Supersymmetric Models with 125 GeV Higgs
Masahiro Yamaguchi(Tohoku University)
17th Lomonosov Conference on Elementary Particle Physics
Moscow State University, 20-26 August, 2015
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Higgs BosonHiggs Boson Mass
LHC combined 125.09±0.21(stat. )±0.11(syst. ) GeV
Signal Strength for Decay Modes CMS combined 1.00±0.14 ATLAS combined 1.18±0.15 consistent with SM prediction still some room to play with (room for BSM)
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Motivations for Supersymmetry• Unnaturalness of Higgs Sector: – gauge hierarchy problem/naturalness problem
• Unification of forces: Grand unification
• Muon g-2: possible deviation from SM
• Call for Beyond SM– Neutrino masses and mixings– Cosmology Connection
• Dark Matter, Baryogenesis, Dark Energy, Inflation
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SUSY Search
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Higgs Mass in MSSMIn MSSM SUSY Higgs Self Coupling = gauge coupling mh < mZ @tree level (SUSY relation)
Large SUSY breaking loop effect can raise the Higgs mass stop-top loops 1) large log mstop/mtop
2) finite A-term(stop-stop-Higgs coupling) contribution
Inoue et al ‘85
Okada, MY, Yanagida ’91Haber, HempflingEllis, Ridolfi, Zwirner
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Higgs Mass @3-loop
Hahn, Heinemeyer,Hollik, Rzehak, Weiglein,2014
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Challenge to Low Energy SUSY?To achieve the observed Higgs mass (125 GeV), we need either1)Heavy stop ( ～ 7TeV) and/or large stop mixing in MSSMor2) Addition of new source of Higgs mass at TeV scale e.g. Vector-like Generation (T+Tbar) Additional Gauge Sym. (eg. U(1)B-Lsym.)
Singlet Extension 7
Singlet Extensions
New Sources to increase Higgs Mass1)tree-level coupling (significant only for small tan )
2)Higgs/Higgsino loop (>0, for heavy singlet boson)
3) Doublet-Singlet Mixing (>0, for light singlet boson) If singlet boson is light, mixing increases doublet Higgs mass.
Jeong, Shoji & MY ‘11, ‘12, ’14Choi, Im, Jeong & MY ‘12
2 |HuHd|2 : new contribution to the Higgs potential
superpotential
New coupling: Higgs-Higgsino-Singlino
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Doublet-Singlet Mixingin CP even Higgs sector
Mixing terms in Scalar Sector
Mass^2 matirx for doublet and singlet Higgses
Mass eigenstates: three mixing angles
θ2: mixing between h and s9
Relations
Constraint on mixing upperbound on higgsino mass parameter (see below.)
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Coupling of SM-like Higgs boson
with from top-stop sector
Chargino loop
Mixings with singlet and with heavier doublet Change of SM-like Higgs coupling
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LHC Constraints on Higgs mixing
• Signal Strength (relative to SM expectation)
• With Singlet Experimental Constraints
2014 Summer
Mainly ggF Mainly VBF
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Experimental ConstraintsMixings compatible with LHC data within 1sigma(2 sigma)
ATLAS
CMS
tan =5 10 15
θ2: mixing between h and sCb 1 ̴� Cb -1 ̴�
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LEP Constraint on Singlet-like Higgs s
e+e- Z s Z bb
LEP constaint is not severe if singlet is heavier than 90 GeV.
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Contours of Higgsino mass parameter tan =5 tan = 10
Approximate Higgsino mass parameter: obtained from the previous relations
yellow: no solution to 125 GeV HiggsWhite: λ >1 (Landau pole)Cyan: μ ̴ <100 GeV (excluded)
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Summary so far:
Doublet-Singlet Mixing in NMSSM
1) realizes m_h=125 GeV by the mixing 2) satisfies LEP constraint on singlet s 3) is compatible with LHC Higgs data 4) favors Relatively Light Higgsino
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Comment on heavy stop case in MSSMCase of Non Universal Higgs Model (NUHM)
A slice of allowed parameter regions (at GUT scale)
In the bulk, all superparticles are heavy >> LHC reachBut near boundary, some of superparticles become light, accessible at LHCPrice: severe fine tuning of parameters
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Case of NUHM
Interesting cases light stop (only one of two stops) light first two generation squarks light Higgsinos light pseudoscalar A light sleptons with muon g-2 within 1 sigma
MY & Yin, in preparation
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Conclusions• 125GeV Higgs appears a challenge to low energy SUSY.
• MSSM: Heavy Stop (>>LHC bound)– Possible to have some light superparticles even in this case (explicit demonstration in NUHM)
• Alternatives to MSSM– New vector-like generation– Gauge symmetry– Singlet richer Higgs sector & neutralino sector
Rich phenomenology expected at LHC RUN2 in either caseStay tuned!
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Thank you very much!
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