Collider and gravitational wave complementarity in exploring the singlet extension of the standard model

Abstract

We present a dedicated complementarity study of gravitational wave and collider measurements of the simplest extension of the Higgs sector: the singlet scalar augmented Standard Model. We study the following issues: (i) the electroweak phase transition patterns admitted by the model, and the proportion of parameter space for each pattern; (ii) the regions of parameter space that give detectable gravitational waves at future space-based detectors; and (iii) the current and future collider measurements of di-Higgs production, as well as searches for a heavy weak diboson resonance, and how these searches interplay with regions of parameter space that exhibit strong gravitational wave signals. We carefully investigate the behavior of the normalized energy released during the phase transition as a function of the model parameters, address subtle issues pertaining to the bubble wall velocity, and provide a description of different fluid velocity profiles. On the collider side, we identify the subset of points that are most promising in terms of di-Higgs and weak diboson production studies while also giving detectable signals at LISA, setting the stage for future benchmark points that can be used by both communities.

Di-Higgs production in the 4b channel and gravitational wave complementarity

“…the justification of this argument still needs a combined analysis of both macroscopic bubble behavior and microscopic particle transport dynamics, we assume tentatively that it is true in our series of papers on this subject [13,15,33,34]. This implies that in the plane of (v w , α), as shown in Fig.…”

A fresh look at the gravitational-wave signal from cosmological phase transitions

“…In order to obtain the amount of energy that is transformed into GWs during a SFOPT, the dynamics of the expanding scalar-field bubbles has to be analyzed. The velocity profile of these bubbles, v(ξ), satisfies the differential equation [22,61,72,73] 2…”

“…10 % of bulk kinetic energy in the form of turbulence (see, e.g., Refs. [22,60]), whereas others use an equal split between turbulence and sound waves (see, e.g., Ref. [75]).…”

“…Electroweak precision tests: According to Ref. [22], measurements of the W -boson mass result in the strongest constraints on the xSM parameter space. As a rule of thumb, the W -boson mass is most constraining for scalar masses m s 300 GeV, where it translates into sin θ 0.2 for v s = 0.1 v h .…”

“…In this paper, we will illustrate our idea by constructing the signal region for a particularly simple BSM model, namely, the real-scalar-singlet extension of the SM (xSM) [40][41][42][43][44][45][46], which supplements the SM Higgs sector by an additional real gauge-singlet scalar, S, that also obtains a nonzero vacuum expectation value (VEV) during the electroweak phase transition [47][48][49][50][51][52][53]. The GW phenomenology of the xSM has been studied before [14,22,37,[54][55][56][57]; however, in our analysis, we are going to look at the GW signal in this model from a new perspective by projecting the results of our parameter scan into the space of peak frequencies and peak amplitudes. This results in sensitivity plots for future space-based GW experiments that are reminiscent of similar plots in the field of DM direct-detection experiments.…”