Particle creation and warm inflation

Aarts, Gert; Tranberg, Anders

doi:10.1016/j.physletb.2007.04.055

Cited by 13 publications

(15 citation statements)

References 27 publications

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“…In this respect we have a different situation than the one considered in the original work on the two stage mechanism [15,16] and more recent numerical work [23]. In fact, we find that the local dissipative effects cease in the limit that the temperature T → 0, as one might expect and in agreement with [17,23].…”

Section: Introductionsupporting

confidence: 43%

Local approximations for effective scalar field equations of motion

2007

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Fluctuation and dissipation dynamics is examined at all temperature ranges for the general case of a background time evolving scalar field coupled to heavy intermediate quantum fields which in turn are coupled to light quantum fields. The evolution of the background field induces particle production from the light fields through the action of the intermediate catalyzing heavy fields. Such field configurations are generically present in most particle physics models, including Grand Unified and Supersymmetry theories, with application of this mechanism possible in inflation, heavy ion collision and phase transition dynamics. The effective evolution equation for the background field is obtained and a fluctuation-dissipation theorem is derived for this system. The effective evolution in general is nonlocal in time. Appropriate conditions are found for when these time nonlocal effects can be approximated by local terms. Here careful distinction is made between a local expansion and the special case of a derivative expansion to all orders, which requires analytic behavior of the evolution equation in Fourier space.

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Section: Introductionsupporting

confidence: 43%

Local approximations for effective scalar field equations of motion

2007

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“…In section III we consider several models of particle production that could arise during inflation, starting with the oscillating and slowly-evolving models, for which particle production rates are well-known and easily checked, and then we apply our method to the catalysed decay.In section IV we use the production rates calculated in the previous section to take a closer look at the evolution of a system which may be expanding and departing from thermal equilibrium. Thermalisation has previously been considered in the context of reheating through numerical solution of classical non-linear field theory [23,24] or using a numerical solution for the non-equilibrium particle propagators [25,26]. We solve the Boltzmann equation in an expanding universe with a source term representing particle production.…”

mentioning

confidence: 99%

Particle production and reheating of the inflationary universe

Moss

Graham

2008

Phys. Rev. D

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Thermal field theory is applied to particle production rates in inflationary models, leading to new results for catalysed or two-stage decay, where massive fields act as decay channels for the production of light fields. A numerical investigation of the Boltzmann equation in an expanding universe shows that the particle distributions produced during small amplitude inflaton oscillations or even alongside slowly moving inflaton fields can thermalise. I. INTRODUCTIONInflationary models give a picture of the early universe that has shown spectacular agreement with observation [1,2,3]. All inflationary models require a mechanism for reheating the universe to take it from the vacuum dominated inflationary phase to the hot radiation-dominated universe which we know must follow. The details of particular reheating mechanisms depend on the interactions between the inflaton and other fields, but the underlying process is particle production which fills the universe with radiation.The original work on reheating in the 1980's introduced particle production in an ad hoc fashion, assuming the rate of particle production by the inflaton φ in the limit of smallφ was proportional toφ n [4, 5, 6]. Most authors settled for n = 2, which has the advantage of being equivalent to a simple friction term in the inflaton equation of motion. At around the same time, a less ad hoc approach was based on particle production caused by an inflaton field oscillating about the minimum of the inflaton potential after the end of inflation [7,8]. This latter approach appeared to be the more consistent, and it is still widely used today.Following this early work, there where several attempts to apply new ideas in thermal field theory to the reheating process. These usually focused on finding effective field equations for the inflaton. The small-φ equation of motion was derived first, using linear response theory [9,10]. This has been used in the theory of warm inflation [11,12,13]. More general forms of the inflaton field equation, which where not limited to small time derivatives and could be applied to the oscillating inflaton, followed later [14,15,16].Renewed interest in particle production was ignited by the discovery of preheating, a nonperturbative process of inflaton decay though parametric resonance [17,18,19,20,21]. Like the earlier work, preheating involves particle production from an oscillating inflaton field. Preheating is a result of very large amplitude oscillations in the inflaton field. Large amplitude oscillations are a feature, though not necessarily a desirable one, of most single-field inflationary models.Preheating may or may not occur depending on the details of the particle model. In this paper we shall focus on models with a mechanism which we call catalysed or two-stage decay [22]. Unlike in the case of pre-heating, we examine what happens when the fields coupled to the inflaton are too massive to be produced directly. Instead, the fields can act as decay channels for the production of light fields. This requires the kind ...

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“…Using eqs. (17,18) and transforming to spatial momentum space yields the Kadanoff-Baym equations for G F (x 0 , y 0 , k) and G ρ (x 0 , y 0 , k) for spatially homogeneous non-Gaussian initial states,…”

Section: E Kadanoff-baym Equations For Non-gaussian Initial Statesmentioning

confidence: 99%

“…for baryogenesis and leptogenesis), and in situations where a single effective description does not exist (e.g. for (p)reheating by inflaton decay and subsequent thermalization) [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Kadanoff-Baym equations with non-Gaussian initial conditions: The equilibrium limit

Garny

Müller

2009

Phys. Rev. D

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The nonequilibrium dynamics of quantum fields is an initial-value problem, which can be described by Kadanoff-Baym equations. Typically, and in particular when numerical solutions are demanded, these Kadanoff-Baym equations are restricted to Gaussian initial states. However, physical initial states are non-Gaussian correlated initial states. In particular, renormalizability requires the initial state to feature n-point correlations that asymptotically agree with the vacuum correlations at short distances. In order to identify physical nonequilibrium initial states, it is therefore a precondition to describe the vacuum correlations of the interacting theory within the nonequilibrium framework. In this paper, Kadanoff-Baym equations for non-Gaussian correlated initial states describing vacuum and thermal equilibrium are derived from the 2PI effective action. A diagrammatic method for the explicit construction of vacuum and thermal initial correlations from the 2PI effective action is provided. We present numerical solutions of Kadanoff-Baym equations for a real scalar Φ 4 quantum field theory which take the thermal initial 4-point correlation as the leading non-Gaussian correction into account. We find that this minimal non-Gaussian initial condition yields an approximation to the complete equilibrium initial state that is quantitatively and qualitatively significantly improved as compared to Gaussian initial states.

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Particle creation and warm inflation

Cited by 13 publications

References 27 publications

Local approximations for effective scalar field equations of motion

Local approximations for effective scalar field equations of motion

Particle production and reheating of the inflationary universe

Kadanoff-Baym equations with non-Gaussian initial conditions: The equilibrium limit

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