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Curvaton Decay by Resonant Production of Higgs Bosons Rose Lerner Helsinki University and Helsinki Institute of Physics [email protected]

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Curvaton Decay by Resonant Production of Higgs Bosons Rose Lerner Helsinki University and Helsinki Institute of Physics Rose.Lerner@Helsinki.Fi Curvaton Decay by Resonant Production of Higgs Bosons Rose Lerner Helsinki University and Helsinki Institute of Physics [email protected] with Kari Enqvist and Daniel Figueroa DESY theory workshop 27th September 2012 ? ? + H ? For “electrically charged curvaton, see JCAP / arXiv:1207.1063 – Arttu Rajantie, Michela D’Onofrio, RL ? + H Outline Introduction What is the curvaton? Linking particle physics and cosmology Curvaton-Higgs coupling expectation difference: thermal background calculations and results Summary Precision cosmology 105 Planck fNL ≤ 5 ? Inflation Inflation is a period of accelerated expansion in the early universe • solves horizon problem • solves flatness problem • dilutes unwanted cosmological relics • generates perturbations that seed structure formation Image: M. Gasperini, G. Veneziano / Physics Reports 373 (2003) Inflation Inflation is a period of accelerated expansion in the early universe • solves horizon problem • solves flatness problem expansion • dilutes unwanted cosmological relics • generates perturbations that seed structure formation Image: M. Gasperini, G. Veneziano / Physics Reports 373 (2003) Inflation Inflation is a period of accelerated expansion in the early universe • solves horizon problem • solves flatness problem expansion • dilutes unwanted cosmological relics • generates perturbations that seed structure formation fluctuations Image: M. Gasperini, G. Veneziano / Physics Reports 373 (2003) Standard inflationary scenario: The scalar field φ is responsible for both the inflationary expansion and generating the perturbations Curvaton scenario: The scalar field φ is responsible for only the inflationary expansion and a different scalar field σ is responsible for generating the perturbations [Enqvist & Sloth (2002); Lyth & Wands (2002); Moroi & Takahashi (2001)] Curvaton mechanism 1 2 2 V( ) 2 m 3 4 r=ρσ/ρtotal; ρσ = ρσ0/a ; ρtotal = ρtotal0/a Curvaton mechanism 1 2 2 V( ) 2 m r inflation a decay << 1 log(t) 3 4 r=ρσ/ρtotal; ρσ = ρσ0/a ; ρtotal = ρtotal0/a Can we use the curvaton to link collider physics and cosmology? + H Observables depend on decay width Curvature Curvaton’s perturbation = 10-5 decay width () ζ (g) coupling to Γ Current understanding: decay product Perturbative decay: Non-perturbative decay: 2 m g m OR 5 2 8 log10(g ) Our idea: Curvaton decay dynamics determined only by coupling to standard model higgs + H Outline Introduction What is the curvaton? Linking particle physics and cosmology Curvaton-Higgs coupling expectation difference: thermal background calculations and results Summary Curvaton coupled to SM higgs Only renormalisable coupling to standard model: curvaton SM higgs (real scalar) Free parameters: g, mσ, σ*, H* • no perturbative decay (no three-point coupling) • but expect non-perturbative decay, just like preheating Preview of results Perturbative decay: no ζ does not occur Non-perturbative decay: large Γ m → too small ζ 5 log10(g ) Blocked non-perturbative decay: much smaller 4 g 4 Γ * m 10 → ok ζ 10 M P Curvaton dynamics σ crosses zero at Non-perturbative decay? • occurs by resonant production of Higgs bosons • only when curvaton crosses zero • and only when Higgs field evolves non- adiabatically: d k 2 dt k effective frequency of Higgs mode Effective frequency (naive) • Higgs equation of motion: Higgs (rescaled) [valid near integer j] 2 2 ( j) K Kcut ( j) • effective frequency: 2 ( j) 2 ( j) x2 Adiabaticity violated if... dk 2 2 • General condition: k 2 K x2 dx K cut 2 2 K 2 • So, 1 k x Kcut • Thus, resonant production of Higgs for 2 2 0 K Kcut and x 1 • Energy transfer then completes in a few hundred oscillations (calculation not shown) Differences from expectations BUT... • if curvaton decays much later than inflaton • and if the thermal bath contains higgs particles THEN curvaton condensate is oscillating in the presence of a thermal bath -> this can block the resonance! Effective frequency (full) • Higgs equation of motion: • effective frequency: 2 2 ( j) K Kcut ( j) Adiabaticity violated if... > 0 < 0 • RHS should be > 0 • Thermal mass of Higgs blocks resonance! • Unblocked after many oscillations: Types of resonance broad or narrow? radiation- dominated or matter-dominated? Preliminary results g H* = 1012 GeV; σ* = 104 H* m/H* Contrary to expectations, the decay of the curvaton by resonant production of particles that are coupled to the thermal bath can be substantially delayed. This means that it is possible to have a curvaton model with “natural” coupling constants, say g = 10-6. Summary • The curvaton is an alternative to generate ζ (within inflationary paradigm) • Careful consideration of curvaton scenario can link cosmology and particle physics • Higgs-Curvaton coupling: decay by resonant production of Higgs is thermally blocked • Higgs-Curvaton coupling: allows a curvaton model with more “natural” couplings.
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