-- BhawnaGomber - 2014-11-03

Search for new phenomena in monophoton final states in proton-proton collisions at √s = 8 TeV

Abstract

Results are presented from a search for new physics in final states containing a photon and missing transverse momentum. The data correspond to an integrated luminosity of 19.6 fb-1 collected in proton-proton collisions at √s =8 TeV with the CMS experiment at the CERN LHC. No deviation from the standard model predictions is observed for these final states. New, improved limits are set on dark matter production and on parameters of models with large extra dimensions. In particular, the first limits on branon production at a hadron collider are found and significantly extend previous limits from LEP. A cross section upper limit of 14.0 fb is set at the 95% confidence level for events with a monophoton final state with photon transverse momentum greater than 145 GeV and missing transverse momentum greater than 140 GeV.

Approved Plots from EXO-12-047 ( click on plot to get .pdf )

Figure Abbreviated Caption
photon_pt8.png Photon transverse momentum distribution for the candidate sample, compared with estimated contribtuions from Standard model backgrounds and a prediction from ADD signal for $M_{D}$ = 2 TeV and $n$ = 3. The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
met8.png The MET distribution for the candidate sample, compared with estimated contributions from SM background and a prediction from ADD signal for $M_{D}$ = 2 TeV and $n$ = 3. The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
tab1.png Summary of estimated backgrounds and observed total number of candidates for 19.6 fb-1 of 2012 data. Backgrounds listed as Others include $W\mu\nu$, $Z(ll)+\gamma$, $\gamma\gamma$ and $\gamma$+jet. A scale factor has been applied on backgrounds estimated from MC and k factor have been applied on $Z(\nu\nu)+\gamma$ and $W(l\nu)+\gamma$ backgrounds.
limit_modind_md2d3_95CL.png Model-independent 95% confidence level upper limits on a signal cross section times acceptance for counting experiments as a function of the cut on the photon transverse momentum.
Tab2.png Observed (expected) model-independent 95% and 90% confidence level upper limits on a signal cross section times acceptance for counting experiments as a function of the cut on the photon transverse momentum.
MD_vs_n_leptonveto10_shape.png Limits on $M_{D}$ as a function of extra dimensions, compared to LO results from similar searches at the Tevatron and LEP along with the CMS 7 TeV results.
Tab5.png The 95% confidence level observed and expected limits on the ADD cross section as a function of $M_{D}$ and extra dimensions.
dm_limit_si_monophoton_leptonveto10_shape.png The 90% confidence level upper limits on the $\chi$-nucleon cross section as a function of $M_{\chi}$ for spin independent scattering. Also shown are the limits from selected experiments with published results along with CMS 7 and 8 TeV results.
Tab3.png This table summarizes the theoretical dark-matter production cross section (where generated photon transverse momentum is greater than 130 GeV and cut-off scale $\Lambda$ is 10 TeV), observed(expected) 90% confidence level upper limits on the dark matter production cross section where a photon with pT greater than 130 GeV is radiated by one of the incoming quarks, 90% confidence level observed(expected) lower limits on the cut-off scale $\Lambda$ and the 90% confidence level observed(expected) upper limits on the $\chi$-nucleon cross section for the vector operator as a function of the dark-matter mass.
dm_limit_sd_monopho_leptonveto_10_shape.png The 90% confidence level upper limits on the $\chi$-nucleon cross section as a function of $M_{\chi}$ for spin dependent scattering. Also shown are the limits from selected experiments with published results along with CMS 7 and 8 TeV results.
Tab4.png This table summarizes the theoretical dark-matter production cross section (where generated photon transverse momentum is greater than 130 GeV and cut-off scale $\Lambda$ is 10 TeV), observed(expected) 90% confidence level upper limits on the dark matter production cross section where a photon with pT greater than 130 GeV is radiated by one of the incoming quark, 90% confidence level observed(expected) lower limits on the cut-off scale $\Lambda$ and the 90% confidence level observed(expected) upper limits on the $\chi$-nucleon cross section for the axial vector operator as a function of the dark-matter mass.
mediator_mass_scan.png Observed limits on the DM mediator mass divided by coupling, $M/\sqrt{g_{\chi}g_{q}}$ as a function of the mediator mass $M$, assuming vector interactions, for DM particle masses of 50 GeV and 500 GeV. The width, $\Gamma$, of the mediator is varied between $M/8\pi$ and $M/3$. The dashed lines show contours of constant coupling.
xsec_branon_shape.png The 95% confidence level upper limits on the Branon cross sections as a function of branon mass.
limits_branon_shape.png The 95% confidence level upper limits on the branon brane tension as a function of branon mass. Also shown is the LEP limits.
Tab6.png The 95% confidence level observed and expected upper limits on the branon brane tension $f$ as a function of the branon mass $M_{B}$ .

Other Unpublished Results ( _click on plot to get .pdf )

photon_pt8_CR.png Photon transverse momentum distribution in the $Z\gamma$ control region. Data is depicted as solid circles with error bars. Standard model backgrounds are shown as colored histograms and the shaded band is their uncertainty. The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
met8_CR.png Missing transverse energy distribution in the $Z\gamma$ control region. Data is depicted as solid circles with error bars. Standard model backgrounds are shown as colored histograms and the shaded band is their uncertainty. The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
photon_pt8_Wgamma.png Photon transverse momentum distribution in the $W\gamma$ control region. Data is depicted as solid circles with error bars. Standard model backgrounds are shown as colored histograms and the shaded band is their uncertainty. The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
met8_Wgamma.png Missing transverse energy distribution in the $W\gamma$ control region. Data is depicted as solid circles with error bars. Standard model backgrounds are shown as colored histograms and the shaded band is their uncertainty. The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
higheesptevent_photon_publc.png 3-D view of the highest photon $p_{T}$ candidate event. Info: run:event:lumisection =207454:771:1095163126; Photon Pt = 653 GeV; MET = 716 GeV
highestpt_rhophi.png Rho-Phi view of the highest photon $p_{T}$ candidate event. Info: run:event:lumisection =207454:771:1095163126; Photon Pt = 653 GeV; MET = 716 GeV
pvalue7_err.png Absolute value of the log10 of pvalue for the candidate sample, compared with estimated contributions from Standard model backgrounds and a prediction from ADD signal for $M_{D}$ = 2 TeV and $n$ = 3 . The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
minmet7_err.png Recalculated minimized MET distribution for the candidate sample, compared with estimated contributions from Standard model backgrounds and a prediction from ADD signal for $M_{D}$ = 2 TeV and $n$ = 3. The bottom panel shows the ratio of data over expected events based on combined statistical and systematic uncertainty.
tower_3d.png 3-D view of the QCD event. Info: run:event:lumisection = 194050:698:652513020; Jet Pt = 965 GeV
rho_phi.png Rho-Phi view of the QCD event. Info: run:event:lumisection = 194050:698:652513020; Jet Pt = 965 GeV
limit_modind_md2d3_90CL.png Model-independent 90% confidence level upper limits on a signal cross section times acceptance for counting experiments as a function of the cut on the photon transverse momentum.
Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf ADD.pdf r1 manage 17.7 K 2014-11-05 - 21:38 BhawnaGomber  
PNGpng ADD.png r1 manage 15.8 K 2014-11-05 - 21:38 BhawnaGomber  
PDFpdf DM_Vector.pdf r1 manage 50.9 K 2014-11-05 - 21:38 BhawnaGomber  
PNGpng DM_Vector.png r1 manage 52.8 K 2014-11-05 - 21:38 BhawnaGomber  
PDFpdf MD_vs_n_leptonveto10_shape.pdf r1 manage 14.1 K 2014-11-03 - 22:25 BhawnaGomber  
PNGpng MD_vs_n_leptonveto10_shape.png r1 manage 14.6 K 2014-11-03 - 22:25 BhawnaGomber  
PDFpdf Model_ind.pdf r1 manage 33.7 K 2014-11-05 - 21:38 BhawnaGomber  
PNGpng Model_ind.png r1 manage 33.7 K 2014-11-05 - 21:38 BhawnaGomber  
PDFpdf Tab2.pdf r1 manage 49.8 K 2014-11-05 - 22:01 BhawnaGomber  
PNGpng Tab2.png r1 manage 55.2 K 2014-11-05 - 22:01 BhawnaGomber  
PDFpdf Tab3.pdf r1 manage 51.7 K 2014-11-05 - 22:01 BhawnaGomber  
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PDFpdf Tab4.pdf r1 manage 48.7 K 2014-11-05 - 22:01 BhawnaGomber  
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PDFpdf Tab5.pdf r1 manage 15.0 K 2014-11-05 - 22:01 BhawnaGomber  
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PDFpdf Tab6.pdf r1 manage 19.5 K 2014-11-05 - 22:19 BhawnaGomber  
PNGpng Tab6.png r1 manage 21.6 K 2014-11-05 - 22:19 BhawnaGomber  
PDFpdf Table_AV.pdf r1 manage 48.9 K 2014-11-05 - 21:38 BhawnaGomber  
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PDFpdf dm_limit_sd_monopho_leptonveto_10_shape.pdf r1 manage 19.0 K 2014-11-03 - 22:27 BhawnaGomber  
PNGpng dm_limit_sd_monopho_leptonveto_10_shape.png r1 manage 29.3 K 2014-11-03 - 22:27 BhawnaGomber  
PDFpdf dm_limit_si_monophoton_leptonveto10_shape.pdf r1 manage 30.7 K 2014-11-03 - 22:25 BhawnaGomber  
PNGpng dm_limit_si_monophoton_leptonveto10_shape.png r1 manage 36.2 K 2014-11-03 - 22:25 BhawnaGomber  
PDFpdf higheesptevent_photon_publc.pdf r1 manage 106.5 K 2014-11-07 - 21:09 BhawnaGomber  
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PDFpdf highestpt_rhophi.pdf r1 manage 85.3 K 2014-11-07 - 21:09 BhawnaGomber  
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PDFpdf limit_modind_md2d3_90CL.pdf r1 manage 14.2 K 2014-11-07 - 21:15 BhawnaGomber  
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PDFpdf limit_modind_md2d3_95CL.pdf r1 manage 14.3 K 2014-11-03 - 22:25 BhawnaGomber  
PNGpng limit_modind_md2d3_95CL.png r1 manage 15.4 K 2014-11-03 - 22:25 BhawnaGomber  
PDFpdf limits_branon_shape.pdf r1 manage 14.4 K 2014-11-05 - 22:33 BhawnaGomber  
PNGpng limits_branon_shape.png r1 manage 45.0 K 2014-11-05 - 22:33 BhawnaGomber  
PDFpdf mediator_mass_scan.pdf r1 manage 16.6 K 2014-11-05 - 22:35 BhawnaGomber  
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PDFpdf rho_phi.pdf r1 manage 84.0 K 2014-11-07 - 21:09 BhawnaGomber  
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