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Author Ferreiro, A.; Navarro-Salas, J.; Pla, S. url  doi
openurl 
  Title R-summed form of adiabatic expansions in curved spacetime Type Journal Article
  Year 2020 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 101 Issue 10 Pages 105011 - 12pp  
  Keywords  
  Abstract The Feynman propagator in curved spacetime admits an asymptotic (Schwinger-DeWitt) series expansion in derivatives of the metric. Remarkably, all terms in the series containing the Ricci scalar R can be summed exactly. We show that this (nonperturbative) property of the Schwinger-DeWitt series has a natural and equivalent counterpart in the adiabatic (Parker-Fulling) series expansion of the scalar modes in an homogeneous cosmological spacetime. The equivalence between both R-summed adiabatic expansions can be further extended when a background scalar field is also present.  
  Address [Ferreiro, Antonio] Univ Valencia, CSIC, Fac Fis, Ctr Mixto,Dept Fis Teor, Valencia 46100, Spain, Email: antonio.ferreiro@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000532656100007 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4395  
Permanent link to this record
 
 
Author Navarro-Salas, J.; Pla, S. url  doi
openurl 
  Title (F, G)-summed form of the QED effective action Type Journal Article
  Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 103 Issue 8 Pages L081702 - 7pp  
  Keywords  
  Abstract We conjecture that the proper-time series expansion of the one-loop effective Lagrangian of quantum electrodynamics can be summed in all terms containing the field-strength invariants F = 1/4F F-mu nu(mu nu) (x), G = 1/4 (F) over tilde F-mu nu(mu nu) (x), including those also possessing derivatives of the electromagnetic field strength. This partial resummation is exactly encapsulated in a factor with the same form as the Heisenberg-Euler Lagrangian density, except that now the electric and magnetic fields can depend arbitrarily on spacetime coordinates. We provide strong evidence for this conjecture, which is proved to sixth order in the proper time. Furthermore, and as a byproduct, we generate some solvable electromagnetic backgrounds. We also discuss the implications for a generalization of the Schwinger formula for pair production induced by nonconstant electric fields. Finally, we briefly outline the extension of these results in the presence of gravity.  
  Address [Navarro-Salas, Jose; Pla, Silvia] Univ Valencia, Dept Fis Teor, Valencia 46100, Spain, Email: jnavarro@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000649081100005 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4834  
Permanent link to this record
 
 
Author Pla, S.; Newsome, I.M.; Link, R.S.; Anderson, P.R.; Navarro-Salas, J. url  doi
openurl 
  Title Pair production due to an electric field in 1+1 dimensions and the validity of the semiclassical approximation Type Journal Article
  Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 103 Issue 10 Pages 105003 - 23pp  
  Keywords  
  Abstract Solutions to the backreaction equation in 1 + 1-dimensional semiclassical electrodynamics are obtained and analyzed when considering a time-varying homogeneous electric field initially generated by a classical electric current, coupled to either a quantized scalar field or a quantized spin-1/2 field. Particle production by way of the Schwinger effect leads to backreaction effects that modulate the electric field strength. Details of the particle production process are investigated along with the transfer of energy between the electric field and the particles. The validity of the semiclassical approximation is also investigated using a criterion previously implemented for chaotic inflation and, in an earlier form, semiclassical gravity. The criterion states that the semiclassical approximation will break down if any linearized gauge-invariant quantity constructed from solutions to the linear response equation, with finite nonsingular data, grows rapidly for some period of time. Approximations to homogeneous solutions of the linear response equation are computed and it is found that the criterion is violated when the maximum value, E-max, obtained by the electric field is of the order of the critical scale for the Schwinger effect, E-max similar to E-crit m(2)/q, where m is the mass of the quantized field and q is its electric charge. For these approximate solutions the criterion appears to be satisfied in the extreme limits qE(max)/m(2) << 1 and qE(max)/m(2) >> 1.  
  Address [Pla, Silvia; Navarro-Salas, Jose] Univ Valencia, Ctr Mixto Univ Valencia, Fac Fis, CSIC,Dept Fis Teor, E-46100 Valencia, Spain, Email: silvia.pla@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000655874700008 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4844  
Permanent link to this record
 
 
Author Beltran-Palau, P.; del Rio, A.; Nadal-Gisbert, S.; Navarro-Salas, J. url  doi
openurl 
  Title Note on the pragmatic mode-sum regularization method: Translational-splitting in a cosmological background Type Journal Article
  Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 103 Issue 10 Pages 105002 - 9pp  
  Keywords  
  Abstract The point-splitting renormalization method offers a prescription to calculate finite expectation values of quadratic operators constructed from quantum fields in a general curved spacetime. It has been recently shown by Levi and Ori that when the background metric possesses an isometry, like stationary or spherically symmetric black holes, the method can be upgraded into a pragmatic procedure of renormalization that produces efficient numerical calculations. In this paper we show that when the background enjoys three-dimensional spatial symmetries, like homogeneous expanding universes, the above pragmatic regularization technique reduces to the well-established adiabatic regularization method.  
  Address [Beltran-Palau, Pau; Nadal-Gisbert, Sergi; Navarro-Salas, Jose] Univ Valencia, Dept Fis Teor, Ctr Mixto, CSIC,Fac Fis, Valencia 46100, Spain, Email: pau.beltran@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000655874400009 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4845  
Permanent link to this record
 
 
Author Ferreiro, A.; Nadal-Gisbert, S.; Navarro-Salas, J. url  doi
openurl 
  Title Renormalization, running couplings, and decoupling for the Yukawa model in a curved spacetime Type Journal Article
  Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 104 Issue 2 Pages 025003 - 8pp  
  Keywords  
  Abstract The decoupling of heavy fields as required by the Appelquist-Carazzone theorem plays a fundamental role in the construction of any effective field theory. However, it is not a trivial task to implement a renormalization prescription that produces the expected decoupling of massive fields, and it is even more difficult in curved spacetime. Focused on this idea, we consider the renormalization of the one-loop effective action for the Yukawa interaction with a background scalar field in curved space. We compute the beta functions within a generalized DeWitt-Schwinger subtraction procedure and discuss the decoupling in the running of the coupling constants. For the case of a quantized scalar field, all the beta function exhibit decoupling, including also the gravitational ones. For a quantized Dirac field, decoupling appears almost for all the beta functions. We obtain the anomalous result that the mass of the background scalar field does not decouple.  
  Address [Ferreiro, Antonio; Nadal-Gisbert, Sergi; Navarro-Salas, Jose] Univ Valencia, Fac Fis, Dept Fis Teor, Valencia 46100, Spain, Email: antonio.ferreiro@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000669563900006 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4896  
Permanent link to this record
 
 
Author Beltran-Palau, P.; del Rio, A.; Navarro-Salas, J. url  doi
openurl 
  Title Quantum corrections to the Schwarzschild metric from vacuum polarization Type Journal Article
  Year 2023 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 107 Issue 8 Pages 085023 - 15pp  
  Keywords  
  Abstract We explore static and spherically symmetric solutions of the 4-dimensional semiclassical Einstein's equations using the quantum vacuum polarization of a conformal field as a source. These solutions may be of interest for the study of exotic compact objects (ECOs). The full backreaction problem is addressed by solving the semiclassical Tolman-Oppenheimer-Volkoff (TOV) equations making use of effective equations of state inspired by the trace anomaly and an extra simplifying and reasonable assumption. We combine analytical and numerical techniques to solve the resulting differential equations, both perturbatively and nonperturbatively in h. In all cases the solution is similar to the Schwarzschild metric up p ffiffito the vicinity of the classical horizon r = 2M. However, at r = 2M + epsilon, with epsilon similar to O(root h), we find a coordinate singularity. In the case of matching with a static star, this leads to an upper bound in the compactness, and sets a constraint on the family of stable ECOs. We also study the corrections that the quantum-vacuum polarization induces on the propagation of waves, and discuss the implications. For the pure vacuum case, we can further extend the solution by using appropriate coordinates until we reach another singular point, where this time a null curvature singularity arises and prevents extending beyond. This picture qualitatively agrees with the results obtained in the effective two-dimensional approach, and reinforces the latter as a reasonable method.  
  Address [Beltran-Palau, Pau; Navarro-Salas, Jose] Univ Valencia, Dept Fis Teor, Burjassot 46100, Valencia, Spain, Email: pau.beltran@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000988649200017 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5543  
Permanent link to this record
 
 
Author Nadal-Gisbert, S.; Navarro-Salas, J.; Pla, S. url  doi
openurl 
  Title Low-energy states and CPT invariance at the big bang Type Journal Article
  Year 2023 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 107 Issue 8 Pages 085018 - 16pp  
  Keywords  
  Abstract In this paper, we analyze the quantum vacuum in a radiation-dominated and CPT -invariant universe by further imposing the quantum states to be ultraviolet regular i.e., satisfying the Hadamard/adiabatic condition. For scalar fields, this is enforced by constructing the vacuum via the states of low-energy proposal. For spin -12 fields, we extend this proposal for a FLRW spacetime and apply it for the radiation-dominated and CPT -invariant universe. We focus on minimizing the smeared energy density around the big bang and give strong evidence that the resulting states satisfy the Hadamard/adiabatic condition. These states are then self -consistent candidates as effective big bang quantum vacuum from the field theory perspective.  
  Address [Nadal-Gisbert, Sergi; Navarro-Salas, Jose] Univ Valencia, Ctr Mixto Univ Valencia, CSIC Fac Fis, Dept Fis Teor, Valencia 46100, Spain, Email: sergi.nadal@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000981997800003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5585  
Permanent link to this record
 
 
Author Marañon-Gonzalez, F.J.; Navarro-Salas, J. url  doi
openurl 
  Title Adiabatic regularization for spin-1 fields Type Journal Article
  Year 2023 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 108 Issue 12 Pages 125001 - 11pp  
  Keywords  
  Abstract We analyze the adiabatic regularization scheme to renormalize Proca fields in a four-dimensional Friedmann-Lemaitre-Robertson-Walker spacetime. The adiabatic method is well established for scalar and spin-1/2 fields, but is not yet fully understood for spin-1 fields. We give the details of the construction and show that, in the massless limit, the renormalized stress-energy tensor of the Proca field is closely related to that of a minimally coupled scalar field. Our result is in full agreement with other approaches, based on the effective action, which also show a discontinuity in the massless limit. The scalar field can be naturally regarded as a Stueckelberg-type field. We also test the consistency of our results in de Sitter space.  
  Address [Maranon-Gonzalez, F. Javier; Navarro-Salas, Jose] Univ Valencia, Dept Fis Teor, CSIC, Burjassot 46100, Valencia, Spain, Email: jnavarro@ific.uv.es  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN (up) 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001121689900014 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 5871  
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