Detecting gravitational waves from cosmological phase transitions with LISA: an update

We derive efficiency factors for the production of gravitational waves through bubble collisions and plasma-related sources in strong phase transitions, and find the conditions under which the bubble collisions can contribute significantly to the signal. We use lattice simulations to clarify the dependence of the colliding bubbles on their initial state. We illustrate our findings in two examples, the Standard Model with an extra |H| 6 interaction and a classically scale-invariant U (1) B−L extension of the Standard Model. The contribution to the GW spectrum from bubble collisions is found to be negligible in the |H| 6 model, whereas it can play an important role in parts of the parameter space in the scale-invariant U (1) B−L model. In both cases the sound-wave period is much shorter than a Hubble time, suggesting a significant amplification of the turbulence-sourced signal. We find, however, that the peak of the plasma-sourced spectrum is still produced by sound waves with the slower-falling turbulence contribution becoming important off-peak.

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“…The parameters relevant for the GW signal are then evaluated at T = T * . These are the strength of the transition [84,85],…”

Section: Phase Transitionmentioning

confidence: 99%

“…In the case of a weak transition with the wall velocity dictated by strong interaction with the plasma, this expression needs a slight modification[85].…”

mentioning

confidence: 99%

Gravitational wave energy budget in strongly supercooled phase transitions

Ellis

Lewicki

et al. 2019

J. Cosmol. Astropart. Phys.

285

365

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“…The addition of new particles coupling to the Higgs can turn it into a strongly first order phase transition, proceeding by the nucleation of bubbles of the true, electroweak symmetry breaking vacuum, in the initially symmetric plasma. This possibility has been widely studied because of its potential for providing electroweak baryogenesis (EWBG) [3][4][5], and gravity waves that might be observable in the upcoming LISA experiment [6,7].…”

Section: Introductionmentioning

confidence: 99%

Fluid equations for fast-moving electroweak bubble walls

Laurent

Cline

2020

Phys. Rev. D

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The cosmological electroweak phase transition can be strongly first order in extended particle physics models. To accurately predict the speed and shape of the bubble walls during such a transition, Boltzmann equations for the CP-even fluid perturbations must be solved. We point out that the equations usually adopted lead to unphysical behavior of the perturbations, for walls traveling close to or above the speed of sound in the plasma. This is an artifact that can be overcome by more carefully truncating the full Boltzmann equation. We present an improved set of fluid equations, suitable for studying the dynamics of both subsonic and supersonic walls, of interest for gravitational wave production and electroweak baryogenesis.

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“…In the case studied in this paper, the scales of both phase transitions imply nucleation temperatures in the range T N ¼ Oð10-100 GeVÞ. This implies that the resulting peak GW frequencies fall within the observational windows of space-based interferometer experiments such as LISA [41]. However, as both phase transitions occur in the same sector, the plasma dynamics generated by the first phase transition is disrupted by the occurrence of the second transition, and one would typically expect a GW signal with a double peak, where the high-frequency peak is lower in amplitude.…”

Section: Gravitational Wavesmentioning

confidence: 92%

QCD baryogenesis

Croon¹,

Howard

Ipek

et al. 2020

Phys. Rev. D

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We explore a simple model which naturally explains the observed baryon asymmetry of the Universe. In this model the strong coupling is promoted to a dynamical quantity, which evolves through the vacuum expectation value of a singlet scalar field that mixes with the Higgs field. In the resulting cosmic history, QCD confinement and electroweak symmetry breaking initially occur simultaneously close to the weak scale. The early confinement triggers a chemical potential between baryons and antibaryons through the interactions of the η 0 meson, resulting in spontaneous baryogenesis. The electroweak sphalerons are sharply switched off after confinement and the baryon asymmetry is frozen in. Subsequently, evolution of the Higgs vacuum expectation value (which is modified in the confined phase) triggers a relaxation to a Standard Model-like vacuum. We identify viable regions of parameter space and describe various experimental probes, including current and future collider constraints and gravitational wave phenomenology.

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Detecting gravitational waves from cosmological phase transitions with LISA: an update

Cited by 656 publications

References 240 publications

Gravitational wave energy budget in strongly supercooled phase transitions

Gravitational wave energy budget in strongly supercooled phase transitions

Fluid equations for fast-moving electroweak bubble walls

QCD baryogenesis

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