Dynamics of false vacuum bubbles with nonminimal coupling

Lee, Bum-Hoon; Lee, Chul H.; Lee, Wonwoo; Nam, Siyoung; Park, Chanyong

doi:10.1103/physrevd.77.063502

Cited by 22 publications

(15 citation statements)

References 98 publications

(61 reference statements)

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“…It may be possible to violate the NEC with exotic forms of matter[39,40], non-minimal coupling[41,42], or quantum gravity effects[43], though these approaches often face challenges that we will not explore further here.…”

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confidence: 99%

Constraints and horizons for de Sitter with extra dimensions

2019

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In order for spacetimes with static extra dimensions to have 4-dimensional de Sitter expansion they must have at least positive curvature, warping sourced by the 4-d expansion, or violate the null energy condition everywhere in the extra dimensions. We show how this constraint arises from the null Raychaudhuri equation, and that it is independent of the matter content, the Einstein equations, and is true point-by-point in the extra dimensions (not integrated), setting it apart from other no-go theorems in the literature. We present two previously known examples -a Freund-Rubin compactification with bulk cosmological constant, and a Randall-Sundrum model where the mismatch between the brane and bulk cosmological constants sources non-trivial warping -which evade the constraint, and discuss the implications for flux compactifications. We also show that any spacetime with static compact extra dimensions and 4-dimensional de Sitter expansion has an apparent horizon and antitrapped region in the extra dimensions, which may have interesting implications for the dynamics of bulk fields in cosmology. * Electronic address: saurya.das@uleth.ca † Electronic address:

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confidence: 99%

Constraints and horizons for de Sitter with extra dimensions

2019

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“…where we rewrote the last two terms as a correction term H µν so that the corrections take the form (7) as outlined in the Introduction. The timelike and null 4-dimensional Raychaudhuri equations thus have the new terms arising from the braneworld…”

Section: Braneworld Gravitymentioning

confidence: 99%

“…Most known classical matter obeys both the null and strong energy conditions, while vacuum energy p = −ρ violates the strong energy condition but still saturates the null energy condition. It may possible to violate the null energy condition with exotic forms of matter [5,6], non-minimal coupling [7,8], or quantum gravity effects [9], though these approaches often face challenges that we will not explore further here. However, since we expect corrections to GR of some form, we do not expect the Einstein equations (3) to always hold.…”

Section: Introductionmentioning

confidence: 99%

“…While we are motivated by the existence of singularities in these backgrounds, and the promise of these alternatives to GR for resolving the singularities, we will not attempt to prove the absence of singularities in this paper. Indeed, a significant amount of work has shown that finding realistic singularity-free spacetimes under computational control is quite challenging, and we expect that true singularity resolution will require physics beyond the perturbative approach of (7). Instead, we aim for a more modest goal, that of finding corrections to GR that lead to potentially positive terms on the right-hand side of the Raychaudhuri equation Eq.…”

Section: Introductionmentioning

confidence: 99%

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Towards the Raychaudhuri equation beyond general relativity

et al. 2018

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In General Relativity, gravity is universally attractive, a feature embodied by the Raychaudhuri equation which requires that the expansion of a congruence of geodesics is always non-increasing, as long as matter obeys the strong or weak energy conditions. This behavior of geodesics is an important ingredient in general proofs of singularity theorems, which show that many spacetimes are singular in the sense of being geodesically incomplete and suggest that General Relativity is itself incomplete. It is possible that alternative theories of gravity, which reduce to General Relativity in some limit, can resolve these singularities, so it is of interest to consider how the behavior of geodesics is modified in these frameworks. We compute the leading corrections to the Raychaudhuri equation for the expansion due to models in string theory, braneworld gravity, f (R) theories, and Loop Quantum Cosmology, for cosmological and black hole backgrounds, and show that while in most cases geodesic convergence is reinforced, in a few cases terms representing repulsion arise, weakening geodesic convergence and thereby the conclusions of the singularity theorems.

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“…On the other hand, the radial coordinate measures the proper size of the spheres of a spherically symmetric spacetime and therefore has to vary continuously across the bubble. Note that the reversion of time direction is equivalent to the introduction of a new family of negative tension bubbles [51,52].…”

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confidence: 99%

Electroweak Phase Transitions in Einstein’s Static Universe

Gogberashvili

2018

Advances in High Energy Physics

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We suggest using Einstein's static universe metric for the metastable state after reheating, instead of the Friedman-RobertsonWalker spacetime. In this case, strong static gravitational potential leads to the effective reduction of the Higgs vacuum expectation value, which is found to be compatible with the Standard Model first-order electroweak phase transition conditions. Gravity could also increase the CP-violating effects for particles that cross the new phase bubble walls and thus is able to lead to the successful electroweak baryogenesis scenario.According to standard cosmology at the electroweak scale, our universe is in radiation dominated phase where all Standard Model particles are massless [1]. Once the temperature drops below the critical value, ∼ 170 GeV, the electroweak phase transition has occurred and the Higgs boson, gauge bosons, and fermions (except neutrinos) acquire masses through the Higgs mechanism. The order of this phase transition depends on the details of the Higgs potential with the temperature dependent terms [2][3][4][5]. To have a first-order phase transition effective Higgs potential of the model should have several minima. Of special importance is the cubic term in effective potential, which is essential to generate a potential barrier between the symmetric and broken phases and thus can provide the phase transition to be of the first order. In the Standard Model the cubic term, 3 , is contributed only by the electroweak gauge bosons. If at zero temperature the Higgs field at the minimum of the potential has the value V ≈ 246 GeV,the parameter is the cubic term of the effective potential of order ofwhere and are the gauge bosons masses. Then the condition that the Higgs effective potential has two minima leads to the very small value for the Higgs self-coupling parameter,which according to (1) is incompatible with the observed Higgs boson mass,This means that within the minimal Standard Model the electroweak phase transition is a smooth crossover, or of the second order [4,5]. On the other hand, the first-order electroweak phase transitions may solve some cosmological problems, like the generation of the baryon asymmetry of the universe (see recent reviews [6,7]). A first-order cosmological phase transition proceeds through the formation and expansion of cosmic bubbles. In this scenario spacetime is separated into two manifolds with their own distinct metrics, which are typically joined across a thin wall (domain wall). The dynamics of such objects can be very complicated, depending on the matter content of the interior (true vacuum) and exterior (false vacuum) regions as well as the tension on the bubble walls and how they interact with the surrounding plasma [8]. In bubble models matter-antimatter asymmetry can be generated at the electroweak scale, because all three Sakharov conditions

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Dynamics of false vacuum bubbles with nonminimal coupling

Cited by 22 publications

References 98 publications

Constraints and horizons for de Sitter with extra dimensions

Constraints and horizons for de Sitter with extra dimensions

Towards the Raychaudhuri equation beyond general relativity

Electroweak Phase Transitions in Einstein’s Static Universe

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