Probing physics behind the electroweak symmetry breaking at future gravitational wave and collider experiments Mitsuru Kakizaki (University of Toyama) The 17 th Regular Meeting of the New Higgs Working Group May 12, 2016 @ University of Toyama l Collaborators: Katsuya Hashino, Shinya Kanemura (University of Toyama) and Toshinori Matsui (University of Toyama à KIAS) l References: - MK, Kanemura, Matsui, PRD 92, no. 11, 115007 (2015) [arXiv:1509.08394] - Hashino, MK, Kanemura, Matsui, arXiv:1604.02069 May 12, 2016 Mitsuru KAKIZAKI 1
Contents 1. Introduction 2. Models with additional singlet scalars (without CSI) 3. CSI models with additional singlet scalars 4. Synergy between measurements of gravitational waves and triple Higgs boson coupling 5. Summary May 12, 2016 Mitsuru KAKIZAKI 2
Motivation l Discovery of the 125 GeV Higgs boson at the CERN LHC: h l The Standard Model (SM) has been established as a low-energy effective theory below GeV O (100) This is not the end of the story l The Higgs sector is still vague: Guiding principle? l Shape of the Higgs potential (multiplets, symmetries, ...)? l l Dynamics behind the electroweak symmetry breaking (EWSB)? l Phenomena beyond the SM (BSM) reported: Baryon asymmetry of the Universe (BAU) l Cosmic inflation l l Existence of dark matter l Neutrino oscillations l Higgs sector = Window to New Physics l The structure of the Higgs sector is related to BSM models Informa8on on new physics can be obtained by inves8ga8ng the proper8es of the Higgs sector May 12, 2016 Mitsuru KAKIZAKI 3
Electroweak baryogenesis l Sakharov’s conditions for BAU 1 st OPT 1. Baryon number violation Sphaleron process 2. Violation of C and CP Tunneling Extended Higgs sctor 3. Departure from thermal equilibrium ϕ c ϕ Strongly first order phase transition (1 st OPT): Potential barrier l SM Higgs sector w/ one doublet: True vacuum l Electroweak phase transition (EWPT) is NOT of 1 st order for m h = 125 GeV l Electroweak baryogenesis (EWBG) is an important physics case relating the Higgs sector to BSM phenomena May 12, 2016 Mitsuru KAKIZAKI 4
Strongly 1 st OPT and triple Higgs boson coupling l Models with extended H iggs sector: l 1 st OPT is easily realized l Signatures are testable at colliders l e.g. Two Higgs doublet model (2HDM): l Condition for strongly 1 st OPT: ϕ c /T c & 1 Large deviation in the triple Higgs boson coupling ( ∆ λ hhh / λ SM hhh & 10%) l ILC 1 TeV can measure λ hhh at 10% accuracy [Fujii et al. (2015)] EWBG can be tested at future colliders [Kanemura, Okada, May 12, 2016 Mitsuru KAKIZAKI 5 Senaha (2005)]
Gravitational waves (GWs) as a probe of EWPT l Ground-based interferometers (aLIGO, KAGRA, aVirgo) l Targets: GWs from binary systems, supernovae, ... l aLIGO made the first direct observation of GWs [LIGO and Virgo (2016)] New era of GW astronomy l Future space-based interferometers (eLISA, DECIGO, BBO) l Sensitive to GWs from the early Universe Synopsis (Strongly 1 st OPT, cosmic inflation, ...) BAU BSM New era for fundamental physics Higgs sector l Goal of our work: l To investigate testability of models of EWSB hhh GWs using the synergy between the measurements of the GWs and the coupling hhh l To exemplify this using models with additional isospin singlet scalars with and without classical scale invariance (CSI) May 12, 2016 Mitsuru KAKIZAKI 6
Contents 1. Introduction 2. Models with additional singlet scalars (without CSI) 3. CSI models with additional singlet scalars 4. Synergy between measurements of gravitational waves and triple Higgs boson coupling 5. Summary May 12, 2016 Mitsuru KAKIZAKI 7
Models with additional singlet scalars (without CSI) l Idea: [MK, Kanemura, Matsui (2015)] l To generally handle strongly 1 st OPT via thermal loop, isosinglet scalars are introduced S i ( i = 1 , · · · , N ) N l For simplicity, symmetry is imposed O ( N ) l Tree-level scalar potential: Φ : SM Higgs doublet l Singlet scalar boson mass: l Undetermined parameters: µ S , m S for each model O ( N ) May 12, 2016 Mitsuru KAKIZAKI 8
Models with additional singlet scalars (without CSI) (contd.) l Effective potential: [MK, Kanemura, Matsui (2015)] Non decoupling loop effect from additional scalars ϕ c /T c l Finite temperature effective potential (high temperature expansion): ϕ c ∝ T c Non decoupling loop effect from additional scalars Typically deviation O (10)% in for strongly 1 st OPT λ hhh May 12, 2016 Mitsuru KAKIZAKI 9
Contents 1. Introduction 2. Models with additional singlet scalars (without CSI) 3. CSI models with additional singlet scalars 4. Synergy between measurements of gravitational waves and triple Higgs boson coupling 5. Summary May 12, 2016 Mitsuru KAKIZAKI 10
CSI models with additional singlet scalars l Idea: See Hashino’s talk [Hashino, Kanemura, Orikasa (2015)] l Mass parameters are absent in the original Lagrangian due to CSI [Bardeen (1995)] l E WPT is directly caused by thermal loop effects l Tree-level potential: ϕ c /T c Φ : SM Higgs doublet l Singlet scalar boson mass: l Triple Higgs boson coupling: independent of N [Hashino, Kanemura, Orikasa (2015)] [Hashino, MK, Kanemura, May 12, 2016 Mitsuru KAKIZAKI Matsui (2015)]
Contents 1. Introduction 2. Models with additional singlet scalars (without CSI) 3. CSI models with additional singlet scalars 4. Synergy between measurements of gravitational waves and triple Higgs boson coupling 5. Summary May 12, 2016 Mitsuru KAKIZAKI 12
See Jinno and Important quantities for GW spectrum Takimoto’s talk Sources of GWs: Bubbles collision Bubble nucleation l 1. Collision of walls φ ≠ 0 2. Compression wave of plasma 3. Plasma turbulence GW spectrum is derived from l finite temperature effective φ = 0 φ = 0 potential V e ff l Bubble nucleation rate per unit volume per unit time: l Transition temperature : T t l Parameter Released false vacuum energy (Latent heat) α ' β (˜ l Parameter β ) ' Inverse of the duration of phase transition May 12, 2016 Mitsuru KAKIZAKI 13
˜ Predicted values of and β α l Condition for strongly 1 st OPT Constraints on ϕ c α = 1 T c and for each model ˜ β models O ( N ) l In CSI models, O ( N ) without CSI scale invariance is violated at finite temperatures � Γ � = 1 ˜ and depend on � N β CSI H 4 α � T = T t models though is common O ( N ) λ hhh l and to be determined ˜ β α by GW observation are useful measures in probing extended scalar sectors [Hashino, MK, Kanemura, Matsui (2016)] May 12, 2016 Mitsuru KAKIZAKI 14
Characteristic relic abundance and frequency of GWs l Collision of walls (Envelope approximation): [Caprini et al. (2015)] l Sound waves (Compression waves of thermal plasma): l Magnetohydrodynamic (MHD) turbulence: l : wall velocity v b κ = κ ( α , v b ) l and : efficiency factors ✏ = 0 . 05 May 12, 2016 Mitsuru KAKIZAKI 15
GW spectrum in CSI models O ( N ) v b = 0 . 95 l Contribution to GWs: DECIGO l Collision: l Sound wave: eLISA l MHD Turbulence: l Benchmark points: N = 1 , 4 , 12 , 60 from the bottom [Hashino, MK, Kanemura, Matsui (2016)] l Experimental prospects: l eLISA: [Caprini et al. (2015)] [Kawamura et al. (2011)] l DECIGO: l Contribution from sound waves is dominant and detectable at future space-based interferometers, eLISA and DECIGO May 12, 2016 Mitsuru KAKIZAKI 16
Comparison of GW spectra v b = 0 . 95 v b = 0 . 2 [Hashino, MK, l CSI O ( N ) Kanemura, models Matsui (2016)] l models O ( N ) without CSI q µ 2 S = 0 l N.B. subsonic wall velocity is preferred for EWBG but not necessarily [No (2011)] May 12, 2016 Mitsuru KAKIZAKI 17
Synergy of measurements of the triple Higgs boson coupling and GWs l What if the coupling hhh is found to be ∆ λ hhh / λ SM hhh = 2 / 3( ' 70%) at future colliders? l Models: l models without CSI predicting O ( N ) ∆ λ hhh / λ SM hhh = 2 / 3( ' 70%) l CSI models O ( N ) l Models with and without CSI can be distinguished at future GW interferometers even if they share common coupling hhh [Hashino, MK, Kanemura, Matsui (2016)] May 12, 2016 Mitsuru KAKIZAKI 18
Transition temperature and wall velocity dependence of detectability of GWs v b = 0 . 95 v b = 0 . 2 [Hashino, MK, Kanemura, Matsui (2016)] T t = 50 GeV T t = 100 GeV May 12, 2016 Mitsuru KAKIZAKI 19
5. Summary l Models with strongly 1 st order EWPT predict large deviation in the triple Higgs boson coupling and generate GWs l We have discussed the complementarity of measurements of the triple Higgs boson coupling and GW spectrum in models with extra scalars with and without CSI l Synergy between observation of GWs and measurement of the triple Higgs boson coupling at future experiments is powerful in revealing dynamics behind the EWSB May 12, 2016 Mitsuru KAKIZAKI 20
Backup slides May 12, 2016 Mitsuru KAKIZAKI 21
Efficiency factor κ [Caprini et al (2015)] May 12, 2016 Mitsuru KAKIZAKI 23
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