arXiv subjects

Hansel Gordillo-Ruiz

Publications and source records attributed to Hansel Gordillo-Ruiz.

3 recordsLinked to original sources

arXiv2026

A multi-axion model of inflation and dark matter

Models with extra dimensions include a tower of massive states that unavoidably contribute to cosmological dynamics. In particular, after compactification, a higher-dimensional axion gives rise to a set of states whose dynamics at early times exhibit the properties of inflation and, at late times, those of dynamical dark matter. Interestingly, natural choices of parameters imply that the inflationary trajectory in field space is approximately geodesic, meaning that inflation is effectively driven by a single inflaton corresponding to the heaviest state. In this scenario, all inflationary observables, including the emerging spectral distortions, are consistent with current observational constraints, and exact numerical solutions of the equations of motion show that reheating can consistently proceed down to temperatures of a few MeV. Furthermore, all states lighter than the inflaton only come to dominate the energy density of the Universe during the matter-dominated era, thus behaving as dark matter at late times. These states undergo a cascade of decays into radiation, while maintaining a sufficient dark-matter abundance to account for the observed relic density. The lightest dark-matter candidate remains stable on timescales far exceeding the age of the Universe, thereby satisfying even the most conservative observational constraints.

hep-ph↗

arXiv2026

Rolling with modular symmetry: quintessence and de Sitter in heterotic orbifolds

Modular invariance is a fundamental symmetry in string compactifications, constraining both the structure of the effective theory and the dynamics of moduli and matter fields. It has also gained renewed importance in the context of swampland conjectures and, independently, flavour physics. We investigate a modular-invariant scalar potential arising from heterotic orbifolds, where the flavour structure and moduli dynamics are jointly shaped by the underlying geometry. Focusing on a string-inspired, two-moduli truncation, we uncover a rich vacuum structure featuring anti-de Sitter minima and unstable de Sitter saddle points. We identify large regions in moduli space supporting multifield hilltop quintessence consistent with observations. All solutions satisfy refined swampland de Sitter bounds. Our results illustrate how modular symmetry can guide the construction of controlled, string-motivated quintessence scenarios within consistent effective theories.

hep-th↗

arXiv2023

The simplest case of dark inflaxion

Dark matter and cosmic inflation represent two of the major puzzles in cosmology. They are typically addressed by introducing separate fields with independent dynamics. On the other hand, extra dimensions might play an important role for observable physics. We introduce a five-dimensional model called dark inflaxion that includes an axion-like particle, whose Kaluza-Klein modes can describe inflation and dark matter. We show that a simple yet natural choice of the mass scale of the effective four-dimensional fields of our model can accommodate simultaneously the observable values of inflationary parameters and dark-matter abundance. It will be interesting to explore the consequences and predictions of more generic scenarios within the scope of our model, which include the possibility of multifield inflation and dark matter.

hep-ph↗