Gravitational wave energy budget in strongly supercooled phase transitions

Abstract

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.

Singlet-doublet fermionic dark matter and gravitational waves in a two-Higgs-doublet extension of the Standard Model

“…VI B, the sound wave contribution to the total GW intensity depends on the suppression factor HR * /Ū f depending on whether it lasts more than a Hubble time or not. We estimate the suppression factor HR * /Ū f following [85,146,147] and found it to be < 1 for all the BPs. Due to this fact, following [85,146,147], we include the suppression factor HR * /Ū f to the sound wave component of the GW intensity.…”

“…We estimate the suppression factor HR * /Ū f following [85,146,147] and found it to be < 1 for all the BPs. Due to this fact, following [85,146,147], we include the suppression factor HR * /Ū f to the sound wave component of the GW intensity. In Figure 10 we have plotted and compared the GW intensities for the chosen benchmarks (Table V) DECIGO, aLIGO, aLIGO+ and LISA following Ref.…”

“…To check the contribution of sound wave component to the total GW intensity we need to estimate the suppression factor HR * /Ū f , whereŪ f denotes the root-mean-square (RMS) fluid velocity and R * denotes the mean bubble separation [85,146,147]. If the calculated suppression factor HR * /Ū f of a given model comes out to be > 1 , then the sound wave lasts more than a Hubble time, otherwise it is an overestimate to the GW signal.…”

Gravitational waves from phase transition in minimal SUSY U(1)B−L model

“…[36] that the bubble wall in plasma always reaches a constant velocity when the next-to-leading order friction is taken into account, and a claim of Ref. [37] that the fraction of energy stored in the bubble wall over the vacuum energy released quickly decreases after the wall reaches the constant velocity, we justifiably neglect source (i). Hence, we only consider sources (ii) and (iii).…”

“…(54), and may enhance the turbulence's contribution compared to Eq. (56) [37]. Nevertheless, we use Eqs.…”