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Analysis of Radion Signatures in CMS: A Focus on f→hh Decay Channels

This study explores the production and decay of radions within the CMS framework, specifically focusing on the decay channel f→hh and its subsequent branches leading to tt and bbbb final states. By analyzing various model parameters, the research aims to characterize the signal effectiveness against potential background events such as tt, W+jj, and Z+jj. Detailed discussions on trigger strategies, selection efficiencies, and invariant mass distributions further enhance understanding. The preliminary results show promising potential for distinguishing signal from background.

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Analysis of Radion Signatures in CMS: A Focus on f→hh Decay Channels

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  1. Radion searches in CMS A first look to fhh G. Dewhirst, L. Fano, S. Gennai, S. Nikitenko Simone Gennai SNS, INFN-Pisa

  2. s Br of radion depends on mf, mh, Lf (scale), x (f-h) mixing Simone Gennai SNS, INFN-Pisa

  3. Simone Gennai SNS, INFN-Pisa

  4. Simone Gennai SNS, INFN-Pisa

  5. Simone Gennai SNS, INFN-Pisa

  6. tjet l p p b b fhhtt bbt+l+bb+n This final state is common also to other scenarios, like MSSM or little Higgs, in the ED case the cross sections are enanched for some model parameters. (MF=300 GeV, Mh=125 GeV) Possible backgrounds: tt, W+jj, Z+jj Simone Gennai SNS, INFN-Pisa

  7. Few words about tt bkg • tt is the most dangerous • Atlas has considered: • ttWWbb l+n+jj+bb, sxBR=180 pb • Probably we should consider also: • ttWW+bb l+n+t+bb l+n+tjet+bb, sxBR=18 pb • considering the t-tagging efficiency and bkg rejection this channel could also contribute. Simone Gennai SNS, INFN-Pisa

  8. Trigger and basic selections • e/m + t-jet trigger will be used • At least 3 jets + 1 e/m to be reconstructed • t-jet identification (HLT + off line) • At least 1 jet b-tagged (off line) • ET missing based selection (to suppress W+jj) • Invariant mass of bb and t+lepton • Invariant mass ot 2 reconstructed Higgs Simone Gennai SNS, INFN-Pisa

  9. Where to find Real tau: • When electron is collinear to 1st L1 Tau: • 30% Real Tau is the 2nd Tau jet • 38% Real Tau is the 1st Central jet • 20% Real Tau is the 2nd Central jet • 8% Real Tau is the 3rd Central jet • ..... • Tau Tagging efficiency = 35% • limiting to first 3 highest energy jets: Eff. = 30% Tau isolation parameters: PtLT>10 GeV RM=0.1 RSIG=0.07 RISO=0.4 1.OR.3 Tracks inside Signal cone. Simone Gennai SNS, INFN-Pisa

  10. B tagging Efficiency • Tagging efficiency : # of events with tagged jet / # matched events • Total Efficiency : Eff. Match X Eff. Tagging • Btagging = Tk>2, sip >2 • As efficiency for 1st and 2nd Jet are different, we can relax selection but requiring 2 tagged jets instead of at least 1. B-jet Simone Gennai SNS, INFN-Pisa

  11. Signal invariant mass distributions FAST Vs FULL No big discrepancy between full and fast simulation for the signal! Simone Gennai SNS, INFN-Pisa

  12. Signal PT distributions FAST Vs FULL Simone Gennai SNS, INFN-Pisa

  13. Preliminary results Efficiency parametrization has been performed in order to have the same number of signal events in both Full and Fast simulation Ev. tt = 107 Ev. W+jj = 0 Ev. Z+jj = 33 Ev. Bkg = 140 Ev Sig = 43 S/sqrt(B+S) = 3.2 Simone Gennai SNS, INFN-Pisa

  14. 3-5 Sigma regions Really PRELIMINARY CMS, 30 fb-1 fhhggbb fhh tt bb Lf (GeV) Mf=300 GeV Mh=125 GeV 3 sigma 5 sigma Theoretically excluded Theoretically excluded x Simone Gennai SNS, INFN-Pisa

  15. -> hh -> bbbb – First View same point: mf = 300 GeV, mh = 125 GeV (*) at least one parton in the final state Simone Gennai SNS, INFN-Pisa

  16. Selection Efficiency - Energetic Threshold 4 Jet ET > 50 GeV : 10% signal 1% QCD (PT>100 GeV) Signal Eff 1 Jet 2 Jet 3 Jet 4 Jet Jet ET 4b QCD – no cut 4b QCD – PT > 100 GeV Eff Eff Simone Gennai SNS, INFN-Pisa Jet ET Jet ET

  17. Selection Efficiency Energetic threshold + btag 1 leading Jet 2 leading tagged Jet 3 leading and next-to-leading tagged Jets Signal Eff b-tag: 2 tracks with Sip2D>1.5 Jet ET 4b QCD – PT > 100 GeV 4b QCD – no cut Eff Eff Simone Gennai SNS, INFN-Pisa Jet ET Jet ET

  18. Signal Kinematics <b jet> = 2.5 <jet> = 4.6 Eta and PT distribution - 4 leading Jets Eta PT Simone Gennai SNS, INFN-Pisa

  19. Signal Reconstruction Best jets combination is chosen minimizing the difference between all possible reconstructed mass M(i,j) – M(k,l) Mbb  124  39 GeV Jets are preselected in the barrel requiring ET>35 GeV Mbbbb  304  64 GeV Simone Gennai SNS, INFN-Pisa

  20. Cuts and Selection Criteria 1 Jet ET > 177 GeV OR 3 Jets ET > 86 GeV OR 4 Jets ET > 70 GeV AND Invariant reconstructed mass: 124 - 1.5s < Mbb < 124 + 1.5s 304 - 1.5s < Mbbbb < 304 + 1.5s Signal: s 58 pb BR(f->hh)  0.33 BR(h->bb)  0.9 Eff  5% 4b QCD (PT>100 GeV): s(qq,gg->bbbb) 930 pb Eff  3% 837*103 events 22.5*103 events 30 fb-1 Simone Gennai SNS, INFN-Pisa

  21. What is missing? • Considering all QCD background sources • Considering resonant backgroud • Check other trigger strategy (using b-tag) Simone Gennai SNS, INFN-Pisa

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