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CMS Results (non-Higgs)
Jorge L. Rodriguez
The CMS Collaboration
Florida International University
December 14, 2013
The LHC and CMS
78 vertices! during special high pileup run. In 2012 <NPU>  23
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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CMS Public Results
http://cms.web.cern.ch/org/physics-papers-timeline
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CMS has published more than 270 papers since startup
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Electroweak, Top, B physics, SM ~ 80
Exotica Searches ~ 66
SUSY Searches ~ 35
Higgs ~ 25
Heavy-Ion Physics ~ 23
Many more papers are in the pipeline
Impossible to show all important results in
30 minutes so I will highlight a few of the
newer results that are public with the full 8
TeV data
Outline:
Standard Model Results
SUSY Model
Exotica
https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResults
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Standard Model Physics
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Inclusive Cross Sections @ 7 and 8 TeV
Triple/quadruple Gauge Couplings
Top Physics
Rare B decays
Inclusive Z/W Cross Sections @ 8 TeV
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Precision measurements are important tests of
SM physics
Inclusive W/Z production cross sections @ 8 TeV
with 18.7/pb
– Dedicated low pileup run & triggers
– WX channel: look for prompt energetic and isolated
lepton with significant MET
– ZX channel: look for two energetic and isolated
leptons
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Results presented as ratio
– Total uncertainties ~ 3.8%
– systematic and some theoretical errors cancel
𝜎 𝑝𝑝 → 𝑊𝑋 × 𝐵 𝑊 → 𝑙𝜈
= 10.99 ± 0.16𝑠𝑡𝑎𝑡 ± 0.39𝑠𝑦𝑠
𝜎 𝑝𝑝 → 𝑍𝑋 × 𝐵 𝑊 → 𝑙𝜈
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Inclusive Z/W Cross Sections @ 8 TeV
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Results on cross-section times BF
𝜎𝑍𝑡𝑜𝑡 × B 𝑍 → 𝑙+ 𝑙− = 1.12 ± 0.01 ± 0.02 nb
𝑡𝑜𝑡
𝜎𝑊
× B W → 𝑙+ 𝜈 = 11.88 ± 0.03 ± 0.52 nb
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The measured and predicted W vs. Z production cross
section (~ 1.5 sigma discrepancy)
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SM: anomalous TGC & QGC
Triple (Quadruple) Gauge Couplings
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Triple/Quadrupole gauge couplings provide important tests of EWK sector, deviation from SM
expectations could point to NP
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An Leff is written in terms of parameters related to SM couplings “LEP parameterization”
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For the 𝑊𝑊𝛾 & 𝑊𝑊𝑍 self interaction terms we used 𝑔1𝑍 ≡ 𝑔1𝑍 − 1, Δ𝜅𝛾 ≡ 𝜅𝛾 − 1, Δ𝜅𝑍 ≡ 𝜅𝑍 − 1, 𝜆𝛾 and 𝜆𝑍 (= 0 SM)
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Similarly for 𝑍𝑍𝛾 & 𝑍𝛾𝛾 ℎ𝑖=1…4 where in SM, to 1-loop CP even ℎ3,4 ≈ 10−4
𝛾(𝑍)
𝛾(𝑍)
CMS reports limits on of these parameters with data
collected at 7 & 8 TeV
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From analysis on production of 𝑊𝛾 and 𝑍𝛾 with 5/fb @ 7 TeV
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Final states: 𝑾𝜸 → 𝒍𝝂𝜸, 𝒁𝜸 → 𝒍𝒍𝜸, 𝒁 → 𝝂𝝂𝜸
Limits at 95% CL on aTGC parameters for the 𝑊𝑊𝛾, ZZ𝛾 & 𝑍𝛾𝛾
(worlds best on ZZ𝛾 & 𝑍𝛾𝛾)
aTGC for𝑍𝛾𝛾
aTGC for𝑍𝑍𝛾
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Miami 2013 Conference: Ft. Lauderdale, December 12-18
aTGC for 𝑊𝑊𝛾
Summary of CMS aTGC Results
https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMPaTGC
ZZ𝑍, 𝑍𝑍𝛾
𝑍𝛾𝛾, 𝑍𝑍𝛾
𝑊𝑊𝑍
𝑊𝑊𝛾
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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CMS aQGC Results
https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMPaTGC
Studies of exclusive two-photon production of 𝑊 + 𝑊 − pp collisions @ 7 TeV
𝑊𝑊𝛾𝛾
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SM: Top Quark Physics
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Top mass Measurements
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Top mass (Yukawa coupling) one of the 19 SM parameters, a critical element in SM
calculations, constraints on Higgs mass and used to investigate internal consistency of SM
CMS’ new top mass is: (Lint = 20/fb with 2010 - 2012 data)
1st Stnd analysis: dileptons, leptons+jets 2010 + dileptons, leptons+jets & all-jets 2011 (5 channels)
2nd 5 channels in Standard + 2 additional “Alt. analysis”
Measurement updates CMS combination results
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CMS 2013 combined result with
with up to 19.6/fb (2010-2012)
𝑚𝑡𝑜𝑝 = 173.49 ± 0.36 stat ± 0.91 syst. GeV
Miami 2013 Conference: Ft. Lauderdale, December 12-18
SM: Top Quark Polarization
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Top quark polarization with 19.7/fb @ 8 TeV
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Event selection & Analysis
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Short decay time: decay products retain spin orientation of the fundamental
original quark
Excellent opportunity to probe for NP by a comparison to precise SM
predictions
In t-channel top quarks ~100% polarized via V-A coupling
Single top production: 𝑡 → 𝑏𝑊 → 𝒃 𝒍𝝂 : one lepton, one b-jet + MET
MLA on the shape of the BDT discriminant
Results
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𝐴𝑡 =
Unfolded cos𝜃 ∗ distribution
Agreement with SM expectation
𝐴𝑃𝑂𝑊𝐻𝐸𝐺
= 0.44
𝑡
𝜇 channel
∗ > 0 − 𝑁 𝑐𝑜𝑠𝜃 ∗ < 0
1
𝑁 𝑐𝑜𝑠𝜃𝑢𝑛
𝑢𝑛
∙ 𝑃𝑡 ∙ 𝛼𝑙 =
∗ > 0 + 𝑁 𝑐𝑜𝑠𝜃 ∗ < 0
2
𝑁 𝑐𝑜𝑠𝜃𝑢𝑛
𝑢𝑛
𝐴𝑡 = 0.41 ± 0.06𝑠𝑡𝑎𝑡 ± 0.16𝑠𝑦𝑠
𝑃𝑡 = 0.82 ± 0.12𝑠𝑡𝑎𝑡 ± 0.32𝑠𝑦𝑠
𝑒 channel
Assuming∙ 𝛼𝑙 =1
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SM: Top Quark Physics
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New combined CMS/ATLAS results for 𝑚𝑡𝑜𝑝
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All 3 stnd CMS plus 2 ATLAS (dileptons + leptons+jets)
Use Best Linear Unbiased Estimate “BLUE” method
Correlations in systematic taken into account in the
combination
LHC 𝑚𝑡𝑜𝑝 = 173.29 ± 0.23 stat ± 0.92 syst. GeV
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CMS/ATLAS combination on top cross section @ 7TeV:
LHC σ 𝑡𝑡 = 173.3 ± 2.3 stat ± 9.9 syst. pb @ 7 TeV
28 new CMS TOP results in 2013
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TOP-13-010: Ratio of top decays to b-jets/jets
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TOP-13-08 : W boson helicity in top decays
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TOP-12-33 : 𝑡𝑡 asymmetry @ 8TeV
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⋯
Miami 2013 Conference: Ft. Lauderdale, December 12-18
A Summary of CMS SM Cross-Section
https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsCombined
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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+ −
SM: 𝐵 → 𝜇 𝜇
(d)
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Large 𝑏𝑏 cross section at the LHC allows us to measure rare
decays of the B and Bs meson
Time integrated branching fractions in SM are small:
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(d)
B 𝐵𝑠 → 𝜇 + 𝜇 − = 3.57 ± 0.30 × 10−9
B 𝐵𝑑 → 𝜇 + 𝜇 − = 1.07 ± 0.10 × 10−9
Simultaneous search for 𝐵𝑠 → 𝜇+ 𝜇− , 𝐵𝑑 → 𝜇+ 𝜇− using 5/fb @ 7
TeV & 20/fb @ 8 TeV
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Search for dimuons with 5.2 < 𝑚𝜇𝜇 < 5.45 GeV
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Normalize to 𝐵 + → 𝐽/𝜓 to minimize uncertainty in 𝑏𝑏 prod x-section
BTDs method is used to extract the number B meson decays
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12 BDT regions defined, are used each with 12 variables: kinematics,
tracking, impact & flight length significance, 4 muon isolation variable…
Main bkg semil-leptonic B combinatorics, modeled in mass
sidebands, MC used to model 𝐵 → ℎ𝜇𝜈, ℎ𝜇𝜇 𝑎𝑛𝑑 Λ 𝑏 → 𝑝𝜇𝜈
B(𝐵𝑠0 → 𝜇− 𝜇+ ) = 3.0+1.0
−0.9 stat.
+0.6
−0.4
syst.
× 10−9
B(𝐵0 → 𝜇− 𝜇+ ) < 1.1 × 10−9 @ 95% CL
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SM: Other B(𝐵 → 𝜇+ 𝜇− ) Measurements
https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsBPH13004
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY
SUSY Search Strategies
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Searches can be categorized by n-leptons in FS
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0 leptons – fully hadronic modes
1 lepton, 2 leptons (OS/SS), multileptons
di photon modes, photon + leptons
Most include n-jets and all include MET
Simplified Model Spectrum (15 topologies)
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I show only a subset of the ≥ 0 leptonic analyses that correspond to 5 different
topologies in the RPC modes
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Focus on a specific decay chains with cross-sections
parameterized in terms of SUSY particle masses and
assume SUSY BF under study are 100%
Limits on 𝜎 × 𝐵𝑟 for specified topologies presented as
reference in which to place limits on different theoretical
models
Searches gluino mediated sbottom & stop production: (T1bbbb & T1tttt): 0-leptons
Search for stop production into single lepton final state: (T2tt & T2bW): 1-lepton
Search for EW production of chargino/neutralino production in final states with
Higgs: (TChiWH): 1-lepton, dilepton(SS), ≥ 3 leptons
And then summarize SUSY mass limits obtained through many other analysis
extracted from the full dataset at @ 8 TeV
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: Gluino production T1tttt & T1bbb
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Final states: ≥ 3 jets with ≥ 1 b-tagged jet + MET
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Event selection: data divided into 176 exclusive bins
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Dominant bkg from 𝑡𝑡
W+jets, Z+jets and QCD
Analysis
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(ZL) Signal sample: no isolated or ID’d leptons
(SL) Control: require a single isolated, ID’d lepton
(LDP) Control: angle Δ𝜙𝑚𝑖𝑛 btw MET vector and pt of
highest jet, selects QCD events
(Zee,Z𝜇𝜇) Control: Events selected from dileptons Z
decays
Backgrounds:
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T1bbbb: gg → 𝑏𝑏 𝑏 ∗ 𝑏 ∗ → 𝑏𝑏 𝑏𝑏𝜒10 𝜒10
T1tttt: gg → 𝑡𝑡𝑡 ∗ 𝑡 ∗ → 𝑡𝑡𝑡 𝑡𝜒10 𝜒10 → 𝑏𝑏 𝑏𝑏𝑊𝑊𝜒10 𝜒10
Perform a global likelihood fit in three simultaneous
variables, MET, HT and number of bjets to 165
exclusive bins.
Results: No excess over SM predictions
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: T1tttt, T1bbbb Interpretation
𝜎 ∶ 𝑚𝜒10 ∶ 𝑚𝑡 contours
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Contour plot shows limits on gluino production cross section in the gluino and neutralino
mass parameter space at the 95% C.L. with 19.4 pb-1 @ 8 TeV
We use SMS assumption i.e., 100% BR for gluino to top/bottom squark + LSP
Limits on gluino mass up to 1.2 TeV (LSP mass = 0) at the 95% C.L
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: Gluino Mass Exclusion Summary
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Summary of other public CMS analysis exclude gluino mass up to 1.3 TeV with 𝑚𝐿𝑆𝑃 = 0
Gluino production to tops, to bottom mesons and to quarks compared to expectations
SUS-12-024
SUS-12-028
SUS-13-004
SUS-13-007
SUS-12-026
SUS-13-008
SUS-13-013
SUS-13-016
SUS-12-024
SUS-12-028
SUS-13-004
Miami 2013 Conference: Ft. Lauderdale, December 12-18
SUS-12-028
SUS-13-012
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SUSY: Stop pair production T2tt, T2bW
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Final states: 1 lepton + jets (b-tagged) + MET
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Event Selection:
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Utilize multi-signal regions in 𝑚𝜒10 𝑣𝑠. 𝑚𝑡 parameter
space
Each BDT employs relevant kinematic variables,
𝑊
𝜒 2 (𝑡/𝑊ℎ𝑎𝑑 ), MET, MT2
… that correspond to region
Cut based cross-check
Backgrounds:
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Single isolated high pT (e or 𝜇)
Njets ≥ 4 with at least one a b-tagged jet
MET>100 GeV and MT>120 GeV…
Analysis: Boosted Decision Trees
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T2tt: 𝑡𝑡 ∗ → 𝑡𝑡𝜒10 𝜒10 → 𝑏𝑊 𝑞𝑞 𝑏𝑊 𝑙𝜈 𝜒10 𝜒10
T2bb: 𝑡𝑡 ∗ → 𝑏𝑏𝜒1+ 𝜒1− → 𝑏𝑏𝑊 𝑞 𝑞 𝑊 𝑙𝜈 𝜒10 𝜒10
Dominant SM: dilepton top pairs, (thad)(tlep) & W+jets
Results: No excess beyond SM predictions
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: T2tt, T2bW Interpretation
𝜎 ∶ 𝑚𝜒10 ∶ 𝑚𝑡 contours
T2tt mode 𝑡 → 𝑡𝜒10 → 𝑏𝑊 + 𝜒10
B=100%
T2bW mode: 𝑡 → 𝑏𝜒1+ → 𝑏𝑊 + 𝜒10
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: Stop Mass Exclusion Summary
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Summary of other public CMS analysis exclude 𝑚𝑡 up to 710 GeV with 𝑚𝐿𝑆𝑃 = 0 @ 95 C.L.
Gluino production to tops, to bottom mesons and to quarks compared to expectations
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Another cut & count analysis as an additional xcheck
Exclusion limits are slightly worse but consistent
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: EWkino production TChiHW
Utilize mH constraints
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TChiHW: 𝜒1± 𝜒20 → 𝑊 ± 𝐻𝜒10 𝜒10
Dominant if 𝜒1± 𝜒20 are wino like, 𝜒10 is bino-like and 𝑚𝜒± (𝜒0 ) − 𝑚𝜒10 > 𝑚𝐻
1
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Event selection for three channels
1.
𝜒1± 𝜒20 → 𝑙𝜈𝑏𝑏𝜒10 𝜒10 : exactly 1 lepton & 2-btagged jets, + MET
2.
𝜒1± 𝜒20 → 𝑊 ± 𝐻(𝑊𝑊)𝜒10 𝜒10 → 𝑙𝜈𝑙𝜈𝑞 𝑞𝜒10 𝜒10 : SS dileptons + jets + MET
3.
𝜒1± 𝜒20 → 𝑊 ± 𝐻 𝑊𝑊, 𝑍𝑍, 𝜏𝜏 𝜒10 𝜒10 → 𝑙𝜈 2𝑙 + 𝜒10 𝜒10 : multi-leptons + MET
Analysis
1.
2.
3.
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2
Define 4 signal regions in MET form 𝑚𝑏𝑏 and count events between100 to 150
GeV around mass of the Higgs.
Additional requirements on lepton 𝑑0 , MT .. form 𝑚𝑙𝑗𝑗 and count events below
120 GeV
Multiple signal regions formed that categories the number and types of
leptons, MET, whether there as SS or SF leptons … The yields are then
compared with background estimates
Results:
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All three channels combined to improve sensitivity
No excess over SM predictions
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: EWkino production Results
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We report limits on 𝜒1± 𝜒20 production cross section as a function of 𝜒1± 𝜒20 mass
assuming equal masses vs mass of 𝜒10 at the 95% C.L. with 19.5 pb-1 @ 8 TeV
For masses of the LSP below 25 we exclude mass of the 𝑚𝜒 < 204 GeV
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY: EWKino Mass Summary
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Exclusion limits for EWK’ino assuming equal masses, in the SMS with 19.5 fb-1 of data
collected at 8 TeV
We exclude masses up to 740 GeV depending on mass of LSP and decay mode
SUS-13-006
SUS-13-017
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY Exclusion Summary
R-parity conserving
violating models
models
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Exotica Searches
Exotica Search Strategies
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A rather large number of BSM theories
CMS has almost 40 new Exotica and
Beyond the 2nd generation (B2G) analyses
on 2012 data
Difficult to organize analyses I am not the
first to notice…
I will summarize our latest results on:
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Dileptons searches
Search for resonances that decay to Vector Bosons
Search for vector-like T2/3 quark (B2G)
Heavy Stable Charged Particles
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Exotica: Di leptons
𝑒 + , 𝜇+
𝑍′ , 𝐺 ∗ …
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Many BSMs predict narrow resonances at TeV scale
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GUT models, SUSY, Extra dimensions, …
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Easy to spot at LHC, √𝑠 more important than L
Signature:
– 𝑝𝑝 → 𝑋 → 𝒍+ 𝒍− : look for OSSF dileptons (𝒍 = 𝐞, 𝝁)
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Dominant DY backgrounds to 𝑒𝑒, 𝜇𝜇, 𝜏𝜏, less dominant
𝑡𝑡, 𝑡𝑊, 𝑊𝑊, 𝑊𝑍 miss ID’d jets
Modeled by MC (NNLO) or data when possible
Analysis & Results
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High pt, isolated, ID’d, back to back leptons (𝑒/𝜇) from
primary vertex
Backgrounds
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Challenge: very stiff tracks degrades momentum resolution
especially in the 𝜇𝜇 channel. @ 1 TeV ~15%
Event selection
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𝑒 − , 𝜇−
Relative fractions of simulated bkgs are fixed by theoretical
cross sections with overall normalization set to data in 60 <
𝑚𝑙𝑙 < 120 GeV
Results: invariant mass spectra agrees with SM
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Exotica: Di leptons Interpretation
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With 20/fb of data @ 8 TeV we set limits at the 95 % C.L. on the ratio
𝜎 𝑝𝑝 → 𝑍 ′ + 𝑋 × 𝐵 𝑍′ → 𝑙+ 𝑙−
𝑅𝜎 =
𝜎 𝑝𝑝 → 𝑍 + 𝑋 × 𝐵 Z → 𝑙+ 𝑙−
•
The likelihood functions for the signal and background shapes and use the narrow width
approximation about ± 40% off the nominal predicted resonance mass for a 𝑍’ and use ± 30
GeV for 𝑍 0 peak
Muons and all electrons, BB + BE
•
Limits on Z’ mass are:
′
– 𝑚(𝑍𝑆𝑆𝑀
) > 2.960 TeV
′
– 𝑚(𝑍𝜓
) > 2.600 TeV
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Exotica: Di Boson Resonance
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Many BSMs predict heavy resonances that can couple to SM
vector bosons
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We search for:
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Gravitons in RS models with warped extra dimension that
decays to SM fermions but are suppressed w.r.t decays to VB
𝑝𝑝 → 𝑋 → 𝑍𝑍 → 𝒒𝒒 𝒍+ 𝒍− : 2 OSSF leptons 1 “fat” jet
𝑝𝑝 → 𝑋 → 𝑊𝑊 → 𝒒𝒒 𝒍𝛎 : exactly 1 lepton, 1 “fat” jet + MET
Event selection
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Isolated ID’d leptons (𝑒𝜇) and PF jets
One VB is reconstructed in leptonic mode the other hadronic
For resonances M > 600 GeV the quarks from the W/Z are
merged into a single jet
Use jet substructure techniques to refine the merged jets
•
•
•
Analysis:
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Jet pruning: remove soft jet components improves jet mass resolution
Construct N-subjettiness (𝜏21 ), allows dipole jets structure to
discriminate between merged jets from regular QCD jets
Signal characterized as a bump in VV invariant mass spectrum
Results:
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Both 𝑿 → 𝒁𝒁 and 𝑿 → 𝑾𝑾 invariant mass spectra agree with
SM expectations
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Exotica: Di Boson Resonance
•
Many BSMs predict heavy resonances that can couple to SM
vector bosons
–
•
We search for:
–
–
•
Gravitons in RS models with warped extra dimension that
decays to SM fermions but are suppressed w.r.t decays to VB
𝑝𝑝 → 𝑋 → 𝑍𝑍 → 𝒒𝒒 𝒍+ 𝒍− : 2 OSSF leptons 1 “fat” jet
𝑝𝑝 → 𝑋 → 𝑊𝑊 → 𝒒𝒒 𝒍𝛎 : exactly 1 lepton, 1 “fat” jet + MET
Event selection
–
–
–
–
Isolated ID’d leptons (𝑒𝜇) and PF jets
One VB is reconstructed in leptonic mode the other hadronic
For resonances M > 600 GeV the quarks from the W/Z are
merged into a single jet
Use jet substructure techniques to refine the merged jets
•
•
•
Analysis:
–
•
Jet pruning: remove soft jet components improves jet mass resolution
Construct N-subjettiness (𝜏21 ), allows dipole jets structure to
discriminate between merged jets from regular QCD jets
Signal characterized as a bump in VV invariant mass spectrum
Results:
–
Both 𝑿 → 𝒁𝒁 and 𝑿 → 𝑾𝑾 invariant mass spectra agree with
SM expectations
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Exotica: Di Boson Resonance 𝑋
•
•
→ 𝑍𝑍
Set upper limit @ 95 C.L. on 𝜎 𝑋 → 𝑉𝑉 ×B 𝑋 → 𝑉𝑉 as a function of the 𝑚𝐺∗ with 2012 data
∗
Lower mass bound the on Bulk Graviton 𝑚(𝐺𝐵𝑢𝑙𝑘
) > 0.710 TeV for the ZZ mode with similar
result from the WW mode
𝑿 → 𝒁𝒁
Miami 2013 Conference: Ft. Lauderdale, December 12-18
𝑿 → 𝑾𝑾
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B2G: Inclusive Search for Vector-like T2/3
•
A non-SM 4th generation or massive partner to top quark
– Can enhance CP violation, heavy 𝜈 could be a DM candidate, could
–
•
help stabilize Higgs mass in absence of MSSM
Vector-like T predicted in Little Higgs models and in warped extra
dimensions
Inclusive search for:
– 𝑝𝑝 → 𝑇𝑇: 2(𝑇 → 𝑏𝑊, 𝑡𝑍, 𝑡𝐻) BF 0.50, 0.25, 0.25
: leptons + jets (bjets) (W-jets)
•
Event selection
–
–
–
•
Analysis:
–
–
–
•
Single lepton channel: 1 Isolated high pt lepton (𝑒𝜇) + ≥ 3 jets with
1 W-jet or 4th jet pT>35 GeV
Multi-lepton channel: exactly 2 or 3 (SS/OS) leptons with n-jets/b-jets
consistent with topology
Use jet substructure techniques used to refine the merged jets “W-jets”
Single lepton + jets uses a BDT (max sensitivity)
Multi-lepton (2 or 3 leptons) 12 cut & count categories OS, SS …
All channels combined in limits.
Results: no excess observed over SM expectations
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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B2G: Inclusive Search for Vector-like T2/3
•
•
Set upper limit @ 95 C.L. on 𝜎 𝑝𝑝 → 𝑇𝑇 ×B 𝑇 → 𝑏𝑊, 𝑡𝑍, 𝑡𝐻 as a function of the 𝑀𝑇
assuming B = 0.5, 0.25, 0.25 with 19.6 pb-1 @ 8 TeV
Lower mass limits @ 95 C.L. between 687 and 782 GeV for all possible BF of the T to the
three decay modes considered
Miami 2013 Conference: Ft. Lauderdale, December 12-18
36
Exotica: Long Lived Particles
•
S. Worm @ SEARCH 2013
Many extension of SM predict heavy long lived (stable) charged
particle HSCP
–
–
•
Signature
–
–
•
Ex: in GMSB, with LSP = gravitino, NLSP = L.L. gluino/stop/stau
A colored NLSP can form an R-hadron, lead to interesting events
Candidates with dE/dx losses ≠ MIP
Candidates with large Time-of-Flight w.r.t. IP
Analysis:
–
Variables:
•
•
•
•
–
–
Five different analysis strategies employed
Use an ABCD method to separate signal from background
•
•
•
•
𝐼ℎ is the energy loss dE/dx as measured with the Silicon Tracker
𝐼𝑎𝑠 a S.C.vM uses dE/dx & compares with MIP
1/b uses Muon sys’s timing info w.r.t. IP
pT the transverse momentum
HSCPs with |Q| < 1e: tracker only is used. Here we use pT and
select tracks with dE/dx less than expected for |Q| = 1e.
HSCPs with |Q| > 1e: tracker + Muon use pT , dE/dx and TOF
optimized for large dE/dx than expected for |Q| = 1e
HSCPs with |Q| = 1e: 3 analyses that either use tracker or the muon
system alone, or both systems together. For these analyses the
track pT , the Ias and/or TOF is used to discriminate btw bkg and
signal
Results: No excess observed over SM
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Exotica: Long Lived Particles, limits on
n charged particles
•
•
•
No significant excess observed over SM predictions in full Run I data
Set upper limits on cross section vs. mass for models where gluinos, stops or
staus are produced
Lower mass limits on gluino with particular R-hadron model assumptions are
made as well as exclude masses for HSCP with |Q| ± 1e as shown.
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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CMS Exotica 95% CL Exclusion Limits
Miami 2013 Conference: Ft. Lauderdale, December 12-18
39
Summary
• The LHC’s pp @ 8 TeV RUN I ended at the end of 2012
– CMS recorded more than 23 fb-1 of data @ 8 TeV
– As well as 6 fb-1 @ 7 TeV in 2010 and 2011
• Standard Model measurements
–
–
–
–
More data and some improvements in systematics => more precise tests of SM
Turning towards rarer processes, rare B decays, diboson production, T(Q)GC…
Many new measurements TOP physics
In general measurements consistent with SM but results are challenging NLO and
NNLO predictions
• SUSY, Exotica and Beyond the 2nd Generation
– Searches for New Physics in SUSY and model BSM continue to push forward with
no evidence so far for BSM physics
– Under the SMS we place limits on SUSY masses up to the 0.2 to 1.3 TeV
excluding a significant, but not all, portion of SUSY parameter space particularly
cMSSM. Natural SUSY is being stressed
• Eagerly awaiting Run II at 13-14 TeV with Lint = 1.0 ± 1034cm-2s-1
Miami 2013 Conference: Ft. Lauderdale, December 12-18
40
SUper SYmmetry
SUSY’s LSP a Dark Matter candidate
A “natural” solution to the Weak Scale hierarchy problem
Coupling constant GUT fixer
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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SUSY Challenges
SUSY spectra quite complicated and model dependent
At the LHC SUSY cross sections are tiny wrt to SM
Miami 2013 Conference: Ft. Lauderdale, December 12-18
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Analysis Generalities
•
Triggers L1 + HLT
–
–
•
Monte Carlos
–
–
–
–
•
Many different triggers used for the analysis discussed
Typically close to 100% efficient
Various generators used Pythia6/8, HERWIG6/++, SHERPA
Matrix Element calculators: Alpgen MadGraph, NCatNLO…
GEANT4: full simulation of particle interaction and digitization
FASTSIM: paramerized simulation of particle interactions
Event selection
–
–
Tracks: general requirement on pT, PV (𝑑𝑥𝑦 𝑑𝑧 ), |h|
Jets:
•
•
•
–
2
Particle Flow (PF) is used throughout
•
–
JetEnergyCorrections applied to all jets they include correction for pileup (IT, EOOT, LOOT),
mismeaurement
Various Jet clustering algorithms used, anti-kT… with some cuts jet cone ΔR = Δ𝜂 2 + Δ𝜙
b quarks: b-tags jets typically use the CSVM algorithm to tag the jets a bjet (b-tagged jet)
Assigns objects to types of events, photons, electrons, charged & neutral hadronic jets, muons
Backgrounds
•
•
Data driven control samples used where possible, sidebands, tag-probe, etc.
Monte Carlos used extensively but corrected by comparing to data
Miami 2013 Conference: Ft. Lauderdale, December 12-18
43
SUSY Strategies
•
SUSY Analyses employ missing momentum/energy transverse mass, and other
variables that discriminate between backgrounds and signal when signal usually have
one or more invisible particles in the final state
•
Some of the more variables used
through out
– MET 𝐸𝑇𝑚𝑖𝑠𝑠 = −∑𝑝𝑇
– 𝐻𝑇 = ∑ 𝑝𝑇
– 𝑀𝑇 =
•
𝑗,𝑙
2𝐸𝑇𝑚𝑖𝑠𝑠 𝑝𝑇 1 − cos(Δ𝜙
Other variables such Razor, 𝛼 𝑇 …
Miami 2013 Conference: Ft. Lauderdale, December 12-18
44
Exotica: Di Boson Resonance
•
Many BSMs predict heavy resonances that can couple to SM
vector bosons
–
•
We search for:
–
–
•
Gravitons in RS models with warped extra dimension that
decays to SM fermions but are suppressed w.r.t decays to VB
𝑝𝑝 → 𝑋 → 𝑍𝑍 → 𝒒𝒒 𝒍+ 𝒍− : 2 OSSF leptons 1 “fat” jet
𝑝𝑝 → 𝑋 → 𝑊𝑊 → 𝒒𝒒 𝒍𝛎 : exactly 1 lepton, 1 “fat” jet + MET
Event selection
–
–
–
–
Isolated ID’d leptons (𝑒𝜇) and PF jets
One VB is reconstructed in leptonic mode the other hadronic
For resonances > 600 GeV the quarks from the hadronic VB are
merged into a single jet
Use jet substructure techniques to refine the merged jets
•
•
•
Analysis:
–
•
Jet pruning: remove soft jet components improves jet mass resolution
Construct N-subjettiness (𝜏21 ), allows dipole jets structure to
discriminate between merged jets from regular QCD jets
Signal characterized as a bump in VV invariant mass spectrum
Results: Both 𝑿 → 𝒁𝒁 and 𝑿 → 𝑾𝑾 invariant mass spectra
agree with SM expectations
Miami 2013 Conference: Ft. Lauderdale, December 12-18
High Purity (1JHP)
Low Purity (1JLP)
45
Exotica: Long Lived Particles Results
The mass is computed
𝑚2
from 𝐼ℎ = 𝐾 2 + C
𝑝
The No. of tracks for the
three analyses
searching for HSCP
with charge = 1e
The No. of tracks in the
search for fractionally
charged HSCP
(Tracker only)
The No. of tracks in
the search for multi
charged HSCP
(Traker + TOF)
Miami 2013 Conference: Ft. Lauderdale, December 12-18
46
SUSY: Other Squark Mass Summary
•
•
Exclusion limits for bottom squark and squark masses, in the SMS from 20 fb-1 of data
collected at 8 TeV (2012)
We exclude squark masses up to 780 GeV depending on mass of LSP and decay mode
SUS-13-002
SUS-13-008
SUS-13-013
Miami 2013 Conference: Ft. Lauderdale, December 12-18
47