Art of lattice and gravity waves from preheating

Huang, Zhiqi

doi:10.1103/physrevd.83.123509

Cited by 77 publications

(84 citation statements)

References 102 publications

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“…Besides, given the property Λ ij,lm (k)Λ lm,pq (k) = Λ ij,pq (k), we can always express the main argument of the GW spectrum asḣ TT ij (k, t)ḣ TT * ij (k, t) =u ij (k, t)Λ ij,lm (k)u lm (k, t). In a discrete grid, however, one needs to be careful with the construction of a lattice projector Λ (L) ij,lm that provides correctly a (lattice version) of the 'transversality' and 'tracelessness' conditions, whenever contracted with some tensor [50,93]. It turns out that constructing a correct lattice projector is not as trivial as one may think.…”

Section: Discussionmentioning

confidence: 99%

Gravitational wave production from preheating: parameter dependence

Figueroa

Torrentí

2017

J. Cosmol. Astropart. Phys.

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Parametric resonance is among the most efficient phenomena generating gravitational waves (GWs) in the early Universe. The dynamics of parametric resonance, and hence of the GWs, depend exclusively on the resonance parameter q. The latter is determined by the properties of each scenario: the initial amplitude and potential curvature of the oscillating field, and its coupling to other species. Previous works have only studied the GW production for fixed value(s) of q. We present an analytical derivation of the GW amplitude dependence on q, valid for any scenario, which we confront against numerical results. By running lattice simulations in an expanding grid, we study for a wide range of q values, the production of GWs in post-inflationary preheating scenarios driven by parametric resonance. We present simple fits for the final amplitude and position of the local maxima in the GW spectrum. Our parametrization allows to predict the location and amplitude of the GW background today, for an arbitrary q. The GW signal can be rather large, as h 2 Ω GW (f p ) 10 −11 , but it is always peaked at high frequencies f p 10 7 Hz. We also discuss the case of spectator-field scenarios, where the oscillatory field can be e.g. a curvaton, or the Standard Model Higgs.1 Note that this differs from the case of Higgs-Inflation [24,25], where the post-inflationary decay of the SM Higgs via parametric resonance [26][27][28][29], belongs to the context of preheating, as the Higgs rather plays there the role of the inflaton, instead of a spectator field.2 Note that we do not consider the case of 'oscillons', which correspond to stable field configurations formed whenever a field oscillates around the minimum of its potential, as long as the potential shape meets certain circumstances, see e.g. [54,55]. For the GW production from oscillons see [56,57].3 There exists nonetheless a parameter-fit analysis of the GW production in Hybrid preheating [49], but this corresponds to a spinodal instability of the daughter field modes, not to parametric resonance.

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Section: Discussionmentioning

confidence: 99%

Gravitational wave production from preheating: parameter dependence

Figueroa

Torrentí

2017

J. Cosmol. Astropart. Phys.

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“…The method, when applied to the GPE, is widely used in the cold atom community and known as the truncated Wigner approximation [21]. More cosmologically oriented readers will recognize the spiritual similarity with semi-classical scalar field lattice simulations used to study preheating [22][23][24][25][26]. The basic idea is to model quantum fluctuations by sampling realizations of the initial quantum state as encoded in the Wigner functional.…”

Section: A Stochastic Semiclassical Simulations: the Truncated Wignermentioning

confidence: 99%

Nonlinear dynamics of the cold atom analog false vacuum

Braden

Johnson

Peiris

et al. 2019

J. High Energ. Phys.

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We investigate the nonlinear dynamics of cold atom systems that can in principle serve as quantum simulators of false vacuum decay. The analog false vacuum manifests as a metastable vacuum state for the relative phase in a two-species Bose-Einstein condensate (BEC), induced by a driven periodic coupling between the two species. In the appropriate low energy limit, the evolution of the relative phase is approximately governed by a relativistic wave equation exhibiting true and false vacuum configurations. In previous work, a linear stability analysis identified exponentially growing short-wavelength modes driven by the time-dependent coupling. These modes threaten to destabilize the analog false vacuum. Here, we employ numerical simulations of the coupled Gross-Pitaevski equations (GPEs) to determine the non-linear evolution of these linearly unstable modes. We find that unless a physical mechanism modifies the GPE on short length scales, the analog false vacuum is indeed destabilized. We briefly discuss various physically expected corrections to the GPEs that may act to remove the exponentially unstable modes. To investigate the resulting dynamics in cases where such a removal mechanism exists, we implement a hard UV cutoff that excludes the unstable modes as a simple model for these corrections. We use this to study the range of phenomena arising from such a system. In particular, we show that by modulating the strength of the time-dependent coupling, it is possible to observe the crossover between a second and first order phase transition out of the false vacuum.

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“…A family of numerical codes-first LATTICEEASY [66] and then DEFROST [67], PSPECTRE [68], and HLATTICE [69]-have been used to explore linear and nonlinear dynamics in expanding space-times. To improve efficiency without reducing accuracy, these codes all employ clever rescalings that reduce the Klein-Gordon equation to a phase-separable equation, and hence, they can use symplectic integrators which require a fraction of the physical memory of other methods.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Gauge field preheating at the end of inflation

2013

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Here we consider the possibility of preheating the Universe via the parametric amplification of a massless, Uð1Þ Abelian gauge field. We assume that the gauge field is coupled to the inflaton via a dilatonlike coupling, a conformal factor with one free parameter. We present the results of high-resolution threedimensional simulations of this model and show that this mechanism efficiently preheats the Universe to a radiation-dominated final state.

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Art of lattice and gravity waves from preheating

Cited by 77 publications

References 102 publications

Gravitational wave production from preheating: parameter dependence

Gravitational wave production from preheating: parameter dependence

Nonlinear dynamics of the cold atom analog false vacuum

Gauge field preheating at the end of inflation

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