Can Feebly Interacting Massive Particles (FIMP) constitute Dark Matter?

Abstract: In this study, we investigate the feasibility of Feebly Interacting Massive particles (FIMP) as possible candidates to constitute the observed Dark Matter abundance in the universe. FIMPs are particles that couple very feebly with known particles in the Standard Model (SM). As such, they do not attain thermal equilibrium with the baryon abundant environment in the early universe before Nucleosynthesis. In contrast to a freeze-out mechanism common for Weakly Interacting Massive Particles (WIMP) as DM candidates, FIMPs are produced by the so-called freeze-in mechanism that we will describe in this study. The purpose of this study is to investigate how the Coleman Weinberg (C-W) mechanism affects the FIMP [freeze-in] mechanism. We specifically consider a minimal extension of SM in which an Electroweak Singlet-scalar ($S$) couples only to the Higgs-boson ($H$); This is called the Higgs-portal mechanism. We study the C-W effective potentials for the Higgs and Dark-scalar singlet and their implications on FIMP mechanism.Using these, we focus on the High-temperature production of the DM with just the $HH\mapsto SS$ to compute the reaction rates, comparing Bose-Einstein statistics ($\Gamma_{HH\mapsto S S}^{B-E}$) to Maxwell-Boltzmann statistics $\Gamma_{HH\mapsto S S}^{M-B}$. We employ only $\Gamma_{HH\mapsto S S}^{B-E}$ to compute DM relic abundance ($Y$) at several Dark-scalar masses ($m_S$) as a function of coupling $k$, establishing that Higgs-Dark scalar coupling $k$ $\mapsto$ $k_{DM}$ corresponding to actual DM abundance lies in between ${10}^{-8.7}$ and ${10}^{-8}$, i.e. ${10}^{-8.7}<k_{DM}<="" div="">