A predictive mirror twin Higgs with small Z 2 breaking
- PDF / 623,685 Bytes
- 22 Pages / 595.276 x 841.89 pts (A4) Page_size
- 103 Downloads / 158 Views
Springer
Received: June 4, Revised: April 23, Accepted: May 10, Published: May 28,
2019 2020 2020 2020
A predictive mirror twin Higgs with small Z2 breaking
a
School of Natural Sciences, Institute for Advanced Study, Princeton, NJ, 08540, U.S.A. b Berkeley Center for Theoretical Physics, University of California, Berkeley, CA 94720, U.S.A. c Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.A. d Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo Institutes for Advanced Study, University of Tokyo, Kashiwa 277-8583, Japan
E-mail: [email protected], [email protected], [email protected], [email protected] Abstract: The twin Higgs mechanism is a solution to the little hierarchy problem in which the top partner is neutral under the Standard Model (SM) gauge group. The simplest mirror twin Higgs (MTH) model — where a Z2 symmetry copies each SM particle — has too many relativistic degrees of freedom to be consistent with cosmological observations. We demonstrate that MTH models can have an observationally viable cosmology if the twin mass spectrum leads to twin neutrino decoupling before the SM and twin QCD phase transitions. Our solution requires the twin photon to have a mass of ∼ 20 MeV and kinetically mix with the SM photon to mediate entropy transfer from the twin sector to the SM. This twin photon can be robustly discovered or excluded by future experiments. Additionally, the residual twin degrees of freedom present in the early Universe in this scenario would be detectable by future observations of the cosmic microwave background. Keywords: Beyond Standard Model, Higgs Physics ArXiv ePrint: 1905.08798 1
Hamamatsu professor.
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP05(2020)155
JHEP05(2020)155
Keisuke Harigaya,a,b,c Robert McGehee,b,c Hitoshi Murayamab,c,d,1 and Katelin Schutzb,c
Contents 1
2 Twin sector 2.1 Twin Higgs mechanism with Z2 breaking 2.2 Twin photon 2.3 Charged twin fermions 2.4 Twin gluons
4 4 5 7 8
3 Twin contributions to ∆Neff
9
4 The helium mass fraction
11
5 Discussion
13
A γ0 → ν ¯0 ν 0 decays
14
B Higgs invisible decays and signal strength
15
1
Introduction
The disparity between the electroweak scale and the Planck scale is one of the most outstanding problems in particle physics (see, e.g., [1]). Explanations have been provided by both supersymmetry and the compositeness of the Higgs, where the electroweak scale originates from a supersymmetry breaking scale [2–5] or a composite scale [6, 7]. Without fine-tuning parameters, these classes of solutions generically predict the existence of a partner to the top quark that is colored and as light as the electroweak scale. Such a particle has not been observed at the Large Hadron Collider (LHC), providing a strong lower bound on its mass, typically around 1 TeV [8–11]. In order to accommodate this bound, these kinds of theories require fine-tuning of their parameters to fix the electroweak s
Data Loading...
