Gravitational waves from first-order phase transition and domain wall

We consider an extension of the Standard Model with a complex singlet scalar, where a global U(1) symmetry is explicitly broken to Z 3 symmetry. We study the two-step electroweak phase transition in the model and find that it can be of first-order if the heavy scalar mass falls in the range of 1-2 TeV and the mixing angle |θ| 0.2 (11.5 •). The Higgs signal strength measurements at the LHC, on the other hand, restrict the mixing angle |θ| 0.4 (23 •). Future colliders including high-luminosity LHC can probe the remaining parameter space of first-order phase transition in this scenario. After the U(1) symmetry breaking, the pseudo-Goldstone boson becomes a dark matter candidate due to a hidden Z 2 symmetry of the model. We find that the pseudo-Goldstone boson can make up a small fraction of the observed dark matter and escape from the constraints of current direct detection. We also show that the stochastic gravitational wave signals from the phase transition are potentially discoverable with future space-based interferometers.

Section: The Model With Z 3 Symmetrymentioning

confidence: 99%

First-order electroweak phase transition in a complex singlet model with ℤ3 symmetry

Chiang

2020

“…This was previously discussed in refs. [21][22][23][24][25][26]. Therefore, it is natural to ask if such GW signals can be probed at the future programs, such as the satellite-based interferometers of LISA [27,28], Taiji [29], and Tianqin [30], or the radio telescope of square kilometer arrays (SKA) [31] and the Japanese space GW antenna (DECIGO) [32].…”

Section: Jhep10(2020)081mentioning

confidence: 99%

Collapsing domain walls in the two-Higgs-doublet model and deep insights from the EDM

Chen

Teng

et al. 2020

We study the domain wall solutions in the general two-Higgs-doublet model (2HDM) with a CP-violating phase. The 2HDM with the spontaneouse CP violation is found to have domain wall solutions whose tensions are $$ \mathcal{O} $$ O (106) GeV3, which are excluded by the Zel’dovich-Kobzarev-Okun bound. With the explicit CP-violating (CPV) terms as the so-called biased term in the scalar potential, domain walls can collapse in the early Universe. The sizes of the explicit CP violation can be constrained from the Big Bang nucleosynthesis. This constraint is converted to the CPV mixing of αc, and is mostly sensitive to the mass splittings between two heavy neutral Higgs bosons. We estimate the possible gravitational wave signals and the electric dipole moment (EDM) predictions due to the domain wall collapsing. It turns out that the peak spectrum of the GW from the domain wall collapsing cannot be probed in any future program. In contrast, the untenable regions with very tiny explicit CPV parameter in the Higgs potential has been partially excluded by the latest electron EDM measurements at the ACME-II and will be further confirmed or excluded by the future ACME-III projection.

“…It is likely that the symmetry breaking patterns in new physics models are associated with non-trivial vacuum structure, which therefore leads to various topological defects [7][8][9][10][11][12][13]. The GWs from different topological defects during the early evolution of the Universe have been studied in many early literatures as well as recent ones, such as domain walls [14][15][16][17][18][19][20][21][22][23] and cosmic strings [3,14,15,[24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

The gravitational waves from the collapsing domain walls in the complex singlet model

Chen

2020

We study the CP domain walls and the consequent gravitational waves induced by the spontaneous breaking of the CP symmetry in the complex singlet extension to the Standard Model. We impose the constraints from the unitarity, stability and the global minimal of the vacuum solutions on the model parameter space. The CP domain wall profiles and tensions are obtained by numerically solving the relevant field equations. The explicit CP violation terms are then introduced to the potential as biased terms to make the domain walls unstable and collapse, The BBN bound on the magnitude of the energy bias is taken into account. To achieve sufficiently strong gravitational wave signals, the domain wall tension σ is required to be at least σ/TeV 3 ∼ O(10 3). We find that the gravitational wave spectrum can be probed in the future SKA and/or DECIGO programs, when the typical mass scale is at least ∼ O(10) TeV and the explicit CP violation terms are as small as O(10 −24)−O(10 −23). The gravitational waves from collapsing domain walls thus provide a complementarity to the probe of extremely small CP violation at high-energy scale.