Vector SIMP dark matter
Received: July
Vector SIMP dark matter
Soo-Min Choi 1 2 4 8 9 10 11
Yonit Hochberg 1 2 4 6 7 9 10 11
Eric Ku ik 1 2 4 6 7 9 10 11
Hyun Min Lee 1 2 4 8 9 10 11
Yann Mambrini 1 2 3 4 9 10 11
Hitoshi Murayama 0 1 2 4 5 9 10 11
Mathias Pierre 1 2 3 4 9 10 11
Universite Paris-Saclay,
0 Department of Physics, University of California , USA
1 91405 Orsay , France
2 Jerusalem 91904 , Israel
3 Laboratoire de Physique Theorique (UMR8627) , CNRS, Univ. Paris-Sud
4 Seoul 06974 , Korea
5 Ernest Orlando Lawrence Berkeley National Laboratory, University of California , USA
6 Department of Physics, LEPP, Cornell University
7 Racah Institute of Physics, Hebrew University of Jerusalem
8 Department of Physics, Chung-Ang University
9 Berkeley , CA 94720 , U.S.A
10 University of Tokyo Institutes for Advanced Study, University of Tokyo
11 scalar S, with the covariant derivative D S =
Strongly Interacting Massive Particles (SIMPs) have recently been proposed as light thermal dark matter relics. Here we consider an explicit realization of the SIMP mechanism in the form of vector SIMPs arising from an SU(2)X hidden gauge theory, where the accidental custodial symmetry protects the stability of the dark matter. We propose several ways of equilibrating the dark and visible sectors in this setup. In particular, we show that a light dark Higgs portal can maintain thermal equilibrium between the two sectors, as can a massive dark vector portal with its generalized Chern-Simons couplings to the vector SIMPs, all while remaining consistent with experimental constraints. ArXiv ePrint: 1707.01434
Beyond Standard Model; Cosmology of Theories beyond the SM; Gauge
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HJEP10(27)6
Symmetry
1 Introduction 2 The model
matter is possible if, for instance, standard 2 ! 2 annihilations proceed with small
couplings [8] or if new annihilation mechanisms are present, such as 3 ! 2 annihilations [9{11]
or forbidden 2 ! 2 channels [12, 13].
The thermal production of Strongly Interacting Massive Particles (SIMPs) [10] is based
on freezeout of 3 ! 2 self-annihilation of dark matter, with coupling between SIMPs and
light Standard Model (SM) particles, which maintain kinetic equilibrium between the two
sectors until freeze-out occurs. Various realizations of SIMP dark matter have been
proposed in the literature, which often contain (pseudo)scalar dark matter particles with dark
abelian or non-abelian gauge symmetries [10, 14{19].
Massive dark vector bosons can
also be SIMP candidates when stemming from non-abelian dark gauge bosons [20{25],
{ 1 {
as can be dark fermions or scalars when accompanied with a light dark photon or
another scalar [26, 27]. Vector SIMP models are particularly predictive since the cubic and
quartic self-interactions of dark matter are determined by a single gauge coupling. If the
non-abelian dark gauge symmetry is spontaneously broken by the Higgs mechanism, the
resulting massive dark Higgs can equilibrate the vector SIMPs and the SM via a Higgs
portal coupling [20{22, 24, 28]. The spin information of the dark matter could be then be
inferred from the invisible Higgs decay, as is the case for the WIMP [29].
In this paper, we consider vector SIMP dark matter in an SU(2)X dark gauge theory,
where the three massive (degenerate) SU(2)X gauge bosons play the role of vector SIMPs.
Equilibration between the dark and visible sectors can be achieved by elastic scattering
between the dark matter and the SU(2)X dark Higgs, provided that the latter is light
enough to be thermalized with the SM via the Higgs portal until freeze-out occurs. As we
will see, the dark Higgs can successfully thermalize the two sectors only when it is close
in mass to the dark matter, in which case additional forbidden 2 ! 2 annihilations are
important as well. Alternatively, the dark U(1)Z0 photon can thermalize the dark and
visible sectors via its kinetic mixing with the SM hypercharge alongside its coupling to
the DM, which proceed through generalized Chern-Simons (CS) terms [30{35]. In both
cases of the Higgs and vector portals, we nd parameter space consistent with all existing
constraints. Our results indicate that the framework can be probed via Higgs/Z-boson
invisible decays as well as dark Higgs/dark photon searches in current and future collider
and beam dump experiments.
This paper is organized as follows. We begin by describing the SU(2)X dark gauge
theory model in section 2, including the relevant Higgs and gauge-mixing vector portals to
the SM. Section 3 discusses the 3 ! 2 annihilation processes setting the DM abundance,
the self-scattering cross sections, and the e ects of forbidden channels on the relic density.
Methods for achieving kinetic equilibrium between the dark and visible sectors via Higgs
mixing and/or gauge mixing are addressed in section 4. We conclude in section 5.
2
The model
Here we present the framework for vector SIMPs: we start with the dark gauge theory, and
then describe the Higgs interactions as well as kinetic ga (...truncated)