Electroweak phase transition with two Higgs doublets near the alignment limit

Transcription

1 Electroweak phase transition with two Higgs doublets near the alignment limit Jérémy Bernon The Hong Kong University of Science and Technology Based on In collaboration with Ligong Bian (Chongqing university), Yun Jiang (Niels Bohr institute) IAS Program on High Energy Physics Hong Kong, January 22nd, 2018

2 Motivations [ATLAS-HIGG ] ττ) [pb] BR( φ σ [ATLAS ] -3 ATLAS Preliminary, -1 L dt = fb, φ b-associated production s=8 TeV ττ Obs 95% CL limit Exp 95% CL limit 1 σ 2 σ [GeV] m φ 2 [5.8, 6.6] DM h 2 =0.1186(20) m ev QCD Series of observations requiring new physics (or large fine tuning) [CMS-HIG ] [ATLAS-CONF ] So far in very good agreement with the SM A connection to the Higgs sector can be found for all these observations Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

3 Motivations [ATLAS-HIGG ] ττ) [pb] BR( φ σ [ATLAS ] -3 ATLAS Preliminary, -1 L dt = fb, φ b-associated production s=8 TeV ττ Obs 95% CL limit Exp 95% CL limit 1 σ 2 σ [GeV] m φ 2 [5.8, 6.6] DM h 2 =0.1186(20) m ev QCD Series of observations requiring new physics (or large fine tuning) [CMS-HIG ] [ATLAS-CONF ] So far in very good agreement with the SM A connection to the Higgs sector can be found for all these observations Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

4 Electroweak baryogenesis Testable in colliders and in the sky, several handles Require a first-order phase transition: nucleation of expending bubbles of true vacuum presence of extra degrees of freedom testable at colliders Diffusion of chiral species through the bubble wall, asymmetry generated due to CP-violating interactions electric dipole moments as important probe Chiral asymmetry changed to baryon asymmetry in the symmetric vacuum by the electroweak sphaleron Enforcing sphaleron rate suppression inside the bubbles to prevent washout of the asymmetry in the true vacuum: v c /T c & 1, termed strong first-order phase transition (SFOPT) restriction of model parameter space Bubbles expend and eventually collide stochastic gravitational waves possibly observable in space-based interferometers Here we look for parameter space regions that leads to a SFOPT and look at the associated LHC phenomenology Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

5 Two-Higgs-doublet models The SM EWSB sector contains one Higgs doublet but there is no reason for such minimality. Simple extension: an additional Higgs doublet ( 1, 2). Omitting the possibility of CP violation in the Higgs sector, the physical spectrum consists of 5 states: 2 CP-even h, H, a CP-odd A and a pair of charged states H ±. i = Ô 1 3 Ô i 2 v i + i + i i v 1 = v cos v 2 = v sin 3 4 H h = 3 c s s c 43Ô 4 2Re 0 Ô2Re 1 v v 2 Both h and H can be identified with the SM-like state: here we consider h-125. The general 2HDM has large tree-level flavor changing neutral currents: forbid them by imposing a Z2-symmetry: 1 æ 1, 2 æ 2 (natural flavour violation) V = m m [m h.c.] ( 1 1) ( 2 2) ( 1 1)( 2 2) ; < + 4 ( 1 2)( 1 2 1)+ 2 5( 1 2) 2 +h.c. Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

6 The alignment limit Higgs basis: the vev v 246 GeV resides entirely in one of the two doublets: H 1 = Ô 1 3 Ô 4 2G + 2 v + h 1 + ig 0,H 2 = Ô 1 3 Ô 4 H1 c s 2H + 1 H 2 s c 2 h 2 + ia 2 V =Y 1 H 1 H 1 + Y 2 H 2 H 2 + Y 3 [H 1 H 2 +h.c.]+ 1 2 Z 1(H 1 H 1) Z 2(H 2 H 2) 2 + Z 3 (H 1 H 1)(H 2 H 0 2) ; + Z 4 (H 1 H 2)(H 1 2 H 1)+ 2 Z 5(H 1 H 2) 2 + # Z 6 (H 1 H 1)+Z 7 (H 2 H 2) $ < H 1 H 2 +h.c. The CP-even mass matrix and eigenstates are: 3 4 M 2 Z1 v H = 2 Z 6 v 2 Z 6 v 2 m 2 A + Z 5v 2 H = h 1 c h 2 s h = h 1 s + h 2 c A SM-like state is obtained if one of the two mass eigenstates is aligned with the direction of the vev: the alignment limit Alignment in the h-125 scenario: c = Z 6 v 2 apple (m 2 H m 2 h )(m2 H Z 1v 2 ) ƒ 0 Here s 0.99 [JB, Gunion, Haber, Jiang, Kraml 15 16] ; m 2 H v 2 : Decoupling limit Z 6 π1: Alignment w/o decoupling Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

7 Potential beyond tree-level V (h 1,h 2,T)=V 0 (h 1,h 2 )+V CW (h 1,h 2 )+V CT (h 1,h 2 )+V th (h 1,h 2,T)+V daisy (h 1,h 2,T) One-loop at zero temperature: V CW (h 1,h 2 )= X i ( 1) 2s i n i ˆm 4 i (h 1,h 2 ) 64 2 apple ˆm 2 ln i (h 1,h 2 ) Q 2 C i [Coleman, Weinberg 73] Finite parts fixed such that there is no shift in vevs and mass matrices from tree-level to loop-level One-loop at finite temperature: Dominant thermal corrections: V daisy (h 1,h 2,T)= V th (h 1,h 2,T)= T X J B,F (y) = T 12 1X l=1 i n i J B,F m 2 i (h 1,h 2 ) T 2 (±1) l y l 2 K 2 ( p yl) X h i n i Mi 2 (h 1,h 2,T) 3 2 m 2 i (h 1,h 2 ) 3 2 i [Dolan, Jackiw 74] [Anderson, Halle 92] [Carrington 92; Arnold, Espinosa 93; Delaunay, Grojean, Wells 07] Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

8 Vacuum histories Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

9 Vacuum histories Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

10 Vacuum histories Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

11 Vacuum histories Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

12 Vacuum histories Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

13 Zero temperature potential and critical parameters Expectation: vc~v and small Tc for small potential depth at zero temperature v V T =0 In the SM: driven by the h-125 mass, but in presence of additional (light) scalars, can expect sizeable modifications [Harman, Huber 16; Dorsh, Huber, Mimasu, No 17] Details of the PT largely independent of the Yukawa structure SM Critical vev largely driven by the potential depth at 0T Critical temperature on the other hand shows small correlation with depth Lines of constant vc Jérémy Bernon IAS Program on High Energy Physics, January 22nd, = v c T c

14 Mass spectra Experimental constraints depend on the Yukawa structure: Type-I and Type-II here Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

15 Mass spectra Experimental constraints depend on the Yukawa structure: Type-I and Type-II here Degeneracy: T parameter + decoupling Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

16 Mass spectra Experimental constraints depend on the Yukawa structure: Type-I and Type-II here Degeneracy: T parameter + decoupling Perturbativity limit Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

17 Mass spectra Experimental constraints depend on the Yukawa structure: Type-I and Type-II here Degeneracy: T parameter + decoupling Perturbativity limit Type-I offers a very wide range of possibilities Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

18 Mass spectra Experimental constraints depend on the Yukawa structure: Type-I and Type-II here Degeneracy: T parameter + decoupling Perturbativity limit Type-I offers a very wide range of possibilities m H ± & 580 GeV (B! X s ) Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

19 Mass spectra Experimental constraints depend on the Yukawa structure: Type-I and Type-II here Degeneracy: T parameter + decoupling Perturbativity limit Type-I offers a very wide range of possibilities m H ± & 580 GeV (B! X s ) H/A!, A! Zh Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

20 Mass spectra Experimental constraints depend on the Yukawa structure: Type-I and Type-II here Degeneracy: T parameter + decoupling Perturbativity limit Type-I offers a very wide range of possibilities Jérémy Bernon IAS Program on High Energy Physics, January 22nd, 2018 m H ± & 580 GeV (B! X s ) H/A!, A! Zh Type-II has much more restricted spectra 9

21 Mass maps Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

22 Mass maps B C B C E D A Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

23 Cross-sections at LHC Run-II Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

24 Trilinear Higgs coupling Requiring ξ>1 leads to enhancement of the trilinear Higgs coupling relative to SM Coupling enhancement largely correlated with the size of ξ Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

25 Baryon asymmetry The softly-broken Z2 symmetric 2HDM potential has one free CP violating phase: Type II, m H = 200 GeV, m A = m H ± Previous eedm = exp (A! ZH) [Dorsch, Huber, Konstandin, No 16] eedm and direct searches are fully complementary Additional tests within LISA: bubble collisions generate sound waves in the plasma: main source of gravitational waves [Hindmarsh, Huber, Rammukainen, Weir 13, 15] Jérémy Bernon IAS Program on High Energy Physics, January 22nd,

26 Conclusions While the properties of the 125 GeV state appear more and more SM-like, the alignment limit of the 2HDM is singled out. Strong complementarity between collider searches, flavour observables and cosmological quantities. SFOPT leads to characteristic mass spectra with distinct signatures at colliders, In particular Higgs-to-Higgs decays but not only Precision determination of the trilinear Higgs coupling is a probe of such scenarios Jérémy Bernon IAS Program on High Energy Physics, January 22nd,