Charged higgs bosons in exotic models
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CHARGED HIGGS BOSONS IN ’EXOTIC’ MODELS. Katri Huitu Department of Physical Sciences, HU and Helsinki Institute of Physics. Outline:. Introduction General 2HDMs R-parity violating models Fermiophobic Higgses Models with Higgs triplets:. Introduction

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Charged higgs bosons in exotic models


Katri HuituDepartment of Physical Sciences, HUandHelsinki Institute of Physics



General 2HDMs

R-parity violating models

Fermiophobic Higgses

Models with Higgs triplets:

Uppsala / Katri Huitu


The dynamics of the electroweak symmetry breaking is not understood in the Standard Model:Higgs boson mass is unstable in radiative corrections

In extensions of the SM scalar sector:* better gauge coupling unification – with scale large enough to be consistent with proton decay;* neutrino mass (seesaw, R-parity breaking)* in cosmology electroweak phase transition may become possible;* one typically gets charged Higgs bosons

Extensions with doublets:

Two Higgs Doublet Model (2HDM), Minimal Supersymmetric Standard Model (MSSM), R-parity violating MSSM, Fermiophobic model …

Extensions with triplets:

Fermiophobic model, Left-right model, Georgi-Machachek model …

Uppsala / Katri Huitu

Electroweak rparameter is experimentally close to 1

constraints on Higgs representations

r=1 (2T+1)2-3Y2=1.

Thus doublets can be added without problems with r.

For the other representations, one has to finetune the VEVs to produce r=1. This may be motivated from other considerations.

Uppsala / Katri Huitu

Other consequences of exotic representations:

Coupling HiZZ receives contribution from any nonsinglet VEV (note that both Higgsstrahlung and gauge boson fusion need this coupling!).Parametrize:

Sum rule for ci:

Choudhury, Datta, KH, NPB 673 (2003) 385.

Uppsala / Katri Huitu

With exotic additional representations of Higgs the doublet VEVs decrease Yukawa couplings increase.

E.g. one Higgs doublet

Measurement of Yukawa coupling constraint on

E.g. top Yukawa coupling

Uppsala / Katri Huitu

Triplet Higgses: real or complex VEVs decrease Yukawa couplings increase.- both representations needed if r=1: real increases r, while complex decreases.

Choudhury, Datta, KH, NPB 673 (2003) 385.

Uppsala / Katri Huitu

b VEVs decrease Yukawa couplings increase. sg

Several contributions in MSSM:

W – top loopH+ - top loopc- - up type quark loopgluino – down type squark loopc0 – down type squark loop

Constructive interference

Constructive or destructive interference with SM, depending on sign(m)

T. Goto, Y. Okada,Prog.Theor.Phys.Suppl.123:213-220,1996.

Uppsala / Katri Huitu

General 2HDM VEVs decrease Yukawa couplings increase.

The Standard Model with two Higgs doubletsf1 and f2 r=1.

The simplest extension of the SM with charged Higgs bosons.

As in the MSSM five physical Higgs bosons: h, H, A, H

The scalar potential

Hermiticity: li are real

Uppsala / Katri Huitu

Type I VEVs decrease Yukawa couplings increase.: one Higgs doublet provides masses to all quarks (up- and down-type quarks) (~SM).

Type II: one Higgs doublet provides masses for up-type quarks and the other for down-type quarks (~MSSM).

Type III,IV: different doublets provide masses for down type quarks and charged leptons.

  • V. Barger, J.L. Hewett, R.J.N. Phillips, Phys. Rev. D 41, 3421–3441 (1990).

Uppsala / Katri Huitu

The branching ratios can be very different from the SM.

tan b is important for phenomenology!

For processes which depend only on quark sector, models I and IV are similar, as well as models II and III.

Uppsala / Katri Huitu

Couplings H-H-V: VEVs decrease Yukawa couplings increase.

Charged Higgs decay modes if mH+<mW+mh:

Uppsala / Katri Huitu

Branching ratios of charged Higgses in 2HDM model II (MSSM): VEVs decrease Yukawa couplings increase.

M. Carena, H. Haber, Prog.Part.Nucl.Phys.50:63-152,2003.

Note that there is no H+W-Z coupling in 2HDM at tree-level No gauge boson fusion in production at hadron colliders

Uppsala / Katri Huitu

Singly charged Higgs mass limit from LEP: VEVs decrease Yukawa couplings increase.

Assumed decay channels

LEP Higgs working group,LHWG note 2001-05.

Uppsala / Katri Huitu

Limits from bsg in 2HDM



In model II the contribution is always bigger than in the SM, while in model I one can have strong cancellations due to –cot b in the coupling.













THDM II: mH+>(244+63/tan b) GeV


Grinstein, Springer, Wise, NPB 339 (1990) 269.

Uppsala / Katri Huitu

R-parity violating MSSM: VEVs decrease Yukawa couplings increase.

2HDM II with supersymmetric partners included, and no R-parity.

MSSM superpotential:

If R-parity (Rp=(-1)3(B-L)+2s) is not assumed, one should add:

Unless the couplings are very small, proton decays fast if both lepton and baryon number violating couplings are allowed

forbid B violating couplings. The bilinear term mixes lepton and Higgs sectors.

charged Higgses mix with charged sleptons

Uppsala / Katri Huitu

A.G. Akeroyd, M.A. Diaz, J. Ferrandis, M.A. Garcia-Jareno, J.W.F. Valle, Nucl.Phys.B529:3-22,1998

Already at tree-level, mH+ can be lighter than in the MSSM with R-parity;

In the MSSM mH+ > mW

Uppsala / Katri Huitu

Limits from b J.W.F. Valle, Nucl.Phys.B529:3-22,1998 sg in R-parity violating MSSM

Model dependent:- Charged Higgs and chargino loops interact destructively- very heavy squarks chargino loops can be neglected

In the case of R-parity violation:Mixing of charged bosons with staus decrease the bounds


R-parity violating MSSM

Diaz, Torrente-Lujan, Valle, NPB 551 (1999) 78.

Uppsala / Katri Huitu

For light charged Higgses (=charged scalar with strongest coupling to squarks) and charginos

R-parity violating MSSM,

mH+ > 75 GeV


mH+ > 110 GeV

Diaz, Torrente-Lujan, Valle, NPB 551 (1999) 78.

Uppsala / Katri Huitu

Important consequences of R-parity violation: coupling to squarks) and charginos

The LSP is no longer stable, but decays to the Standard Model particles

little or no missing energy in the processes. lots of jets and leptons. sparticles can be produced singly.

Phenomenology depends on the LSP: stau LSP  tn (l-type coupling)  tb (l’-type coupling)  through the Higgs component, if only bilinear couplings

mimics H+

If not LSP, stau decays through stautc0

Uppsala / Katri Huitu

E.g. bilinear R-parity violating branching ratios: coupling to squarks) and charginosH+ may decay through mixing with stau

Akeroyd et al, NPB 529 (1998) 3.

Uppsala / Katri Huitu

Fermiophobic Higgs bosons coupling to squarks) and charginos

Coupling to fermions very suppressed or zero, e.g. 2HDM type I or a triplet model (to be discussed).

Clear signal for Higgs decay h gg or h  VV (V=W,Z)

= cos a / sin b 0 (even if exactly zero, a coupling can arise in radiative corrections)



Production at LHC:

pp  H+/-h, with the decay H+/-  hW*, h gg

Uppsala / Katri Huitu

A.G. Akeroyd, M.A. Diaz, coupling to squarks) and charginosJ. Pacheco, Phys.Rev.D70:075002,2004.

Double h production, h gg

Mcharged Higgs=150 GeV

Uppsala / Katri Huitu

Models with triplet Higgses coupling to squarks) and charginos

The simplest model contains one complex triplet

The minimal Higgs content is

Seesaw mechanism provides masses for neutrinos:

Uppsala / Katri Huitu

Singly charged Higgs is a mixture of doublet and triplet charged Higgs decay modes

Modes common with 2HDMs:

KH,Laitinen,Maalampi, NPB 598 (2001) 13.



Branching ratios different due to the Dll –coupling and tree-level H+W-Z-coupling.


Uppsala / Katri Huitu

A vertex possible at tree-level only in models with larger than doublet presentations.

In a model with triplets, proportional to the triplet VEV.

The coupling comes from the kinetic term:

The vertex is given by

Uppsala / Katri Huitu

A charged Higgs boson can be produced from gauge boson fusion,

High pT jets to the forward and backward directions from the scalar boson;

No color flow in the central region;

Use kinematic cuts to separate signal


E. Asakawa, S. Kanemura, Phys.Lett.B626:111-119,2005.

Uppsala / Katri Huitu

Doubly charged Higgs in triplet models: fusion,

Doubly charged Higgs does not mix with anything and it does not couple to quarks.

Doubly charged Higgs is a clear evidence of triplet representations.

Uppsala / Katri Huitu

M. Kuze, Y.Sirois, fusion,Prog.Part.Nucl.Phys.50:1-62,2003

Doubly charged Higgs mass limit

Uppsala / Katri Huitu

A special case of triplet models is a supersymmetric left-right model, based on

Because of the gauged B-L, the R-parity is exactly conserved, but breaks spontaneously.

The model contains minimally two right-handed triplet Higgses and two bidoublet Higgses.

Typically one doubly charged Higgs is light and decays to leptons.

Uppsala / Katri Huitu

D left-right model, based on++WR+WR+,D+WR+,D+D+


# of events





Discovery limits for D++R at LHC.

Maalampi, Romanenko, Phys.Lett.B532:202-208,2002

Uppsala / Katri Huitu

Summary left-right model, based on

Differences to MSSM:

Coupling(triplet model)

Mass can be lower than in the MSSM

New particles: H++ (triplet model with seesaw)

Branching ratios different: H+nt (2HDM, triplet) H+tc (R-parity violation) H+W*h, hgg (fermiophobic) H+W+Z (triplet)

Uppsala / Katri Huitu