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 DM Models & Signatures in CMS searches  Analyzing CMS data  MonoJet, MonoLepton, MonoPhoton, MonoTop, Top pairs  SUSY Searches  Perspectives for.

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Presentation on theme: " DM Models & Signatures in CMS searches  Analyzing CMS data  MonoJet, MonoLepton, MonoPhoton, MonoTop, Top pairs  SUSY Searches  Perspectives for."— Presentation transcript:

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2  DM Models & Signatures in CMS searches  Analyzing CMS data  MonoJet, MonoLepton, MonoPhoton, MonoTop, Top pairs  SUSY Searches  Perspectives for LHC Run 2 OUTLINE 2

3 Introduction 3

4 DM models in CMS searches  Most of the CMS DM searches use Effective Field Theories : ⇒ MonoJet, MonoLepton, MonoPhoton, Top pair  Validity: M V >> √s = O(10 TeV)  Search parameters : cut-off scale  ; DM mass m   Operators : probe spin-(in)dependent interactions 4

5 5 ISR jet/photon Mono-jet/photon Recoiling W Mono-lepton Single top Mono-top DM Production in Colliders

6 MonoJet : event selection  Jet p T >110 & |  |<2.4  p T fractions : ch. had. ≥ 20% & neutr. had. ≤ 70% & photons ≤ 70%  Accept 2 nd jet ( p T >30 & |  |<4.5 & D  J1J2 <2.5 ) ; Veto 3 rd jet (p T,  )  MET ≡ Missing Transverse Energy = Vectorial sum of the visible objects  7 MET Regions : MET > {250, 300, 350, 400, 450, 500, 550} GeV  Lepton veto : e/m(p T >10 & R iso <0.2) t(p T >20 & |h|<2.3) Kill QCD, ttbar Kill V, VV, top 6

7 MonoJet : signal extraction Single-bin counting experiment after optimal MET cut Z   Wjets are estimated using  +jets and cross checked with Z-> . 7

8 MonoJet : results Vector coupling Spin-independent interaction Axial-Vector coupling Spin-dependent interaction 8 CDMS excess CMS PAS EXO-12-048

9 MonoLepton  Advantages : clean leptonic signature less background @ LHC easier to trigger than monojet/monophoton  Interferences sensitive to different couplings for Up- and Down- type quarks  Largest  for  =-1  M  > 100 GeV steep drop (limited  -space)  ”edge” depends on .  Shape m T depends on  ! Master variable  transverse mass m T 9

10 MonoLepton : event selection   : ID & R iso 45 &  p T <30%  Veto 2 nd  (p T >25) kill cosmics & DY  e : ID & A iso 100 & IsoCalo<3%  Veto 2 nd e (pT>35) kill DY  Back-to-back lepton and MET  0.4 < pT(l) / MET < 1.5   > 2.5 10

11 Major backgrounds = MC x SF from data High mT tail : fit m T shape analysis : multi-bin counting 11 MonoLepton : signal extraction

12 MonoLepton : results 12 CMS PAS EXO-12-060 Axial-Vector coupling Spin-dependent interaction Vector coupling Spin-independent Interaction Comparable to monojet reach

13 MonoPhoton : event selection Kill  +jet 13  MET > 140   (MET,  ) > 2.0  “MET ID” :  2 fit using unclustered energy remove fake MET  Lepton veto : ≥1 isolated lepton  R iso < 0.2 (e) / 0.1 (  ) Kill W(l )+   Photon :  E T > 145 GeV & |  |<1.44 (purity)  ID : H/E < 0.05 & ECAL energy deposit’s shape  Anomalous signals removal, timing cut (BX±3ns)  PF isolation : surrounding h ±,0 and photons  Fake photons from electrons removed

14 MonoPhoton : signal extraction Single-bin counting experiment after p T (  ) cut Major backgrounds = MC x SF from data Beam halo timing distribution in data 14

15 MonoPhoton : results 15 CMS PAS EXO-12-047

16 Top Pairs & MonoTop  Heavy quarks enhance sensitivity to scalar interactions  Two possible final states :  Signatures: 1. Large MET + 2 leptons + ≥2 Jets @low pT 2. Large MET + 1 lepton  Top pairs  MonoTop  Probe couplings that favor heavy quarks  FCNC diagrams with new particle in the final state  Search for scalar & vector DM particle  Signature : t  bW(qq)  1 b-jet + 2 jets + MET 16

17 Top Pairs dileptonic  Leptons : R iso 20 ; |  | < 2.4 (  ), 2.5 (e)  Leptons : m L1L2 >20 ; m ll = m Z ± 15 GeV ; scalar pT sum > 120 ;  <2  Jets : ≥2 Jets pT>30 & |h|<5 & loose ID  Jets : scalar pT sum < 400  MET > 320  Irreducible backgrounds = MC x SF from data tt, t, DY, VV  Fakes : 1 or 2 mis-ID lepton(s) Fit (S,B) to data 17 CMS PAS B2G-13-004

18 Top Pairs semileptonic  1 Lepton : R iso 30 ; |  | < 2.1 (  ), 2.5 (e)  Jets : ≥3 Jets pT>30 & |  |<4 & loose ID & ≥1 b-jet  Jets/MET :  (Jet1+Jet2, MET) > 1.2  MET>320 GeV & m T >160 GeV & m T2 W (W decay kinematics)>200 GeV  All backgrounds = MC x SF from data Fit (S,B) to data q1q1 q2q2 18 CMS PAS B2G-14-004

19 Top Pairs : results Semileptonic Dileptonic 19

20 MonoTop : event selection  2 jets pT>60, 3 rd jet pT>40 ; m3j<250 ; 1 b-jet ; all jets : |eta|<2.4  4 th jet veto : pT > 35  Lepton veto : pT>10(20) m(e) ; |h|<2.4(2.5) m(e) ; Riso ≤ 2  MET > 350 20 CMS PAS B2G-12-022, arXiv:1410.1149, submitted to PRL

21 MonoTop : results 21 CMS PAS B2G-12-022

22 SUSY Searches 22 CMS PAS SUS-13-020

23 23 pMSSM Interpretations DCS stands for Direct CMS Search No astrophysical data included NB, absolute distributions strongly depend on the choice of priors

24 24 CMS data slightly prefer lower densities and heavier WIMP. Relic density and WIMP mass  = Xsec coefficient Z = signed Bayesian analog of the frequentist “n-sigma” Z > 5 means discovery Z < -1.64 means exclusion at 95% CL Relic densityNeutralino mass

25 Summary  CMS covers already a broad panel of final states, with sensitivities to various scenarios  So far, no new signal observed   Upper limits on the production cross sections between 10 -1 and 10 -2 pb  Upper limits on  -nucleon interaction cross sections between 10 -38 and 10 -42 cm 2  Collider results mainly limits below M  < 10 GeV 25

26 Perspectives for LHC Run 2  Running conditions : 13 TeV, 25 ns, = 40 expect factor 4 in rate  Need to optimise X+MET triggers to cope with such conditions  Refine background estimations and reduce associated uncertainties  Physics models : EFT validity is an important limitation to current searches switch to simplified models with extra search parameters wrt EFT searches 26


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