Abstract
We consider a novel scenario for Vector Strongly Interacting Massive Particle (VSIMP) dark matter with local SU(2)X × U(1)Z′ symmetry in the dark sector. Similarly to the Standard Model (SM), after the dark symmetry is broken spontaneously by the VEVs of dark Higgs fields, the approximate custodial symmetry determines comparable but split masses for SU(2)X gauge bosons. In this model, we show that the U(1)Z′ -charged gauge boson of SU(2)X (X±) becomes a natural candidate for SIMP dark matter, annihilating through 3 → 2 or forbidden 2 → 2 annihilations due to gauge self-interactions. On the other hand, the U(1)Z′ -neutral gauge boson of SU(2)X achieves the kinetic equilibrium of dark matter through a gauge kinetic mixing between U(1)Z′ and SM hypercharge. We present the parameter space for the correct relic density in our model and discuss in detail the current constraints and projections from colliders and direct detection experiments.
Highlights
One possibility for going beyond the WIMP paradigm is to modify drastically the thermal history of dark matter, allowing for extremely feeble couplings between the visible and dark sectors
We propose in this work to analyse in detail a simple SU(2)X × U(1)Z extension of the Standard Model (SM), where the charged non-abelian vector boson X± is the dark matter candidate, while the Zμ boson plays a role of the portal between the visible and hidden sectors through its kinetic mixing with the SM hypercharge gauge boson Bμ
We consider the elastic scattering between dark matter and electron through Z portal couplings to achieve a kinetic equilibrium for Strongly Interacting Massive Particle (SIMP) dark matter
Summary
We considered the expansions of dark Higgs fields about nonzero VEVs by a singlet. (vS s), and a Higgs field HX in several representation of SU(2)X :. Due to the VEV of the dark Higgs HX in a nontrivial representation of SU(2)X , such as Φ, T , Q4 or Q5, masses of dark-charged gauge bosons, Xμ, Xμ†, are given by m2X. For a vanishing Z charge of the dark Higgs HX or in the limit of a vanishing gZ , the dark-neutral gauge boson has mass m2X3,0 = gX2 I2vI2,. The most general dark gauge boson masses with VEVs of Higgs fields in arbitrary representations are given in the appendix A. In this case, the dark charged gauge boson is still the lightest gauge boson in the dark sector, so that the 2 → 2 annihilation of Xμ, Xμ† is forbidden while 3 → 2 processes with gauge self-interactions become dominant for determining the relic density of Xμ, Xμ†. Concerning the self-interacting processes for dark-charged gauge bosons, we can use the above interactions by ignoring the mixing between dark Higgs and SM Higgs bosons and the mixings between dark-neutral gauge bosons and SM neutral gauge bosons
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