In the context of non-standard cosmologies, an early matter-dominated (EMD) era can significantly alter the conventional dark matter (DM) genesis. In this work, we reexamine the impact of an EMD on the weakly- and feebly-interacting massive particle (WIMP and FIMP) paradigms. EMD eras significantly modify the genesis of DM because of the change in the Hubble expansion rate and the injection of entropy. The WIMP paradigm can be realized with couplings much smaller than in the standard cosmological scenario, whereas much larger couplings are required in the FIMP case. Using the singlet-scalar DM model as a case study, we show that these results can lead to a continuous transition between the WIMP and FIMP scenarios, with results that are also applicable to other DM models. This broadens the parameter space consistent with observed DM levels and suggests that even elusive FIMP scenarios may be within the reach of future experimental searches.
We consider multi-component dark matter in a model where one dark matter component is feebly interacting (FIMP) while the second is weakly interacting (WIMP). The model contains an inert scalar doublet and a complex scalar singlet and features a discrete $Z_4$ symmetry. We determine the parameter space that satisfies theoretical constraints, collider constraints, relic density as well as direct and indirect detection limits. We discuss the possibility to probe the model through collider and astrophysical searches. We find that it is possible that the FIMP forms the dominant DM component, in th…
A dark matter (DM) having feeble interaction with the visible sector can thermalise via substantial interaction with a Weakly Interacting Massive Particle (WIMP). Such DM candidates are categorised as pseudo-FIMP (pFIMP). pFIMP can provide both direct and indirect search prospects via WIMP loop. This work focuses into such possibilities. We provide all such one loop graphs involving scalar, fermion and vector boson particles via which pFIMP can interact with the Standard Model assuming both of them are stabilised via $\mathbb{Z}_2\otimes \mathbb{Z}_2^{\prime}$ symmetries. We elaborate upon a m…
WIMP (Weakly Interacting Massive Particle), FIMP (Feebly interacting Massive Particle) and EWIP (Extremely Weakly Interacting Particle) dark matter are different theoretical frameworks that have been postulated to explain the dark matter. In this paper we examine an intermediate scenario that combines features from these three frameworks. It consists of a weakly interacting particle --a la WIMP-- that does not reach thermal equilibrium in the early Universe --a la FIMP-- and whose relic density is determined by the reheating temperature of the Universe --a la EWIP. As an example, an explicit r…
Dark matter models can give rise to specific signatures at particle physics experiments or in cosmology. The details of the cosmological history can also influence the new physics signals to be expected at e.g. collider experiments. In these proceedings, we briefly summarize the case of dark matter weakly to feebly coupled to Standard Model fermions through t-channel portal dividing the discussion into three main regimes. We also underline the interplay between cosmology and particle physics.
We explore the simplest viable dark matter model with a real singlet scalar, vector-like singlet and doublet fermions. The Yukawa couplings associated with the fermion sector play a crucial role in getting the current relic density through Freeze-in and Freeze-out mechanism. We discuss the constraints from the recent muon anomalous magnetic moment experimental data and relic density. We also perform the collider analysis for the FIMP dark matter in the context of 14 TeV LHC experiments with the MATHUSLA100/200 detector. Our analysis shows that one can get enough events $>3$ for heavy charged f…
Electroweak Symmetry Breaking (EWSB) is known to produce a massive universe that we live in. However, it may also provide an important boundary for freeze-in or freeze-out of dark matter (DM) connected to Standard Model via Higgs portal as processes contributing to DM relic differ across the boundary. We explore such possibilities in a two-component DM framework, where a massive $U(1)_X$ gauge boson DM freezes-in and a scalar singlet DM freezes-out, that inherits the effect of EWSB for both the cases in a correlated way. Amongst different possibilities, we study two sample cases; first when on…
We consider an extension of the Standard Model that explains the neutrino masses and has a rich dark matter phenomenology. The model has two dark matter candidates, a vector WIMP and a fermion FIMP, and the sum of their relic densities matches the total dark matter abundance. We extensively study the dark matter production mechanisms and its connection with the neutrino sector, together with various bounds from present and future experiments. The extra scalar field in the model may induce a first-order phase transition in the early Universe. We study the production of stochastic gravitational …
We explore a two component dark matter model with a fermion and a scalar. In this scenario the Standard Model (SM) is extended by a fermion, a scalar and an additional pseudo scalar. The fermionic component is assumed to have a global ${\rm U(1)}_{\rm DM}$ and interacts with the pseudo scalar via Yukawa interaction while a $\mathbb{Z}_2$ symmetry is imposed on the other component -- the scalar. These ensure the stability of both the dark matter components. Although the Lagrangian of the present model is CP conserving, however the CP symmetry breaks spontaneously when the pseudo scalar acquires…
We present an extension of the SM involving three triplet fermions, one triplet scalar and one singlet fermion, which can explain both neutrino masses and dark matter. One triplet of fermions and the singlet are odd under a $Z_2$ symmetry, thus the model features two possible dark matter candidates. The two remaining $Z_2$-even triplet fermions can reproduce the neutrino masses and oscillation parameters consistent with observations. We consider the case where the singlet has feeble couplings while the triplet is weakly interacting and investigate the different possibilities for reproducing th…
Despite the compelling amount of evidence for the existence of dark matter, its exact nature is still one of the main open questions in modern physics. A great experimental effort has been performed to probe one of the most popular dark matter candidates, the Weakly Interacting Massive Particle or WIMP, however, there has not been any conclusive detection yet. Hence, these searches place strong constraints on the WIMP paradigm. The community has therefore started to consider alternatives who are able to evade the strong experimental constraints. Such a candidate that has gained a lot of attent…
A feebly interacting massive particle (FIMP), contrasting with a weakly interacting massive particle (WIMP), is an intriguing dark matter (DM) candidate. Light (keV-scale) FIMP DM is of particular interest: its radiative decay leaves a line signal in x-ray spectra; and it is warm dark matter (WDM) and alters the galactic-scale structure formation of the Universe from that with WIMP DM. Once a possible x-ray line is reported (e.g., $3.5 \,\mathrm{keV}$ line and $7 \,\mathrm{keV}$ FIMP DM is inferred), one has to check whether or not this FIMP DM is compatible with the structure formation. Here …
In this analysis we demonstrate the freeze-in realization of a non-abelian vector boson dark matter (DM). We choose to elaborate an existing $SU(2)_N$ extension ($N$ stands for neutral) of the Standard Model (SM) with an additional $U(1)=S^{'}$ global symmetry, which stabilizes the vector boson ($X,\bar{X}$) as DM through unbroken $S=T_{3N}+S^{'}$ and as lightest odd $S$ particle. The analysis reveals that the contribution to the freeze-in production of DM from the decay of a heavier scalar bidoublet $ζ_1^{0,\pm} \to ζ_2^{0,\pm}X$ is important even after the freeze-out of $ζ_1^{0,\pm}$ in equi…
We explore the idea of an alternative candidate for particle dark matter namely Feebly Interacting Massive Particle (FIMP) in the framework of a two component singlet scalar model. Singlet scalar dark matter has already been demonstrated to be a viable candidate for WIMP (Weakly Interacting Massive Particle) dark matter in literature. In the FIMP scenario, dark matter particles are slowly produced via "thermal frreze-in" mechanism in the early Universe and are never abundant enough to reach thermal equilibrium or to undergo pair annihilation inside the Universe's plasma due to their extremely …
We explore the dark matter freeze-in mechanism within the gauge mediation framework, which involves a hidden Feebly Interacting Massive Particle (FIMP) coupling feebly with the messenger fields while the messengers are still in the thermal bath. The FIMP is the fermionic component of the pseudo-moduli in a generic metastable supersymmetry (SUSY) breaking model and resides in the hidden sector. The relic abundance and the mass of the FIMP are determined by the SUSY breaking scale and the feeble coupling. The gravitino, which is the canonical dark matter candidate in the gauge mediation framewor…
From WIMP to FIMP during reheating: collider vs non-collider probes for p-wave annihilation
Institute of Physics（印度物理研究所）；Homi Bhabha National Institute（霍米·巴巴国立大学）；Indian Institute of Technology Guwahati（印度理工学院古瓦哈提分校）；Indian Institute of Technology Hyderabad（印度理工学院海得拉巴分校）；Indian Institute of Science Education and Research, Thiruvananthapuram（印度科学教育与研究学院（特鲁万南特拉普拉姆））；SRM University-AP（SRM安得拉邦大学）
The tightening of the constraints on the standard thermal WIMP scenario has forced physicists to propose alternative dark matter (DM) models. One of the most popular alternate explanations of the origin of DM is the non-thermal production of DM via freeze-in. In this scenario the DM never attains thermal equilibrium with the thermal soup because of its feeble coupling strength ($\sim 10^{-12}$) with the other particles in the thermal bath and is generally called the Feebly Interacting Massive Particle (FIMP). In this work, we present a gauged U(1)$_{L_μ-L_τ}$ extension of the Standard Model (S…
The scotogenic model is one of the simplest scenarios for physics beyond the Standard Model that can account for neutrino masses and dark matter at the TeV scale. It contains another scalar doublet and three additional singlet fermions (N_i), all odd under a Z_2 symmetry. In this paper, we examine the possibility that the dark matter candidate, N_1, does not reach thermal equilibrium in the early Universe so that it behaves as a Feebly Interacting Massive Particle (FIMP). In that case, it is found that the freeze-in production of dark matter is entirely dominated by the decays of the odd scala…
We consider an extension of the Standard Model that accounts for the muon $g-2$ tension and neutrino masses and study in detail dark matter phenomenology. The model under consideration includes a WIMP and a FIMP scalar dark matter candidates and thus gives rise to two-component dark matter scenarios. We discuss different regimes and mechanisms of production, including the novel freeze-in semi-production, and show that the WIMP and FIMP together compose the observed relic density today. The presence of the extra scalar fields allows phase transitions of the first order. We examine the evolution…
The freeze-in production of Feebly Interacting Massive Particle (FIMP) dark matter in the early universe is an appealing alternative to the well-known - and constrained - Weakly Interacting Massive Particle (WIMP) paradigm. Although challenging, the phenomenology of FIMP dark matter has been receiving growing attention and is possible in a few scenarios. In this work, we contribute to this endeavor by considering a $Z^\prime$ portal to fermionic dark matter, with the $Z^\prime$ having both vector and axial couplings and a mass ranging from MeV up to PeV. We evaluate the bounds on both freeze-i…
Many experiments exploring weakly interacting massive particles (WIMPs) such as direct, indirect and collider searches have been carried out until now. However, a clear signal of a WIMP has not been found yet and it makes us to suspect that WIMPs are questionable as a dark matter candidate. Taking into account this situation, we propose two models in which dark matter relic density is produced by decay of a metastable particle. In the first model, the metastable particle is a feebly interacting massive particle, which is the so-called FIMP produced by freeze-in mechanism in the early universe.…
The absence of any confirmative signals from extensive DM searching motivates us to go beyond the conventional WIMPs scenario. The feebly interacting massive particles (FIMPs) paradigm provides a good alternative which, despite of its feebly interaction with the thermal particles, still could correctly produce relic abundance without conventional DM signals. The Infrared-FIMP based on the renormalizable operators is usually suffering the very tiny coupling drawback, which can be overcome in the UltraViolet-FIMP scenario based on high dimensional effective operators. However, it is sensitive to…
The non-thermal dark matter (DM) production via the so-called freeze-in mechanism provides a simple alternative to the standard thermal WIMP scenario. In this work, we consider a popular $U(1)_{B-L}$ extension of the standard model (SM) in the context of inverse seesaw mechanism which has at least one (fermionic) FIMP DM candidate. Due to the added $\mathbb{Z}_{2}$ symmetry, a SM gauge singlet fermion, with mass of order keV, is stable and can be a warm DM candidate. Also, the same $\mathbb{Z}_{2}$ symmetry helps the lightest right-handed neutrino, with mass of order GeV, to be a stable or lon…
We investigate the production of neutralino dark matter in a cosmological scenario featuring an early matter dominated era ending at a relatively low reheating temperature. In such scenarios different production mechanisms of weakly interacting massive particles (WIMPs), besides the well--studied thermal production, can be important. This opens up new regions of parameter space where the lightest neutralino, as the best--known supersymmetric (SUSY) WIMP, obtains the required relic abundance. Many of these new sets of parameters are also compatible with current limits from colliders as well as …
The adiabatic perturbation of dark matter is damped during the kinetic decoupling due to the collision with relativistic component on sub-horizon scales. However the isocurvature part is free from damping and could be large enough to make a substantial contribution to the formation of small scale structure. We explicitly study the weakly interacting massive particles as dark matter with an early mater dominated period before radiation domination and show that the isocurvature perturbation is generated during the phase transition and leaves imprint in the observable signatures for small scale s…
We investigate a new bound on the low reheating temperature in a scenario where the Universe experiences early matter-domination before reheating after which the standard big bang cosmology begins. In many models of dark matter (DM), the small scale fluctuations of DM grow during the early matter-domination era and seed the formation of the ultracompact minihalos (UCMHs). Using the constraints on the number of UCMHs from gamma-ray observations, we find a lower bound on the reheating temperature between ${\cal O}(10)~{\rm MeV} - {\cal O}(100)~{\rm MeV}$ for WIMP dark matter depending on the nat…
We study the possibility of generating baryon asymmetry of the universe from dark matter (DM) annihilations during non-standard cosmological epochs. Considering the DM to be of weakly interacting massive particle (WIMP) type, the generation of baryon asymmetry via leptogenesis route is studied where WIMP DM annihilation produces a non-zero lepton asymmetry. Adopting a minimal particle physics model to realise this along with non-zero light neutrino masses, we consider three different types of non-standard cosmic history namely, (i) fast expanding universe, (ii) early matter domination and (iii…
Low-reheating scenario in dark Higgs inflation and its impact on dark photon dark matter production
Aliah University（阿利亚大学）；Chung-Ang University（中央大学）；University of Shanghai for Science and Technology（上海理工大学）；Tongji University（同济大学）；Korea Institute for Advanced Study（韩国高等研究院）
(Abridged) Despite the success of Cold Dark Matter (CDM) in explaining a wide range of observations, the microscopic nature of dark matter is still unknown. Attempts to detect WIMPs, the most commonly studied form, have not yet succeeded. Some predictions are even in apparent conflict with observations (e.g. cuspy-cored halos and `missing satellite problem'). Therefore, it is important to consider different forms of CDM. We focus on dark matter comprised of ultralight bosons that form a Bose-Einstein Condensate (BEC), described by a complex scalar field, and solve the Klein-Gordon and Einstein…
Strongly interacting singlet scalar dark matter during reheating
LAPTh, CNRS, Université Savoie Mont-Blanc（拉普物理实验室，法国国家科学研究中心，萨瓦省蒙布朗大学）；New York University Abu Dhabi（纽约大学阿布扎比分校）；Skobeltsyn Institute of Nuclear Physics, Moscow State University（莫斯科国立大学斯科别尔钦核物理研究所）
Impact of Supercooling on Direct Searches for Dark Matter and Gravitational Wave Backgrounds
ETH Zürich（苏黎世联邦理工学院）；Universität Zürich（苏黎世大学）；SISSA International School for Advanced Studies（国际高等研究院）；Università degli Studi di Roma la Sapienza（罗马第一大学）
