Studies On WIMP And FIMP Dark Matter Candidates

Dark matter cannot be explained by standard models,the proportion of dark matter in cosmic matter is about five times that of ordinary baryonic matter,it plays a very important role in the universe,so it is very meaningful to study dark matter.In this paper,we focus on the properties of Weakly Interacting Massive Particles(WIMP)and Feebly Interacting Massive Particles(FIMP)as dark matter candidates.For WIMP,we introduce the Right-Hand Neutrino Portal Model,which extends the righthand neutrinos and dark sector on the basis of the standard model.Right-hand neutrinos can explain the tiny mass problem of left-hand neutrinos in the standard model through seesaw mechanism.The dark sector contains at least one scalar singlet Φ and fermi singlet X.We assume that the dark sector is in a Z2 discrete symmetry,all the standard model particles and right-handed neutrinos are singlet under the Z2 symmetry,while the dark sector particles are charged under the Z2 symmetry,which ensures that the dark matter particles will not easily interact with the charged particles in the standard model.The lightest particle in the dark sector is relatively stable and is considered as a dark matter candidate.Then,according to different situations,both types of particles in the dark sector may become dark matter candidates.For these two types of dark matter,we first calculate the samples that meet the correct range of relic abundance,and then add Higgs invisible decay width constraints,dark matter direct search and indirect search experiments constraints in the parameter space composed of these samples.Finally,the mass of dark matter is more than 70 GeV,and the main coupling mode of dark matter producting is the Right-Hand Neutrino Portal coupling.For FIMP,we introduce the dark sector based on the Neutrinophilic Two Higgs Doublet Model.The composition and symmetry of the the dark sector are consistent with the above,but we only set fermi χ as the FIMP dark matter candidate.The right-hand neutrinos and the newly introduced scalar doublet provide tiny mass for the left-hand neutrinos through Yukawa interaction.In addition,right-hand neutrinos have three different decay channels,N→lLΦv*and N→lLΦv are used to study leptogenesis mechanism and,N→χφ is used to study dark matter.With hierarchical right-hand neutrino masses,the explicit calculation shows that successful thermal leptogenesis is viable even for TeV-scale lightest right-hand neutrino with 0.4<vv<1 GeV and lightest left-hand neutrino mass m1(?)10-11 eV.When the relic abundance of dark matter satisfied with the experimental results.With the change of decay parameter K,warm and cold dark matter in the KeV to MeV range is naturally expected.