arXiv subjects

S. Peyman Zakeri

Publications and source records attributed to S. Peyman Zakeri.

8 recordsLinked to original sources

arXiv2026

Dark matter interpretation of GRB 221009A: a singlet scalar explains LHAASO data

In this work, we propose a dark matter (DM) interpretation of the intensive gamma ray burst GRB 221009A. This indirect detection approach devotes to the decay of DM particles into high energy (HE) photons. In this context, a singlet scalar DM generated at the redshift of GRB 221009A is up-scattered by the high energy cosmic rays (HECRs) during its propagation to Earth. This highly boosted DM then possesses a high flux and undergoes a dominant di-photon decay before reaching the detector. The Large High Altitude Air Shower Observatory (LHAASO) probes such energetic gamma rays whereby has recorded a $\sim$13 TeV event for the aforementioned GRB.

hep-ph↗

arXiv2026

Asymmetric Two-Component Scalar FIMP Dark Matter

We propose a two-component asymmetric feebly interacting massive particle (FIMP) dark matter (DM) model in which both DM candidates are complex scalar fields. The model is an extension of the standard model (SM) by two scalar DM components and a heavy scalar mediator, stabilized by a $\mathbb{Z}_2 \times \mathbb{Z}_2'$ symmetry. DM is produced via the freeze-in mechanism through the Higgs portal, while the CP-violating decay of the heavy mediator generates an asymmetry in the first component, which is partially transferred to the second component via quartic interactions. By solving the Boltzmann equations numerically, we compute the relic density and perform a detailed scan over the parameter space. The observed relic density $Ω_{\text{DM}} h^2 = 0.12 \pm 0.001$ is successfully reproduced for benchmark parameters $m_{ϕ_1}=0.1$~GeV, $m_{ϕ_2}=0.5$~GeV, $M_S=100$~GeV, and $μ_{12}=3\times10^{-9}$, with the second component contributing only about $5\%$ to the total abundance. We also examine phenomenological constraints. The DM self-interaction cross section lies orders of magnitude below the Bullet cluster bound ($σ/m < 0.47$~cm$^2$/g) and the more stringent double radio relic limit ($σ/m < 0.22$~cm$^2$/g). The invisible Higgs decay branching ratio is $\sim 6\times10^{-18}$, well below the LHC upper limit, and direct detection prospects are negligible due to the small Higgs portal couplings. Our model establishes a novel connection between two-component DM, the freeze-in mechanism, and DM asymmetry.

hep-ph↗

arXiv2026

Sterile Neutrino as an Asymmetric Dark Matter

We propose a minimal and predictive framework for asymmetric sterile neutrino dark matter (DM) produced via freeze-in. The standard model (SM) is extended by a gauge-singlet Dirac sterile neutrino carrying a conserved dark charge, a real scalar mediator, and an auxiliary singlet fermion. DM is generated through the out-of-equilibrium decay of the mediator, which simultaneously produces a particle{antiparticle asymmetry in the sterile sector controlled by a CP-violating parameter. We show that the observed relic abundance can be naturally reproduced without thermal equilibration with the SM plasma. The resulting non-thermal momentum distribution is colder than a thermal Fermi{Dirac spectrum, ensuring consistency with structure formation constraints. Combining relic density, Lyman-α, Higgs invisible decay, and big bang nucleosynthesis (BBN) bounds, we identify correlated and predictive regions of the parameter space characterized by non-trivial relations among the sterile neutrino mass and the decay parameters. This scenario provides a self-consistent realization of Dirac asymmetric sterile neutrino DM within an asymmetric freeze-in (AFI) framework, offering a constrained and testable alternative to conventional production mechanisms.

hep-ph↗

arXiv2020

Singlet scalar dark matter in the non-commutative space-time: a viable hypothesis to explain the gamma-ray excess in the galactic center

We explore the non-commutative space-time to revive the idea that gamma-ray excess in the galactic center can be the result of particle dark matter annihilation. In the non-commutative theory, the photon spectrum is produced by direct emission during this annihilation where a photon can be embed in the final state together with other direct products in new vertices. In the various configurations of dark matter phenomenology, we adopt the most common model known as singlet scalar. Calculating the relevant aspects of the model, we can obtain the photon flux in the galactic center. Comparing our numerical achievements with experimental data reveals that non-commutative space-time can be a reliable framework to explain the gamma-ray excess.

hep-ph↗

arXiv2018

A Minimal Model For Two-Component FIMP Dark Matter: A Basic Search

In the multi-component configurations of dark matter phenomenology, we propose a minimal two-component configuration which is an extension of the Standard Model with only three new fields; one scalar and one fermion interact with the thermal soup through Higgs portal, mediated by the other scalar in such a way that the stabilities of dark matter candidates are made simultaneously by an explicit $Z_2$ symmetry. Against the most common freeze-out framework, we look for dark matter particle signatures in the freeze-in scenario by evaluating the relic density and detection signals. A simple distinguishing feature of the model is the lack of dark matter conversion, so the dark matter components act individually and the model can be adapted entirely to both singlet scalar and singlet fermionic models, separately. We find dark matter self-interaction as the most promising approach to probe such feeble models. Although the scalar component satisfies this constraint, the fermionic one refuses it even in the resonant region.

hep-ph↗

arXiv2018

Searching for Vector-Like Quarks in a Fermionic Dark Matter Model with Pseudoscalar: A Resonance Case

We propose a minimal model of a fermionic dark matter with a pseudoscalar mediator and N generation of vector-like quarks. We calculate the relic density and obtain new constraint on the generation of the aforementioned quarks. Concerning phenomenological aspects, we probe the presenting model via direct and indirect approaches. Finally, as an illustrative example, we evaluate a resonance case which has been (would be) the subject of major experiments aiming to detect new particles. Performing this analysis results in significant constraints on the coupling strength of the vector-like quarks.

hep-ph↗

arXiv2016

Freeze-in production of Fermionic Dark Matter with Pseudo-scalar and Phenomenological Aspects

In this paper, we study freeze-in production of fermionic dark matter with a pseudo scalar as the mediator between dark sector and Standard Model (SM). While the fermionic DM is non-thermal, we will explain two scenarios in which production of pseudo-scalar particles are either thermal or non thermal. We'll present elaborate discussion to derive yield quantity and relic density and illustrate these values for the different range of model parameters. We'll investigate constraints on parameters space coming from invisible Higgs decay at LHC. For the case of extremely small couplings and zero mixing between SM Higgs field with pseudo scalar field which pseudo scalar boson can play role of DM, we will justify recent observation of merging galaxies with a case of self-interacting DM. We'll show that influence of DM annihilation in this case, would provide a better fit to the AMS-02 data of positron flux.

hep-ph↗

arXiv2016

Non-monotonic Casimir interaction: The role of amplifying dielectrics

The normal and the lateral Casimir interactions between corrugated ideal metallic plates in the presence of an amplifying or an absorptive dielectric slab has been studied by the path-integral quantization technique. The effect of the amplifying slab, which is located between corrugated conductors, is to increase the normal and lateral Casimir interactions, while the presence of the absorptive slab diminishes the interactions. These effects are more pronounced if the thickness of the slab increases, and also if the slab comes closer to one of the bounding conductors. When both bounding ideal conductors are flat, the normal Casimir force is non-monotonic in the presence of the amplifying slab and the system has a stable mechanical equilibrium state, while the force is attractive and is weakened by intervening the absorptive dielectric slab in the cavity. By replacing one of the flat conductors by a flat ideal permeable plate the force becomes non-monotonic and the system has an unstable mechanical equilibrium state in the presence of either an amplifying or an absorptive slab. When the left side plate is conductor and the right one is permeable, the force is non-monotonic in the presence of a double-layer DA (dissipative-amplifying) dielectric slab with a stable mechanical equilibrium state, while it is purely repulsive in the presence of a double-layer AD (amplifying-dissipative) dielectric slab.

cond-mat.mes-hall↗