Teruki Kamon. Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University & Department of Physics Kyungpook National University

Transcription

1 Stopping at the LHC Using M3 Teruki Kamon Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University & Department of Physics Kyungpook National University 20th International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY 2012) Beijing, China, August 16, 2012 August 2012 Stopping at the LHC using M3 1

2 Goals [July 4, 2012] Higgs-like boson at 125 GeV and heavy gluino and 1 st /2 nd generation squarks Light Stop, Light Stau, Higgsino-Bino LSP [Stop Goal #1 Excess] It has been shown that the dilepton and single lepton final states are golden modes to detect an excess beyond the SM processes. [Stop Goal #2] Show MET not originated by two top quarks. Reconstruction of two top quarks in fully hadronic final state Test an alternative technique (M3) arxiv: (Pheno Project #10) M3 = invariant mass of those three jets that yield the vectorial sum with maximum p T, including one b-tagged jet and two untagged jets. 2

3 Stop Searches in Market mt2^w Yang Bai, Hsin-Chia Cheng, Jason Gallicchio, Jiayin Gu, Stop the Top Background of the Stop Search 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 tops David E. Kaplan, Keith Rehermann, Daniel Stolarski, Searching for Direct Stop Production in Hadronic Top Data at the LHC M3 to tag tops Bhaskar Dutta, Teruki Kamon, Nikolay Kolev, Kuver Sinha, Kechen Wang, Searching for Top Squarks at the LHC in Fully Hadronic Final State 3

4 Snapshot of Stop Searches Final States Dilepton+Jets+MET 1L+Jets+MET Jets+MET 4 tops Techniques at Razor mt2, mt2^w FatJet/ TopTagger/ Cambrige-Aachen Algorithm Bi-Event Subtraction Technique (BEST) M3 4

5 TTbar SM processes: TTbar + jets, Single stop production, W + jets, Z + jets, QCD Once we require large MET, a major surviving decay mode is Lost Lepton +Jets+MET Baseline Selection: 4 jets + 2 loose b s (>100, 30 s) + MET (> 100) + Lepton veto pt(e) > 10, Iso < 5 GeV pt(m) > 10, Iso < 5 GeV pt(t h ) > 20, e = 60%, f = 2% 5

6 M3 (TOP PAS) M 3 M 2 M 6

7 C Stop Search Strategy A arxiv: M3, twice B 7

8 Reference Stop: Final Selection ~ t (400) & ~ 0 1 (100) Stage 1: Tagging top (j 1, j 2, b) using M3(twice) Stage 2: Probing j 1, j 2, b (lost lepton) Stage 3: Clean-up Two Top system 8

9 Stage 1: Tagging 1 st Top ~33% more signal p T ( t 200 ) M(jjb) top M(jjb) stop p T (top) > 200 GeV 40 < M(jj) < 120 & 120 < M(jjb) < 220 p T ( W ) M(jjb) top M(jjb) stop 9

10 Stage 2: Probing 2 nd Top A B 10

11 Stage 3: Clean-ups C A B 11

12 Mixed-up B A 12

13 Stage 4 & 5: Two-Top System Baseline selection cuts: 4 jets + 2 loose b s + MET Final selection cuts Stage 1: Tagging leading p T top (j 1, j 2, b) Stage 2: Probing j 1, j 2, b (lost lepton) Stage 3: Clean-up system Stage 4: W mass cut Stage 5: Top mass cut 40 < M(jj) < 120 & 120 < M(jjb) < 220 B 40 < M(jj) <

14 Mixed-up B A 14

15 Pheno #10 Summary (I) arxiv: v1 [hep-ph] Tilman Plehn, Michael Spannowsky, Michihisa Takeuchi tt 0,1, 2 j tt 3 j tt 2 j 0.8 S/B is more or less consistent 15

16 Pheno #10 Summary (II) 16

17 Summary An observation of MET along with two reconstructed top quarks in fully hadronic state is a challenging task... [arxiv: ] 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. Stomping at Texas 17