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

• 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…

Introduction

Charged Higgs boson in the 2HD model

General Higgs potential

with VEVs

where and

~

Goldstone mode

where the mass is

Charged Higgs mode

Note that at tree level in the MSSM

relevant tbH+ couplings

Phenomenology is governed by at tree level.

Higgs sector in the LR model

Two triplets

a bidoublet

: breaking of SU(2)R and its L-R partner

: electroweak symmetry breaking and fermion masses

with VEVs

Note that

define

Charged Higgs boson in the LR model

Mass matrix

where

Charged Higgs mass

Diagonalization by

relevant tbH+ couplings

similarly for lepton sector

Light charged Higgs from t Hb at Tevatron

Light charged Higgs boson :

Absence of observed charged Higgs boson

Constrained by

Present constraints on H

CDF collaboration, PRL 96, 042003 (2006)

Pair production of charged Higgs boson at LEP

ALEPH collaboration, PLB 543, 1 (2002)

B and charged Higgs boson

R. Barlow, ICHEP 2006

Charged Higgs boson in the LR model

allowedallowed

D.-W. Jung, K. Y. Lee., Phys. Rev. D 76, 095016 (2007)

top quark decay after tt pair production

108 top quarks produced

More than 105 charged Higgs expected

Full reconstruction is impossible due to many neutrinos. (MT2?)

Light charged Higgs production at the LHC

D.-W. Jung, K. Y. Lee., Phys. Rev. D 78, 015022 (2008)

in the LR model

in the 2HD model

≫ 1

2

1

( )

Decay of the light charged Higgs boson

SUSY parameters : Mh-max scenario

One lepton mode (2HD model)

• 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

: H+ into tau associated with the leptonic W decays Thies Ehrich, ATLAS Collaboration

Backgrouds

Single lepton triggers

Tau triggers

20tan

Cut flow

Hadronic mode (2HD model)

• Similar to the previous case

: Both tau from H+ and W boson decay hadronically Elias Coniavitis, ATLAS Collaboration

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-

: discriminating between the signal and the SM-like tt background

Likelihood discriminant

Likelihood > 0.6

To reflect that the charged higgs is heavier than W boson.

Heavy charged Higgs production at the LHC

dominant channel :

K-factors for the NNLO QCD corrections

considered

N. Kidonakis, JHEP 05, 011 (2005).

D.-W. Jung, K. Y. Lee., Phys. Rev. D 78, 015022 (2008)

M. Flechl., ATLAS Collaboration, presented at Prospects for Charged Higgs Discovery at Hadron Collider, Uppsala, Sweden (2008)

D.-W. Jung, K. Y. Lee., Phys. Rev. D 78, 015022 (2008)

in the LR model

in the 2HD model

Decay of heavy charged Higgs boson

≪ 1

D.-W. Jung, K. Y. Lee., Phys. Rev. D 78, 015022 (2008)

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.

Backup Slides

D0 collaboration, PRL 100, 031804 (2008)

2 22 ( ) ( ) ( ) ( )

2 ( ) ( ) 1 cos

T T T T T

T T

M p e p p e p

p e p

Transverse mass

Edges of transverse mass distribution are crucially related to the mass of W’.

Trigger system for the charged Higgs at the LHC