Cosmological constant problem on the horizon

Firouzjahi, Hassan

doi:10.48550/arxiv.2201.02016

Cited by 2 publications

(18 citation statements)

References 44 publications

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“…A variety of studies bear relation in different ways with these investigations, see e.g. [63][64][65][66][67][68][69][70][71][72][73][74][75][76] and corresponding references. However, it was only recently, in the aforementioned work [57], where an explicit form of the RVM vacuum density could be derived within the QFT context.…”

Section: Introductionmentioning

confidence: 99%

Renormalizing the vacuum energy in cosmological spacetime: implications for the cosmological constant problem

Moreno-Pulido,

Peracaula

2022

Preprint

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The renormalization of the vacuum energy in quantum field theory (QFT) is usually plagued with theoretical conundrums related not only with the renormalization procedure itself, but also with the fact that the final result leads usually to very large (finite) contributions incompatible with the measured value of Λ in cosmology. As a consequence, one is bound to extreme fine-tuning of the parameters and so to sheer unnaturalness of the result and of the entire approach. We may however get over this adversity using a different perspective. Herein, we compute the zero-point energy (ZPE) for a nonminimally coupled (massive) scalar field in FLRW spacetime using the off-shell adiabatic renormalization technique employed in previous work. The on-shell renormalized result first appears at sixth adiabatic order, so the calculation is rather cumbersome. The general off-shell result yields a smooth function ρ vac (H) made out of powers of the Hubble rate and/or of its time derivatives involving different (even) adiabatic orders ∼ H N (N = 0, 2, 4, 6, ...), i.e. it leads, remarkably enough, to the running vacuum model (RVM) structure. We have verified the same result from the effective action formalism and used it to find the β-function of the running quantum vacuum. No undesired contributions ∼ m 4 from particle masses appear and hence no fine-tuning of the parameters is needed in ρ vac (H). Furthermore, we find that the higher power ∼ H 6 could naturally drive RVM-inflation in the early universe. Our calculation also elucidates in detail the equation of state of the quantum vacuum: it proves to be not exactly −1 and is moderately dynamical. The form of ρ vac (H) at low energies is also characteristic of the RVM and consists of an additive term (the so-called 'cosmological constant') together with a small dynamical component ∼ νH 2 (|ν| ≪ 1). Finally, we predict a slow (∼ ln H) running of Newton's gravitational coupling G(H). The physical outcome of our semiclassical QFT calculation is revealing: today's cosmic vacuum and the gravitational strength should be both mildly dynamical.

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Section: Introductionmentioning

confidence: 99%

Renormalizing the vacuum energy in cosmological spacetime: implications for the cosmological constant problem

Moreno-Pulido,

Peracaula

2022

Preprint

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“…Curiously we see for the neutrino with the mass at the order 10 −2 eV we need only one patch to cover the entire cosmos. This suggests that the neutrino field maybe behind the observed value of dark energy ρ Λ ∼ (10 −2 ) 3 eV [8].…”

Section: The Cosmological Constant Problemmentioning

confidence: 89%

“…The cosmological constant problem was revisited recently in [8] with the emphasis on the role of (A)dS horizon associated to the vacuum zero point energy. It was argued that if the vacuum energy density is the sole distribution of energy then the spacetime filled with the vacuum zero point energy is unstable to quantum perturbations.…”

Section: Introductionmentioning

confidence: 99%

“…In this work we extend the analysis of [8] to the black hole backgrounds and calculate the vacuum zero point energy and its variance. This is a well-motivated question.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the recent detection of gravitational waves by the LIGO team [14,15] from the merging of binary astrophysical black holes have left no doubt on the reality of black holes in Nature. So it is natural to study the vacuum zero point energy in a black hole background and examine if the conclusions reached in [8] holds true in a black hole background as well.…”

Section: Introductionmentioning

confidence: 99%

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Cosmological Constant and Vacuum Zero Point Energy in Black Hole Backgrounds

Firouzjahi

2022

Preprint

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We study the quantum vacuum zero point energy in the Schwarzschild black hole as well as in the Nariai limit of the dS-Schwarzschild backgrounds. We show that the regularized vacuum energy density near the black hole and also in the Nariai setup match exactly with the corresponding value in the flat background, scaling with the fourth power of the mass of the quantum field. The horizon radius of the dS space created from the vacuum zero point energy introduces a new length scale which should be compared with the black hole horizon radius. There is an upper limiting mass for the black hole immersed in the vacuum zero point energy which is determined by the mass of the Nariai metric associated to the dS background constructed from zero point energy. This result supports the proposal made recently that the dS spacetime created from the vacuum zero point energy develops strong inhomogeneities on sub-horizon scales in which the regions inside the dS horizon radius may collapse to form black holes.

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Cosmological constant problem on the horizon

Cited by 2 publications

References 44 publications

Renormalizing the vacuum energy in cosmological spacetime: implications for the cosmological constant problem

Renormalizing the vacuum energy in cosmological spacetime: implications for the cosmological constant problem

Cosmological Constant and Vacuum Zero Point Energy in Black Hole Backgrounds

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