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The Higgs Boson and the Cosmology of the Early Universe Mikhail Shaposhnikov Blois 2018

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The Higgs Boson and the Cosmology of the Early Universe Mikhail Shaposhnikov Blois 2018 The Higgs Boson and the Cosmology of the Early Universe Mikhail Shaposhnikov Blois 2018 Rencontres de Blois, June 4, 2018 – p. 1 Almost 6 years with the Higgs boson: July 4, 2012, Higgs at ATLAS and CMS 3500 ATLAS Data Sig+Bkg Fit (m =126.5 GeV) 3000 H Bkg (4th order polynomial) 2500 Events / 2 GeV 2000 1500 s=7 TeV, ∫Ldt=4.8fb-1 1000 s=8 TeV, ∫Ldt=5.9fb-1 γγ→ 500 H (a) 200100 110 120 130 140 150 160 100 0 -100 Events - Bkg (b) -200 100 110 120 130 140 150 160 Data S/B Weighted 100 Sig+Bkg Fit (m =126.5 GeV) H Bkg (4th order polynomial) 80 weights / 2 GeV Σ 60 40 20 (c) 8100 110 120 130 140 150 160 4 0 -4 (d) -8 Σ weights - Bkg 100 110 120 130 140 150 160 m γγ [GeV] Rencontres de Blois, June 4, 2018 – p. 2 What did we learn from the Higgs discovery for particle physics? Rencontres de Blois, June 4, 2018 – p. 3 The ideas of the authors of the BEH mechanism were right Rencontres de Blois, June 4, 2018 – p. 4 The Standard Model is now complete Rencontres de Blois, June 4, 2018 – p. 5 126 125 U U U GeV Triumph of the SM in particle physics No significant deviations from the SM have been observed Rencontres de Blois, June 4, 2018 – p. 6 126 125 U U U GeV Triumph of the SM in particle physics No significant deviations from the SM have been observed The masses of the top quark and of the Higgs boson, the Nature has chosen, make the SM a self-consistent effective field theory all the way up to the quantum gravity Planck scale MP . Rencontres de Blois, June 4, 2018 – p. 6 Triumph of the SM in particle physics No significant deviations from the SM have been observed The masses of the top quark and of the Higgs boson, the Nature has chosen, make the SM a self-consistent effective field theory all the way up to the quantum gravity Planck scale MP . MH < 175 GeV : SM is a weakly coupled theory up to Planck energies MH > 111 GeV: Our EW vacuum is stable or metastable with a lifetime greatly exceeding the Universe age. 129 128 λ Strong coupling 127 126 , GeV h 125 m max M 124 H 123 320 80 20 10 tU 10 tU 10 tU M crit zero 122 170 171 172 173 174 175 176 177 energy M MPlanck Fermi mt, GeV Rencontres de Blois, June 4, 2018 – p. 6 How can we use the Higgs discovery for Cosmology? Rencontres de Blois, June 4, 2018 – p. 7 How can we use the Higgs discovery for Cosmology? Since the SM a self-consistent effective field theory all the way up to the Planck scale, we can try describe the evolution of the Universe within the SM from the very early stages, such as inflation and Big Bang, till the present days! Rencontres de Blois, June 4, 2018 – p. 7 Universe with the Strandard Model: very early times Rencontres de Blois, June 4, 2018 – p. 8 SM + gravity Higgs field in general must have non-minimal coupling to gravity: 2 2 4 MP ξh SG = d x g R R − ( − 2 − 2 ) Z p Jordan, Feynman, Brans, Dicke,... Consider large Higgs fields h>MP /√ξ, which may have existed in the early Universe The Higgs field not only gives particles their masses h, but also ∝ determines the gravity interaction strength: M eff = M 2 + ξh2 h P P ∝ For h > MP (classical) physics is the same (M /M eff does not p√ξ W P depend on h)! Rencontres de Blois, June 4, 2018 – p. 9 Physical effective potential does not depend on the Higgs field. Potential in Einstein frame U(χ) λM4/ξ2/4 Standard Model λ v4/4 λM4/ξ2/16 0 0 v 0 0 χ χ - canonically normalized scalar field in Einstein frame. Rencontres de Blois, June 4, 2018 – p. 10 Cosmological inflation Rencontres de Blois, June 4, 2018 – p. 11 MP Stage 1: Higgs inflation, h > √ξ , slow roll of the Higgs field U(χ) λM4/ξ2/4 inflation λM4/ξ2/16 0 χ χ 0 end COBE χ Makes the Universe flat, homogeneous and isotropic Produces fluctuations leading to structure formation: clusters of galaxies, etc Rencontres de Blois, June 4, 2018 – p. 12 CMB parameters - spectrum and tensor modes, ξ & 1000 ns = 0.97, r = 0.003 Rencontres de Blois, June 4, 2018 – p. 13 MP MP Stage 2: Big Bang, ξ <h< √ξ , Higgs field oscillations U(χ) λM4/ξ2/4 λM4/ξ2/16 Reheating 0 χ χ 0 end COBE χ All particles of the Standard Model are produced Coherent Higgs field disappears The Universe is heated up to T M /ξ 1014 GeV ∝ P ∼ The universe is symmetric - no charge asymmetries Rencontres de Blois, June 4, 2018 – p. 14 First great feature of the SM in cosmology Presence of the fundamental scalar field – Higgs boson, which can play a role of the inflaton and make the Universe flat, homogeneous and isotropic and produce quantum fluctuations necessary for structure formation. Hot Big Bang due to Higgs field oscillations. All this is possible because of the Higgs-gravity coupling : ξH2R. Rencontres de Blois, June 4, 2018 – p. 15 Two other great features of the SM in cosmology: Universe at the electroweak scale Rencontres de Blois, June 4, 2018 – p. 16 Baryon number non-conservationists The rate of B non-conservation exactly as we would like it to have for baryogenesis! energy Msph 4π 160 exp( ) 10− , T = 0 − αW ∼ Γ exp Msph , T<T ∼ T c − -2 -1 1 2 topological number 5 4 (αW ) T , T>Tc These reactions are in thermal equilibrium for 100 GeV T <T < (α )5M 1012 GeV ∼ c W Pl ∼ Rencontres de Blois, June 4, 2018 – p. 17 Electroweak phase transition First order phase transition: a mechanism to go out of thermal equilibrium. The universe is supercooled in the symmetric phase bubbles of new → (Higgs) phase are nucleated. Size of the critical bubble: Higgs phase 1 R (αW Tc)− Higgs phase ∼ symmetric T 100 GeV phase c ∼ Bubble size at percolation: 6 10− cm. Higgs phase ∼ Rencontres de Blois, June 4, 2018 – p. 18 Bubble wall baryogenesis Cohen, Kaplan, Nelson 1. Symmetric phase: φ†φ 2. Higgs phase: φ†φ = 0 h i ≃ h i 6 0 fermions are almost mass- fermions are massive and → → less and B-nonconservation is B-nonconservation is exponen- rapid. tially suppressed. ⇓ Fermions interact in a CP-violating way (reflected and transmitted) with the surface of the bubble ⇓ Baryon asymmetry of the Universe after EW phase transition. Rencontres de Blois, June 4, 2018 – p. 19 Mechanism B is not conserved B = 0 v B is conserved v v B =/ 0 q _ q _ q q _ q q Rencontres de Blois, June 4, 2018 – p. 20 Phase transition in SM Kajantie, Laine, Rummukainen, MS T T symmetric phase critical point critical point A VAPOUR B WATER Higgs phase ICE MH P Typical condensed matter phase Electroweak theory diagram (pressure versus tem- hφ†φi ≪ (250GeV )2 perature) T = 109.2 ± 0.8GeV , No EW phase transition with 125 MH = 72.3 ± 0.7GeV GeV Higgs boson! † 2 hφ φiT =0 ∼ (250 GeV) Rencontres de Blois, June 4, 2018 – p. 21 CP violation in the SM MS; Farrar, MS; Gavela, Hernandez, Orloff, Pene, Quimbay; Huet, Sather Relevant measure of CP violation: Jarlskog determinant 6 2 4 4 2 2 20 D G s s2s3sinδm m m m 10− ∼ F 1 t b c s ∼ with possible amplifications due to finite temperature effects. Too small to give the observed baryon asymmetry ! Rencontres de Blois, June 4, 2018 – p. 22 Universe is empty in the Standard Model: matter has annihilated with antimatter! Rencontres de Blois, June 4, 2018 – p. 23 Universe is empty in the Standard Model: matter has annihilated with antimatter! Also, there is no candidate for Dark Matter particle in the SM Rencontres de Blois, June 4, 2018 – p. 23 Universe is empty in the Standard Model: matter has annihilated with antimatter! Also, there is no candidate for Dark Matter particle in the SM In addition, observations of neutrino oscillations : in the original SM neutrinos are massless and do not oscillate Rencontres de Blois, June 4, 2018 – p. 23 Universe is empty in the Standard Model: matter has annihilated with antimatter! Also, there is no candidate for Dark Matter particle in the SM In addition, observations of neutrino oscillations : in the original SM neutrinos are massless and do not oscillate Though SM works well in particle physics, it fails in cosmology and neutrino physics Rencontres de Blois, June 4, 2018 – p. 23 Universe is empty in the Standard Model: matter has annihilated with antimatter! Also, there is no candidate for Dark Matter particle in the SM In addition, observations of neutrino oscillations : in the original SM neutrinos are massless and do not oscillate Though SM works well in particle physics, it fails in cosmology and neutrino physics Neutrinos, baryogenesis and dark matter : window to physics beyond the Standard Model! Rencontres de Blois, June 4, 2018 – p. 23 However, extensions of the SM are very far from being unique: Baryon asymmetry: there is just one number nB/nγ to explain: many scenarios were proposed. Dark matter, absent in the SM: plephora of different candidates, 22 the masses of DM particles can be as small as (10− ) eV O (super-light scalar fields) or as large as (1020) GeV (wimpzillas, O Q-balls).
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