Trilepton+top signal from chargino-neutralino decays of MSSM charged Higgs bosons 17 June 2004, 9 th Nordic LHC Physics Workshop, Copenhagen 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

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 Our aim is to perform a similar study using ATLFAST

Event Production Used HERWIG for event production and ATLFAST for fast detector simulation Will show results for one point, tanβ = 10 and m A = 350 GeV, in the Parameter Set A Events produced: –10 6 signal events; gb → H + t, H + → χχ and t → bqq –10 7 background events; gg → tt (other bkg channels will be investigated in the future) Luminosity: 100 fb -1 was assumed Cross Section: –Signal; NLO σ = 75fb –Bkg tt; Herwig’s logfile σ = fb Signal Branching Ratio: –H + is forced to decay to χχ and t is forced to decay hadronically BR TOT = BR(H + → χχ)*BR(t→bqq) = 0.77*2/3 = 0.51 Tilman Plehn, “Charged Higgs boson production in bottom- gluon fusion”, PHYSICAL REVIEW D 67, (2003) Not enough bkg statistics!

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: Tracking Cut The three leptons have to be isolated according to the tracker as well The isolation criteria in previous cut was only based on ATLFASTs calorimeter Tracking in ATLFAST gives impractically large files The “true MC particles” was used to see if any particle was too close (ΔR < 0.3) to any of the three leptons A track efficiency of 0.9 was assumed* * This is probably an underestimation since according to S. Gadomski (ATL- CONF ) the efficiency of finding muons is 98% for the Inner Detector

Cuts: Tracking Cut The three leptons have to be isolated according to the tracker as well

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 if j>2) 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. For j=2: 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 j = 2 j = 3

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

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 Tag Cut 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 500 GeV This cut will be needed only for susy background with many hard jets For now the parameters are chosen not to decrease the significance of this analysis with only tt bkg

Cuts: Jet Cut Reject if the p T sum of the non top jets with p T > 50 GeV extends 500 GeV

Cuts: Other Cuts For the 3 isolated leptons p Tmax < 150 GeV and p Tmin < 40 GeV Missing transverse energy should be larger than 40 GeV M eff < 150 GeV

Cuts: Other Cuts For the 3 isolated leptons p Tmax 40 GeV Missing transverse energy should be larger than 40 GeV M eff < 150 GeV

CMS’ Results for this Point

10 7 tt background events don't give enough statistics Used where The Significant with weights =, w = br*cs*L / (# simulated events) Not Enough MC C. Hansen and B. Mohn, “Beach Discussions”, CERN HEP Physics School, Spain, 2004

Not Enough MC

Future Work Get significance for points in the tanβ vs. m A plane Explore the 5σ discovery potential Make 5σ scans for different Parameter Sets Scan Other Sets Background Look at more backgrounds; ttZ, ttγ, tth, χχ, q, g  Statistics SweGrid is right NOW producing more tt events Pure 3l+N Herwig; force χχ→3l+N BR(H + →χχ→3l+N) from diagrams achieved indirectly from ISAJET