Decay of a scalar condensate in two different approaches

Abstract

Decay of a scalar condensate via interactions with (quasi-)particles is of interest to many fields in physics, including cosmology. In cosmology, the decay of an inflaton condensate leads to the production of daughter particles and reheating of the Universe. In computing the decay rate, two quantum field theoretic approaches can be found in the literature: one is based on parametric resonance of mode functions of the daughter particle; another is based on the $S$-matrix of a coherent state and Feynman-diagrammatic perturbation theory. We modify the latter from the previous literature in a way that manifests what we are computing and does not include unwanted Feynman diagrams. We notice the equivalence of these two approaches and demonstrate it by explicitly computing the decay rate at lower orders in the double expansion of the amplitude of coherent oscillation (or narrow resonance) and velocity of the daughter particle.

32 pages, 6 figures, version accepted for publication in JHEP

References in corpus (11)

• Warm Inflation and its Microphysical Basis
• Primordial Curvature Fluctuation and Its Non-Gaussianity in Models with Modulated Reheating
• Inflaton Oscillations and Post-Inflationary Reheating
• Gravitational portals in the early Universe
• Gravitational Portals with Non-Minimal Couplings
• Implications of time-dependent inflaton decay on reheating and dark matter production
• Decay of Scalar Condensation in Quantum Field Theory
• Dissipation of oscillating scalar backgrounds in an FLRW universe
• Non-perturbative Corrections to Particle Production from Coherent Oscillation
• Fate of homogeneous ${\mathbb{Z}}_2$-symmetric scalar condensates
• QFT approach to dressed particle processes in preheating and non-perturbative mechanism in kinematically-forbidden regime