Discovery potential for H + decaying to SUSY particles 30 March 2005, ATLAS Higgs Working Group Meeting, CERN Christian Hansen Uppsala University Nils Gollub Uppsala University Ketevi Assamagan BNL Tord Ekelöf Uppsala University Bjarte Mohn Bergen University

Introduction Not possible to cover low tanβ region with SM decays  Try susy decays Discovery Potentials for H + (from 2→2 processes) when H + → SM particles D. Cavalli et al., “Search for H+   decays”, ATL-PHYS K. Assamagan, “The Charged Higgs in Hadronic Decays With the ATLAS Detector”, ATL-PHYS K. Assamagan, “The Hadronic  decay of a Heavy H+ in ATLAS”, ATL-PHYS ATLAS 300 fb -1

Introduction (cont) The channel with where N = invisible final state particles and with has been studied with CMSJET. M. Bisset, F. Moortgat and S. Moretti, “Trilepton+top signal from chargino-neutralino decays of MSSM charged Higgs bosons at the LHC”, hep-ph/ v2 1 Oct 2003

Introduction (cont) CMS’ result : Parameter Set A : M 2 = 210 GeV μ = 135 GeV m l̃R = 110 GeV m g ̃ = 800 GeV m q = 1 TeV where soft slepton and squark masses are degenerate for all generations, where m l̃R = m l̃L and where M 1 = 3/5tan 2 θ W M 2 hep-ph/ v2 1 Oct 2003 We have now performed a similar study using ATLFAST

Event Production Used HERWIG for event production and ATLFAST for fast detector simulation (ATLAS 7.0.3) Have MC data for tanβ = 3, 5, 8, 10, 15, 20, 25, 30, 35, 40 and m A = 200, 220, , 300, 350, 400, 450, 500 GeV, in the Parameter Set A ProcessNumber Events Produced gb → H + t, H + → χχ → 3l+N and t → bqq  4·10 5 for each (tanβ, m A ) gg → tt10 8 gg → ttZ2·10 7 gg → tth10 7 for each (tanβ, m A ) gg → χχ10 7 for each (tanβ, m A ) gg → q, g  10 6 for each (tanβ, m A ) Signal SM Bkg SUSY Bkg

Signal Cross Section ; NLO from SM-Bkg Cross Section ; CS(tt) = 737 pb (NLO) CS(ttZ) = 431 fb (LO from Herwig) SUSY-Bkg Cross Section; (LO from Herwig) Cross Section Tilman Plehn, “Charged Higgs boson production in bottom-gluon fusion”, PHYSICAL REVIEW D 67, (2003)

Signal Branching Ratio: H + is forced to decay to χχ which are forced to decay to 3 leptons and a number N of undetectable particles The top is forced to decay hadronically e.g. for tanβ = 20, m A = 350 BR TOT = BR(H + → χχ →3l+N)*BR(t→bqq) = 0.26*2/3 = 0.18 Signal Branching Ratio

The Signal Examples of H + → 3l+N

Cuts: 3 Lepton Cut Events must have exactly three isolated leptons (e or μ) with p T > 20, 7, 7 GeV, all with |η| < 2.4

Cuts: 2l Mass Cut The invariant mass of the two same flavor, opposite sign leptons have to be less than 63 GeV χ 0 j → 2 same flavor, opposite sign leptons + one or more undetectable particle(s) Out of the three isolated leptons at least 2 are required to have same flavor and opposite sign The inv. mass of these two is kinematically constrained. –E.g. if χ 0 j only decayed to one undetectable particle (χ 0 1 ) it follows that –If tanβ = 10 and m A = 350 GeV we have m(χ 0 1 ) = 78 GeV, m(χ 0 2 ) = 131 GeV and m(χ 0 3 ) = 146 GeV  M llmax = 51 (68) GeV for j = 2 (j = 3) If third lepton has same flavor, the biggest M ll are used for the cut 10 < M ll < 63

Cuts: 2l Mass Cut The invariant mass of the two same flavor, opposite sign leptons have to be less than 63 GeV Signal events, gb → H + t All Backgrounds

Cuts: 2l Mass Cut The invariant mass of the two same flavor, opposite sign leptons have to be less than 63 GeV

Cuts: Top Cut Must have at least three jets with p T > 20 GeV in |η| < 4.5 Among these select 3 top jets by min( |m jjj – m t | ) < 35 GeV Among these select 2 W jets by min( |m jj – M W | ) < 15 GeV

Cuts: B Cut, NOT USED! The third jet must be b-tagged

Cuts: B Cut, NOT USED! The third jet must be b-tagged

Cuts: B Cut, NOT USED! The third jet must be b-tagged

Cuts: Jet Cut Reject if the p T sum of the non top jets with p T > 50 GeV extends 300 GeV Signal events, gb → H + t All Backgrounds

Cuts: Jet Cut Reject if the p T sum of the non top jets with p T > 50 GeV extends 300 GeV

Cut Results L = 300 fb -1

5-  Discovery Contour for H + Set A

5-  Discovery Contour for H +

Conclusions and Future Work Our paper is currently an ATLAS communication: (ATL-COM-PHYS ) Paper More Sets More MSSM parameter sets need to be analysed for a more general conclusion Contour The 5-  significance contour for H + through H + → χχ encloses major part of intermediate tanβ region CMS Our discovery region is about same size as that obtained for CMS. Different shapes, due to –Different cuts –Different used cross sections (We: NLO for signal & tt and LO for the rest. They: LO for all) –Different detector descriptions (ATLFAST vs. CMSJET)