Property of 125 GeV Higgs Boson from LHC Data Seminar at Academia Sinica 07/04/2012 Muneyuki Ishida 石田宗之

Higgs Boson Particle producing fermion masses. Electro-weak symmetry breaking. The only particle not yet discovered in Standard Model. Interaction of the Higgs sector, not yet tested. Discovering Higgs is the first priority at LHC. 4PM Today(Taiwan time), Public announcement at CERN on the Latest data of Higgs!

gg: gluon fusion : dominant top quark triangle + bottom quark triangle VV: (qq-> qqh) Vector boson fusion : clear signal tree-level coupling in SM V->Vh(qq->V h) Higgs strahlung Higgs Production Mechanism

The previous data 126 GeV by ATLAS 125 GeV by CMS Diphoton enhancement gg-fusion (γγ ｊｊ event) VV- fusion

Basic Formula of Collider Physics

At 125 GeV BF(hSM) is predicted as bb ττ WW* ZZ* gg cc γγ Zγ BF(%) Direct method : changing the γγ coupling : basically hSM : New particles contribute to the loop. Indirect method: reducing or Switching off bb and ττ channel -> 3 times enhamcement compared with hSM hSM has tree-level coupling to bb producing mb. New Higgs is considered.

R = 0.58γ bb +0.06γ ττ +0.24γ VV +0.09γ gg = Γ h tot /Γ SM h tot (Γ SM h tot =4.07MeV)  Total Width of the 125 GeV Higgs

Determation of total width of 125GeV Higgs

γγ Enhancement SUSY : MSSM (previous works) Stop loop : scalar Chargino loop: No color γγ Ratio generally does not deviate much from unity. (NMSSM is different) UED KK modes of W,q,l γγ Ratio : 50% enhancement at most.  Very difficult to obtain gγ > 2 (ATLAS 126GeV Higgs)

Direct method to get γγ Enhancement Production and decay mechanism of h SM gg-fusion g g t h h W t t W W γ γ h t t t γ γ

Mechanism of Higgs Production/Decay gg-fusion  γγ No Tree-level couplings to Higgs If Exotic heavy particles contribute to loop  the effective couplings deviate from SM prediction. If mass of the exotic is produced by Higgs mechanism, its contrib. does not become small when the exotic is super heavy. 4th generation search VBF (VV-fusion)  γγ Big tree-level coupling : Effect from the exotics is small. W,Z h 2m W 2 /v 2m Z 2 /v

g, γ γ γ Exotics X = f, S fermion or Scalar

Ratio of the couplings

The case that exotic masses are produced not from the Higgs λ f = Y f v/m f λ S =Y S v/2m S 2 -1< λ f,S < 1 : We take this region as allowed. λ f,S = 1 corresponds to Higgs mechanism. Vγ （ =Ratio of σ(VV  h  γγ) to that of h SM ） >2 gγ （ =Ratio of σ(gg  h  γγ) to that of h SM ） >1 gV （ =Ratio of σ(gg  h  VV) to that of h SM ） <1 Searching for the solution satisfying this cond.

S8 : Exotic Scalar Color 8 Qs=1 No Solution F8 : Exotic fermion Color 8 Qf=1 There is a Solution ！ Leptogluon (it can decay to lepton + gluon)

No Go Theorem By using the direct method,(where we keep tree-level h SM couplings,) it is very difficult to reproduce Vγ>2, gγ>1 The only solutions with Q f <1 Ｆ８（ or Ｆ６） higher color representation: more steep. Scalar : length of lines becomes ¼. X-axis scales with Q 2.

Indirect method It is very difficult to obtain γγ enhancement by direct method where tree-level couplings are taken to be the same values as h SM. ghtt=gh SM tt, ghbb=gh SM bb, ghWW=gh SM WW No Go Theorem  Tree-level couplings must be changed! This line is studied in detail by a very recent work by J. Chang, K. Cheung, P.-Y.Tseng, T.C.Yuan arXiv: [hep-ph]

2Higgs Doublet Model of type II or MSSM

h,H,A and H + NG-boson : Eaten ↓ by Z-boson

The ratios of the h couplings to h SM W top bottom top bottom : bottom contirib. is significant when tan β ~ 10

XC : Cross section Ratios to h SM ↙ Γ h,tot / Γ hSM, tot Diphoton cross sections relative to h SM is sharply enhanced and reach maximum 3 at α = 0. bb, ττ strongly suppressed at α = 0.  Γγγ Enhamcement by Indirect mechanism ( reduction of total width)

ττ suppression

FT model with α ＝０ and 0.06 Γ h, tot = 1.5 MeV : FT model Higgs(α=0) Γ hSM, tot = 4.07 MeV  Diphoton enhancement is explained by the reduction of total width. Tevatron bb: less than 3 sigma significance

No h  bb and No h  ττ at present No Higgs in bb channel by ATLAS in Higgs strahlung : ZH -> ℓ+ℓ−b¯b, WH -> ℓνb¯b and ZH -> ν¯νb¯ b 110 < mH < 130 GeV 4.6 – 4.7 fb−1 at 7 TeV, No significant excess of events above the background. ATLAS No h  ττ arXiv: [hep-ex]. CMS No h  ττ arXiv: [hep-ex]. Consistent with our picture. What today?

Flavor tuning of the mixing angle α in MSSM

Reproducing Higgs mass

3-loop calculation by H3m package, implemented by the above formula.

M H12 2 = 0 Requires a very severe constraint on pseudoscalar mass m A. mH 2 = m A 2 + M Z 2 s 2β 2 mH +2 = m A 2 + M W 2 μ=M SUSY, X t = -2M SUSY case tan β mA mH mH+ 45 3MZ/2 164GeV 159GeV  already excluded. 28 MZ 129GeV 122GeV 14 MZ/2 102GeV 92GeV All these SUSY Higgs bosons should have masses comparable to mh.

LHC gg  A  bb,ττ Enhanced compared with Standard model in large tanβ LEPII pair production of H+ H- Very severe constraint already. Will soon be probed by LHC.

Cross section Ratio XC of H, A Vτ Vb gτ gγ gW gZ Vγ H A gτ is sensitive to tanβ proportional to (tanβ) 2 Discovery of H,A by this channel  tanβ determined at the same time.

Decay Branching Fraction of H,A bb ττ gg γγ WW* ZZ* H 91% A dominantly decays to bb. H+ decays to τν and cs

t  H + b

BF(t  Hb ) < 0.01 (0.05) for m H + =125(90) GeV  5 < tanβ < 11 (3 < tanβ < 21) Light H + is still viable. (m H + >78.6 GeV at LEP).

Concluding Remarks Enhancement of the diphoton cross section is explained by the flavor-tuned(FT) model, h = Hu0 Maximum : 3 in the case of no mixing α = 0 Enhancement is explained by the reduction of the b¯b decay width compared to hSM.  reduction of the h to τ τ signal. The vanishing of the neutral Higgs mixing angle α requires that the masses of SUSY Higgs bosons MH, MA and MH+ are the electroweak scale. Their production and decays are unambiguously predicted by the FT model.  They can be probed by the LHC experiments. In reality, the value of α should not be precisely zero.  a cancellation of tree-level and radiative corrections in the MH 12. branching fractions could be shifted somewhat with non-zero but small α. If one of the neutral SUSY Higgs bosons has a mass similar to that of the h-boson, there may be confusion in separating the signals. The allowed “sweet-spot” for a A-boson of mass about mh is tanβ = 5-10.