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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).