susy$searches$atcms$charm.physics.ucsb.edu/people/claudio/talks/susy2012.pdfsusy$searches$at7$ tev$...
TRANSCRIPT
SUSY searches at CMS
Claudio Campagnari UC Santa Barbara
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Outline
• Brief re-‐cap of 2010-‐11 results (7 TeV) • Next fronFer (1): Natural SUSY • Next fronFer (2): EWK-‐ino • Next fronFer (3): compressed spectra • A few words about RPV SUSY (also Stealth SUSY) • 8 TeV data, first look • CommunicaFon of results • Conclusions
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SUSY searches at 7 TeV
The iniFal SUSY program at CMS was designed to be 1. Generic – Signature based searches not tuned to a parFcular SUSY model
2. Broad – Cover many possible signatures. – Use different methods
• eg: 4 methods/variables for the all hadronic channel (αT, MHT, MT2, razor) • CounFng as well as shapes
3. Robust – As “data driven” and MC-‐less as possible
• eg: standard method of normalizing MC to control region and “extrapolate” to signal region is used as li_le as possible
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Example: ETmiss spectrum in single leptons
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ContribuFon from SM dileptons esFmated from data dilepton sample
BG from dileptons + SM single lepton, esFmated from data lepton PT spectrum
Final states we looked at (all with ETmiss)
• Fully hadronic • 1 lepton • 2 leptons – Same-‐sign – Opposite sign, but not Z – Z
• MulFleptons • 1 photon • 2 photons
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In almost all cases “lepton” also means τ
Most of these searches have a version with b-‐tags
We find no excess of events over the SM
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CMSSM interpretaFon
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SMS interpretaFon
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The next fronFer (1): “Natural SUSY”
• CMS & ATLAS searches have excluded light squarks and gluinos up to ~ 1 TeV
• But are generally not as sensiFve to 3rd generaFon squarks
• RelaFvely light stops are needed for naturalness – Gluino cannot be too heavy either
Stop is the flavour du jour at the CERN cafeteria
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Looking for natural SUSY
• Search for stops and sbo_oms in gluino decays – Because in natural SUSY the gluino cannot be too heavy – Because if the other squarks are very heavy, then the gluino will decay into sbo_oms and stops with high BR
• Search for stop and sbo_om pair producFon – To close the loophole that the “gluino is too heavy”
• ExisFng “generic” searches can be re-‐interpreted in this context – There is sensiFvity!
• New targeted searches are being developed for pair producFon – A change of modus operandi at CMS….no real results yet
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Stop from gluino decays
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Simplified
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Same as previous page, but for sbo3oms
Sbo_oms from gluinos again, but different sbo_om decay mode
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Early 8 TeV result
Stop Pair ProducFon
More dedicated searches in the works
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Sbo_om pair producFon (1)
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Sbo_om pair producFon (2)
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Early 8 TeV result
The next fronFer (2): EWK producFon High Luminosity à begin to be sensiFve to EWK producFon
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http://www.thphys.uni-heidelberg.de/~plehn/"
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Models with decays into sleptons Models with decays into W and Z
• Trilepton + MET final states • Same-‐sign dileptons to increase eff.
• Zàℓℓ + ℓ + MET • Zàℓℓ + W/Zàjet-‐jet + MET • Four leptons
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χ+χ0 Limits Limits in GMSB model with high rate of ZZ+MET
New 7 TeV result
[GeV]µ140 160 180 200 220 240 260 280 300
[fb]
σ
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combined observed UL)σ1±combined median expected UL (
2j observed ULl2 observed ULl4
)σ1± theory (NLOσ
CMS Preliminary -1 = 4.98 fbint = 7 TeV, Ls
missTGMSB ZZ + E
[GeV]±
1χ∼
= m02χ∼
m100 150 200 250 300 350 400 450 500 550 600
[GeV
]0 1χ∼
m
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400
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800LEP2 slepton limitLEP2 chargino limit
)=0.5)l , BF(3Ll~ ( miss
T+El3)=1)τ-l+l , BF(Rl
~ ( missT+El3
)=0.5)l , BF(3Ll~(SS) ( l & 2T+Mll+Ml3
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, BF(WZ)=1)l~ (no T+Mll+Ml2j & 3l2
01χ∼
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1χ∼
m = 0.5l~m
01χ∼m >
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1χ∼ = m0
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CMS Preliminary -1 = 4.98 fbint = 7 TeV, Ls
[1] K. Matchev and S. Thomas, "http://prd.aps.org/abstract/PRD/v62/i7/e077702"[2] P. Meade, M. Reece, and D. Shih "http://www.springerlink.com/content/yg780th511075556/?MUD=MP"[3] J. Ruderman and D. Shih http://arxiv.org/abs/1103.6083"
Next FronFer (3) : compressed spectra
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SensiFvity turns over as spectrum becomes compressed
This area is (conservaFvely?) not probed unFl the producFon details are be_er understood
Compressed spectra…what’s coming
• New analysis techniques under development
• “Parked” triggers – Lower thresholds on MET and jets – To be processed at the end of 2012
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What about RPV SUSY? • Not studied in a great deal of detail • Lots of possibiliFes • However: many of the “exoFca” searches are de-‐facto sensiFve to RPV signatures – Because they tend to look at high mass scales – Example: 3rd generaFon leptoquark search interpreted as stop search in RPV SUSY (EXO-‐12-‐002)
• Same-‐sign SUSY dilepton searches are also sensiFve – Because the ETmiss requirements are quite loose
• A systemaFc characterizaFon is missing – Is it even possible?
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An RPV example: gluinoà3 quarks
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Exclude gluino masses below 460 GeV (assuming 100% BR into three jets)
Stealth SUSY
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Almost degenerate hidden sector parFcles, results in very li_le ETmiss
• Two photons and at least 4 jets • First search of this kind • Signal is excess of high ST = HT + Etmiss + ΣPT(γ)
• This is a variable that is sensiFve to high mass scales
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Exclude squark masses below 1430 GeV
8 TeV data
A few searches updated with ~ 4 t-‐1 @ 8 TeV
– Hadronic αT – Same-‐sign dileptons with b-‐tags
– Photon(s) + MET
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Unfortunately, no excess to report
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Early 8 TeV results
Extend the gluino exclusion in these scenarios which are interesFng because of naturalness by ~ 60 GeV
Gauge-‐mediated SUSY breaking scenarios Depending on the nature of χ0, single or double photon final states can dominate
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γγ + MET
γ + MET
Early 8 TeV results
CommunicaFon of Results (1)
• Three years ago many were hoping (dreaming?) that at SUSY12 we would be basking in the glory of the discovery of SUSY
• And we would be having spirited discussions on how to disentangle the SUSY spectrum – LHC Inverse Problem anyone?
• Alas, it’s limits-‐all-‐the-‐9me
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CommunicaFons of Results (2)
• We make many pre_y colorful plots….
• There have been many discussions on how to make our results as useful as possible for the community – Some quite ambiFous
• At CMS we pursue two complementary relaFvely simple avenues
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Avenue 1: SMS efficiency maps Can be used by a phenomenologist to “calibrate” a “simple” MC
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Example efficiency map for αT search for well defined Simplified Model
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Avenue 2: Provide efficiency and turn on curves
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To be used by phenomenologist to “build” a “simple” MC
Example from SameSign dilepton analysis: lepton efficiencies and HT turn-‐on curves
Feedback by users of these informaFon appreciated
Conclusions
• Probed a wide variety of SUSY-‐moFvated final states • Nothing found so far, but developed detailed understanding of BG à prerequisite for discovery
• TransiFoning to targeted searches opFmized for specific, well-‐moFvated models (eg. ewk SUSY, natural SUSY)
• Analyses of 8 TeV data are in progress. Expect ~ 20 t-‐1 by the end of the year
• Stay tuned
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Much more on CMS SUSY results in parallel sessions
• B. Casal Larana – Searches for SUSY in hadronic final
states at CMS • I. Melzer-‐Pellmann
– Searches for SUSY in final states with single leptons at CMS
• D. Sprenger – Searches for SUSY in events with
di-‐leptons at CMS • K. Theofilatos
– Searches for SUSY in final states with photons at CMS
• C. Sanders – Searches for SUSY in events with
taus at CMS
• W. Waltenberger – InterpretaFons of CMS SUSY
analyses in the simplified model space (SMS)
• M. D'Alfonso – Searches for top and bo_om
squarks at CMS • D. Dobur
– Search for chargino or neutralino producFon at CMS
• Y. Chen – New results using the razor at the
LHC • A. Bhay
– Search for Dark Ma_er at CMS
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h_ps://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSUS
The End
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