Effective action for cosmological scalar fields at finite temperature

Cheung, Yeuk-Kwan E.; Drewes, Marco; Kang, Jin U.; Kim, Jong Chol

doi:10.1007/jhep08(2015)059

Cited by 22 publications

(65 citation statements)

References 146 publications

(389 reference statements)

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“…The calculations of these quantities using Feynman diagrams make up the major part of work reported in this article. If we set H to 0, our results match up with those obtained, in [1], using a Minkowski-space propagator in loops. In addition we observe non-trivial features that are not revealed in flat spacetime.…”

Section: Introductionsupporting

confidence: 79%

Dynamics of scalar fields in an expanding/contracting cosmos at finite temperature *

Ming

Cheung

2020

Chinese Phys. C

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This paper extends the study of the quantum dissipative effects of a cosmological scalar field by taking into account the cosmic expansion and contraction. Cheung, Drewes, Kang and Kim [1] calculated the effective action and quantum dissipative effects of a cosmological scalar field. The analytic expressions for the effective potential and damping coefficient were presented using a simple scalar model with quartic interaction. Their work was done using Minkowski-space propagators in loop diagrams. In this work we incorporate the Hubble expansion and contraction of the comic background, and focus on the thermal dynamics of a scalar field in a regime where the effective potential changes slowly. We let the Hubble parameter, H, attain a small but non-zero value and carry out calculations to first order in H. If we set H = 0 all results match those [1] in flat spacetime. Interestingly we have to integrate over the resonances, which in turn leads to an amplification of the effects of a non-zero H. This is an intriguing phenomenon which cannot be uncovered in flat spacetime. The implications on particle creations in the early universe will be studied in a forthcoming work.

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Section: Introductionsupporting

confidence: 79%

Dynamics of scalar fields in an expanding/contracting cosmos at finite temperature *

Ming

Cheung

2020

Chinese Phys. C

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“…There have been some re-derivations of equations of the type (2) in the literature [35][36][37][38][39][40][41], most recently [42]. In the following we will assume that (2) holds during reheating and discuss the individual terms.…”

Section: Equation Of Motion For ϕmentioning

confidence: 99%

“…The equation of motion for φ would contain a noise term, see e.g. [36][37][38][39]42]. 5 See [43] for a different viewpoint.…”

Section: How the Reheating Era Affects The Cmbmentioning

confidence: 99%

What can the CMB tell about the microphysics of cosmic reheating?

Drewes

2016

J. Cosmol. Astropart. Phys.

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In inflationary cosmology, cosmic reheating after inflation sets the initial conditions for the hot big bang. We investigate how CMB data can be used to study the effective potential and couplings of the inflaton during reheating and constrain the underlying microphysics. If there is a phase of preheating that is driven by a parametric resonance or other instability, then the thermal history and expansion history during the reheating era depend on a large number of microphysical parameters in a complicated way. In this case the connection between CMB observables and microphysical parameters can only established with intense numerical studies. Such studies can help to improve CMB constraints on the effective inflaton potential in specific models, but parameter degeneracies usually make it impossible to extract meaningful best-fit values for individual microphysical parameters. If, on the other hand, reheating is driven by perturbative processes, then it can be possible to constrain the inflaton couplings and the reheating temperature from CMB data. This provides an indirect probe of fundamental microphysical parameters that most likely can never be measured directly in the laboratory, but have an immense impact on the evolution of the cosmos by setting the stage for the hot big bang.

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“…The spectral self-energy Π − p from the setting-sun diagram in Fig. 14 has a general expression [44,84]…”

Section: Discussionmentioning

confidence: 99%

“…In cases where it is significant, it is generally not justified to use an effective kinetic equation of the form (3), the validity of which is based on a strong hierarchy between the microscopic timescale ∼ 1/m φ and the macroscopic time scales 1/Γ and 1/H, cf. e.g [44,53]…”

mentioning

confidence: 99%

CMB constraints on the inflaton couplings and reheating temperature in α-attractor inflation

Drewes

Kang

Mun³

2017

J. High Energ. Phys.

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We study reheating in α-attractor models of inflation in which the inflaton couples to other scalars or fermions. We show that the parameter space contains viable regions in which the inflaton couplings to radiation can be determined from the properties of CMB temperature fluctuations, in particular the spectral index. This may be the only way to measure these fundamental microphysical parameters, which shaped the universe by setting the initial temperature of the hot big bang and contain important information about the embedding of a given model of inflation into a more fundamental theory of physics. The method can be applied to other models of single field inflation.

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Effective action for cosmological scalar fields at finite temperature

Cited by 22 publications

References 146 publications

Dynamics of scalar fields in an expanding/contracting cosmos at finite temperature *

Dynamics of scalar fields in an expanding/contracting cosmos at finite temperature *

What can the CMB tell about the microphysics of cosmic reheating?

CMB constraints on the inflaton couplings and reheating temperature in α-attractor inflation

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