Inflationary magnetogenesis with reheating phase from higher curvature coupling

Bamba, Kazuharu; Elizalde, E.; Odintsov, Sergei D.; Paul, Tanmoy

doi:10.1088/1475-7516/2021/04/009

Cited by 33 publications

(26 citation statements)

References 195 publications

(330 reference statements)

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“…[52,53]). However, if the reheating is perturbative as originally suggested in the new inflationary scenario [54] the effect of the duration of the reheating phase may be relevant (see also [47]).…”

Section: Post-inflationary Phases Preceding the Radiation Epoch And Reheating Dynamicsmentioning

confidence: 96%

“…As already suggested in the previous paragraph the continuity of the extrinsic curvature is an excellent starting point also in this case. More detailed models of reheating could be certainly useful and might affect the magnetogenesis scenarios (as suggested in [47]). In this paper we adopted the approximation of the sudden reheating which is also the one often employed in order to set limits on the tensor to scalar ratio and on the total number of inflationary e-folds.…”

Section: )mentioning

confidence: 99%

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Inflationary magnetogenesis in the perturbative regime

Giovannini

2021

Class. Quantum Grav.

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While during inflation a phase of increasing gauge coupling allows for a scaleinvariant hyperelectric spectrum, when the coupling decreases a flat hypermagnetic spectrum can be generated for typical wavelengths larger than the effective horizon. After the gauge coupling flattens out the late-time hypermagnetic power spectra outside the horizon in the radiation epoch are determined by the hyperelectric fields at the end of inflation whereas the opposite is true in the case of decreasing coupling. Instead of imposing an abrupt freeze after inflation, we consider a smooth evolution of the mode functions by positing that the gauge couplings and their conformal time derivatives are always continuous together with the background extrinsic curvature. The amplified gauge power spectra are classified according to their transformation properties under the duality symmetry. After clarifying the role of the comoving and of the physical spectra in the formulation of the relevant magnetogenesis constraints, the parameter space of the scenario is scrutinized. It turns out that a slightly blue hyperelectric spectrum during inflation may lead to a quasi-flat hypermagnetic spectrum prior to matter radiation equality and before the relevant wavelengths reenter the effective horizon. In this framework the gauge coupling is always perturbative but the induced large-scale magnetic fields can be of the order of a few hundredths of a nG and over typical length scales between a fraction of the Mpc and 100 Mpc prior to the gravitational collapse of the protogalaxy.

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Section: Post-inflationary Phases Preceding the Radiation Epoch And Reheating Dynamicsmentioning

confidence: 96%

Section: )mentioning

confidence: 99%

Inflationary magnetogenesis in the perturbative regime

Giovannini

2021

Class. Quantum Grav.

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“…The considerations reported here are therefore quite general since what ultimately matters is the overall evolution of the gauge coupling and their interplay with the anomalous terms; in this sense it could even be possible that λ and λ depend on a general function of the scalar curvature or of some other curvature invariant (see e.g. [46]). While both λ and λ break Weyl invariance when λ → 0 the duality symmetry [40][41][42] must be recovered.…”

Section: Introductionmentioning

confidence: 95%

Baryogenesis, magnetogenesis and the strength of anomalous interactions

Giovannini

2021

Eur. Phys. J. C

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The production of the hypermagnetic gyrotropy is investigated under the assumption that the gauge coupling smoothly evolves during a quasi-de Sitter phase and then flattens out in the radiation epoch by always remaining perturbative. In the plane defined by the strength of the anomalous interactions and by the rate of evolution of the gauge coupling the actual weight of the pseudoscalar interactions turns out to be always rather modest if major deviations from the homogeneity are to be avoided during the inflationary phase. Even if the gauge power spectra are related by duality only in the absence of anomalous contributions, an approximate duality symmetry constrains the late-time form of the hypermagnetic power spectra. Since the hypermagnetic gyrotropy associated with the modes reentering prior to the phase transition must be released into fermions later on, the portions of the parameter space where the obtained baryon asymmetry is close to the observed value are the most relevant for the present ends. For the same range of parameters the magnetic power spectra associated with the modes reentering after symmetry breaking may even be of the order of a few hundredths of a nG over typical length scales comparable with the Mpc prior to the collapse of the protogalaxy.

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“…The simplest way to generate magnetic fields of observable strengths today seems to break the conformal invariance of the electromagnetic action (in this context, see, for example, Refs. [20][21][22][23][24][25][26][27][28]). Often, this is achieved by coupling the electromagnetic field to either the scalar field that drives inflation [22,24] or to the Ricci scalar describing the background [23,25,27,28].…”

Section: Introductionmentioning

confidence: 99%

“…[20][21][22][23][24][25][26][27][28]). Often, this is achieved by coupling the electromagnetic field to either the scalar field that drives inflation [22,24] or to the Ricci scalar describing the background [23,25,27,28]. In fact, it has also been discovered that the addition of a parity violating term in the electromagnetic action can significantly enhance the amplitude of magnetic fields generated during inflation [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

On the challenges in the choice of the non-conformal coupling function in inflationary magnetogenesis

Tripathy,

Chowdhury,

Jain

et al. 2021

Preprint

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Primordial magnetic fields are generated during inflation by considering actions that break the conformal invariance of the electromagnetic field. To break the conformal invariance, the electromagnetic fields are coupled either to the inflaton or to the scalar curvature. Also, a parity violating term is often added to the action in order to enhance the amplitudes of the primordial electromagnetic fields. In this work, we examine the effects of deviations from slow roll inflation on the spectra of non-helical as well as helical electromagnetic fields. We find that, in the case of the coupling to the scalar curvature, there arise certain challenges in generating electromagnetic fields of the desired shapes and strengths even in slow roll inflation. When the field is coupled to the inflaton, it is possible to construct model-dependent coupling functions which lead to nearly scale invariant magnetic fields in slow roll inflation. However, we show that sharp features in the scalar power spectrum generated due to departures from slow roll inflation inevitably lead to strong features in the power spectra of the electromagnetic fields. Moreover, we find that such effects can also considerably suppress the strengths of the generated electromagnetic fields over the scales of cosmological interest. We illustrate these aspects with the aid of specific inflationary models that have been considered to produce specific features in the scalar power spectrum. Further, we find that, in such situations, if the strong features in the electromagnetic power spectra are to be undone, the choice of the coupling function requires considerable fine tuning. We discuss wider implications of the results we obtain.

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Inflationary magnetogenesis with reheating phase from higher curvature coupling

Cited by 33 publications

References 195 publications

Inflationary magnetogenesis in the perturbative regime

Inflationary magnetogenesis in the perturbative regime

Baryogenesis, magnetogenesis and the strength of anomalous interactions

On the challenges in the choice of the non-conformal coupling function in inflationary magnetogenesis

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