Searches for BSM Higgs bosons at LHC A

Searches for BSM Higgs bosons at LHC A. Nikitenko (IC), LHC 2 TSP 2011

• LHC searches for – MSSM neutral f->tt – MSSM charged Higgs in t->H+b decays • H+->tn • H+->cs – double charged Higgs – NMSSM Higgs a 1 ->mm • Conclusions

MSSM Higgs bosons • Five Higgs bosons: h, H, A, H+/ • Higgs sector is defined at tree level by MA, tanb – rad. corrections introduce dependence on other model parameters • Upper limit on mh ~ 135 Ge. V

MSSM neutral f->tt • gfbb. MSSM = gfbb. SM x tanb (f=A) at tree level – s. SM(gg->H) ~ 20 -10 pb at m. H = 115 -140 Ge. V • Br (f->tt) ~ 10 %

t and b tagging is the tool for searches

t tagging performance QCD jets 1 and 3 prongs, p. T > 20 Ge. V

Z->tt measurement

b tagging performance emistag ~ 0. 1 %, eb ~ 50 %

b(b)Z as a benchmark for MSSM b(b)H J. Campbell talk on CMS meeting, 2006 • Data vs MC – kinematics – cross-sections 4 FS vs 5 FS • relevant for low mass Higgs boson • b-PDF ALPGEN and Sherpa MC Mad. Graph MC

4 FS vs 5 FS in b(b)f cross-section “Santander matching” 5 FS 4 FS • by R. Harlanger, M. Kramer, M. Schumacher CERN-PH-TH/2011134. Presently used in SUSY H->tt ATLAS and CMS analyses

ATLAS SUSY f->tt analysis with 1. 06 fb-1 • Important extensions of 2010 data analysis – MMC method for mtt calculation for l+thad analysis • A. Elagin, P. Murat, A. Pranko, A. Safonov. ar. Xiv: 1012. 4686 – adding thad final state in the analysis • Di-t jet trigger is exploited

mass reconstruction • tt mass reconstruction methods used: – (mtteff )2= (pt+ + pt- + pmiss)2 in em channel – MMC method in ethad+mthad channels – visible mass in thad channel • “t embedding” technique is used to obtain tt mass shape from Z->mm (and W->mn) data events

Event yields after selections (1. 06 fb-1)

Limits on sf BR(f->tt) • Shown separately for gg->f and bbf production • lthad final states provide the most stringent limit • em and thad improve limits for small and large Higgs boson masses respectively

Exclusion in m. A-tanb plane (1. 06 fb-1) em t ht h combined lth

CMS SUSY f->tt analysis of 2011 data combines b-tagged and non-b-tagged events Final states used: t mt h t et m t mt m non-b-tag

-1 CMS results for f->tt with 1. 6 fb • Sensitivity is much improved vs 36 pb-1 analysis due to – more data analyzed – combining b-tag and non-b-tag analyses

• Remark on gg->f generation – CMS used PYTHIA, ATLAS used POWHEG – both generators do not include b-quark in the loop: • acceptance for gg->f is overestimated; how much ? top-loop vs b-loop in gg->h : different Higgs p. T ! m. H=115 Ge. V Spira et al. hep-ph/0604156

Searches for t->H+b (m. H+ < mt) T. Plehn et al. , hep-ph/0312286 m H+ < mt m H+ > mt pp->tb. H+ is in MC@NLO (T. Plehn et al) recipie for m H+ ~ mt: add tt and tb. H+ 4 FS and 5 FS NLO calculations exist • H+->tn assuming BR(H+->tn)=1 - high tanb • H+->cs assuming RB(H+->cs)=1 – very low tanb

CMS H+->tn. Topologies considered: Ntt. SUSY > Ntt. SM mth mt h Ntt. SUSY > Ntt. SM m Ntt. SUSY < Ntt. SM

Individual analyses H+->tn: event yields and BR t->H+b limits fully hadr. mth em

Results of H+->tn analysis with 1. 1 fb-1 assuming BR(H+->tn) = 1

ATLAS search for H+->cs

Fit to improve W->jj and H+->cs separation in di-jet mass distribution before fit after fit

Results of H+->cs analysis with 35 pb-1 assuming BR(H+->cs)=1 • Presence of H+->cs changes – mjj shape – event yield • smaller than SM tt

Search for NMSSM Higgs boson a 1 ->mm • NMSSM solves MSSM ”m-term problem” by introducing additional complex singlet scalar field S – neutral Higgs boson sector expands to three CP-even scalars (h 1, h 2, h 3), two CP-odd scalars (a 1, a 2) – “Ideal”- NMSSM Higgs scenarios” : 2 mt < ma 1 < 2 mb (prefers ma 1 close to 2 mb) Dermisek, Gunion 2010 • s(gg->a 1) x BR(a 1 ->mm) is defined by tanb and q. A – a 1 =cosq. A a. MSSM + sinq. A a. S Dermisek, Gunion 2009 s(pb)

Event selection and results • Selections – two isolated muons p. T > 4 Ge. V – Likelihood Ratio selections • remove pairs not coming from the decay of a single particle

Search for double charged Higgs • Higgs boson triplet F 0, F++ is predicted in little Higgs models • F++ Yukawa coupling matrix YFlilj is proportional to the light neutrino mass matrix and allows to test the neutrino masses by measuring BR(F++->lilj) – A. Hektor, M. Kadastik, M. Muntel et al. , Nucl. Phys. B 787 (2007) 198 -210 NLO cross-sections: M. Muhlleitner M. Spira Phys. Rev. D 68 (2003) 117701

Results 3 lepton events - No evidence for F++ found - New upper limits on m F++ 4 lepton events Signal at BP 4

Conclusions • Start hunting for Higgs boson(s) in new territory – thanks to excellent detectors, reconstruction algorithms, fast data access and re-processing • No Higgs boson(s) found yet – very big hope it will be there this or next year

CMS SUSY f->tt analysis of 2011 data combines b-tagged and non-b-tagged events Final states used: t mt h t et m t mt m non b-tag

-1 CMS results for f->tt with 1. 1 fb • Sensitivity is much improved vs 2010 analysis due to – more data analyzed – combining b-tag and no-b-tag analyses