Quantized Fields and Particle Creation in Expanding Universes. I

Parker, Leonard

doi:10.1103/physrev.183.1057

Cited by 1,334 publications

(1,272 citation statements)

References 7 publications

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“…We find that the predicted rate of particle production during the recent vacuum-dominated era is the same as that found by other methods. It has been shown [24] that this production rate also agrees with that found by the Bogolubov transformation technique [8,31]. This agreement of the particle production rate given by the imaginary part of our effective action, adds confidence to the validity of the acceleration resulting from the real part of the same term in the effective action.…”

Section: Discussionsupporting

confidence: 85%

“…The imaginary part of the effective action is related to the probability of the production of at least one pair of particles [8], following Schwinger [22]. When the imaginary part is small, this probability is given by…”

Section: Particle Production and Effective Temperaturementioning

confidence: 99%

“…Renormalization methods have long been extended to quantized fields propagating in the curved spacetime of general relativity [6] (see also [7] and references therein), but predicted quantum vacuum effects of curved spacetime have been too small to be directly observed. Quantum vacuum effects in curved spacetimes have also been explored in connection with particle creation by the expansion of the universe and by black holes [8,9]. In addition, vacuum effects of self-interacting scalar fields have been invoked to produce inflation of the very early universe [10].…”

Section: Introductionmentioning

confidence: 99%

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Erratum: New quantum aspects of a vacuum-dominated universe [Phys. Rev. D62, 083503 (2000)]

Parker¹,

Raval²

2003

Phys. Rev. D

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In a new model that we proposed, nonperturbative vacuum contributions to the effective action of a free quantized massive scalar field lead to a cosmological solution in which the scalar curvature becomes constant after a time tj (when the redshift z ∼ 1) that depends on the mass of the scalar field and its curvature coupling. This spatially-flat solution implies an accelerating universe at the present time and gives a good one-parameter fit to high-redshift Type Ia supernovae (SNe-Ia) data, and the present age and energy density of the universe. Here we show that the imaginary part of the nonperturbative curvature term that causes the cosmological acceleration, implies a particle production rate that agrees with predictions of other methods and extends them to non-zero mass fields. The particle production rate is very small after the transition and is not expected to alter the nature of the cosmological solution. We also show that the equation of state of our model undergoes a transition at tj from an equation of state dominated by non-relativistic pressureless matter (without a cosmological constant) to an effective equation of state of mixed radiation and cosmological constant, and we derive the equation of state of the vacuum. Finally, we explain why nonperturbative vacuum effects of this ultralow-mass particle do not significantly change standard early universe cosmology.

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Section: Discussionsupporting

confidence: 85%

Section: Particle Production and Effective Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Erratum: New quantum aspects of a vacuum-dominated universe [Phys. Rev. D62, 083503 (2000)]

Parker¹,

Raval²

2003

Phys. Rev. D

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“…Quite generically a quantum field coupled to a curved background leads to the creation of quanta which is often called cosmological particle production [37][38][39][40][41], or in the case of a black hole, Hawking radiation [42,43]. Also in flat space there are closely related processes: in Schwinger pair creation particles are produced due to a background electric field [44] (for a recent review, see [45]) and in the Unruh effect because of constant acceleration [46].…”

Section: Introductionmentioning

confidence: 99%

Massive scalar field evolution in de Sitter

Markkanen

Rajantie

2017

J. High Energ. Phys.

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The behaviour of a massive, non-interacting and non-minimally coupled quantised scalar field in an expanding de Sitter background is investigated by solving the field evolution for an arbitrary initial state. In this approach there is no need to choose a vacuum in order to provide a definition for particle states, nor to introduce an explicit ultraviolet regularization. We conclude that the expanding de Sitter space is a stable equilibrium configuration under small perturbations of the initial conditions. Depending on the initial state, the energy density can approach its asymptotic value from above or below, the latter of which implies a violation of the weak energy condition. The backreaction of the quantum corrections can therefore lead to a phase of super-acceleration also in the non-interacting massive case.

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“…Particle creation from non-vacuum initial states was considered in many papers; in the cosmological case -beginning with the pioneering paper by Parker [12], see the recent review [13] for many references. However, the primary quantities studied in these papers were the number of created particles and the average value of the energy-momentum tensor of a quantum field on a FRW background.…”

Section: Introductionmentioning

confidence: 99%

Quantum-to-classical transition of cosmological perturbations for non-vacuum initial states

1997

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Transition from quantum to semiclassical behaviour and loss of quantum coherence for inhomogeneous perturbations generated from a non-vacuum initial state in the early Universe is considered in the Heisenberg and the Schrödinger representations, as well as using the Wigner function. We show explicitly that these three approaches lead to the same prediction in the limit of large squeezing (i.e. when the squeezing parameter |r k | → ∞): each two-modes quantum state (k, − k) of these perturbations is equivalent to a classical perturbation that has a stochastic amplitude, obeying a non-gaussian statistics which depends on the initial state, and that belongs to the quasi-isotropic mode (i.e. it possesses a fixed phase). The Wigner function is not everywhere positive for any finite r k , hence its interpretation as a classical distribution function in phase space is impossible without some coarse graining procedure. However, this does not affect the transition to semiclassical behaviour since the Wigner function becomes concentrated near a classical trajectory in phase space when |r k | → ∞ even without coarse graining. Deviations of the statistics of the perturbations in real space from a Gaussian one lie below the cosmic variance level for the N -particles initial states with N = N (|k|) but may be observable for other initial states without statistical isotropy or with correlations between different k modes. As a way to look for this effect, it is proposed to measure 0 the kurtosis of the angular fluctuations of the cosmic microwave background temperature.

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Quantized Fields and Particle Creation in Expanding Universes. I

Cited by 1,334 publications

References 7 publications

Erratum: New quantum aspects of a vacuum-dominated universe [Phys. Rev. D62, 083503 (2000)]

Erratum: New quantum aspects of a vacuum-dominated universe [Phys. Rev. D62, 083503 (2000)]

Massive scalar field evolution in de Sitter

Quantum-to-classical transition of cosmological perturbations for non-vacuum initial states

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