Running couplings from adiabatic regularization

Ferreiro, Antonio; Navarro-Salas, José

doi:10.1016/j.physletb.2019.03.026

Cited by 29 publications

(65 citation statements)

References 47 publications

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“…With this new choice the adiabatic expansion can be recalculated, giving us slightly different subtraction terms. An exhaustive analysis of this ambiguity can be found in [46]. The ambiguity on the subtractions, leads to an ambiguity on the physical observables.…”

Section: Appendix B: Matching Hadamard Coefficients With Scalar Adiabmentioning

confidence: 99%

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Adiabatic regularization for Dirac fields in time-varying electric backgrounds

2020

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The adiabatic regularization method was originally proposed by Parker and Fulling to renormalize the energy-momentum tensor of scalar fields in expanding universes. It can be extended to renormalize the electric current induced by quantized scalar fields in a time-varying electric background. This can be done in a way consistent with gravity if the vector potential is considered as a variable of adiabatic order one. Assuming this, we further extend the method to deal with Dirac fields in four spacetime dimensions. This requires a self-consistent ansatz for the adiabatic expansion, in presence of a prescribed time-dependent electric field, which is different from the conventional expansion used for scalar fields. Our proposal is consistent, in the massless limit, with the conformal anomaly. We also provide evidence that our proposed adiabatic expansion for the fermionic modes parallels the Schwinger-DeWitt adiabatic expansion of the two-point function. We give the renormalized expression of the electric current and analyze, using numerical and analytical tools, the pair production induced by a Sauter-type electric pulse. We also analyze the scaling properties of the current for a large field strength.

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Section: Appendix B: Matching Hadamard Coefficients With Scalar Adiabmentioning

confidence: 99%

“…III A. However, there exist an inherent ambiguity in the method [46]. It is possible to choose a slightly different expression for the leading term…”

Section: Introduction Of a Mass Scale And Renormalization Ambiguitiesmentioning

confidence: 99%

Adiabatic regularization for Dirac fields in time-varying electric backgrounds

2020

Self Cite

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“…For related studies, see e.g. [54][55][56][57] and [58][59][60][61][62], some of them extending the subject to the context of supersymmetric theories [68][69][70] and also to supergravity [71]. More recently the matter has also been addressed successfully in the framework of the effective action of string theories [72][73][74].…”

Section: Introductionmentioning

confidence: 99%

“…This renormalization method is based on the WKB approximation of the field modes in the expanding universe. We perform the cal-culation in two ways, one through a modified form of the ARP [61] and the second (presented in one appendix) involving dimensional regularization (DR). The common result is that the properly renormalized VED, obtained upon inclusion of the renormalized value of ρ at a given scale, does not contain the unwanted contributions proportional to the fourth power of the particle masses (∼ m 4 ) and hence it is free from large induced corrections to the VED.…”

Section: Introductionmentioning

confidence: 99%

Running vacuum in quantum field theory in curved spacetime: renormalizing $$\rho _{vac}$$ without $$\sim m^4$$ terms

2020

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The $$\Lambda $$Λ-term in Einstein’s equations is a fundamental building block of the ‘concordance’ $$\Lambda $$ΛCDM model of cosmology. Even though the model is not free of fundamental problems, they have not been circumvented by any alternative dark energy proposal either. Here we stick to the $$\Lambda $$Λ-term, but we contend that it can be a ‘running quantity’ in quantum field theory (QFT) in curved space time. A plethora of phenomenological works have shown that this option can be highly competitive with the $$\Lambda $$ΛCDM with a rigid cosmological term. The, so-called, ‘running vacuum models’ (RVM’s) are characterized by the vacuum energy density, $$\rho _{vac}$$ρvac, being a series of (even) powers of the Hubble parameter and its time derivatives. Such theoretical form has been motivated by general renormalization group arguments, which look plausible. Here we dwell further upon the origin of the RVM structure within QFT in FLRW spacetime. We compute the renormalized energy-momentum tensor with the help of the adiabatic regularization procedure and find that it leads essentially to the RVM form. This means that $$\rho _{vac}(H)$$ρvac(H) evolves as a constant term plus dynamical components $${{\mathcal {O}}}(H^2)$$O(H2) and $$\mathcal{O}(H^4)$$O(H4), the latter being relevant for the early universe only. However, the renormalized $$\rho _{vac}(H)$$ρvac(H) does not carry dangerous terms proportional to the quartic power of the masses ($$\sim m^4$$∼m4) of the fields, these terms being a well-known source of exceedingly large contributions. At present, $$\rho _{vac}(H)$$ρvac(H) is dominated by the additive constant term accompanied by a mild dynamical component $$\sim \nu H^2$$∼νH2 ($$|\nu |\ll 1$$|ν|≪1), which mimics quintessence.

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“…The method of adiabatic subtraction for regularization of both cases scalar and spinor QED in an expanding universe has been extensively studied in Refs. [99][100][101][102]. In this paper our main goals are investigation of the induced energy-momentum tensor of the Dirac field in de Sitter QED and further exploring validity of the adiabatic subtraction regularization.…”

Section: Introductionmentioning

confidence: 99%

Induced energy-momentum tensor of a Dirac field in 2D de Sitter QED

Botshekananfard

Bavarsad

2020

Phys. Rev. D

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We compute the expectation value of the energy-momentum tensor in the in-vacuum state of the quantized Dirac field coupled to a uniform electric field background on the Poincaré path of the two dimensional de Sitter spacetime (dS 2 ). The adiabatic regularization scheme is applied to remove the ultraviolet divergencies from the expressions. We find, the off-diagonal components of the induced energy-momentum tensor vanishes and the absolute values of the diagonal components are increasing functions of the electric field which decrease as the Dirac field mass increases. We derive the trace anomaly of the induced energy-momentum tensor, which agrees precisely with the trace anomaly derived earlier in the literature. We have discusses the backreaction of the induced energy-momentum tensor on the gravitational field.

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Running couplings from adiabatic regularization

Cited by 29 publications

References 47 publications

Adiabatic regularization for Dirac fields in time-varying electric backgrounds

Adiabatic regularization for Dirac fields in time-varying electric backgrounds

Running vacuum in quantum field theory in curved spacetime: renormalizing $$\rho _{vac}$$ without $$\sim m^4$$ terms

Induced energy-momentum tensor of a Dirac field in 2D de Sitter QED

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