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Higgs decays to γγ and Zγ in models with Higgs extensions

Higgs decays to γγ and Zγ in models with Higgs extensions. Kei Yagyu (National Central U .). Collaboration with Cheng-Wei Chiang ( National Central U.). arXiv : 1207.1065 [ hep -ph ]. Academia Sinica , September 14 th. Plan of Talk. Introduction - SM Higgs sector

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Higgs decays to γγ and Zγ in models with Higgs extensions

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  1. Higgs decays to γγ and Zγ in models with Higgs extensions Kei Yagyu (National Central U.) Collaboration with Cheng-Wei Chiang (National Central U.) arXiv: 1207.1065 [hep-ph] Academia Sinica, September14th

  2. Plan of Talk • Introduction - SM Higgs sector - Current states of the Higgs search at LHC • Extended Higgs sectors • Higgs decays into γγ and Zγ • Summary

  3. Higgs, 希格斯, ヒッグス • God particle? - Trigger the electroweak symmetry breaking - The Higgs VEV: Unique mass scale (Excepted for ΛQCD) - Origin of Mass: Gauge bosons → Higgs mechanism Quarks & Leptons → Yukawa interaction The “God” really has been discovered at the LHC ??

  4. Higgs sector in the SM V(φ) Higgs potential Φ: isospin SU(2)scalar doublet Higgs VEV φ0 φ+ V SU(2)L×U(1)Y → U(1)EM Physical state: Only one neutral component h Origin of Mass V <F> Fermion mass Higgs mass Gauge boson mass f + f F <F> g2 y λ <F> f 0 <F> F <F> F = f mh2 = λv2 mV2 = g2v2 mf = y v All the masses of particles are given by the Higgs VEV.

  5. Higgs sector in the SM V(φ) Higgs potential Φ: isospin SU(2)scalar doublet Higgs VEV φ0 φ+ V SU(2)L×U(1)Y → U(1)EM Physical state: Only one neutral component h Higgs Interaction V F Yukawa interaction Self interaction Gauge interaction f + f F F g2 y λ F f 0 F F F F = f ∝ mh2/v2 ∝ mV2 / v2 ∝ mf / v All the Higgs interactions are proportional to the mass

  6. Higgs search at collider experiments X e+e- (LEP, ILC), pp (Tevatron), pp (LHC),… ・ ・ ・ Higgs boson Production Decay Beam Detector Depends on Detector performance, … Collision particle, Center of mass energy, … Theory (Model) Theory (Model) We should know the production and decay property of the Higgs boson.

  7. Branching fraction γ, g h f W+, Z γ, g h h f W-, Z ‣bb mode: Large branching ratio, but huge background ‣γγ, ZZ(*)→ 4 lepton mode: Tiny branching ratio, but small background

  8. Higgs boson production at the LHC Gluon Fusion ~ 10 pb W/Z association V. Sharma, talk at Moriond (2011) Vector Boson Fusion ~ 1 pb Top quark association

  9. Current states of the Higgs search at the LHC ‣The Higgs-like particle has been found at around 126 GeV at the LHC with 5σ. h → γγ h → ZZ* → 4 lepton Historic Milestone but only the Beginning. R. Heuer, July 4th, CERN

  10. Current states of the Higgs search at the LHC Signal strength (σobs/σSM) in each mode 1207.7235 [hep-ex], ATLAS 1207.7214 [hep-ex], CMS

  11. Current states of the Higgs search at the LHC Signal strength (σobs/σSM) in each mode 1207.7235 [hep-ex], ATLAS 1207.7214 [hep-ex], CMS H → ZZ and H→ WW modes are good agreement to the SM prediction.

  12. Current states of the Higgs search at the LHC Signal strength (σobs/σSM) in each mode 1207.7235 [hep-ex], ATLAS 1207.7214 [hep-ex], CMS Obs. H → γγ signal seems to be large compared to the SM prediction.

  13. Current states of the Higgs search at the LHC Signal strength (σobs/σSM) in each mode 1207.7235 [hep-ex], ATLAS 1207.7214 [hep-ex], CMS H → ττ and H → bb modes have large uncertainty. At CMS, H → ττmode did not seem to be discovered yet.

  14. SM-like Higgs boson? • At present, observed new resonance at 126 GeVlooks like the SM-like Higgs boson. (-Consistent with the precision measurements at LEP, - Observed from expected events γγ and ZZ → H is spin 0 or 2) • Large deviation from the SM in H→γγ mode • No observation from H→ττ mode 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!

  15. Extended Higgs sector

  16. Explanation by extended Higgs sectors • Tiny neutrino masses - The type II seesaw model - Radiative seesaw models (e.g. Zee model) • Dark matter - Higgs sector with an unbroken discrete symmetry • Baryon asymmetry of the Universe - Electroweak baryogenesis Introduced extended Higgs sectors SU(2) doublet Higgs + Singlets, Doublets and Triplets, … Beyond the SM Extended Higgs sectors Determine

  17. What is the true Higgs sector? There are hints to determine the structure of the Higgs sector. +0.0017 1. Electroweak rho parameter ρexp =1.0008 -0.0007 Additional Doublets or Singlets Additional Triplets or Higher isospin reps. →ρtree= 1 →In general, ρtree≠1 Small triplet VEV or Custodial sym. (Georgi-Machacek model) 2. Flavor Changing Neutral Current(FCNC) Tree level FCNC process should be suppressed. Extension of Multi-doublets → In general, there appears the FCNC at the tree level. A discrete Z2 symmetry is often imposed to avoid the tree level FCNC. Glashow, Weinberg

  18. Testing an extended Higgs sector at colliders • Direct way：Discovery of extra Higgs bosons Ex. Charged Higgs boson, CP-odd Higgs boson, … • Indirect way: Precise measurement for the Higgs couplings Ex. hhh, hff, hVV

  19. Testing an extended Higgs sector at colliders • Direct way：Discovery of extra Higgs bosons Ex. Charged Higgs boson, CP-odd Higgs boson, … • Indirect way: Precise measurement for the Higgs couplings Ex. hhh, hff, hVV We discuss the 2 Higgs doublet model and the Higgs triplet model as important examples.

  20. Two Important examples • 2 Higgs Doublet Model (2HDM) - Many new physics models deduce the 2HDM. ex. MSSM, Dynamical Sym. breaking models, Radiative seesaw models, and so on. - Source of the CP-violation • Higgs Triplet Model (HTM) - Tiny neutrino masses can be generated via the type-II seesaw mechanism. Cheng, Li(1980); Schechter, Valle, (1980); Magg, Wetterich, (1980); Mohapatra, Senjanovic, (1981).

  21. Higgs potential in the 2HDM The Higgs potential under the softly broken Z2 sym. (Φ1 → + Φ1, Φ2 → -Φ2) Physical scalar states: 8-3 = 5 Goldstone bosons Tanβ = v2/v1 CP-even Higgs Charged Higgs CP-odd Higgs Mass formulae (sin(β-α) ~1 ) SM-like Higgs boson Extra Higgs bosons

  22. W－ H－ γ γ b t s s b t Φ２ Φ２ Φ１ u u e e d d Φ２ Φ２ Φ１ u u e e d d Φ１ Four types of the Yukawa interaction Imposing Z2 symmetry →　Only one of the two doublet couples to each fermion. Bs→ sγ • Barger, Hewett, Phillips PRD 41 (1990) • Grossman NPB 426 (1994) Type-I Type-II (MSSM) Aoki, Kanemura, Tsumura, Yagyu, PRD 80, 2009 Type-X Type-Y In the Type-I and Type-X 2HDM, a light charged Higgs boson can be allowed.

  23. CP-odd Higgs (A) decay in the case withsin(β-α) = 1, mA = mH=150 GeV Type X Type II (MSSM-like) (μ+) (μ-) Kanemura, Tsumura, Yokoya, PRD 85 (2012)

  24. Higgs potential in the HTM The Higgs potential Physical scalar states: 10 -3 = 7 Case I (λ5 >0) Case II (λ5<0) Doubly-charged Higgs NG bosons Mass2 Mass2 H++ A, H CP-odd Higgs CP-even Higgs Singly-charged Higgs Mass formulae (vΔ/vφ << 1 ) H+ H+ Triplet-like H++ A, H SM-like

  25. Branching ratio of H++ With mass splitting (mH++ - mH+ = 10 GeV) Without mass splitting Phenomenology with the mass splitting is drastically different from that without the mass splitting

  26. Mass reconstruction vΔ = 10-2 GeV Aoki, Kanemura, KY, PRD85(2012) qq’ → H+H → (l+νbb)(bb) qq → HA → (bb)(bb) qq’ → H++H-→ (l+l+ννbb)(jjbb) MT, Minv MT MT 130 fb 42 fb 33 fb 12 fb H++ 8.0 fb (14 TeV) 2.8 fb (7 TeV) 140 GeV Signal only H+ 130 GeV 119 GeV H, A 114 GeV h mH++ mH+ mH, mA All the masses of the Δ-like scalar bosons may be reconstructed.

  27. Higgs decays into the γγ and Zγ

  28. Testing an extended Higgs sector at colliders • Direct way：Discovery of extra Higgs bosons Ex. Charged Higgs boson, CP-odd Higgs boson, … • Indirect way: Precise measurement for the Higgs couplings Ex. hhh, hff, hVV We discuss Higgs decays into the diphoton (hγγ) and the Z + photon (hZγ).

  29. Higgs to the diphoton channel ATLAS, ICHEP CMS, ICHEP The signal strength σOBS/σSM exceeds 1 at the both experiments: 1.56± 0.43 (CMS), 1.9±0.5 (ATLAS). ‣ If this excess is really established, it must be explained by effects of new physics beyond the SM! We focus on new physics effects to the H → γγ and H → Zγ modes.

  30. h → γγ and h → Zγ decays in the SM ‣The hγγ and hγZverteces are induced at the 1-loop level. Top quark loop contribution W boson loop contribution (Z) (Z) ‣Decay rate Ellis, Gaillard, Nanopoulos, (1976) ; Ioffe, Khoze, (1978); Shifman, Vainshtein, Voloshin, Zakharov, (1979) Cahn, Chanowitz, Fleishon, (1979); Bergstrom, Hulth, (1985)

  31. h → γγ and h → Zγ decays in the SM ‣The hγγ and hγZverteces are induced at the 1-loop level. Top quark loop contribution W boson loop contribution (Z) (Z) ‣Decay rate Ellis, Gaillard, Nanopoulos, (1976) ; Ioffe, Khoze, (1978); Shifman, Vainshtein, Voloshin, Zakharov, (1979) Cahn, Chanowitz, Fleishon, (1979); Bergstrom, Hulth, (1985) ‣Input parameters: mh = 126 GeV, mt = 173 GeV W and top loop effects are destructive with each other.

  32. h → γγ and h → Zγ decays in the SM ‣The hγγ and hγZverteces are induced at the 1-loop level. Top quark loop contribution W boson loop contribution (Z) (Z) ‣Decay rate Ellis, Gaillard, Nanopoulos, (1976) ; Ioffe, Khoze, (1978); Shifman, Vainshtein, Voloshin, Zakharov, (1979) Cahn, Chanowitz, Fleishon, (1979); Bergstrom, Hulth, (1985) ‣Input parameters: mh = 126 GeV, mt = 173 GeV W and top loop effects are destructive with each other. How these predictions are changed by new physics effects?

  33. New physics effects to h→γγ(Z) ‣ Any charged new particle which couples to the Higgs boson can contribute to the h→ γγ and h→ Zγ processes. (Z) (Z) (Z) Spin 1/2 Spin 1 Spin 0 Ex. 4th generation fermion, Chargino… Ex. Charged Higgs boson, Squark, Slepton… Ex. W’ boson… In this talk, we focus on modes with extended Higgs sector, where new charged scalar bosons are introduced to the SM.

  34. Previous works and our work There are several papers where the h→γγ mode is studied in an extended Higgs sector. Posch 2011; Arhrib, Benbrik, Gaur 2012; Ferreira, Santos, Sher, Silva 2012 ・ 2 Higgs doublet model Arhrib, Benbrik, Chabab, Moultakae, Rahilib 2012; Kanemura, Yagyu 2012; Akeroyd, Moretti 2012 ・ Higgs triplet model ・ Zee model (2HDM + charged singlet) Kanemura, Kasai, Lin, Okada, Tseng, Yuan 2000 We study the h→γγ(Z) more comprehensiveway in various extended Higgs sectors.

  35. Classes of extended Higgs sectors ‣ 3 classes of extended Higgs sectors. Class I : Models with one singly-charged scalar boson SM H± Ex. 2HDM Class II : Models with one singly-charged and one doubly-charged scalar boson Ex. Higgs triplet model, Zee-Babu model SM H± H±± Class III : Models with two singly-charged scalar bosons Ex.: Radiative seesaw models (Zee model, Kauss-Nasri-Trodden model, Aoki-Kanemura-Seto model) SM H1± H2±

  36. List of models ‣ We consider Higgs sectors with additional SU(2)Lsinglets (S), doubles (D)and triplets (T). Class I Class II Class III (Y = 1) Singlet (Y = 2) Doublet (Y = 1/2) (Y = 0) Triplet (Y = 1) There are 13 models depending on the # of scalar fields.

  37. SM-like Higgs boson ‣ We assume the SM-like Higgs boson (h): -The Yukawa coupling (hff) and the gauge coupling (hVV) is the same as those in the SM. X ・ ・ ・ h Production Decay Only h→γγand h→Zγdecay modes can be modified significantly. The other decay rates are almost the same as the SM. Same as the SM Modified decay rate directly affects to the number of events.

  38. Modified decay rates ‣ Decay rates are modified by new contributions from charged scalar bosons: ‣ The Higgs couplings with charged scalars (λSSh) and the Z boson (gSSZ) can be defined as Points enhanced when λSSh is negative. 1. Decay rate of h→γγ is suppressed when λSSh ispositive. 2. Decay rate of h→ Zγdepends on the isospin (I3) of the scalar boson. Measuring both h→γγ and h→Zγ would be a useful tool to determine the true Higgs sector.

  39. Relevant terms in Class I and II Φ : SM doublet ⊃ : Extra scalar field 1, 2 ⊃

  40. Relevant terms in Class III Mixing angle: ⊃ = M1= M2 = M3 = M ≠ M1= M2 = M3 = M

  41. Results (Class I and Class II) mH+ = mH++ = 200 GeV Class I ΔB (h → X) = [Br(h → X)NP- Br(h → X)SM]/Br(h → X)SM Not allowed by the vacuum stability bound. Class II

  42. Results (Class I and Class II) mH+= mH++= 200 GeV Class I R = Br(h → Zγ)NP/ Br(h → γγ)NP Not allowed by the vacuum stability bound. Class II

  43. Results (Class III) mH1+ = 200 GeV, mH2+ = 300 GeV, M = 308 GeV ΔB (h → X) = [Br(h → X)NP- Br(h → X)SM]/Br(h → X)SM

  44. Results (Class III) mH1+ = 200 GeV, mH2+ = 300 GeV, M = 308 GeV R = Br(h → Zγ)NP/ Br(h → γγ)NP

  45. Summary • To know the true Higgs sector → To determine physics beyond the SM. • Direct way : Discovery extra Higgs bosons Decay of the extra Higgs is important to discriminate each Higgs sector. -Type-II 2HDM: qq→ HA → 4b, Type-X 2HDM: qq→ HA → 4τ, 2τ + 2μ - Decay of H++ in HTM: H++ → l+l+ (Small vΔ), H++ → W+W+ (Large vΔ), H++ → H+W+ (Large mass splitting). 2. Indirect way: Precise test of the Higgs couplings (hγγ and hZγ) h → γγand h → Zγdecay modes are sensitive to the new physics models. 　　　→ Measuring both modes may be useful. We focused on effects of charged scalar boson which are introduced from various extended Higgs sectors. Class I: H±, Class II: H± + H±±, Class III: H1± + H2± When a charged scalar mass is taken to be around 200 GeV, h → γγ can be enhanced~ 15 %, ~ 80 % and ~ 30 % in Class I, II and III, respectively compared with the SM prediction.

  46. Scalar loop function

  47. Potential in models Class III In models w/ φSM + S1+ + S2+, φSM + D1+ D2, φSM + T10+ T20 , μ is absent. In models w/ φSM + D + S, φSM + D + T0, M3 and λ3 are absent.

  48. Heavy case (mS = 400 GeV ) Class I Class II

  49. Dubinin, Schreiber, Vologdin, Eur.Phys.J. C30 (2003) Measurement hZγ coupling at linear colliders h → Zγ decay process has been analyzed via the vector boson fusion process at the future linear collider. mh = 120 GeV, root(s) = 500 GeV, integrated L = 1 ab-1 Accuracy of ΔBR (h → Zγ) is expected to be 48 % By using polarized beam, this would be improved to be 29 %.

  50. Branching ratios of H+, H and A ★ The H+→ f0W+ mode can be dominant in the case of Δm ≠ 0. ★ The f0 → bb mode can be dominant when vΔ > MeV.

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