Preheating after Higgs inflation: Self-resonance and gauge boson production

Abstract

We perform an extensive analysis of linear fluctuations during preheating in Higgs inflation in the Einstein frame, where the fields are minimally coupled to gravity, but the field-space metric is nontrivial. The self-resonance of the Higgs and the Higgsed gauge bosons are governed by effective masses that scale differently with the nonminimal couplings and evolve differently in time. Coupled metric perturbations enhance Higgs self-resonance and make it possible for Higgs inflation to preheat solely through this channel. For ξ 100 the total energy of the Higgs-inflaton condensate can be transferred to Higgs particles within 3 efolds after the end of inflation. For smaller values of the nonminimal coupling preheating takes longer, completely shutting off at around ξ 30. The production of gauge bosons is dominated by the gauge boson mass and the field space curvature. For large values of the nonminimal coupling ξ 1000, it is possible for the Higgs condensate to transfer the entirety of its energy into gauge fields within one oscillation. For smaller values of the nonminimal coupling gauge bosons decay very quickly into fermions, thereby shutting off Bose enhancement. Estimates of non-Abelian interactions indicate that they will not suppress preheating into gauge bosons for ξ 1000.1 For inflation on the flat plateau one should consider ξ 440 (e.g. [20]). In models of hilltop or inflection point inflation, smaller values of ξ are possible, although UV corrections are expected to be larger. In order to provide a treatment of Higgs inflation as complete as possible without referring to specific unknown physics, we choose to consider a broad range of non-minimal couplings that go below ξ ≈ 400. 2 See [25] for a way to alter the predictions of α-attractor models through multi-field effects.

Some like it hot: R2 heals Higgs inflation, but does not cool it

“…Therefore, even though both R 2 -healed and "pure" Higgs inflation reheat via the generation of longitudinal weak gauge bosons, the underlying dynamics are rather different. In particular, we confirm that the spike in the mass of the longitudinal gauge bosons [24][25][26] does not produce the weak bosons in the amount sufficient for reheating [30].…”

“…As the two coupled scalars (14) begin to oscillate, they produce particles and eventually can reheat the Universe. Since particle production in pure R 2 -inflation [32][33][34] exploits very slow gravitational dynamics, rather than the fast electroweak dynamics that cause reheating in pure Higgs inflation [21,22,26], one expects the Higgs homogeneous fields to be responsible for the early-time reheating in the mixed Higgs-R 2 case. Particle production in the scalar sector (scalarons and Higgs bosons) is described by the following quadratic action (derived from (4) and (5)) for inhomogeneous perturbations H(t, x) andΦ(t, x),…”

“…The crucial ingredient -the evolution of longitudinal components of the weak gauge bosonswas missed there. The dependence of this component on the external Higgs field (inflaton) turns out to be spiky [24][25][26], leading to violent production of longitudinal modes of the weak gauge bosons and very rapid reheating of the Universe. This finding is dangerous due to the strong coupling problem, since the reheating dynamics happen right inside the strong coupling domain, making any analysis unreliable.…”

Dynamical emergence of scalaron in Higgs inflation

“…18 An interesting feature is that its mass squared diverges at the energy scale µ 1 at which α 1 vanishes, and becomes tachyonic above µ 1 . It might 17 The spin-2 (d-wave) part of the self-healed amplitude in our theory also develops a pole. Its residue has an opposite sign from that of the spin-0 (s-wave) part, as long as the poles are not tachyonic.…”

Nonlinear Dynamics of Preheating after Multifield Inflation with Nonminimal Couplings

“…In this Letter we significantly expand this work, employing lattice simulations to study the complete preheating phase, deep into the nonlinear regime. We restrict attention to coupled scalar fields, and neglect the production of Standard Model particles such as fermions or gauge fields [20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Nonetheless, we are able to analyze the typical timescales required for the Universe to achieve a radiationdominated EOS; for the produced particles to backreact on the inflaton condensate, ultimately draining away its energy; and for rescattering among the particles to yield a thermal spectrum.…”