Cross_Section_with_fit_signal_and_pull.pdf r1 manage 11.1 K 2011-07-25 - 18:22 ChiyoungJeong  
PNGpng DijetMass_Cross_Section_with_fit_signal_and_pull.png r1 manage 23.1 K 2011-07-25 - 18:22 ChiyoungJeong  
PDFpdf EventDisplay_10th_lego.pdf r1 manage 62.4 K 2011-07-25 - 18:24 ChiyoungJeong  
PNGpng EventDisplay_10th_lego.png r1 manage 66.8 K 2011-07-25 - 18:25 ChiyoungJeong  
PDFpdf EventDisplay_10th_rhophi.pdf r1 manage 33.9 K 2011-07-25 - 18:25 ChiyoungJeong  
PNGpng EventDisplay_10th_rhophi.png r1 manage 33.4 K 2011-07-25 - 18:26 ChiyoungJeong  
PDFpdf EventDisplay_1st_lego.pdf r1 manage 60.3 K 2011-07-25 - 18:23 ChiyoungJeong  
PNGpng EventDisplay_1st_lego.png r1 manage 64.7 K 2011-07-25 - 18:23 ChiyoungJeong  
PDFpdf EventDisplay_1st_rhophi.pdf r1 manage 32.1 K 2011-07-25 - 18:23 ChiyoungJeong  
PNGpng EventDisplay_1st_rhophi.png r1 manage 31.6 K 2011-07-25 - 18:24 ChiyoungJeong  
PDFpdf Slide07.pdf r3 r2 r1 manage 133.9 K 2011-07-26 - 23:10 ChiyoungJeong  
PNGpng Slide07.png r4 r3 r2 r1 manage 211.7 K 2011-07-26 - 23:11 ChiyoungJeong  
PDFpdf c_DijetMass_calo_pf_fat_log.pdf r1 manage 8.7 K 2011-07-25 - 18:18 ChiyoungJeong  
PNGpng c_DijetMass_calo_pf_fat_log.png r1 manage 16.9 K 2011-07-25 - 18:18 ChiyoungJeong  
PDFpdf c_resoncnace.pdf r1 manage 4.7 K 2011-07-25 - 18:19 ChiyoungJeong  
PNGpng c_resoncnace.png r1 manage 17.2 K 2011-07-25 - 18:20 ChiyoungJeong  
PDFpdf c_xs_sys.pdf r1 manage 9.7 K 2011-07-25 - 18:20 ChiyoungJeong  
PNGpng c_xs_sys.png r1 manage 30.3 K 2011-07-25 - 18:21 ChiyoungJeong  
PDFpdf data_over_fit.pdf r1 manage 7.2 K 2011-07-25 - 18:21 ChiyoungJeong  
PNGpng data_over_fit.png r1 manage 14.9 K 2011-07-25 - 18:22 ChiyoungJeong  
PDFpdf expected_qg.pdf r1 manage 8.8 K 2011-07-25 - 18:26 ChiyoungJeong  
PNGpng expected_qg.png r1 manage 23.7 K 2011-07-25 - 18:27 ChiyoungJeong  
PDFpdf limittable.pdf r1 manage 89.7 K 2011-07-26 - 00:52 ChiyoungJeong  
PNGpng limittable.png r1 manage 76.0 K 2011-07-26 - 00:51 ChiyoungJeong  
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Topic revision: r7 - 2013-03-01 - SungwonLee
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