arXiv subjects

Esau Cervantes

Publications and source records attributed to Esau Cervantes.

6 recordsLinked to original sources

arXiv2026

Light Dark Matter from Self-cooling Dark Sectors

Light thermally produced dark matter is subject to strong bounds stemming from its free-streaming impact on suppressing structure formation. In this paper we show that these limits are significantly alleviated if the dark sector undergoes self-cooling, a new mechanism for lowering the temperature of the dark sector plasma through cannibal self-interactions during freeze-in production. We find that the Lyman-$α$ bounds can be modified by a few orders of magnitude in the sub-MeV region and frozen-in dark matter saturating the observed energy density can be as light as $\approx$ 1.9 (0.7) keV, compared to the $\approx$ 5.7 (1.9) keV warm dark matter limits determined from simulations. Interestingly, a secondary phase of cooling due to simultaneously efficient inverse cannibal- and decay-processes can dominate the modifications of Lyman-$α$ bounds, rather than self-thermalization via cannibal-reactions itself.

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arXiv2026

Dynamics of Self-Interacting Dark Sectors

This thesis investigates the dynamics of self-interacting dark sectors in the early Universe populated through the freeze-in mechanism. The main focus is on scenarios with self-number-changing reactions of the form $2\leftrightarrow3$, and on how these interactions modify the thermal history and phenomenology of the dark sector. Several realizations are studied, including scalar theories with $\mathbb{Z}_2$ and $\mathbb{Z}_3$ symmetries, self-interacting dark matter coupled to an unstable mediator, and cannibal dark matter production during non-instantaneous reheating. The thermal evolution is obtained by solving coupled Boltzmann equations for the relevant number densities and temperatures, accounting for both freeze-in production and cannibal interactions. The resulting parameter space can be strongly constrained, effectively invisible, or potentially accessible to future searches, depending on the realization considered. Finally, the thesis studies a hidden U(1) gauge sector populated via freeze-in, where continuous energy injection can induce an inverse first-order phase transition and temporarily restore the symmetric phase, linking phase-transition dynamics and chemical equilibration in hidden sectors.

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arXiv2026

KineticXGPU: A Tensorized Collision Operator for Dark-Sector Self-Scattering

In this work, we present KineticXGPU, a PyTorch-based implementation of the $2\to 2$ elastic self-collision operator for dark-sector momentum distributions. The discretized collision operator can be expressed as tensor contractions and is therefore well suited for GPUs. As an application, we study a two-source freeze-in scenario in which the final distribution can develop a bimodal shape. We show that increasing the strength of elastic self-interactions progressively erases this structure and drives the distribution toward a Maxwell-Boltzmann distribution. We compare the phase-space formulation with a set of fluid equations that couple the number density and velocity dispersion. We also compare CPU and GPU runtimes and demonstrate the computational advantage of the tensorized approach. The code is publicly available on GitHub.

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arXiv2025

Freezing-in Cannibals with Low-reheating Temperature

The freeze-in mechanism provides a compelling framework for dark matter (DM) production, particularly suited to scenarios involving feeble interactions with the Standard Model (SM). In this work, we highlight a possible interplay of a non-instantaneous reheating phase and dark sector self-interactions, specifically $2 \to 3$ and $3 \to 2$ cannibalization processes. As an example we study the freeze-in production of a complex scalar DM candidate stabilized by a $\mathbb{Z}_3$ symmetry permitting cubic self-couplings, enabling number-changing interactions that drive internal thermalization and significantly modify the dark sector number density and temperature evolution. We numerically solve the coupled Boltzmann equations for the DM number density and temperature alongside the evolving SM bath, accurately capturing the dynamics of a prolonged reheating epoch. Our analysis reveals a rich and distinctive phenomenology arising from the interplay between the Universe's thermal history, Higgs portal mediated production, and cannibalistic self-interactions. Compared to scenarios with instantaneous reheating or negligible self-interactions, our framework opens new viable regions in parameter space, particularly for light DM, potentially within reach of future probes.

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arXiv2025

Freezing-in Cannibal Dark Sectors

Self-Interacting Dark Matter models can successfully explain dark matter (DM) production through interactions confined within the dark sector. However, they often lack measurable experimental signals due to their secluded nature. Including a feeble interaction with the visible sector through a Higgs portal leads not only to potential detection avenues and richer thermal production dynamics, but also to a possible explanation of the initial dark sector population through the freeze-in mechanism. In this work we study, by solving the full system of coupled Boltzmann equations for the number densities and temperatures of all the involved states, three scenarios of this type where the DM is: a real scalar with broken $\mathbb{Z}_2$, a complex scalar with unbroken $\mathbb{Z}_3$, and a $\mathbb{Z}_3$ scalar with an additional scalar mediator. All of these models have viable dark matter candidates in a cannibal phase while having different detection profiles. We show that cosmological bounds can be either exacerbated or evaded by changing the dark sector interactions, leading to potential signatures in long-lived particle and indirect detection experiments.

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arXiv2023

Higgs-portal dark matter from non-supersymmetric strings

Large classes of non-supersymmetric string models equipped with standard-model features have been constructed, but very little of their phenomenology is known. Interestingly, their spectra exhibit scalar fields whose only couplings to observed particles is through a multi-Higgs sector. On the other hand, bottom-up models with Higgs portals offer still an acceptable framework for dark matter. We explore realizations of such Higgs portals in promising heterotic orbifold models without supersymmetry. We find that a sample model includes Higgs vacua that are stable at one-loop, in which the Higgs sector is compatible with particle-physics observations and a scalar can account for the measured dark matter abundance. In such vacua, interesting constraints on the masses of the dark matter candidate and the heavy Higgs sector are uncovered. These compelling results are not limited to string models, as they can be embedded in similarly motivated bottom-up schemes.

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