Phenomenology of the Higgs Triplet Model

Testing the custodial symmetry in the Higgs sector of the Georgi-Machacek model at the LHC Kei Yagyu (National Central U)C.-W. Chiang, KY, arXiv: 1211.2658 [hep-ph], to be published in JHEPNational Taiwan University, 17th December 2012Plan of the talkIntroduction - Current status of the Higgs boson search at the LHC

Extended Higgs sectors - Motivation - The Georgi-Machacek model

Phenomenology - Higgs decays - Higgs productions - Simulation study at the LHC - Higgs to and Z decay

Summary

The Higgs-like particle has been found at around 126 GeV at the LHC with 5. Historic Milestone but only the Beginning.

h ZZ* 4 leptonh R. Heuer, July 4th, CERN Current states of the Higgs search at the LHCCurrent states of the Higgs search at the LHCSignal strength (obs/SM) in each modeHadron Collider Physics Symposium 2012, ATLAS

Hadron Collider Physics Symposium 2012, CMS

Current states of the Higgs search at the LHCSignal strength (obs/SM) in each modeHadron Collider Physics Symposium 2012, ATLAS

Hadron Collider Physics Symposium 2012, CMS

H ZZ and H WW modes are good agreement to the SM prediction. Current states of the Higgs search at the LHCSignal strength (obs/SM) in each modeHadron Collider Physics Symposium 2012, ATLAS

Hadron Collider Physics Symposium 2012, CMS

Obs. H signal seems to be large compared to the SM prediction. Current states of the Higgs search at the LHCSignal strength (obs/SM) in each modeHadron Collider Physics Symposium 2012, ATLAS

Hadron Collider Physics Symposium 2012, CMS

H bb and H modes still have a large uncertainty. The SM-like Higgs boson?At present, observed new resonance at 126 GeV looks like the SM-like Higgs boson. (-Consistent with the precision measurements at LEP, - Observed from expected events and ZZ H is spin 0 or 2)Large deviation from the SM prediction in H modeThe central value for the H mode exceeds 0.

We need to collect more data in order to clarify the property of the new particle w/126 GeV.Still there are possibilities to consider non-minimal Higgs sectors! Extended Higgs sectorWhy extended Higgs sector?No principle in the Higgs sector - Negative 2 term Just an assumption - Higgs boson as an elementary scalar. Cause for the quadratic div. in the Higgs mass correction.

Phenomena which cannot be explained in the SM - Neutrino masses - Dark matter - Baryon asymmetry of the Universe Why extended Higgs sector?No principle in the Higgs sector Supersymmetry, Dynamical symmetry breaking, Little Higgs models,

Phenomena which cannot be explained in the SM - Neutrino masses Rad. seesaw models, type-II seesaw mechanism - Dark matter Discrete sym. in the Higgs sector e.g. Inert doublet - Baryon asymmetry of the Universe Electroweak baryogenesisNew physics modelsExtended Higgs sectorO(100) GeVhigher than TeV scalePredictDetermineHow can we know the true Higgs sector?Basic two constraints from experimentsThere are hints to determine the structure of the Higgs sector. 1. Electroweak rho parameter

exp = 1.0008Additional doublets or singlets Additional triplets or higher isospin Reps. tree = 1 In general, tree 1-0.0007+0.00172. Flavor Changing Neutral Current (FCNC)Tree level FCNC processes should be suppressed. Models with multi-doublet structure There appear tree level FCNCs.

Additional doublet(s) FCNC, Additional triplet(s) Rho parameter In this talk, we focus on the possibility that the Higgs sector has triplets. The minimal Higgs Triplet ModelThe Higgs triplet field is added to the SM.

M : Mass of triplet scalar boson. v : VEV of the triplet HiggsCheng, Li (1980); Schechter, Valle, (1980); Magg, Wetterich, (1980);Mohapatra, Senjanovic, (1981).Important new interaction terms:SU(2)IU(1)YU(1)L21/2031-2Lepton number breaking parameterNeutrino mass matrix

O(1)O(0.1) eVO(0.1) eV246 GeVO(100) GeVThe HTM can be tested at colliders !!13The minimal Higgs Triplet ModelThe Higgs triplet field is added to the SM.

M : Mass of triplet scalar boson. v : VEV of the triplet HiggsCheng, Li (1980); Schechter, Valle, (1980); Magg, Wetterich, (1980);Mohapatra, Senjanovic, (1981).Important new interaction terms:SU(2)IU(1)YU(1)L21/2031-2Lepton number breaking parameterNeutrino mass matrix

Non-zero v breaks the custodial symmetry deviates from unity at the tree level.We discuss the extension of the HTM to keep the custodial symmetry. 14The Georgi-Machacek (GM) Model Two isospin triplet Higgs fields are introduced to the SM.SU(2)IU(1)YU(1)L21/2031-2200 The doublet field and the triplet fields can be expressed as SU(2)LSU(2)R form:

If we take two triplet VEVs are the same: =

The minimal extension of the HTM. HTMGMSU(2)L SU(2)R SU(2)V (Custodial Symmetry)SU(2)RSU(2)L

Georgi, Machacek (1985)Decomposition : 2 2 : 3 3Irreducible decomposition5 + 3 + 13 + 15-plet Higgs

h, H1Mixing (angle ) : SM-like Higgs + Singlet Higgs

Mixing (angle ): Goldston bosons + 3-plet HiggsThe Higgs bosons belonging to the same multiplet are degenerate in mass because of the custodial symmetry. Interactions(Usual) Yukawa interactionGauge interactionffH3tancos/cos, sin/cos sinh, H1 cos*cos, cos*sin(Neutrino) Yukawa interactionffh, H1H5VVVV l lH3 l l H5 l lh, H11/sincos/sincos/sinHiggs potential

The most general SU(2)LSU(2)R invariant potential: There are 9 parameters in the potential: [m1, m2, 1, 2 : dimension full, 1 5 : dimension less]

2 VEVs : v, v, 4 masses : mH5, mH3, mH1, mh, 1 mixing angle : and reminding 2 parameters: 1, 2.

P18Decoupling limit

The mass formulae ( = 0)

In the limit of v 0 ( 0, M22 0) Triplet-like Higgs bosons are decoupled when M12 is taken to be large values.

There is a relationship among the masses:

Consequences of the custodial sym.1. Electroweak rho parameter is unity at the tree level Triplet VEV can be taken to be O(10) GeV. 2. Mass degeneracies among 5- and 3-plet Higgs bosons; mH5++ = mH5+ = mH50 = mH5, mH3+ = mH30 = mH33. Specific interactions; 5-plet Higgs can couple to gauge boson pairs. 3-plet Higgs can couple to fermion pairs .We focus on the features 2 and 3 in order to identify the custodial symmetric GM model at the LHC. PhenomenologyDecay of the 5-plet Higgs bosons

H5++H5+H50m = mH3 mH5The case of m > 0 is the same as the case of m=0. mH3 = 150 GeV, m > 0 Decay of the 3-plet Higgs bosons

m > 0 m < 0 mH3 = 150 GeV4 regions on the v m planeDecays of the triplet-like Higgs bosons can be classified into 4 distinctive regions depending on the v and m.

4 regions on the v m planeRegion I: small v and small m5-plet Higgs decays3-plet Higgs decays l l H5 llH34 regions on the v m planeRegion III: small v and large m

l l H55-plet Higgs decays VH5H33-plet Higgs decays VH3H5 VH3H14 regions on the v m planeRegion IV: large v and large m

5-plet Higgs decays VH5H33-plet Higgs decaysH5VV VH3H5 VH3H14 regions on the v m plane

Region II: large v and small mH5VV5-plet Higgs decays3-plet Higgs decaysffH3We discuss the phenomenology for Region II.

Production modes for 5- and 3-plet Higgs 1. Drell-Yan Process: 2. Mixed Drell-Yan Process:3. Vector boson fusion Process4. Gauge boson associate Process5. Yukawa Process

H5H3H5 , H3

H5, H3

VH5H5Both 5-plet3-plet

H3+H30, H3+, tH30

Production modes for 5- and 3-plet Higgs 1. Drell-Yan Process: 2. Mixed Drell-Yan Process:3. Vector boson fusion Process4. Gauge boson associate Process5. Yukawa Process

H5H3H5 , H3

VH5H5H3+H30, H3+, tBoth 5-plet3-pletH30H5, H3Production cross sections

H5++H5+H50Production cross sections

H5++H5+H50VBFProduction cross sections

H5++H5+H50VBFAssociatedProduction cross sections

H5++H5+H50Mixed DYStrategyThe VBF and associated processes

H5

H5V2 forward jets taggingThe mass degeneracy of the 5-plet may be tested. H5+ and H50 may be detected. Transverse mass cut + b-jet veto H5++ may be detected. Transverse mass cutThe mass degeneracy of the 3-plet may be tested. The mixed DY process

H5H3ScenariomH3 = 150 GeV, mH5 = 140 GeV, v = 20 GeV, = 0 Concrete example for Region II

Branching fractions: BR(H5VV) ~ 100 %, BR(H3+ cs) ~ 30%, BR(H3+ ) ~ 70%, BR(H30 bb) ~ 90%

We perform the signal & background analysis by using MadGraph5 with the parton level.

We consider the hadronic decay of the 3-plet Higgs bosons5-plet Higgs reconstructionsSignalBackgroundpp W+W+jj, pp W+Z jj, pp W+W- / ZZ jj , tt

We use the VBF and associated production processes. distributions

Difference of the pseudo-rapidity: distributions

Difference of the pseudo-rapidity: > 3.5, ( > 4.0 for event)

MT distributions

Transverse mass:

MT distributions

Transverse mass:

50 GeV < MT < 150 GeVSignal and background events(int. luminosity 100 fb-1)

b-jet tagging efficiency: 0.63-plet Higgs reconstructions

We use the mixed DY production processes. 5-plet Higgs bosons diboson decay, 3-plet Higgs bosons dijet decay

Distributions in the mixed DY process

The cut cannot be applied to the mixed DY process, while the MT cut can be used. Signal and background events(int. luminosity 100 fb-1)

After taking the same MT cut, the signal significance can exceed 5 in both the events. Mjj distributions

The masses of H3+ and H30 may be measured by the peak in the dijet invariant mass distribution. The dijet invariant mass distribution after taking the MT cut:

Higgs decays into and Z

RRZ+

Higgs to and Z decay

Current LHC data of h mode can be explained when mH5