arXiv subjects

Mohid Farhan

Publications and source records attributed to Mohid Farhan.

5 recordsLinked to original sources

arXiv2026

Dark Matter and Dark Energy in Three-Higgs Doublet Model

This article discusses the incorporation of dark matter and dark energy into a new physics model called the Three-Higgs Doublet Model. Dark matter and dark energy are accommodated as CP-even and $Z_2$-odd scalars in their respective inert doublets. By leveraging a $Z_2$ symmetry to suppress certain interactions, we model the behavior of dark matter. Similarly, by imposing a shift symmetry, dark energy can be mimicked within the same framework for the current cosmic epoch. The dark matter relic density is calculated for our model using \texttt{micrOMEGAs}. It is shown that despite the inclusion of dark energy, dark matter relic density can be brought within observational bounds and match existing literature. Furthermore, the one-loop and two-loop Renormalization Group Equations (RGEs) were computed using \texttt{SARAH} to ensure radiative stability over a large range of energies. This study lays the groundwork for a future study of dark matter-dark energy interactions in the early universe and the exploration of different early universe dynamics.

hep-ph↗

arXiv2026

The Impossible Triangle: A No-Go for Symmetry-Protected Scalar Portals in Interacting Dark Energy

The $S_8$ tension motivates interacting dark energy (IDE), but embedding IDE in UV-complete physics faces severe naturalness challenges. We analyze four symmetry-protected DM--DE portals ( quartic ($\tfrac{1}{2}λϕ^2χ^2$), trilinear ($gϕχ^2$), derivative ($(c_6/Λ^2)(\partial_μϕ)^2χ^2$), and fermionic Yukawa ($yϕ\barψψ$) )within a $Z_2$-symmetric Inert Doublet + Singlet Model. The trilinear portal requires $β\sim 0.45$ ($g \sim 10^{-16}\,\mathrm{GeV}$), overshooting the radiative bound $g \lesssim 10^{-42}\,\mathrm{GeV}$ by $\sim 26$ orders (tuning $Δ\sim 10^{52}$). The quartic portal needs $λ\sim \mathcal{O}(1\text{--}10)$ versus $λ\lesssim 10^{-86}$ ($Δ\sim 10^{87}$). The derivative portal saturates dynamically at $\lesssim 4\%$ suppression. The Yukawa portal yields $Δ\sim 10^{52}$, persisting even with SUSY cancellation. No single-mediator model simultaneously satisfies technical naturalness and resolves the $S_8$ tension. Viable solutions require either multi-field tuned cancellations or explicit symmetry breaking with quantified fine-tuning.

hep-ph↗

arXiv2026

Layered dark structure with a Structuring Field: A $Z_4$-symmetric Inert Doublet-Singlet realization and implications for the $S_8$ tension

We introduce the Layered Dark Sectors with a Structuring Field (LDS-SF), a structured cosmological framework where the internal architecture of a multi-component dark sector naturally generates scale-dependent growth of structure. In this framework, the characteristic scale dependence is derived from the dominant eigenvalue, $λ(k)$, of the dark sector's perturbation matrix. This structurally-driven mechanism modifies structure growth while preserving the standard $Λ$CDM background expansion and General Relativity. We provide a minimal realization of this framework within a two-component DM $Z_4$-symmetric Inert Doublet Singlet Model ($Z_4$-IDSM). By integrating out the heavy inert doublet mediator, we derive a contact-interaction Effective Field Theory (EFT) for a 60~GeV singlet dark matter candidate. This interaction manifests macroscopically as an effective sound speed $c_s^2$, which we map to the LDS-SF eigenmode evolution. We implement this system into the CLASS Boltzmann code, employing a late-time activation function that projects virialized halo properties into the linear perturbation framework. We also compute the relic density using micrOMEGAs to further stress-test the relic abundance predictions of viable parameters. Our numerical analysis demonstrates that while the model remains indistinguishable from $Λ$CDM at the era of recombination, it introduces a targeted suppression of the matter power spectrum at late times ($z < 10$) and small scales ($k > 0.1~h/\text{Mpc}$). Confronting the model with Planck CMB, BAO, and growth-rate measurements, we find three instances of couplings that successfully alleviate the $S_8$ tension, bringing the predicted amplitude into $1σ$ agreement with weak-lensing data from KiDS-1000 and DES. This work establishes LDS-SF as a mathematically consistent and observationally viable extension of standard cosmology.

hep-ph↗

arXiv2026

Symmetry-Protected Momentum Exchange between Dark Matter and Dark Energy

We present a particle physics motivated realization of interacting dark energy in which a radiatively stable dark energy sector couples to weakly interacting massive particle dark matter through pure momentum exchange. The dark energy field arises as a pseudo-Nambu-Goldstone Boson from a complex scalar singlet charged under a softly broken global $U(1)_S$, while dark matter is identified with an inert scalar doublet stabilized by a discrete $Z_4$ symmetry. This symmetry structure allows renormalizable dark matter-dark energy portal operators; however, requiring the dark energy field to emerge as a radiatively stable pseudo-Nambu-Goldstone Boson necessitates their absence, leaving derivative interactions as the leading coupling. As a result, energy transfer between the dark sectors is absent at the background level, while momentum exchange modifies the evolution of cosmological perturbations. We implement the resulting interacting dark energy model self-consistently in the Boltzmann code CLASS and study its impact on the growth of structure. We find that, despite sizeable momentum exchange, the suppression of the clustering amplitude $σ_8$ saturates above the level required to fully resolve current low-redshift tensions. Our results demonstrate that symmetry-protected, momentum-exchange-only dark sector interactions possess an intrinsic limit on structure suppression, providing a theoretically controlled benchmark for interacting dark energy scenarios.

astro-ph.CO↗

arXiv2025

Relic Density Topology as a Discriminatory Tool: A Comparative Analysis of IDM, MSSM, and NMSSM Dark Matter

This study proposes a diagnostic mechanism based on the relic density topology to discriminate between the Inert Doublet Model (IDM), the Minimal Supersymmetric Standard Model (MSSM), and the Next-to-Minimal Supersymmetric Standard Model (NMSSM). Using a unified numerical scan with micrOMEGAs over the heavy-mass regime ($m_{x} > 300$ GeV), we contrast the phenomenological profiles of these frameworks. We demonstrate that the IDM admits a broad, stable viability plateau driven by efficient gauge couplings, while the MSSM and NMSSM typically overproduce dark matter, reaching the Planck relic density only through narrow, fine-tuned resonance channels. A quantitative fine-tuning measure reveals the IDM's viable parameter space is an order of magnitude more natural than its SUSY counterparts. Furthermore, by examining the thermal decoupling epoch ($z_{f}$) and the CMB energy-injection parameter ($p_{ann}$), we confirm that all identified viable regions are consistent with cosmological observations, and that the models exhibit different thermal history scenarios for the Universe. Our findings establish a multi-faceted discriminative framework: the IDM is characterized by a robust plateau and low fine-tuning, the MSSM by a sharp slepton-mediated annihilation dip, and the NMSSM by a diluted signature due to singlino admixture. The discovery of a heavy WIMP without sharp resonance features would therefore phenomenologically favor scalar doublet extensions over minimal supersymmetric frameworks.

hep-ph↗