Scalar field dynamics in Friedmann-Robertson-Walker spacetimes

Boyanovsky, D.; Cormier, D.; Vega, H. J. de; Holman, R.; Singh, Anupam; Srednicki, Mark

doi:10.1103/physrevd.56.1939

Cited by 125 publications

(152 citation statements)

References 39 publications

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“…[3,4,8]. In summary, quadratic and logarithmic divergences are absorbed in the mass term while the coupling constant absorbs a logarithmically divergent piece [4,7]. The renormalized quantum fluctuations take the form…”

Section: Evolution Equationsmentioning

confidence: 99%

Nonequilibrium dynamics in quantum field theory at high density: The “tsunami”

Cao

Vega

2001

Phys. Rev. D

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The dynamics of a dense relativistic quantum fluid out of thermodynamic equilibrium is studied in the framework of the Φ 4 scalar field theory in the large N limit. The time evolution of a particle distribution in momentum space (the tsunami) is computed. The effective mass felt by the particles in such a high density medium equals the tree level mass plus the expectation value of the squared field. The case of negative tree level squared mass is particularly interesting. In such case dynamical symmetry restoration as well as dynamical symmetry breaking can happen. Furthermore, the symmetry may stay broken with vanishing asymptotic squared mass showing the presence of out of equilibrium Goldstone bosons. We study these phenomena and identify the set of initial conditions that lead to each case. We compute the equation of state which turns to depend on the initial state. Although the system does not thermalize, the equation of state for asymptotically broken symmetry is of radiation type. We compute the correlation functions at equal times. The two point correlator for late times is the sum of different terms. One stems from the initial particle distribution. Another term accounts for the out of equilibrium Goldstone bosons created by spinodal unstabilities when the symmetry is asymptotically broken. Both terms are of the order of the inverse of the coupling for distances where causal signals can connect the two points. The contribution of the out of equilibrium Goldstones exhibits scaling behaviour in a generalized sense. 11.15.Pg,11.30.Qc

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Section: Evolution Equationsmentioning

confidence: 99%

Nonequilibrium dynamics in quantum field theory at high density: The “tsunami”

Cao

Vega

2001

Phys. Rev. D

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“…In the next section we recall the CTP formalism, using a variation of the Keldyshbasis, and apply it to φ 3 theory on a de Sitter background (for other applications of the CTP formalism to interacting fields in cosmology see [39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56]). Subsequently we analyze contributions to correlation functions with small external momenta, that are generated after horizon exit (but still during inflation).…”

Section: Introductionmentioning

confidence: 99%

Classical approximation to quantum cosmological correlations

Meulen¹,

Smit²

2007

J. Cosmol. Astropart. Phys.

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Abstract:We investigate up to which order quantum effects can be neglected in calculating cosmological correlation functions after horizon exit. As a toy model, we study φ 3 theory on a de Sitter background for a massless minimally coupled scalar field φ. We find that for tree level and one loop contributions in the quantum theory, a good classical approximation can be constructed, but for higher loop corrections this is in general not expected to be possible. The reason is that loop corrections get non-negligible contributions from loop momenta with magnitude up to the Hubble scale H, at which scale classical physics is not expected to be a good approximation to the quantum theory. An explicit calculation of the one loop correction to the two point function, supports the argument that contributions from loop momenta of scale H are not negligible. Generalization of the arguments for the toy model to derivative interactions and the curvature perturbation leads to the conclusion that the leading orders of non-Gaussian effects generated after horizon exit, can be approximated quite well by classical methods. Furthermore we compare with a theorem by Weinberg. We find that growing loop corrections after horizon exit are not excluded, even in single field inflation.

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“…Nonequilibrium dynamics in quantum field theory has become, during the last years, a very active field of research in particle physics [1][2][3][4][5][6], in cosmology [7][8][9][10][11][12][13][14][15][16][17][18][19][20] , and in solid state physics [21]. The outline of typical computational experiments is as follows: a quantum field ψ(x, t) is driven by a classical field degree of freedom (Higgs, inflaton, condensate) φ(t) which takes an initial value away from a local or global minimum of the classical or effective action; the time development is then studied including the back reaction of the quantum field in one-loop, Hartree or large-N approximations.…”

Section: Introductionmentioning

confidence: 99%

Choice of initial states in nonequilibrium dynamics

1998

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Imposing initial conditions to nonequilibrium systems at some time t 0 leads, in renormalized quantum field theory, to the appearance of singularities in the variable t−t 0 in relevant physical quantities, such as energy density and pressure. These "initial singularities" can be traced back to the choice of initial state. We construct here, by a Bogoliubov transformation, initial states such that these singularities are eliminated. While the construction is not unique it can be considered a minimal way of taking into account the nonequilibrium evolution of the system prior to t 0 .1

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Scalar field dynamics in Friedmann-Robertson-Walker spacetimes

Cited by 125 publications

References 39 publications

Nonequilibrium dynamics in quantum field theory at high density: The “tsunami”

Nonequilibrium dynamics in quantum field theory at high density: The “tsunami”

Classical approximation to quantum cosmological correlations

Choice of initial states in nonequilibrium dynamics

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