Search for Dark Matter and Large Extra Dimensions in Monojet Events in pp Collisions at sqrt(s)=7 TeV

Abstract

A search has been made for events containing an energetic jet and an imbalance in transverse momentum using a data sample of pp collisions at a center-of-mass en- ergy of 7 TeV. This signature is common to both dark matter and extra dimensions models. The data were collected by the CMS detector at the LHC and correspond to an integrated luminosity of 5.0 fb-1 . The number of observed events is consistent with the standard model expectation. Constraints on the dark matter-nucleon scat- tering cross sections are determined for both spin-independent and spin-dependent interaction models. For the spin-independent model, these are the most constraining limits for a dark matter particle with mass below 3.5 GeV/c2 , a region unexplored by direct detection experiments. For the spin-dependent model, these are the most strin- gent constraints over the 0.1200 GeV/c2 mass range. The constraints on the Arkani- Hamed, Dimopoulos, and Dvali model parameter MD determined as a function of the number of extra dimensions are also an improvement over the previous results.

Search for New Physics with a Mono-Jet and Missing Transverse Energy in pp Collisions at sqrt(s) = 7 TeV, 36 pb-1

Search for dark matter and large extra dimensions in monojet events in pp collisions at sqrt(s)= 7 TeV, 5 fb-1

Approved Plots from EXO-11-059 ( click on figures to get .pdf )

The background is normalized to the data-driven predictions, where this is available. A dark matter signal (for axial-vector couplings and Mc = 1 GeV/c2) is shown as a dashed blue line and an ADD signal (with MD = 2 TeV, δ = 3) is shown as a dashed red line.

Figure (PDF files) Abbreviated Caption
Met_200.jpg Distribution of MET, after MET>200 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 and Lepton Veto cuts. Data are compared with Monte Carlo SM expectations, and an example of ADD and DarkMatter signal are presented.

Met.jpg Distribution of MET, after MET>350 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 and Lepton Veto cuts. Data are compared with Monte Carlo SM expectations, and an example of ADD and DarkMatter signal are presented.

Jet1Pt.jpg Distribution of pT(j1), after pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 , MET > 350 GeV and Lepton Veto cuts. Data are compared with Monte Carlo SM expectations, and an example of ADD and DarkMatter signal are presented.

NJet4_met200.jpg Distribution of Jet Multiplicity, after MET>200 ĞeV, pT(j1) >110 GeV, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 and Lepton Veto cuts. Data are compared with Monte Carlo SM expectations, and an example of ADD and DarkMatter signal are presented.

NJet4.jpg Distribution of Jet Multiplicity, after MET>350 ĞeV, pT(j1) >110 GeV, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 and Lepton Veto cuts. Data are compared with Monte Carlo SM expectations, and an example of ADD and DarkMatter signal are presented.

dPhi_Jet1_Jet2.jpg Distribution of DPhi betwen Jet1 and Jet2, after MET>350 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4 and Lepton Veto cuts. Data are compared with Monte Carlo SM expectations, and an example of ADD and DarkMatter signal are presented.

dPhi_Jet1_Jet2.jpg Distribution of DPhi betwen Jet1 and Jet2, after MET>350 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 and Lepton Veto cuts. Data are compared with Monte Carlo SM expectations, and an example of ADD and DarkMatter signal are presented.

WMT_mass_0_200.jpg Distribution of W transverse mass for single muon sampe, after MET>350 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 . Data are compared with Monte Carlo SM expectations.

WMT_mass_50_100.jpg Distribution of W transverse mass in W transverse mass window 50-100 GeV for single muon sampe, after MET>350 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 . Data are compared with Monte Carlo SM expectations.

WPT_mass_50_100.jpg Distribution of W transverse momentum in W transverse mass window 50-100 GeV for single muon sampe , after MET>350 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 . Data are compared with Monte Carlo SM expectations.

ZM_mass_60_120.jpg Distribution of Z mass in Z mass window 60-120 GeV for dimuon sample, after MET>350 ĞeV, pT(j1) >110 GeV, NJets <= 2, pT(j2) >30 GeV/c, abs(eta(j1))<2.4, DPhi(j1, j2) < 2.5 . Data are compared with Monte Carlo SM expectations.

ADD_md_d2.jpg MD Limits for δ=2 , Observed and expected CLs limits on ADD versus theoretical cross section and as a function of MD. Limits are shown on dimension δ=2.

ADD_md_d4.jpg MD Limits for δ=4, : Observed and expected CLs limits on ADD versus theoretical cross section and as a function of MD. Limits are shown on dimension δ=4.

ADD_md_d6.jpg MD Limits for δ=6 , : Observed and expected CLs limits on ADD versus theoretical cross section and as a function of MD. Limits are shown on dimension δ=6.

ADD_NumOfDim_vs_MD.jpg ADD model Limit on Fundamental Mass Scale MD in TeV versus Number of Extra Dimension

dm_limit_si.jpg Comparison of the 90% CL upper limits on the dark matter-nucleon scattering cross section versus dark matter mass for the spin-independent models with results from various direct detection experiments

dm_limit_sd.jpg Comparison of the 90% CL upper limits on the dark matter-nucleon scattering cross section versus dark matter mass for the spin-dependent models with results from various direct detection experiments.

Event-177783-273-442962676-3DTower.png The cylindrical view of an example MonoJet event (pT of Jet) = 574.2 GeV, MET = 598.3 GeV. pT of tracks > 10 GeV.

Event-177783-273-442962676-Lego.png The lego view of an example MonoJet event (pT of Jet) = 574.2 GeV, MET = 598.3 GeV. pT of tracks > 10 GeV.

Event-177783-273-442962676-RhoPhi.png The X-Y view of an example MonoJet event (pT of Jet) = 574.2 GeV, MET = 598.3 GeV. pT of tracks > 10 GeV.

Event-177783-273-442962676-RhoZ.png The R-Z view of an example MonoJet event (pT of Jet) = 574.2 GeV, MET = 598.3 GeV. pT of tracks > 10 GeV.

Table_TotalBackground.png SM background predictions compared with data passing the selection cuts for various Missing Transverse Energy thresholds in number of events corresponding to integrated luminosity of 5 fb-1. The uncertainties include both statistical and systematic uncertainties. Contributions from ttbar, ZJets, single t and QCD multijet processes are determined from simulation and are assumed to have 100% uncertainty. In last row, 95% C.L. upper limits on possible contributions from new physics are given.

Table_DMLimit.png Observed 90% CL limits on the dark matter-nucleon cross section and effective contact interaction scale L for the spin-dependent and spin-independent interactions.

Table_ADDLimit.png Observed and expected 95% CL lower limits on the ADD model parameter MD (in TeV) as a function of δ, with and without NLO k-factors applied.

Event-AnaWminus.png An example event display of W(mu+nu) + jets event derived from the same dataset as signal. The W(mu+nu) + jets events are used to predict the inclusive W+jet background in monojet analysis.

Event-AnaMuon-Dimuon.png An example event display of Z(mu+mu) + jets event derived from the same dataset as signal. The Z(mu+mu) + jets events are used to predict the invisible Z background in monojet analysis.

Event-DiJet-CorrectMET.png An example event display of signal candidates where two high pT Jet is found in an event. A second jet is allowed, as signal because events typically contain an initial or final state radiated jet. The DPhi(j1, j2) < 2.5 radians is applied to suppress QCD dijet events.

-- MehmetVergili - 10-May-2012

Topic attachments
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JPEGjpg ADD_NumOfDim_vs_MD.jpg r2 r1 manage 17.8 K 2012-06-28 - 06:28 MehmetVergili  
PDFpdf ADD_NumOfDim_vs_MD.pdf r2 r1 manage 9.5 K 2012-06-28 - 06:29 MehmetVergili  
JPEGjpg ADD_md_d2.jpg r2 r1 manage 25.4 K 2012-06-28 - 06:29 MehmetVergili  
PDFpdf ADD_md_d2.pdf r2 r1 manage 11.4 K 2012-06-28 - 06:30 MehmetVergili  
JPEGjpg ADD_md_d4.jpg r2 r1 manage 26.9 K 2012-06-28 - 06:30 MehmetVergili  
PDFpdf ADD_md_d4.pdf r2 r1 manage 11.4 K 2012-06-28 - 06:31 MehmetVergili  
JPEGjpg ADD_md_d6.jpg r2 r1 manage 26.7 K 2012-06-28 - 06:31 MehmetVergili  
PDFpdf ADD_md_d6.pdf r2 r1 manage 11.4 K 2012-06-28 - 06:32 MehmetVergili  
PNGpng Event-177783-273-442962676-3DTower.png r1 manage 295.5 K 2012-05-10 - 07:13 MehmetVergili  
PNGpng Event-177783-273-442962676-Lego.png r1 manage 192.5 K 2012-05-10 - 07:13 MehmetVergili  
PNGpng Event-177783-273-442962676-RhoPhi.png r1 manage 271.4 K 2012-05-10 - 07:14 MehmetVergili  
PNGpng Event-177783-273-442962676-RhoZ.png r1 manage 137.5 K 2012-05-10 - 07:15 MehmetVergili  
PNGpng Event-AnaMuon-Dimuon.png r1 manage 315.0 K 2012-05-10 - 07:16 MehmetVergili  
PNGpng Event-AnaWminus.png r1 manage 291.4 K 2012-05-10 - 07:16 MehmetVergili  
PNGpng Event-DiJet-CorrectMET.png r1 manage 287.9 K 2012-05-10 - 07:18 MehmetVergili  
JPEGjpg Jet1Pt.jpg r2 r1 manage 28.8 K 2012-06-28 - 06:33 MehmetVergili  
PDFpdf Jet1Pt.pdf r2 r1 manage 14.6 K 2012-06-28 - 06:33 MehmetVergili  
JPEGjpg Met.jpg r2 r1 manage 27.7 K 2012-06-28 - 06:34 MehmetVergili  
PDFpdf Met.pdf r2 r1 manage 13.5 K 2012-06-28 - 06:35 MehmetVergili  
JPEGjpg Met_200.jpg r1 manage 26.7 K 2012-06-28 - 07:36 MehmetVergili  
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JPEGjpg NJet4.jpg r2 r1 manage 20.9 K 2012-06-28 - 06:37 MehmetVergili  
PDFpdf NJet4.pdf r2 r1 manage 11.7 K 2012-06-28 - 06:37 MehmetVergili  
JPEGjpg NJet4_met200.jpg r1 manage 19.7 K 2012-06-29 - 08:46 MehmetVergili  
PDFpdf NJet4_met200.pdf r1 manage 12.1 K 2012-06-29 - 08:46 MehmetVergili  
PNGpng Table_ADDLimit.png r2 r1 manage 31.4 K 2012-06-28 - 07:00 MehmetVergili  
PNGpng Table_DMLimit.png r2 r1 manage 68.9 K 2012-06-28 - 07:00 MehmetVergili  
PNGpng Table_TotalBackground.png r4 r3 r2 r1 manage 75.0 K 2012-06-29 - 08:16 MehmetVergili  
JPEGjpg WMT_mass_0_200.jpg r3 r2 r1 manage 22.8 K 2012-06-28 - 07:44 MehmetVergili  
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JPEGjpg dm_limit_sd.jpg r2 r1 manage 21.6 K 2012-06-28 - 06:51 MehmetVergili  
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