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Charged Higgs boson at the LHC. 이강영 ( 건국대학교 ). @ 연세대학교 2009. 10. 29. Contents. Introduction Theoretical background Present experimental constraints Light charged Higgs boson at the LHC Heavy charged Higgs boson at the LHC Summary. Introduction. H + : singly charged scalar boson
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Charged Higgs boson at the LHC 이강영 (건국대학교) @ 연세대학교 2009. 10. 29.
Contents • Introduction • Theoretical background • Present experimental constraints • Light charged Higgs boson at the LHC • Heavy charged Higgs boson at the LHC • Summary
Introduction • H+: singly charged scalar boson • Exists when there is extra Higgs sector more than SM singlet. • 2HD model • MSSM and more extensions (NMSSM etc.) • LR model • Other GUT-based model • Little Higgs model • And others…
Charged Higgs boson in the 2HD model ~ General Higgs potential with VEVs where and
Goldstone mode Charged Higgs mode where the mass is Note that at tree level in the MSSM relevanttbH+ couplings Phenomenology is governed by at tree level.
Higgs sector in the LR model Two triplets : breaking of SU(2)R and its L-R partner a bidoublet : electroweak symmetry breaking and fermion masses with VEVs Note that define
Charged Higgs boson in the LR model Mass matrix where Diagonalization by Charged Higgs mass
relevanttbH+ couplings similarly for lepton sector
Present constraints on H Light charged Higgs fromt Hb at Tevatron Light charged Higgs boson : Absence of observed charged Higgs boson Constrained by
Pair production of charged Higgs boson at LEP ALEPH collaboration, PLB 543, 1 (2002)
B and charged Higgs boson R. Barlow, ICHEP 2006
allowed allowed D.-W. Jung, K. Y. Lee., Phys. Rev. D 76, 095016 (2007)
Light charged Higgs production at the LHC topquark decay after tt pair production 108 top quarks produced More than 105 charged Higgs expected Full reconstruction is impossible due to many neutrinos. (MT2?)
Decay of the light charged Higgs boson in the 2HD model ≫ 1 ( ) in the LR model SUSY parameters : Mh-max scenario
One lepton mode (2HD model) : H+ into tau associated with the leptonic W decays Thies Ehrich, ATLASCollaboration • Standard model top pair production with two W bosons, one decaying into tau and one decaying into lepton. • Standard model top pair production with two W bosons with misidentified tau-jets. • Single top production • W + jets production • QCD processes Backgrouds
Single lepton triggers Tau triggers
Hadronic mode (2HD model) : Both tau from H+ and W boson decay hadronically Elias Coniavitis, ATLASCollaboration • Similar to the previous case Backgrounds Triggers • Trigger A : a tau and missing energy • Trigger B : a tau, missing energy, and three jets Large cross section makes this channel promising in search of H+.
Selection cuts Cuts I : selecting events agreeing with the signal final state. - Cuts II : reducing the QCD background by identifying the tt topology
Likelihood discriminant : discriminating between the signal and the SM-like tt background To reflect that the charged higgs is heavier than W boson. Likelihood > 0.6
Heavy charged Higgs production at the LHC dominant channel : K-factors for the NNLO QCD corrections considered N. Kidonakis, JHEP 05, 011 (2005).
M. Flechl., ATLAS Collaboration, presented at Prospects for Charged Higgs Discovery at Hadron Collider, Uppsala, Sweden (2008)
Decay of heavy charged Higgs boson in the LR model ≪ 1 in the 2HD model
Heavy charged Higgs with the tau mode in the 2HD model M. Flechl., ATLAS Collaboration, presented at Prospects for Charged Higgs Discovery at Hadron Collider, Uppsala, Sweden (2008)
Summary • Discovery of the charged Higgs boson is a clear evidence of the new physics beyond the SM. • Discovery potential of the light charged Higgs boson in the 2HD model has been studied. • Discovery potential of the heavy charged Higgs boson in the 2HD model has been studied with tau mode. • The charged Higgs boson in the LR model should be studied without tau mode.
Transverse mass • Edges of transverse mass distribution are crucially related to the mass of W’. D0 collaboration, PRL 100, 031804 (2008)