Boltzmann or Bogoliubov? Approaches compared in gravitational particle production

We study cosmological gravitational particle production as applied to “rapid-turn” models of inflation involving two scalar fields. We are interested in the production of massive spin-0 particles that only interact gravitationally and provide a candidate for the dark matter. Specifically, we study two models of rapid-turn multifield inflation, motivated in part by the de Sitter swampland conjecture, that are distinguished by the curvature of field space and the presence or absence of field space ‘angular momentum’ conservation. We find that one of these models leads to insufficient particle production and cannot explain the observed dark matter relic abundance. The second model is able to explain the origin of spin-0 dark matter via gravitational production, and we identify the relevant region of parameter space that is consistent with measurements of the dark-matter relic abundance, the dark-matter-photon isocurvature perturbations, and the spectrum of curvature perturbations that is probed by cosmological observations. Our work demonstrates the compatibility of the de Sitter swampland conjecture with completely dark matter.

Section: Jhep02(2023)181mentioning

confidence: 99%

Completely dark matter from rapid-turn multifield inflation

Kolb

Long

McDonough

et al. 2023

“…In this subsection, we calculate the energy gain E of the SM radiation due to the Higgs pair production at the expense of the inflaton field. The process that is considered is a quantum production from a vacuum state, |0 , to the two-Higgs-boson final state, |hh , in the presence of the classical inflaton field, see also [13,26,30,47,48]. Due to the energy conservation, the energy density gained by the Higgs pair production from the vacuum must be equal to the energy loss of the inflaton field.…”

Section: Higgs Boson Production From Oscillating Inflatonmentioning

confidence: 99%

Higgs boson induced reheating and ultraviolet frozen-in dark matter

Ahmed

Grza̧dkowski

Socha

2023

A reheating phase in the early universe is an essential part of all inflationary models during which not only the Standard Model (SM) quanta are produced but it can also shed light on the production of dark matter. In this work, we explore a class of reheating models where the reheating is induced by a cubic interaction of the inflaton ϕ to the SM Higgs boson h of the form ghϕMPlϕ|h|2 adopting the α-attractor T-model of inflation. Assuming inflaton as a background field such interaction implies a ϕ-dependent mass term of the Higgs boson and a non-trivial phase-space suppression of the reheating efficiency. As a consequence, the reheating is prolonged and the maximal temperature of the SM thermal bath is reduced. In particular, due to oscillations of the inflaton field the ϕ-dependent Higgs boson mass results in periodic transitions between phases of broken and unbroken electroweak gauge symmetry. The consequences of these rapid phase transitions have been studied in detail. A purely gravitational reheating mechanism in the presence of the inflaton background, i.e., for ghϕ = 0, has also been investigated. It turned out that even though it may account for the total production of SM radiation in the absence of ghϕ, its contribution to the reheating is subdominant for the range of ghϕ considered in this work. Approximate analytical solutions of Boltzmann equations for energy densities of the inflaton and SM radiation have been obtained. As a dark matter candidate a massive Abelian vector boson, Xμ, has been considered. Various production mechanisms of Xμ have been discussed including (i) purely gravitational production from the inflaton background, (ii) gravitational freeze-in from the SM quanta, (iii) inflaton decay through a dim-5 effective operator, and (iv) Higgs portal freeze-in and Higgs decay through a dim-6 effective operator. Parameters that properly describe the observed relic abundance have been determined.

“…In situations where there are coherent oscillations of the inflaton, some contributions to GPP can be interpreted as coming from scattering of the inflaton quanta into χs via graviton exchange [16,21,59,62]. Below, we explain a novel computation of this coefficient that gives not only the amplitudes of nφ → 2χ during the inflaton coherent oscillations, but also the interference between amplitudes with different n ≥ 1.…”

Section: Jhep12(2022)108 3 Novel Computation Of the Bogoliubov Coeffi...mentioning

confidence: 99%

Quantum interference in gravitational particle production

Basso

Chung

Kolb

et al. 2022

Previous numerical investigations of gravitational particle production during the coherent oscillation period of inflation displayed unexplained fluctuations in the spectral density of the produced particles. We argue that these features are due to the quantum interference of the coherent scattering reactions that produce the particles. We provide accurate analytic formulae to compute the particle production amplitude for a conformally- coupled scalar field, including the interference effect in the kinematic region where the production can be interpreted as inflaton scattering into scalar final states via graviton exchange.