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

Journal of High Energy Physics

Bo-Qiang Lu¹  Cheng-Wei Chiang² 

[1] Department of Physics, National Taiwan University, 10617, Taipei, Taiwan, Republic of China;Department of Physics, National Taiwan University, 10617, Taipei, Taiwan, Republic of China;Institute of Physics, Academia Sinica, 11529, Taipei, Taiwan, Republic of China;

关键词: Phase transitions;    Beyond Standard Model;    Dark matter;    Higgs physics;    Hadron-Hadron scattering (experiments);   

DOI  :  10.1007/JHEP07(2020)082

来源: Springer

【 摘 要 】

We consider an extension of the Standard Model with a complex singlet scalar, where a global U(1) symmetry is explicitly broken to ℤ3 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 ℤ2 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.

【 授权许可】

Unknown