Tachyonic production of dark relics: a non-perturbative quantum study

Abstract

We study production of dark relics during reheating after the end of inflation in a system consisting of a non-minimally coupled spectator scalar field and the inflaton. We derive a set of renormalized quantum transport equations for the one-point function and the two-point function of the spectator field and solve them numerically. We find that our system can embody both tachyonic and parametric instabilities. The former is an expected result due to the non-minimal coupling, but the latter displays new features driven by a novel interplay of the two-point function with the Ricci scalar. We find that when the parametric instability driven by the two-point function takes place, it dominates the total particle production. The quantitative results are also found to be highly sensitive to the model parameters.

Late vacuum choice and slow roll approximation in gravitational particle production during reheating

“…Although this particular model, in its simplest version, is ruled out by CMB observations, it allows us to compare our results with previous literature (see e.g. [15,16,19,21,22]), and, furthermore, our analysis can be carried out in the same way for more realistic potentials. The dynamics for the inflaton is analytically solved at the onset of inflation, while the transition to the reheating epoch is modeled numerically.…”

“…The theory of quantum fields in curved spacetimes accommodates a plethora of unexpected phenomena such as Hawking radiation [1], the Unruh effect [2], or entanglement across horizons [3][4][5][6], that have changed our perspective on the interplay between quantum fields and gravity. Gravitational particle production due to the spacetime dynamics [7,8] is one of these phenomena and can be particularly important during the early stages of the universe, since it may be able to explain the dark matter abundance, as it has been extensively discussed in the literature [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The rapidly evolving spacetime during inflation [24][25][26] and the consequent transient to reheating [27][28][29][30][31] can produce a significant density of particles for any field non-conformally coupled to the geometry, regardless of its interaction with other fields.…”

Vector dark matter production during inflation and reheating

“…These ideas have been applied mainly to scalar fields [16][17][18][19][20][21][22][23][24], but also to vectors and fermions in the references [25][26][27][28][29]. Moreover, recent works have shown that if one wants to consider gravitational production to obtain robust constraints on the parameters of the field, a detailed characterization of spacetime dynamics is needed.…”

Quantum transport theory for neutrinos with flavor and particle-antiparticle mixing

“…The true particle-antiparticle mixing on the other hand, is relevant e.g. for particle production in the early universe during the (p)reheating phase after inflation [56,57].…”