Two-step electroweak symmetry-breaking: theory meets experiment
We study the phenomenology of a hypercharge-zero SU (2) triplet scalar whose existence is motivated by two-step electroweak symmetry-breaking. We consider both the possibility that the triplets are stable and contribute to the dark matter density, or that they decay via mixing with the standard model Higgs boson. The former is constrained by disappearing charged track searches at the LHC and by dark matter direct detection experiments, while the latter is constrained by existing multilepton collider searches. We find that a two-step electroweak phase transition involving a stable triplet with a negative quadratic term is ruled out by direct detection searches, while an unstable triplet with a mass less than 230 GeV is excluded at 95% confidence level.
Additional Information© 2020 The Authors. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited. Article funded by SCOAP3. Received: February 3, 2020; Accepted: April 15, 2020; Published: May 11, 2020. We thank Giovanna Cottin and Yong Du for helpful discussion of the disappearing charged track searches. This work was supported in part by the Australian Research Council. Feynman diagrams were drawn using the TikZ-Feynman package . The work of MJRM was supported in part under U.S. Department of Energy Contract DE-SC0011095 and National Natural Science Foundation of China grant number 19Z103010239.
Submitted - 2001.05335.pdf