arXiv subjects

Yuber F. Perez-Gonzalez

Publications and source records attributed to Yuber F. Perez-Gonzalez.

At least 19 recordsLinked to original sources

arXiv2026

Hawking emission of massive vector fields by Kerr black holes

We compute, for the first time, the Hawking emission spectrum of massive vector (Proca) fields by spinning Kerr black holes, determining the associated greybody factors and the resulting mass and spin loss functions. We show, in particular, that the scalar (longitudinal) polarization of the Proca field has a spectrum approaching that of a free scalar field in the massless limit (in which it becomes a pure gauge mode), although we find substantial differences for finite mass. The contribution of the two vector (transverse) polarization modes coincides, as expected, with the one obtained by Page for the Maxwell field in the massless limit. The black hole's evaporation rate is dominated by the scalar mode for slowly spinning black holes and by the two vector modes as the black hole approaches extremality. As for other fields, we find that Proca Hawking emission is Boltzmann-suppressed for Hawking temperatures $T_H\lesssim |μ-Ω_H|$, where $μ$ is the field mass and $Ω_H$ is the angular velocity of the black hole's horizon. This implies that highly spinning black holes can efficiently emit massive vector fields at temperatures parametrically below the field's mass. Finally, we also find that superradiant emission is more pronounced for massive vector fields, with a maximum amplification factor of $\simeq 7\%$ (compared to $\simeq 4\%$ for massless photons).

gr-qc↗

arXiv2026

$\tt BlackHawk$ $\tt v3.0$: Hawking Radiation from Regular Black Holes

We present $\tt BlackHawk$ $\tt v3.0$, a major update of the public code designed to compute Hawking radiation spectra of black holes. Building upon previous versions, this release considerably extends the range of black hole geometries that can be studied by implementing several new spherically symmetric metrics: the Bardeen and Hayward regular black holes, the Simpson-Visser and Peltola-Kunstatter black-bounces, the D'Ambrosio-Rovelli black hole-to-white hole metric, and the Babichev-Charmousis-Lehébel black hole. For each metric, we compute the corresponding Hawking temperatures and greybody factors, enabling the determination of primary Hawking emission spectra for particles of different spins. The greybody factors are obtained through dedicated numerical routines based on the companion code $\tt GrayHawk$. Additionally, $\tt BlackHawk$ $\tt v3.0$ introduces several technical improvements aimed at enhancing precision and efficiency, providing a highly versatile tool. The code is publicly available at https://blackhawk.hepforge.org/

gr-qc↗

arXiv2026

Bose-enhanced Neutrino Decays in a Thermal Medium

We compute the decay width of neutrinos in a thermal medium using finite-temperature quantum field theory, focusing on non-standard decays into lighter neutrinos and a scalar or light vector boson. We derive general expressions for the thermal decay rate and show that finite-temperature effects can dramatically enhance neutrino decays when the parent and daughter states are nearly degenerate in mass. In this regime, the emitted boson is kinematically soft and undergoes strong Bose enhancement, leading to decay widths that can exceed their vacuum values by a couple of orders of magnitude. We demonstrate that this effect is largely insensitive to the Lorentz structure of the underlying interaction and arises generically from the interplay of thermal occupation factors and quasi-degenerate kinematics. Our results highlight a previously underappreciated feature of neutrino decay in thermal environments and provide a general framework applicable to a broad class of fermionic decay processes.

hep-ph↗

arXiv2026

Dynamic Neutrino Mass Ordering and Its Imprint on the Diffuse Supernova Neutrino Background

Neutrino masses may have evolved dynamically throughout the history of the Universe, potentially leading to a mass spectrum distinct from the normal or inverted ordering observed today. While cosmological measurements constrain the total energy density of neutrinos, they are not directly sensitive to a dynamically changing mass ordering unless future surveys achieve exceptional precision in detecting the distinct imprints of each mass eigenstate on large-scale structures. In this work, we investigate the impact of a dynamic neutrino mass spectrum on the diffuse supernova neutrino background (DSNB), which is composed of neutrinos from all supernova explosions throughout cosmic history and is on the verge of experimental detection. The dynamic evolution of neutrino masses with redshift changes the propagation of neutrinos inside the supernova. Since neutrino oscillations are highly sensitive to the mass spectrum, we show that the electron neutrino survival probability carries distinct signatures of the evolving neutrino mass spectrum. Our results show that a dynamic neutrino mass spectrum can modify the DSNB flux in an energy-dependent way. However, we find that the current level of spectral shape uncertainty in DSNB modeling makes a direct detection beyond the reach of present and near-future experiments. Nonetheless, our study highlights the DSNB as a probe of redshift-dependent neutrino properties once the astrophysical systematics are brought under control.

hep-ph↗

arXiv2026

ULYSSES the Third: An Odyssey Towards a Unified Python Toolkit for Leptogenesis

We present the third release of $\texttt{ULYSSES}$, a Python package for the numerical evaluation of the baryon asymmetry generated through leptogenesis. This version includes code implementing state-of-the-art density matrix equations for low-scale leptogenesis with three quasi-degenerate right-handed neutrinos. We extend the validity of the code in this scenario beyond the 100 GeV right-handed neutrino mass scale, into the regime of resonant leptogenesis, by including neutrino production rates valid in both the relativistic and non-relativistic regimes. In addition, in the high-scale vanilla scenario, we provide routines for computing $ΔL = 1$ scattering processes, enabling full phase-space evolution of the right-handed neutrino and lepton asymmetry. A new $\texttt{--extended}$ parameter interface allows users to pass model-specific inputs beyond the standard leptogenesis runcard without modifying the core infrastructure and demonstrate its use with a toy module that simultaneously solves the vanilla leptogenesis equations and the freeze-in production of dark matter. On top of these improvements, we introduce an alternative parametrisation of the Casas-Ibarra matrix, update the default neutrino oscillation parameters and report cross-checks of the new low-scale leptogenesis module against published benchmarks and independent codes. $\texttt{ULYSSES}$ is publicly available on $\href{https://github.com/earlyuniverse/ulysses}{\texttt{GitHub}}$ and pip-installable from PyPI.

hep-ph↗

arXiv2026

Multi-messenger Constraints on a Primordial Black Hole Origin of the KM3-230213A Event

Black holes are expected to end their lifetime in a burst of Hawking radiation, emitting all Standard Model particles at ultra-high energies. The evaporation of a nearby primordial black hole (PBH) has been proposed as an explanation for the high-energy neutrino-like event reported by KM3NeT. Such a scenario requires the source to be extremely close to Earth, implying detectable gamma-ray and cosmic-ray emission. Accounting for the time-dependent field of view of gamma-ray observatories, we find that current experiments should have observed a pre-burst signal, while neutrino telescopes would also detect lower-energy events before the burst. The absence of such multimessenger signals strongly disfavors a PBH origin of the KM3-230213A event in the minimal 4D Schwarzschild scenario.

astro-ph.HE↗

arXiv2026

nuSTORM as a Precision Probe of the Standard Model and New Physics

The Neutrinos from Stored Muons (nuSTORM) facility will generate neutrino beams from both muon and meson decays in a storage ring, providing a neutrino flux known to the percent level. This unprecedented precision enables a rich physics programme, including high-precision tests of the Standard Model and searches for new phenomena. In this paper we demonstrate nuSTORM's sensitivity to key Standard Model processes such as, measurements of the weak mixing angle at low $Q^2$ and the rare process of neutrino trident production. We also show its powerful reach for a diverse range of beyond-the-Standard-Model scenarios, including eV-scale sterile neutrinos, Kaluza-Klein excitations from large extra dimensions and lepton flavour violation. Furthermore, nuSTORM can place significant constraints on heavy QCD axions and other axion-like particles produced in rare kaon decays. These capabilities establish nuSTORM as a powerful and complementary probe to long baseline experiments and collider searches.

hep-ph↗

arXiv2026

Emergent Large Lepton Mixing from Neutrino Refraction in Dark Matter

We propose a novel origin for the disparity between quark and lepton flavor mixing based on the refractive nature of neutrino masses. We postulate that the fundamental mixing in both the quark and lepton sectors is CKM-like, together with tiny vacuum neutrino masses, while the observed PMNS mixing matrix emerges dynamically from coherent forward scattering of neutrinos on an ultralight dark matter background. The resulting in-medium Hamiltonian rotates CKM mixing angles into large effective lepton mixings, naturally realizing quark--lepton complementarity without invoking new flavor symmetries. This framework links neutrino mass generation, flavor mixing, and dark matter, and predicts environment-dependent neutrino oscillation effects testable in current and future experiments.

hep-ph↗

arXiv2026

Chasing Serendipity: Tackling Transient Sources with Neutrino Telescopes

The discovery of ultra-high-energy neutrinos by IceCube marked the beginning of neutrino astronomy. Yet, the origin and production mechanisms of these neutrinos remain an open question. With the observation of several neutrino events with energies about the PeV, transient sources - astrophysical objects that emit particles in brief, localized bursts - have emerged as promising candidates. In this work, we revisit the identification of such sources in IceCube and future neutrino telescopes, focusing on how both the timing and sky localization of the source affect the detection sensitivity. We present a framework to account for the source's right ascension in determining the effective area of detectors not located at the poles, such as KM3NeT. As a case study, we investigate evaporating primordial black holes (PBHs) as transient neutrino sources, showing that the detection prospects and localization accuracy are strongly influenced by the PBH's position in the sky. Our results emphasize the complementarity between neutrino and gamma-ray observatories and showcase the potential of a global network of neutrino detectors to identify and localize transient events that might be missed by traditional photon-based instruments.

astro-ph.HE↗

arXiv2026

Could a Primordial Black Hole Explosion Explain the extremely high-energy KM3NeT neutrino Event?

A black hole is expected to end its lifetime in a cataclysmic runaway burst of Hawking radiation, emitting all Standard Model particles with ultra-high energies. Thus, the explosion of a nearby primordial black hole (PBH) has been proposed as a possible explanation for the $\sim 220$~PeV neutrino-like event recently reported by the KM3NeT collaboration. If the event originated from a PBH, the source would need to lie at $(1-7)\times 10^{-5} \mathrm{pc}$ - depending on the assumed effective area - thus within the Solar System. At such proximity, the resulting flux of gamma rays and cosmic rays would be detectable at Earth. By incorporating the time-dependent field of view of gamma-ray observatories, we show that LHAASO should have recorded $\mathcal{O}(10^8)$ events between fourteen and seven hours prior to the KM3NeT detection. IceCube and KM3NeT \textit{itself} should likewise have detected of order a few hundred events in the range $1~\mathrm{TeV} \lesssim E_ν\lesssim 1~\mathrm{PeV}$ during the 24 hours preceding the burst. The absence of any such multi-messenger signal, particularly in gamma-ray data, strongly disfavors the interpretation of the KM3-230213A event as arising from evaporation in a minimal four-dimensional Schwarzschild scenario.

hep-ph↗

arXiv2025

Updated Constraints on Large Extra Dimensions from Reactor Antineutrino Experiments

We investigate constraints on large extra dimensions (LED) using the latest results from reactor antineutrino experiments. Specifically, we analyze the full data sets from Daya Bay, RENO, KamLAND, NEOS, and STEREO to derive updated bounds. For the case of one extra dimension, we find constrains on its radius $a$ of $a \lesssim 0.58~{\rm μm}$ ($a \lesssim 0.12~{\rm μm}$) at the $99\%$ confidence level for normal (inverted) ordering, an improvement of approximately $\sim 20\%$ ($\sim 25\%$) with respect to previous bounds, assuming a massless lightest active neutrino. Furthermore, we present new limits on $4+d$ LED scenarios, with $d = 2, 3, 4$ denoting the number of extra dimensions, based on the same reactor data and assuming equal radii for all extra dimensions. We find that the constraints become increasingly stringent with a larger number of extra dimensions. In particular, $d = 4$ with a massless lightest active neutrino, we obtain limits of $a \lesssim 0.28~{\rm μm}$ for normal and $a \lesssim 0.05~{\rm μm}$ for inverted orderings at the $99\%$ confidence level.

hep-ph↗

arXiv2025

Cosmic neutrino background detection in the minimally extended Standard Model

We investigate the sensitivity of relic neutrino detection methods within the Standard Model, extended to include right-chiral neutrino singlets with Majorana mass terms. In particular, we study neutrino capture on unstable nuclei, the Stodolsky effect, coherent scattering, and an accelerator experiment. We demonstrate that the sensitivity transitions smoothly between Dirac and Majorana regimes, depending on the scale of lepton number violation. Importantly, neutral current interactions lead to transitions between the light and heavy neutrino states, necessitating the use of a density matrix formalism for accurate sensitivity calculations. As the oldest source of neutrinos in the universe, relic neutrinos would be able to provide an ultimate constraint on the lepton number violating scale, $m_R\gtrsim 10^{-33}~{\rm eV}$, below which neutrinos would behave as Dirac fermions for all practical purposes.

hep-ph↗

arXiv2025

Page Time of Primordial Black Holes in the Standard Model and Beyond

The Page time marks the moment when the von Neumann entropy of the emitted Hawking radiation equals the Bekenstein-Hawking entropy of an evaporating black hole, which is assumed to quantify its degrees of freedom as seen from the outside. Beyond this point, from unitarity we would expect that the entropy of the radiation begins to decrease, ensuring that information is eventually recovered. In this work, we investigate the dependence of the Page time on black hole properties and the particle content of nature. Specifically, we analyze its sensitivity to the Standard Model (SM) and potential Beyond-the-SM degrees of freedom, incorporating the effects of particle masses. We find that a Schwarzschild primordial black hole (PBH) with an initial mass of $6.23\times 10^{14}~{\rm g}$ would have a Page time equal to the age of the Universe, assuming emission of SM particles only. We further explore the impact of a non-negligible PBH angular momentum, finding that light spin-2 particles are predominantly emitted before the Page time. Specifically, for initial angular momenta values exceeding $a_\star > 0.5$, approximately $70\%$ of the total graviton emission occurs prior to the Page time for PBHs with an initial mass $M_{\rm BH} \lesssim 10^{10}~{\rm g}$. Finally, we discuss the implications for PBH phenomenology, particularly regarding potential constraints from $ΔN_{\rm eff}$ measurements.

astro-ph.CO↗

arXiv2025

Neutrino Emission and Plasma Heating from Primordial Black Holes: An Improved Approach to $N_\mathrm{eff}$ Constraints

We investigate the impact of neutrino emission via Hawking radiation from primordial black holes (PBHs) on the cosmological effective number of neutrino species, $N_{\mathrm{eff}}$, after neutrino decoupling. By comparing this effect with observational limits, we derive bounds on the abundance of light PBHs. Our analysis incorporates two previously unaccounted-for effects: the emission of secondary neutrinos from unstable particles, which increases $N_{\mathrm{eff}}$, and the modification of the neutrino-photon temperature ratio due to particle emission heating the photon plasma, which lowers $N_{\mathrm{eff}}$. Overall, including these effects allows us to impose constraints on PBHs with initial masses in the range $10^9~{\rm g}\lesssim M_{\rm ini} \lesssim 10^{13}~{\rm g}$. However, our limits remain less stringent than those derived from Big Bang Nucleosynthesis.

astro-ph.CO↗

arXiv2025

Baryogenesis via Asymmetric Evaporation of Primordial Black Holes

We revisit baryogenesis from the asymmetric evaporation of light primordial black holes, focusing on scenarios where gravitational effects induce a matter antimatter asymmetry. In particular, we consider a higher-dimension operator coupling the Kretschmann scalar to a baryon-number-violating current which generates an effective chemical potential at the black hole horizon and leads to asymmetric Hawking radiation. Relative to earlier studies, we account for entropy dilution from evaporation, incorporate chemical potential dependent greybody factors and numerically track the fully coupled evolution of a PBH population in an expanding universe. We show that the observed baryon asymmetry can be reproduced within a viable region of parameter space for several PBH mass spectra including log-normal, critical-collapse, and power-law distributions.

hep-ph↗

arXiv2025

Probing the Cosmic Neutrino Background and New Physics with TeV-Scale Astrophysical Neutrinos

We use recent evidence of TeV neutrino events from the most significant astrophysical sources detected by IceCube -- NGC 1068, TXS 0506+056, PKS 1424+240 -- to constrain the local and global overdensity of relic neutrinos and to explore potential new neutrino self-interactions. Assuming a relic neutrino overdensity, such high-energy neutrinos have travelled considerable distances through a sea of relic neutrinos and could have undergone scattering, altering their observed flux on Earth. Considering only Standard Model interactions, we constrain the relic overdensity to $η\leq 2 \times 10^{14}$ at the 90$\%$ confidence level, assuming the sum of neutrino masses saturates the cosmological bound, $\sum_i m_i = 0.13$ eV. We demonstrate that this limit improves for larger neutrino masses and study how it depends on the scale of the overdensity region. Considering new interactions between TeV-scale neutrinos and relic neutrinos, mediated by a light boson, we probe couplings of approximately $g \sim 10^{-2}$ with current data for a boson mass around the MeV scale. We demonstrate that this limit improves with larger neutrino masses and the scale of the overdensity region.

hep-ph↗

arXiv2025

Gray-body factors: Method matters

The calculation of gray-body factors is essential for understanding Hawking radiation and black hole thermodynamics. While the formalism developed by Chandrasekhar is effective for static black holes, it faces significant challenges in Kerr spacetimes, particularly in the superradiant regime, where a specific choice of coordinates introduces numerical inaccuracies. To address these limitations, an alternative method based on re-scaling radial coordinates and employing Frobenius-like expansions has been investigated. We compare the gray-body factors obtained for a near-maximally rotating black hole using both methods and find that the Chandrasekhar formalism systematically overestimates the values in the superradiant regime compared to well-established analytical results. Specifically, for a spin parameter of $a_* = 0.999$, the Chandrasekhar method yields values approximately twice as large as the correct result. Since this approach has been implemented in \texttt{BlackHawk}, we assess the impact of these discrepancies on constraints derived from gamma-ray observations of highly spinning primordial black holes.

gr-qc↗

arXiv2025

Primordial black hole probes of heavy neutral leptons

Primordial black holes (PBH), while still constituting a viable dark matter component, are expected to evaporate through Hawking radiation. Assuming the semi-classical approximation holds up to near the Planck scale, PBHs are expected to evaporate by the present time, emitting a significant flux of particles in their final moments, if produced in the early Universe with an initial mass of $\sim 10^{15}$ g. These ``exploding'' black holes will release a burst of Standard Model particles alongside any additional degrees of freedom, should they exist. We explore the possibility that heavy neutral leptons (HNL), mixing with active neutrinos, are emitted in the final evaporation stages. We perform a multimessenger analysis. We calculate the expected number of active neutrinos from such an event, including contributions due to the HNL decay for different assumptions on the mixings, that could be visible in IceCube. We also estimate the number of gamma-ray events expected at HAWC. By combining the two signals, we infer sensitivities on the active-sterile neutrino mixing and on the sterile neutrino mass. We find that, for instance, for the scenario where $U_{τ4}\neq 0$, IceCube and HAWC could improve current constraints by a few orders of magnitude, for HNLs masses between 0.1 - 1 GeV, and a PBH explosion occurring at a distance of $\sim 10^{-4}$ pc from Earth.

hep-ph↗