Abstract
We propose an extension of the standard model (SM) by including a dark sector comprising of three generations of heavy right-handed neutrinos, a singlet scalar and a singlet Dirac fermion, where the latter two particles are stable and are viable candidates of dark matter (DM). In the early Universe, the CP-violating out-of-equilibrium decay of heavy right-handed neutrinos to singlet Dirac fermion and scalar in the dark sector generates a net DM asymmetry. The latter is then transported to the visible sector via a dimension eight operator which conserves $B-L$ symmetry and is in thermal equilibrium above the sphaleron decoupling temperature. An additional light singlet scalar is introduced which mixes with the SM Higgs and pave a path for annihilating the symmetric components of the DM candidates. Then we discuss the constraints on singlet-doublet Higgs mixing from invisible Higgs decay, signal strength at LHC and direct search of DM at terrestrial laboratories. At tree level the neutrinos are shown to be massless since the symmetry of dark sector forbids the interaction of right-handed neutrinos with the SM particles. However, at one loop level the neutrinos acquire sub-eV masses as required by the oscillation experiments.
Highlights
The evidence from the galaxy rotation curve, gravitational lensing, and large scale structure of the Universe irrefutably proves the existence of dark matter (DM) in a large scale (≳ a few kpc) [1]
We propose an extension of the standard model (SM) by including a dark sector comprised of three generations of heavy right-handed neutrinos, a singlet scalar, and a singlet Dirac fermion, where the latter two particles are stable and are viable candidates of dark matter (DM)
We extended the standard model by including a dark sector which consists of three generations of heavy right-handed neutrinos NiR; i 1⁄4 1, 2, 3, a singlet Dirac fermion χ, and a singlet scalar φ0, where the latter two particles represent the DM
Summary
The evidence from the galaxy rotation curve, gravitational lensing, and large scale structure of the Universe irrefutably proves the existence of dark matter (DM) in a large scale (≳ a few kpc) [1]. We extend the SM by including a dark sector, as shown, comprised of three generations of heavy right-handed neutrinos, a singlet scalar φ0, and a singlet Dirac fermion χ These particles are charged under an additional symmetry, Uð1ÞB−L × Uð1ÞD × Z2, while remaining inert with respect to the SM gauge group. Violating out-of-equilibrium decay of heavy right-handed neutrinos to χφ0 in the early Universe generates a net B − L asymmetry [11,12]. The latter is transferred to the visible sector by a dimension-eight operator [13,14,15], O8.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.