Higgs as a Probe of New Physics Shinya KANEMURA Osaka University - PowerPoint PPT Presentation

Higgs as a Probe of New Physics Shinya KANEMURA Osaka University Strings and Fields 2017 , at YITP, Kyoto Univ., 8 August 2017

This talk IntroducKon Probing the Higgs sector at future colliders Higgs potenKal and EW Phase TransiKon GravitaKonal waves as a probe of Higgs sector Summary

IntroducKon

Quarks and leptons Standard Model 3-generaKons Massive Gauge principle: InteracKon Isospin Color Hypercharge B µ Gluon Massive Massless Spontaneous Symmetry Breaking: Mass SU (2) I × U (1) Y → U (1) em Photon Weak bosons

Quarks and leptons Standard Model 3-generaKons Massive Gauge principle: InteracKon Isospin Color Hypercharge B µ Gluon Massive Massless Spontaneous Symmetry Breaking: Mass SU (2) I × U (1) Y → U (1) em Photon Weak bosons TentaKvely introducing a scalar doublet (Higgs field) � φ + � Φ = ↓VEV 246GeV φ 0 φ 0 = 1 ( v + h + iz ) √ 2 Higgs boson μ 2 < 0

LHC experiment ATLAS/CMS July 2012 Discovery of a scalar parKcle Mass 125 GeV, … Spin, Pality 0 + Coupling with many parKcles hγγ, hgg, hZZ, hWW, hττ, h), hbb, … IdenKfied as a Higgs boson Measured couplings turned out to be consistent with the SM Higgs TentaKve SM Higgs sector works well! No BSM parKcle has been found S M predic<on Standard Model is enough?

ATLAS-CONF-2015-044 Run 1 Best fit values for combinaKon of ATLAS and CMS Assump<on, absense of BSM par<cles in the loops and BR BSM =0 + 0.10 κ Z = 1.00 − 0.11 + 0.09 κ W = 0.91 − 0.09 + 0.15 κ t = 0.89 − 0.13 + 0.14 κ τ = 0.90 − 0.13 + 0.22 κ b = 0.67 − 0.20 Roughly Higgs couplings are determined by 20 %

ATLAS RUN II Results Masbuchi-san’s Slide

The LHC Run II data show … No contradicKon with the SM predicKon No signal for new BSM phenomena The SM is enough?

The LHC Run II data show … No contradicKon with the SM predicKon No signal for new BSM phenomena The SM is enough? If the SM is correct up to very high scales, we may be able to get important informaKon at the Planck scale

The UV behaviour of the SM arXiv:1205.6497, Degrassi et al We are one the edge! At Planck Scale, λ( M pl ) < 0, but the theory saKsfies τ EW >> τ U the condiKon of the meta-stable vacuum

Beyond the Standard Model There are many reasons to consider New Physics beyond SM UnificaKon of Law – Paradigm of Grand UnificaKon – Yukawa structure (flavor physics) Problem in the SM Higgs – Hierarchy Problem, Shape of Higgs sector, Nature, … BSM Phenomena – Dark Maoer – Neutrino mass and mixing – Baryon Asymmetry of Universe – InflaKon, Dark Energy, Gravity,… New Physics is necessary At which scale? If TeV scale, they should have connecKon with Higgs physics 12

Higgs problems Higgs boson was found, but Higgs sector is unknown ・ Nature of Higgs boson Hierarchy Problem New paradigm of New Physics ・ Structure MulKplet structure, Symmetry, … RelaKon to new paradigms Only one Higgs? and BSM phenomena ・ Higgs PotenKal EW Symmetry Breaking Dynamics of EWSB EW Phase TransiKon μ 2 < 0 By the discovery of h (125), these problems became fronKer

Higgs is a key to new physics • It is the weakest part in the SM (dirty) • Its structure remains unknown • It relates to the physics beyond the SM • It can be tested by current and future experiments We can access to the new physics empirically via the Higgs physics!

Nature of Higgs Higgs Nature ⇔ BSM Paradigm – Elementary Scalar SUSY – Composite of fermions Dynamical Symmetry Breaking – A vector field in extra D Gauge Higgs UnificaKon – Pseudo NG Boson Minimal Composite Models – …… …… Each new paradigm predicts a specific Higgs sector (eg. MSSM: two Higgs doublets, Gauge-Higgs Uni.: Higgs couplings are weaker)

Neutrino mass and Higgs Neutrino OscillaKon → Tiny mass ( < eV) Majorana mass Seesaw Mechanism Seesaw Mediated by Large mass of RH neuKrnos ← Right-handed Tiny mass N R Neutrinos AlternaKve Scenario by quantum effects Zee model Quantum effect due to addiKonal Mass around Tiny mass scalar fields Quantum TeV scale suppression Physics of specific extended Higgs sectors 16

Baryogenesis and Higgs = n b − n b η B = n B Baryon Number ( = (5 − 7) × 10 − 10 ) n γ n γ of the Universe Baryogenesis What is the mechanism to generate the baryon asymmetric Universe from the symmetric one? 17

Baryogenesis and Higgs = n b − n b η B = n B Baryon Number ( = (5 − 7) × 10 − 10 ) n γ n γ of the Universe Baryogenesis What is the mechanism to generate the baryon asymmetric Universe from the symmetric one? 1. ΔB ≠ 0 Sphaleron process Sakharov’s Chiral gauge theory 2. C and CP violaKon CondiKon KM phase 3. Departure from thermal Strongly first order Sakharov 1967 phase transiKon equilibrium SM could saKsfy these condiKons but excluded by the data 18

Baryogenesis and Higgs = n b − n b η B = n B Baryon Number ( = (5 − 7) × 10 − 10 ) n γ n γ of the Universe Baryogenesis What is the mechanism to generate the baryon asymmetric Universe from the symmetric one? 1. ΔB ≠ 0 Sphaleron process Sakharov’s Chiral gauge theory 2. C and CP violaKon CondiKon KM phase 3. Departure from thermal Strongly first order Sakharov 1967 phase transiKon equilibrium SM could saKsfy these condiKons but excluded by the data Scenario of Baryogenesis 1. Electroweak Baryogenesis Physics of (extended) Higgs sector 2 . Leptogenesis New physics at very high scales 19

Higgs is a window to new physics SUSY Dynamical symmetry breaking Higgs as a pNGB Higgs portal new physics Gauge Higgs UnificaKon CW mechanism scenarios Higgs portal dark maoer Inert scalar models RadiaKve neutrino mass models Electroweak baryogenesis … It is important to experimentally determine the Higgs sector to explore new physics beyond SM

Probing the Higgs sector at colliders

Extended Higgs sectors MulKplet Structure (with addiKonal scalars) Φ SM +Isospin Singlet, Φ SM +Doublet (2HDM), Φ SM +Triplet, … AddiKonal Symmetry Discrete or ConKnuous? Exact or Soyly broken? InteracKon Weakly coupled or Strongly Coupled? Decoupling or Non-decoupling?

Extended Higgs sectors MulKplet Structure (with addiKonal scalars) Φ SM +Isospin Singlet, Baryogenesis Φ SM +Doublet (2HDM), CP ViolaKon Φ SM +Triplet, … 1 st OPT Neutrino Mass Type III Seesaw AddiKonal Symmetry RadiaKve Seesaw Discrete or ConKnuous? Dark Maoer (Inert scalar) Exact or Soyly broken? EffecKve Theory of BSM (MSSM, NMSSM, … .) InteracKon Models of Dynamical Weakly coupled or Strongly Coupled? Symmetry Breaking Decoupling or Non-decoupling?

Simplest Extension 2 Higgs doublet model (2HDM) Sharing the VEV Field Mixing CP-odd Charged New ParKcles ↑ Other three are unphysical h (125) Nambu-Goldstone bosons AddiKonal bosons DeviaKon in the couplings of h (125) SM 2HDM hVV 1 → hVV sin(β − α)

ExploraKon of extended Higgs sector is performed by both ・ Discovery of addiKonal scalars ・ DetecKng deviaKons from the SM

Run1 7-8 TeV 20} -1 LHC: Hadron Collider Run 2,3 13-14 TeV 300} -1 HL-LHC 14 TeV 3000} -1 Machine At some probability, elementary process for discovery with very large energy can occur • Direct searches of addiKonal Higgs bosons p h (125) , H, A, H + , H ++ , … p h, H, A, … • Indirect test by finding deviaKons from SM EW parameters m W , S, T, U, Zff, Wff’, WWV, ... Couplings of h (125) hWW, hZZ, hγγ, hff, hhh, … Precision rather limited by huge QCD backgrounds

Lepton Collider e + Machine for precision measurements! e − Simple KinemaKcs Low QCD backgrounds Beam polarizaKon (linear collider) Energy Scan (linear collider)

Lepton Collider e + Machine for precision measurements! e − Simple KinemaKcs Low QCD backgrounds Beam polarizaKon (linear collider) Energy Scan (linear collider) InternaKonal Linear Collider (ILC) Next GeneraKo Linear Collider E nergy 250GeV (500 GeV, 1TeV) TDR published Technically ready WaiKng for approval Hosted by Japan (Iwate)

Higgs coupling measurements Future Current hVV coupling by about 0.4% (95% CL) Measurement Yukawa coupling by a few % (95% CL) accuracy at ILC (500-up) Snowmass Higgs Working Group Report 2013

DeviaKon = New Physics scale

DeviaKon = New Physics scale Scaling factor κ i : factor of deviaKon from the SM value L e ff = L SM + v 2 Coupling of h (125) and weak bosons M 2 O (6) V (=W, Z) hVV SM value κ V 2 =sin 2 (β−α) DeviaKon Excluded by κ V 2 Unitarity bounds m H (GeV)

DeviaKon = New Physics scale Scaling factor κ i : factor of deviaKon from the SM value L e ff = L SM + v 2 Coupling of h (125) and weak bosons M 2 O (6) V (=W, Z) hVV SM value κ V 2 =sin 2 (β−α) DeviaKon If a 2% deviaKon in κ V 2 Excluded by κ V 2 Unitarity bounds The second Higgs H must be lighter than 800 GeV m H (GeV) Precision test has the similar power to the direct search

Complementarity Direct detecKon of the Type-II 2HDM heavier Higgs boson H at LHC Indirect limits allowed by tree unitarity H HL-LHC when κ V 2 =0.98 m H (GeV) H Region of discovery Indirectly, new physics can at LHC300 be surbeyed by detecKng H → τ τ deviaKons even out of the direct search regions tanβ SK, Tsumura, Yagyu, Yokoya, 2014