Search for Pair Production of First-Generation Scalar Leptoquarks Using Events Containing Two Electrons And Two Jets Produced in pp Collisions at √s = 7 TeV

Abstract

A search for pair production of first-generation scalar leptoquarks is performed in the final state containing two electrons and two jets using proton-proton collision data at √s = 7 TeV. The data sample used corresponds to an integrated luminosity of 33 pb-1 collected with the CMS detector at the CERN LHC. The number of observed events is in good agreement with the predictions for the standard model background processes, and an upper limit is set on the leptoquark pair production cross section times β^2 as a function of the leptoquark mass, where β is the branching fraction of the leptoquark decay to an electron and a quark. A 95% confidence level lower limit is set on the mass of a first-generation scalar leptoquark at 384 GeV for β =1, which is the most stringent direct limit to date.

Plots from PAPER EXO-10-005 based on 33.2 pb-1 (click on plot to get .pdf)

In the following plots:

  • Pre-selection is defined as:
    • at least two electrons with p_T > 30 GeV and abs(η) < 2.5
    • at least two jets with p_T > 30 GeV and abs(η) < 3
    • minimum ΔR between any of the 2 selected electrons and any of the 2 selected jets greater than 0.7.
    • M_ee > 50 GeV
    • S_T > 250 GeV (scalar sum of the p_T of the 2 selected electrons and 2 selected jets)
  • Full selection includes the pre-selection cuts and
    • M_ee > 125 GeV
    • S_T > f(LQ mass hypothesis)
  • The Z+jets MC has been normalized using the data/MC ratio (1.20 +- 0.14) determined at the Z boson mass after the pre-selection.
  • Other backgrounds include W+jets, di-boson, and single top.
  • All background histograms are cumulative.
  • The black dots are data, with the square root of the number of entries used as uncertainties.

Figure Abbreviated Caption
Mee_FullPreSel_allPreviousCuts.png M_ee after pre-selection
sT_fullSeleNoPreStCut.png S_T after full selection (except the cut on S_T itself)
xs95CL_vs_m_log.png Upper limit on the LQ cross section x Beta^2 vs. LQ mass
beta_vs_m_excl.png Minimum Beta for LQ hypothesis exclusion vs. LQ mass

Additional APPROVED Plots based on 33.2 pb-1 (click on plot to get .pdf)

pT1stEle_allPreviousCuts.png p_T 1st electron after pre-selection
Eta1stEle_allPreviousCuts.png Eta 1st electron after pre-selection
pT2ndEle_allPreviousCuts.png p_T 2nd electron after pre-selection
Eta2ndEle_allPreviousCuts.png Eta 2nd electron after preselection
Pt1stJet_allPreviousCuts.png p_T 1st jet after preselection
Eta1stJet_allPreviousCuts.png Eta 1st jet after preselection
Pt2ndJet_allPreviousCuts.png p_T 2nd jet after preselection
Eta2ndJet_allPreviousCuts.png Eta 2nd jet after preselection
sT_allPreviousCuts.png S_T after preselection (except the cut on S_T itself)
Mej_allPreviousCuts.png M_ej after pre-selection. There are 2 ways to combine the 2 leading electrons and the 2 leading jets to make 2 candidate LQs; the pair of M_{ej} values with minimum difference is used.
Mej_allOtherCuts.png Mej after final selection for M_LQ=300 GeV. There are 2 ways to combine the 2 leading electrons and the 2 leading jets to make 2 candidate LQs; the pair of M_{ej} values with minimum difference is used.

Event Displays of the 3 Highest-S_T events (Black or White background) from the PAPER analysis (33.2 pb-1)

  • The details on the 7 events that passed the final selection (prior to final S_T cut) in this file

run148864_ls435_evt501826759_ST585GeV
lego_run148864_ls435_evt501826759_ST585GeV_BLACK.png rho_phi_run148864_ls435_evt501826759_ST585GeV_BLACK.png lego_run148864_ls435_evt501826759_ST585GeV.png rho_phi_run148864_ls435_evt501826759_ST585GeV.png
run148822_ls204_evt218300385_ST367GeV
lego_run148822_ls204_evt218300385_ST367GeV_BLACK.png rho_phi_run148822_ls204_evt218300385_ST367GeV_BLACK.png lego_run148822_ls204_evt218300385_ST367GeV.png rho_phi_run148822_ls204_evt218300385_ST367GeV.png
run149181_ls1209_evt1189919527_ST305GeV
lego_run149181_ls1209_evt1189919527_ST305GeV_BLACK.png rho_phi_run149181_ls1209_evt1189919527_ST305GeV_BLACK.png lego_run149181_ls1209_evt1189919527_ST305GeV.png rho_phi_run149181_ls1209_evt1189919527_ST305GeV.png

-- PaoloRumerio - 28-Nov-2010

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf Eta1stEle_allPreviousCuts.pdf r1 manage 7.0 K 2010-11-28 - 15:38 PaoloRumerio Eta 1st electron after preselection
PDFpdf Eta1stJet_allPreviousCuts.pdf r1 manage 7.2 K 2010-11-28 - 15:42 PaoloRumerio Eta 1st jet after preselection
PDFpdf Eta2ndEle_allPreviousCuts.pdf r1 manage 6.9 K 2010-11-28 - 15:41 PaoloRumerio Eta 2nd electron after preselection
PDFpdf Mej_allOtherCuts.pdf r1 manage 6.4 K 2010-11-28 - 15:45 PaoloRumerio Mej after final selection for MLQ=300 GeV
PDFpdf Mej_allPreviousCuts.pdf r1 manage 9.1 K 2010-11-28 - 15:45 PaoloRumerio Mej after preselection
PDFpdf Pt1stJet_allPreviousCuts.pdf r1 manage 8.6 K 2010-11-28 - 15:41 PaoloRumerio  
PDFpdf Pt2ndJet_allPreviousCuts.pdf r1 manage 8.2 K 2010-11-28 - 15:43 PaoloRumerio Pt 2nd jet after preselection
PDFpdf beta_vs_m_excl.pdf r2 r1 manage 5.2 K 2011-01-21 - 11:29 PaoloRumerio Minimum Beta for LQ hypothesis exclusion vs. LQ mass
Texttxt events.txt r1 manage 2.4 K 2011-01-21 - 14:50 PaoloRumerio Details of the 7 events in the final selection
PDFpdf pT1stEle_allPreviousCuts.pdf r1 manage 8.7 K 2010-11-28 - 15:36 PaoloRumerio Pt 1st electron after preselection
PDFpdf pT2ndEle_allPreviousCuts.pdf r1 manage 7.4 K 2010-11-28 - 15:40 PaoloRumerio Pt 2nd electron after preselection
PDFpdf sT_allPreviousCuts.pdf r1 manage 9.3 K 2010-11-28 - 15:48 PaoloRumerio St after preselection
PDFpdf sT_fullSeleNoPreStCut.pdf r2 r1 manage 6.6 K 2011-01-21 - 11:26 PaoloRumerio St after preselection and Mee cut
PDFpdf xs95CL_vs_m_log.pdf r3 r2 r1 manage 5.2 K 2011-01-21 - 11:27 PaoloRumerio Upper limit on the LQ cross section x Beta^2 vs. LQ mass
Edit | Attach | Watch | Print version | History: r11 < r10 < r9 < r8 < r7 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r11 - 2011-01-30 - 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 & 2008-2023 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
or Ideas, requests, problems regarding TWiki? use Discourse or Send feedback