Prospects for. Teruki Kamon

Transcription

1 Prospects for SUSY Light of 2012 in Light Stop Teruki Kamon Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University & Department of Physics Kyungpook National University LHC Workshop Kyungpook National University, Korea June 22, 2012 June 2012 Prospects for SUSY

2 Prologue Pheno Projects Light Higgs and Heavy 1 st /2 nd Generation Squarks Light Stop and Light Stau Pheno Project #10: Light Stop Summary OUTLINE 2

3 Pheno Projects at A Glance Phys. Lett. B 505 (2001) 161 (Tevatron) Phys. Lett. B 538 (2002) 121 (Tevatron) Phys. Lett. B 611 (2005) 223 (ILC) Phys. Lett. B 618 (2005) 182 (ILC) B s mm: CDF PRL 107 (2011) Eur. Phys. J. C46 (2006) 43 (LHC+ILC) Supersymmetry Parameter Analysis: SPA Convention and Project Phys. Lett. B 639 (2006) 46 (LHC14) Phys. Lett. B 649 (2007) 73 (LHC14) Phys. Rev. Lett. 100 (2008) (LHC14) Phys. Rev. D 79 (2009) (LHC14) Phys. Rev. D 82 (2010) (LHC14) Focus Point (unpublished) attempted to reconstruct two tops Phys. Lett. B 703 (2011) 475 ( BEST at LHC7) Phys. Rev. D 85 (2012) (Mirage at LHC14) arxiv: accepted in PRD (LFV at LHC14) arxiv:12**.???? Stops via Tops (LHC8) SUSY Jets+MET+Taus at LHC7 CMS SUS PAS CMS SUS Paper (in preparation) M(top) mass (SKKU + TAMU) Bhaskar Dutta, Teruki Kamon, Nikolay Kolev, Kuver Sinha, Kechen Wang 3

4 Exciting Time! LEP + Tevatron LEP + Tevatron + LHC Narrowing down the Higgs boson mass! The current SM Higgs mass region allowed by LHC+Tevatron+LEP is quite SUSY-friendly 4

5 But, Keep in mind they are preliminary results; Keep in mind they are small numbers; Keep in mind we will run in the next year. Dec. 13,

6 CMS 2011 Physics Precision measurements Very rare decays Searches for new physics with MET No signs of new physics (yet) 6

7 But, The maximum squark and gluino masses excluded by current LHC limits are ~ 1 TeV 7

8 We are focusing on 3G The 3 rd generation may be very special 1) Light stop search (this talk) 2) RPV stop search (Daejung s talk) EXO (2011 data) 3) SUSY stau-neutralino coannihilation search in jets + MET SUS (2011 data) 4) Development of BEST to detect W jj and t Wb in jets + MET (2012 data) 5) Light stau search (2012 data) 6) 8

9 My Daughter s View I need ~ t I need c 1, c 2, Uh Oh! The hosts are in 9

10 Benchmark Point 10

11 Benchmark Point 11

12 Stop Searches in Market Stop searches in 2012 Tilman Plehn, Michael Spannowsky, Michihisa Takeuchi, Stop searches in Stop degenerate case Daniele S.M. Alves, Matthew R. Buckley, Patrick J. Fox, Joseph D. Lykken, and Chiu-Tien Yu, Stops and MET: the shape of things to come Spin correlation for stop Zhenyu Han, Andrey Katz, David Krohn, and Matthew Reece, (Light) Stop Signs "FatJet" to tag top David E. Kaplan, Keith Rehermann, Daniel Stolarski, Searching for Direct Stop Production in Hadronic Top Data at the LHC 12

13 Snapshot of Stop Searches Final States Dilepton+Jets+MET 1L+Jets+MET Jets+MET 4 tops Techniques at Razor mt2 TopTag (boosted top) M3 13

14 TTbar + jets Single stop production W + jets Z + jets QCD SM Backgrounds s 7 T e V Two tops along with MET. Challenging, but we need all hadronic channel (6 jets) tjjb tag in one side, W+b tag in other 14

15 TTbar Once we require large MET, a surviving decay mode of TTbar events is Lepton+Jets+MET 6 jets (2 loose b s) + MET + Lepton veto pt(e) > 10, Iso < 5 GeV pt(m) > 10, Iso < 5 GeV pt(t h ) > 20, e = 60%, f = 2% Still a major surviving decay mode is Lost Lepton + Jets + MET mode e, b m,t W t j W t j q q b 15

16 Baseline Selection Cuts E T 50 ~ t (4 5 0 ) 0 & ~ c (1 0 0 ) fb tt 3 je ts Baseline Selection: 4 non b-jets (>100, >30 s) + 2 loose b s (>30 s) + MET (>200) tt 4 je ts S B(top) S/B S/ (S+B)

17 M(top) or M(Ttbar) in Market Kinematical fit (c 2 ), NN M3 FatJet/ TopTagger/ Cambrige-Aachen Algorithm Bi-Event Subtraction Technique (BEST) mt2 Razor alphat 17

18 CMS TOP PAS p T Kinematical Fits 60, 60, 60, 60, 50, 40 (at least 2b jets) 18

19 CMS TOP PAS Kinematical Fits in m + jets 19

20 M3 (TOP PAS) q q M 3 M 2 e b, m,t W t j W t j b M 20

21 Cambrige-Aacgen Algorithm EXO PAS Z t t q q W b t t W b 21

22 HEPTopTagger Michihisa Takeuchi (Uni Heidelberg), Top Reconstruction for New Physics Search (Feb 17, 2012) R C/A < 1.5 FatJet Tagged Teruki Kamon Prospects for SUSY

23 Detection of Wjj and twb Bi-Event Subtraction Technique pp t t j ( W b) ( W b) j j l j pp W jjjj l BEST: jet mixing from two different events (TTbar, TTbar), (TTbar,W), (W,W) 23

24 M(TTbar) using mt

25 Razor Christopher Rogan, Kinematical variables towards new dynamics at the LHC arxiv: v2 [hep-ph], CALT Abstract: At the LHC, many new physics signatures feature the pair-production of massive particles with subsequent direct or cascading decays to weaklyinteracting particles, such as SUSY scenarios with conserved R-parity or $H \to W(\ell\nu)W(\ell\nu)$. We present a set of dimension-less variables that can assist the early discovery of processes of this type in conjunction with a set of variables with mass dimension that will expedite the characterization of these processes. 25

26 Stop Search Strategy 3 1 q q M3, twice e, 2 b m,t W t W t j b t 0 ĉ 1 j 0 ĉ 1 26

27 Reference Stop: Final Selection ~ t (4 5 0 ) (1 0 0 ) Stage 1: Tagging top (j 1, j 2, b) using M3(twice) & 0 c ~ 1 Stage 2: Probing j 1, j 2, b (lost lepton) Stage 3: Clean-up Two Top system 27

28 E T 200 Stage 1: Tagging 1 st Top M 3 Two entries / events 200 p T M(jjb) top M(jjb) stop ( jjb ) 40 < M(jj) < 120 M(jjb) top M(jjb) stop M ( jj ) M 3 28

29 40 < M(jj) < 120 & 120 < M(jjb) < 220 E T 200 Stage 1: Tagging 1 st Top M3 twice M3 once ~33% more signal p T ( t 200 ) M(jjb) top M(jjb) stop p T (top) > 200 GeV S B(top) S/B S/ (S+B) p T ( W ) M(jjb) top M(jjb) stop

30 Stage 2: Probing 2 nd Top M(jjb) top 1 q q >1.3 ( b, M(jjb) stop M E T ) e, 2 b m,t W t j W t j b >170 M T M(jjb) top M(jjb) stop ( b, M E T ) 30

31 Stage 2: Probing 2 nd Top M(jjb) top 1 q q >1.3 ( b, M(jjb) stop M E T ) e 2 b, m,t W t j b W t S B(top) S/B S/ (S+B) j >170 M T M(jjb) top M(jjb) stop ( b, M E T ) 31

32 Stage 3: Clean-ups 3 1 j 1 j 2 ( b, M E T ) M(jjb) top M(jjb) stop e, 2 b m,t W t j 1 W t j 2 b ( j 1, M E T ) M(jjb) top M(jjb) stop 32

33 Number of Events/20 GeV Stage 4 & 5: Clean-ups Preliminary 3 M(jjb) sum M(jjb) top M(jjb) stop Improving statistics S B(top) S/B S/ (S+B) M ( jjb ) 40 < M(jj) < < M(jj) < 120 & 120 < M(jjb) <

34 Analysis Summary (8 TeV, 50 fb -1 ) Baseline selection cuts: 4 jets + 2 loose b s + MET Final selection cuts Stage 1: Tagging leading pt top (j 1, j 2, b) Stage 2: Probing j 1, j 2, b (lost lepton) Stage 3: Clean-up Two Top system Stage 4: W mass cut Stage 5: top mass cut 8 TeV 450 GeV Stop S B(top) S/B S/ (S+B) Baseline selection [1] 1 st Top [2] 2 nd Top [3] Clean-up [4] W mass [5] Top mass

35 Analysis Summary (8 TeV, 50 fb -1 ) arxiv: v1 [hep-ph] tt 0,1, 2 j Define pre-selection cuts: 6 jets (2 loose b s) + MET Final selection cuts Stage 1: Tagging leading pt top (J1, J2, B) Stage 2: Probing j1, j2, b (lost lepton) Stage 3: Clean-up Two Top system Stage 4: W mass cut Stage 4: top mass cut tt n j ( n 0,1,2,3,4,5,6) 8 TeV 450 GeV Stop S B(top) S/B S/ (S+B) Baseline selection [1] 1 st Top [2] 2 nd Top [3] Clean-up [4] W mass [5] Top mass fb 0.37 fb 35

36 Analysis Summary (8 TeV, 50 fb -1 ) arxiv: v1 [hep-ph] tt 0,1, 2 j Define pre-selection cuts: 6 jets (2 loose b s) + MET Final selection cuts Stage 1: Tagging leading pt top (J1, J2, B) Stage 2: Probing j1, j2, b (lost lepton) Stage 3: Clean-up Two Top system Stage 4: W mass cut Stage 4: top mass cut tt n j ( n 0,1,2,3,4,5,6) 8 TeV 450 GeV Stop S B(top) S/B S/ (S+B) Baseline selection [1] 1 st Top [2] 2 nd Top [3] Clean-up [4] W mass [5] Top mass tt 2 j 1.22 More or less consistent 0.12 fb 0.37 fb 0.8 tt 3 j 36

37 Stop Searches in 2012 (I) arxiv: v1 [hep-ph] 37

38 Stop Searches in 2012 (II) Decreasing, because of FatJet? 38

39 Summary arxiv: v1 [hep-ph] The dilepton final state is considered as a golden mode to detect an excess beyond the SM process. However, it is not provide an conclusive answer. All-hadronic mode would be a key, but challenging, mode where one requires to detect two top quarks. A simple kinematical selection technique, M3, is used to tag top quarks in 3-jet system (p T > 200 GeV) and shown to be effective as in an analysis using TopTagger. M3 can be a complementary technique to search for stops for masses around GeV. 39

40 Backup 40

41 Properties used to identify b-jets Hard fragmentation functions Relatively large mass Long lifetime Semi-leptonic decays B-Tagging (at CMS) b-tagging Variables 2D and 3D impact parameters (closest approach to primary vertex) Flight distance Invariant mass of tracks at vertex Number of tracks at vertex (~ 5 for b) Likelihood variables based on these parameters ~70% eff. with light mistag rate ~ 2% 41

42 Tau-Tagging (at CMS) Tau leptons decay to hadrons ~ 65% of the time Tau identification to hadronic decays: Reconstruct decay modes using reconstructed PF particles TAU Cut based: mass of the mesons, rejection against e/m, and isolation 42

43 Any Further Improvements? m LSP =

44 Few assumptions Many assumptions SUSY Mass Techniques Christopher Lester et al., ICHEP2010, arxiv: Missing momentum M eff, Razor, H T shat min M TGEN M T2 / M CT M T2 (with kinks ) M T2 / M CT ( parallel / perp ) M T2 / M CT ( subsystem ) Polynomial constraints Multi-event polynomial constraints Whole dataset variables Max Likelihood / Matrix Element 44