3.Phenomenology of Two Higgs Doublet Models

Charged Higgs Bosons

• One of the most important features of all 2 HDMs is existence of

charged Higgs scalars • Yukawa couplings associated with

Singly charged Higgs mass limit from LEP:

Assumed decay channels

,H cs

78.6Hm GeV

LEP Higgs working group,LHWG note 2001-05.

• Yukawa interactions of charged Higgs can affect various decays and mixing associated with flavors

• For large type I is fermiophobic, type X is leptophilic which could lead to a huge branching ratio for

• Those models are not constrained by rare B decays. • Large contributions to rare B decays are possible in type II,

Y should be constrained by experimental results of rare B decays

Constraints from Flavor Physics

Barger/Hewett/Phillips, 1990

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.

𝐻±→𝜏±𝜈

• Type II (Y) model

- the couplings of charged Higgs to t-quark and b-quark are

or

- potentially large virtual effects in b-quark decays and mixing.

- A very strong bound on come from studies of

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.

𝐵→𝑋 𝑠𝛾

V

Full NLO QCD results

Uncertainty range of theoretical predictions (Ciuchini et al, 1998) issuch that mH+>250-300 or so GeV is required in type II

• Other sever constraint for type II model :

- : not a loop process but proceeds through tree-level virtual

exchange.

- severe constraints at large .

¿1.13±0.05

2006 ICHEP

Crivelli et al.arXiv:1303.5877

Bounds for type II model

(Haisch ‘08)

Solid line : from

Bounds for type I model

(Branco et.al ‘11)

dashed line : from

Productions of Charged Higgs• Light charged Higgs :

Top decay can produce light charged Higgs : t Hb

Constrained by (Tevatron)

• Production of light charged Higgs at the LHC :

BR(tH±b)~mtop2 cot2β+mb

2 tan2β

108 top quarks producedMore than 105 charged Higgs ex-pected

• Heavy charged Higgs production at the LHC

dominant channel :

Via gluon fusion, ggtbH+

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

Search for light charged Higgs at the LHC

• Via decay channels - for light charged Higgs below top mass :~100 %

H± decay BR. into different final states for tan = 20

H+ Decay W Decay

,had qq

,had l

, lep qq

Discovery potential

CMS Note 2006/056

Search for heavy charged Higgs at the LHC

• Above top mass: - BR(H+tb)~0.8-1 - H+tb results in complex final states :3 or 4 b jets

• Crucial to supress very large kinematically similar ttbar+jets background

H+ Decay W Decay

,had qq

tb l & qq

xBR (pb)Channels of interest:

Discovery potential

with systematics

without systematics Background: FAST simul.

without systematics

ATLAS CMS

systematics included Background: Full simul.

- promising channel for heavy charged Higgs

Search for neutral Higgs

Mass spectrumsFor MA> 150 GeV (decoupling

limit)The heavy MSSM Higgs:MA≈ MH ≈MH

±

Sven HeinemeyerAtlas meeting 29.01.2008

Pythia 6.226 FeynHiggs2.2

S.G, H.Bilokon,V.Chiarella,G.NicolettiATL-PHYS-PUB-2007-001

For MA< 135 GeV (Mhmax scenario)

The ligth Higgs is SM-like

MA≈ Mh

Pythia 6.226

Production of neutral Higgses

• Main production mechanism ~SM• For high and moderate tanb the production with b quarks is enhanced• For mA >>mZ A/H behave very similar →decoupling region• A, H, H± cross section ~tanb2

V*=W/Z

Production Cross Section

=h,H,A

Abdelhak Djouadi arXiv:hep-ph/0503173v2 (2005)

• At small tanb gg→h,H,A dominant• Vector boson fusion process pp→qq→qq+WW/ZZ→qq+h/H important at m h ~ m hmax

• Higgsstrahlung neglegible

• At high tanb associated b quarks production dominates pp → bb →h/H/A+ bb

Branching Ratio for Neutral Higgs Decays

Production rate

• Decay bb dominates, tt lower background weaker sensitivy on SUSY parameters

2),,( fmAHh

• Decoupling region MA≥ 150 GeV tanb ≈30or MA≥ 400-500 GeV tanb=3

Abdelhak Djouadi arXiv:hep-ph/0503173v2 (2005)

Branching Ratio for Neutral Higgs Decays

•Decay bb, tt dominates•Decay mm possible

•Intense coupling region tanb ≈30 MA~ 120-140 GeV Coupling to W,Z up quarks suppressedCoupling down quark (b) and t enhanced

Abdelhak Djouadi arXiv:hep-ph/0503173v2 (2005)

Discovery Potential Signal cross section uncertainties 17% Systematic experimental uncertainties based on detector expected performances:e.g. muon efficiency, muon PT scale, muon resolution, Jet energy scale, Jet energy resolution, btag efficiency, b-tagging fake rate. Based on detector expected performance 10-20%Large systematic uncertainties demand for data-driven method background estimation

Combined 0-b-jet and 1 b-jet analysispreliminary preliminary

Pair ProductionsTrilinear coupling can be large for Heavy Higgs

(Robert N. Hodgkinson )

Pair Productions``Feasibility study of Higgs pair creation in gamma-gamma collider’’ (Norizumi Maeda )

For measuring Higgs self coupling

Higgs mass =125 GeV

Optimized photon collision E = 270 GeV

(BR=0.43)

Project I1. Let us consider an SU(2) gauge theory with scalar fields that

make up the triplet representation as follows:

In the theory, we require invariance under the gauge transform :

=exp) , where the exponential factor is a 3x3 matrix,

and the operator generates isospin rotations about axis and

satisfies SU(2) algebra (explicitly,

Project IAs usual, the covariant derivative takes the form In this theory, SU(2) gauge symmetry is spontaneously broken , and the vacuum is given by .The scalar potential of the theory is given by +We can shift the scalar fields and expand about the minimum configuration by using

Φ=𝑒𝑥𝑝[ 𝑖𝑣 (𝜁1𝑇1+𝜁2𝑇2)]( 00

𝑣+𝜂)

Project I(a) Show that becomes a massive Higgs scalar.(b) Obtain the mass of .(c) Show that the would-be Goldstone bosons disappear entirely.(d) Show that the vector bosons corresponding to the (broken symmetry) generators and acquire a common mass (e) Show that the gauge boson remains massless and explain why? (Hint, Exploit the gauge invariance by transforming to unitary gauge.)

Project IIFor the scalar potential of two Higgs doublet models given by

(a)Derive the minimization conditions of V (taking .(b)Show that would-be Goldstones (three) are eaten by gauge

bosons (i.e. disappear).(c)Obtain masses of 5 Higgs bosons (2 neutral CP even, 2

charged and a CP-odd).