Abstract
We study the freeze-in production of Feebly Interacting Massive Particle (FIMP) dark matter candidates through a neutrino portal. We consider a hidden sector comprised of a fermion and a complex scalar, with the lightest one regarded as a FIMP candidate. We implement the Type-I Seesaw mechanism for generating the masses of the Standard Model (SM) neutrinos by introducing three heavy neutrinos which are assumed to be degenerated, for simplicity, and are also responsible for mediating the interactions be- tween the hidden and the SM sectors. We assume that an early matter-dominated (EMD) era took place for some period between inflation and Big Bang Nucleosynthesis, making the Universe to expand faster than in the standard radiation-dominated era. In this case, the hidden and SM sectors are easily decoupled and larger couplings between FIMPs and SM particles are needed from the relic density constraints. In this context, we discuss the dynamics of dark matter throughout the modified cosmic history, evaluate the relevant constraints of the model and discuss the consequences of the duration of the EMD era for the dark matter production. Finally, we show that if the heavy neutrinos are not part of the thermal bath, this scenario becomes testable through indirect detection searches.
Highlights
Experiments, the strong constraints on this framework [2] and the absence of new particles at the LHC motivate exploring alternative scenarios
We study the freeze-in production of Feebly Interacting Massive Particle (FIMP) dark matter candidates through a neutrino portal
As an interesting consequence of an early matter-dominated (EMD) era, we explore the sensitivity of the indirect detection of FIMP annihilations to heavy neutrinos, which subsequently decay into Standard Model (SM) states
Summary
We consider the Standard Model (SM) content and introduce an extra fermion, χ, and a scalar, S, both comprising the hidden/dark sector. LiLYνijH (N j)R + h.c. corresponding to the Lagrangian of the hidden sector, containing the kinetic and mass terms of χ and S (eq (2.2)), the term responsible for the generation of neutrinos masses (eq (2.3)) and the term leading to the interactions between the hidden and the visible sectors (eq (2.4)). Corresponding to the Lagrangian of the hidden sector, containing the kinetic and mass terms of χ and S (eq (2.2)), the term responsible for the generation of neutrinos masses (eq (2.3)) and the term leading to the interactions between the hidden and the visible sectors (eq (2.4)) In this model, Yνij stands for the Yukawa coupling matrix (the structure will be discussed later), Li are the left-handed leptons, with i = 1, 2, 3 being the generation index, the subscript denotes the interaction basis, mχ, mS and mN are the χ, S and N masses, respectively, and H = iσ2H∗, with H being the SM Higgs doublet: H=. Since we want to focus on the neutrino portal, such scalar portal interactions are temporarily ignored, and the exact form of the scalar potential V (S) is, irrelevant
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
