LHC Higgs Signatures from Extended Electroweak Guage Symmetry

Transcription

1 LHC Higgs Signatures from Extended Electroweak Guage Symmetry Tomohiro Abe Tsinghua U. based on JHEP 1301 (013) 08 In collabollations with Ning Chen, Hong-Jian He Tsinghua U. HPNP013, February 15th

2 1. Motivation. Model 3. LHC signatures of the Higgs bosons 4. Summary

3 Introduction LHC found a new particle around 15 GeV! photon signal is larger than the SM Higgs prediction Are there any new physics? (or statistics...) 4"! +, &(5(=(7%89(:(5(;<,()0 +, &(5(6(7%89(:(5(;</()0 ATLAS W,Z H # bb s = 7 TeV: "Ldt = 4.7 fb H # & & s = 7 TeV: "Ldt = fb (*) H # WW H # $ $ s = 7 TeV: "Ldt = 4.8 fb s = 8 TeV: "Ldt = 5.9 fb (*) H # ZZ Combined -1 # l%l% -1 s = 7 TeV: "Ldt = 4.7 fb -1 s = 8 TeV: "Ldt = 5.8 fb -1-1 # 4l -1 s = 7 TeV: "Ldt = 4.8 fb -1 s = 8 TeV: "Ldt = 5.8 fb -1 s = 7 TeV: "Ldt = fb -1 s = 8 TeV: "Ldt = fb -1 µ = 1.4 ± 0.3 m H = 16.0 GeV 1 γγ 1 (33 1 ( 1 ττ 1 (00 (? 1 (5(,.;<;(>% Signal strength (µ) +, -,. / $%&'()*'(σ#σ!"

4 How to enhance di-photon signal? h γ γ is loop induced process h t γ h γ W γ γ new particle modify the amplitude of this process new particle s spin = 0, 1/, 1... which is better? naively, if new particle coupling to the higgs is the same sign as the SM case, gauge boson loop enhance the amplitude Does W help enhancing this signal? h W Let us extend gauge sector and see what happen! γ γ

5 1. Motivation. Model 3. LHC signatures of the Higgs bosons 4. Summary

6 Model : gauge sector electroweak gauge symmetry SU() 0 SU() 1 U(1) two Higgs fields for electroweak symmetry H 1 = (, ) 0 ( breaking h 1,π1,π 1 1,π 1 3 ) H = (1, ) 1/ ( h,π,π 1,π 3 ) All π s are eaten by the gauge bosons mass eigenstates are given as linear combinations spin 1: spin 0: W ±, Z, γ, W ±,Z h, H h = cos αh 1 sin αh H = sin αh 1 + cos αh

7 ) Model : fermion sector vector like fermions as well as chiral fermions Fermions SU() 0 SU() 1 U(1) SU(3) c ( ) 1 Ψ 0L (1) ( ) 1 Ψ 1L (1) ( ) 1 Ψ 1R (1) Ψ u R (0) 3 (1) Ψ d R ( 1) 3 (1) chiral vector like chiral chiral reasons why we introduce vector like fermions: 1. they are mixed with chiral fermions, and relax S parameter constraint mw constraint. they can enhance σ(gg h)

8 Model: W ff coupling and mw gw ff ~ 0 is possible by tuning parameter (ideal delocalization) ( ) 1+r g W ff g 1 sin θ f Then r S parameter is OK with light m W m W m W r = H H 1 fermion mixing angle αs 4 sin θ W M W M W g W ff g W ff direct detection bounds through Drell-Yan process can be ignored Hereafter we set gw ff = 0 fermion sector depend on m w/mw

9 Model : Higgs couplings (1) g WWh = m W v ( r 3 ( )) (1 + r ) cos α 1 m sin α + O W 3/ (1 + r ) 3/ m W g SM WWh gwwh gwwh SM r 1 r r Α Π smaller than SM Br( h γγ, WW, ZZ) highly depend on r and α

10 Model : Higgs couplings () g W W h = m W v ( r (1 + r ) cos α r sin α + O 3/ (1 + r ) 3/ ( m W m W )) gw' W' h MW' v r 1 r r Α Π

11 Model : summary of matter contens Extra particles ( u c t d s b )( ν e ν µ ν τ e µ τ ( u c t d s b W Z SM particles )( νe ν µ ν τ e µ τ γ W Z g Higgs bosons hh ) ) W ±,Z 380 (wwz coupling) W ± 91,Z 80 Mass(GeV) 170 t u,d,c,s,t,b e,µ,τ,ν e,ν µ,ν τ a few TeV (T parameter) 15 h O(1)TeV H

12 1. Motivation. Model 3. LHC signatures of the Higgs bosons 4. Summary

13 ggh ggh ggh W (left panel) and M W = 600 GeV (right panel). The heavy fermion mass is set as, M F =.5TeV for both panels. The maximal enhancement factor is R ggh 1.6 (left panel) and R ggh 1. (right panel). σ(gg h)/σ(gg h)sm M W' 400 GeV M W' 600 GeV r =1 ggh Α Π highly depending on mixing angle, α. depending on mw. bigger than SM due to the heavy fermion loops. Figure 7. The ratio R ggh of the production cross section via gluon fusion process as a function of Higgs mixing angle α. We take the Higgs mass M h = 15 GeV and input f 1 = f. The heavy masses are taken to be, M F =.5TeV and M W = 400 GeV (blue curve) or M W = 600 GeV (red curve).

14 σ(gg h) x BR / SM.5!!.5!!.0 WW ZZ.0 WW ZZ $ Br / SM $ BR / SM "/# "/# depending on α and mw In r =1 case γ γ signal can be enhanced! WW and ZZ signals are suppressed

15 σ(gg h) x BR / SM.5 ##.5 ##.0 WW ZZ.0 WW ZZ $ Br / SM $ Br / SM !/" !/" In r 1 case γ γ signal can be enhanced! WW and ZZ signals are compareble with the SM case

16 σ(vbf/wh/zh) other production processes W W W /Z h W/Z W does not propagate because gw ff = 0 in our set up difference from the SM is gwwh coupling σ(pp hqq ) σ(pp hqq ) SM = ( ) ( σ(pp hw ) gwwh r 3 ) = σ(pp hw ) SM gwwh SM (1 + r ) cos α 1 sin α 1 3/ (1 + r ) 3/ These production xsec is always smaller than SM

17 σ(vbf/wh/zh) x BR(h ff) / SM Σ Br 3 site Σ Br SM Σ Br 3 site Σ Br SM a Α Π c Α Π Σ Br 3 site Σ Br SM b m W = 400GeV, r = Α Π (ex) σ(vbf) Br(h ττ bar ) < SM suppressed to improve the result, for example, we need to change parameter space give up ideal delocalization change fermion sector itself...

18 1. Motivation. Model 3. LHC signatures of the Higgs bosons 4. Summary

19 Summary LHC found a new particle around 15 GeV γγ signal is larger than the SM Higgs boson case We consider SU()xSU()xU(1) model σ(gg h γγ)/σsm > 1 is possible σ(gg h WW/ZZ) /σsm 1 these are compatible with the current LHC data other production process is suppressed, for example σ(vbf) Br(h ττ bar ) < SM These results highly depend on parameter choice and structure of fermion sector. It is worthwhile to study more general analysis in this gauge symmetry.

20 BACKUP SLIDES 0

21 Model : fermion mass terms mass terms ( Ψ u 0L Ψu 1L ) ( 1 y 1f 1 0 M 1 y uf )( Ψ u 1R Ψ u R ) ( Ψ d 0L Ψd 1L ) ( 1 y 1f 1 0 M 1 y df )( Ψ d 1R Ψ d R ) +(h.c.) mass m u 1 y 1 y u f 1 f 4 M m u M y 1 f y u f M H 1 = f 1 /, H = f / We assume M >> y1f1, yf yx determine the SM fermion masses yx 0 except top sector

22 Model : why gwwh/sm < 1? perturbative unitarity of longitudinal gauge boson scattering In the SM, Higgs cancels the E behavior W h

23 Model : why gwwh/sm < 1? perturbative unitarity of longitudinal gauge boson scattering In the SM, Higgs cancels the E behavior W h In our model, W and heavy Higgs as well as light Higgs W W h H both spin 1 and spin 0 particles contribute WWh coupling is smaller than the SM one

24 Model : perturbative unitarity () unitarity sum rules for couplings (here W stands for both W ± and Z) to cancel O(E 4 ) terms g WWWW = g WWW + g WWW to cancel O(E ) terms 4g WWWW M W =3g WWWM W +3g WWW M W + g WWh + g WWH gwww gwww SM by precision measurement now we see the following realtion (g WWh ) ( gwwh SM )

25 Model : lower bound on Mw R.S.Chivukula et.al Phys.Rev.D74: (006) triple gauge boson coupling L = igwwz SM (1 + κ Z ) W µ + Wν Z µν ( )( 1 + g Z 1 W + µν W µ WµνW +µ) Z ν ig SM WWZ K.Hagiwara, R.D.Peccei, D.Zeppenfeld, and K.Hikasa, Nucl.Phys. B8,53(1987) This model prediction κ Z = g Z 1 = 1 c M W M W ( M 4 + O W M 4 W ) c = M W M Z constraint from LEP-II g Z 1 < 0.08 (95%C.L.) M W 380GeV

26 Model : parameters in Higgs sector Higgs VEVs H 1 = f 1 /, H = f / They are related to the Fermi constant GF 1 f1 + 1 f 1 v we introduce the VEV ratio r r = f /f 1 we use GF (or v) and r = f/f1 instead of f1 and f mixing angle between two Higgses α h = cos αh 1 sin αh H = sin αh 1 + cos αh two input parameters in Higgs sector: α and r

27 σ(gg h) x BR / SM!(gg " h)!br /SM gg && WW Z& ZZ bb -,%% -, cc # H /$!(gg " h)!br /SM gg 1 bb -,%% -, cc - && 0.5 Z& 0 WW, ZZ # H /$ α /π α /π depending on α and mw In r =1 case γ γ signal can be enhanced! WW and ZZ signals are suppressed

28 Model : Higgs couplings (3) g ffh m f v ( ) r cos α 1 sin α g SM 1+r 1+r ffh gffh gffh SM r 1 r r Α Π gffh is smaller than SM

29 Model : Higgs couplings (4) g FFh m F v ( 1+r r m W m W cos α m f m F m W m W ) r sin α (1 + r ) 3/ 0.1 m F v gffh mf v r 1 r r Α Π

30 Model : Higgs couplings (4) g FFh m F v ( 1+r r m W m W cos α m f m F m W m W ) r sin α (1 + r ) 3/ 0.1 m F v suppression factors gffh mf v r 1 r r Α Π gffh is much suppressed, because F is almost vector like fermion

31 Comment on the heavy higgs constraint on heavy Higgs mass from LHC Σ Br 3 site Σ Br SM c H ZZ 4 leptons 3site: Α 0.5Π CMS 7 8 TeV H ZZ 4 ATLAS 7 8 TeV H ZZ 4 3site: Α 0.8Π 3site: Α 0.6Π Σ Br 3 site Σ Br SM Text d H WW leptons + MET 3site: Α 0.5Π CMS 7 8 TeV H WW Ν ATLAS 7 TeV H WW Ν 3site: Α 0.6Π 3site: Α 0.8Π M H GeV M H GeV mw = 400 GeV, r =1 case mh < 600 GeV is allowed because gwwh < gwwh SM very loose constraint on α 0.8π ( α 0.8π is prefered for h γγ enhancement)

32 Model : constraint from S parameter S parameter at tree level two ways to reduce S parameter (i) Heavy W mass αs 4 sin θ W M W M W g W ff g W ff f : SM fermion... but light W seems good for changing Br(h γ γ) we do not consider this case here (ii) small gw ff couplings gw ff = 0 by tuning the mixing angle (ideal delocalization) we consider this case in this talk

33 W decay mode c a m W = 400GeV, r =1 W' WZ Br W' Br W' W' WZ W' hw Α Π d W' WZ W' hw Α Π Br W' W' hw Α Π yellow reasion is consistent with ATLAS and CMS within 1σ W WZ is dominant W hw is subdominant other channels are negligible

34 σ(gg h)/σ(gg h)sm contributions from top and extra fermions t, t u,d,s,c,b σ(gg h) r σ(gg h) SM cos α 1 sin α +5 m 1 1+r 1+r M + m 1 r cos α 1 1+r sin α +5 1+r 1+r r r cos α 1+r MW MW cos α first two terms : sum of the top and heavy top contritutions last term : contributions from u, d, s, c, and b. m1 /(M + m1 ) : mixing angle in fermion sector. assume ideal delocalization in the second line g W ff g 1 1+r r ( M W M W m 1 = y 1f 1 M ) + y 1 v 4M

35 partial decay width / SM partial decay width (tree processes) Γ(h f f) Γ(h f f) SM = Γ(h WW) Γ(h WW) SM = ( g ffh gffh SM ( gwwh g SM WWh ) ( ) ( ) r cos α 1 sin α 1 1+r 1+r r 3 ) (1 + r ) cos α 1 sin α 1 3/ (1 + r ) 3/ Γ(h ff) and Γ(h WW) is smaller than the SM

36 partial decay width / SM partial decay width (loop induced processes) Γ(h gg) Γ(h gg) SM Γ(h γγ) Γ(h γγ) SM r cos α 1 1+r sin α +5 1+r 1+r r r cos α r sin α 1+r 1+r 47 r MW MW MW MW cos α cos α first two terms: t, t ( and W, W ) contributions last terms: others

37 Model : Yukawa interaction Yukawa y ij 1 Ψi 0L H 1Ψ j 1R M ij Ψ i 1L Ψj 1R Ψi 1L H ( y ij u 0 0 y ij d )( ) Ψ u j R +(h.c.) Ψ d R i and j : generation indices To avoid FCNC, we assume Minimal Flavor Violation y ij 1 = y 1δ ij, M ij = Mδ ij Flavor structure is determind by yu and yd y1 is constrained by S parameter or gw ff coupling

38 Model: W ff coupling and mw gw ff ~ 0 is possible by tuning parameter (ideal delocalization) 1+r ( g W ff g 1 r M W ) MW + y 1 v 4M S parameter is OK with light mw A Bonus: direct detection bound is also OK we often see the lower bound on m W ~ TeV this is derived with the following assumptions: gw ff = gwff W is produced via Drell-Yan process therefore constraint is changed if gw ff < gwff

39 BR / SM BR /SM ff gg # # Z # WW ZZ !/" example: mh = 15 GeV, mw = 400 GeV, M = 500 GeV, and r = 1 γγ can be ehnahced.