Quantum versus classical instability of scalar fields in curved backgrounds

Mendes, Raissa F. P.; Matsas, George E. A.; Vanzella, Daniel A. T.

doi:10.1103/physrevd.89.047503

Cited by 18 publications

(27 citation statements)

References 24 publications

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“…(6)-(7) with respect to a small perturbation of the scalar field, ϕ ¼ ϕ 0 þ δϕ, which can have either classical or quantum [22,23] origins. Since Eqs.…”

Section: Stellar Stability In Scalar-tensor Theoriesmentioning

confidence: 99%

Possibility of setting a new constraint to scalar-tensor theories

Mendes

2015

Phys. Rev. D

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Scalar-tensor theories (STTs) are a widely studied alternative to general relativity (GR) in which gravity is endowed with an additional scalar degree of freedom. Although severely constrained by solar system and pulsar timing experiments, there remains a large set of STTs which are consistent with all present day observations. In this paper, we investigate the possibility of probing a yet unconstrained region of the parameter space of STTs based on the fact that stability properties of highly compact neutron stars in these theories may radically differ from those in GR.

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“…(6)-(7) with respect to a small perturbation of the scalar field, ϕ ¼ ϕ 0 þ δϕ, which can have either classical or quantum [22,23] origins. Since Eqs.…”

Section: Stellar Stability In Scalar-tensor Theoriesmentioning

confidence: 99%

Possibility of setting a new constraint to scalar-tensor theories

Mendes

2015

Phys. Rev. D

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“…Additionally, a semiclassical version of this effect [36] (cf. also [37][38][39][40] and [41] for a connection with the Damour-Esposito-Farèse model [15,16]) has been shown to awaken the vacuum state of a quantum field leading to an exponential growth of its vacuum energy density in the background of a relativistic star.…”

Section: A Spontaneous Scalarizationmentioning

confidence: 99%

Relativistic stars in scalar-tensor theories with disformal coupling

Minamitsuji

Silva

2016

Phys. Rev. D

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We present a general formulation to analyze the structure of slowly rotating relativistic stars in a broad class of scalar-tensor theories with disformal coupling to matter. Our approach includes theories with generalized kinetic terms, generic scalar field potentials and contains theories with conformal coupling as particular limits. In order to investigate how the disformal coupling affects the structure of relativistic stars, we propose a minimal model of a massless scalar-tensor theory and investigate in detail how the disformal coupling affects the spontaneous scalarization of slowly rotating neutron stars. We show that for negative values of the disformal coupling parameter between scalar field and matter, scalarization can be suppressed, while for large positive values of the disformal coupling parameter stellar models cannot be obtained. This allows us to put a mild upper bound on this parameter. We also show that these properties can be qualitatively understood by linearizing the scalar field equation of motion in the background of a general relativistic incompressible star. To address the intrinsic degeneracy between uncertainties in the equation of state of neutron stars and gravitational theory, we also show the existence of universal equation of state independent relations between the moment of inertia and compactness of neutron stars in this theory. We show that in a certain range of the theory's parameter space the universal relation largely deviates from that of General Relativity, allowing, in principle, to probe the existence of spontaneous scalarization with future observations.

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“…For more on the relation between the instability and the scalarization process, see, e.g., Refs. [56][57][58][59].…”

Section: Conclusion and Final Remarksmentioning

confidence: 99%

From quantum to classical instability in relativistic stars

et al. 2015

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It has been shown that gravitational fields produced by realistic classical-matter distributions can force quantum vacuum fluctuations of some nonminimally coupled free scalar fields to undergo a phase of exponential growth. The consequences of this unstable phase for the background spacetime have not been addressed so far due to known difficulties concerning backreaction in semiclassical gravity. It seems reasonable to believe, however, that the quantum fluctuations will "classicalize" when they become large enough, after which backreaction can be treated in the general-relativistic context. Here we investigate the emergence of a classical regime out of the quantum field evolution during the unstable phase. By studying the appearance of classical correlations and loss of quantum coherence, we show that by the time backreaction becomes important the system already behaves classically. Consequently, the gravity-induced instability leads naturally to initial conditions for the eventual classical description of the backreaction. Our results give support to previous analyses which treat classically the instability of scalar fields in the spacetime of relativistic stars, regardless of whether the instability is triggered by classical or quantum perturbations.

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Quantum versus classical instability of scalar fields in curved backgrounds

Cited by 18 publications

References 24 publications

Possibility of setting a new constraint to scalar-tensor theories

Possibility of setting a new constraint to scalar-tensor theories

Relativistic stars in scalar-tensor theories with disformal coupling

From quantum to classical instability in relativistic stars

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