arXiv subjects

Michael Zantedeschi

Publications and source records attributed to Michael Zantedeschi.

At least 19 recordsLinked to original sources

arXiv2026

Black Hole Memory Burden and its Signatures in Gravitational Waves from Mergers

Swift memory burden (MB) implies that the information stored in a black hole (BH) can modify its classical dynamics when the BH is perturbed. This influences the gravitational waves (GWs) emitted during BH mergers. In this paper, we investigate how the BH memory load is determined by the features of the collapsing source. We show that the memory load can vastly exceed the information content of its progenitor. An extreme example is a BH formed in a two-particle collision, which exhibits maximal MB. We then derive bounds for BHs formed through stellar collapse and examine the impact of swift MB on BH quasinormal modes, quantifying the MB-induced frequency shift of GWs. These findings imply that GW observations probe the fundamental mechanisms of BH information storage as well as their formation history.

gr-qc↗

arXiv2026

On the predictivity of axion dark matter in the presence of Peccei-Quinn breaking

It is shown that the post-inflationary quantum chromodynamics (QCD) axion need not lead to a unique one-parameter prediction for the dark matter abundance whenever small explicit Peccei-Quinn symmetry breaking becomes dynamically relevant before the QCD transition. Although strongly constrained by the strong CP bound, such breaking remains phenomenologically viable and introduces a mass scale $\mu$ that can control the early-time dynamics, as the QCD contribution to the axion mass is thermally suppressed at high temperatures. In this case, the axion string-wall network annihilates earlier, and the relic abundance is no longer primarily set by QCD dynamics alone, but instead depends on $\mu$, in addition to $f_a$, the axion decay constant. This effect overlaps with the parameter space relevant for QCD axion dark matter and, depending on ultraviolet parameters and initial conditions, can extend across it entirely.

hep-ph↗

arXiv2026

Cosmological Implications of the Slingshot Effect: Gravitational Waves, Primordial Black Holes and Dark Matter

In this paper, we explore the implications of the so-called slingshot effect. It represents a rather general phenomenon occurring when a localized source, such as a monopole, quark, or a $D$-brane, crosses a domain wall separating the confined (Higgsed) and unconfined (Coulomb) phases of the crossing source. The crossover is accompanied by a stretched ``string'' of proper co-dimensionality that confines the source to the domain wall. The effect takes place for different setups, such as phase transitions leading to confinement, both electric and magnetic, as well as in string theoretic inflation with $D$-branes. We discuss the role of the phenomenon in sourcing gravitational waves and dark matter in the form of Kaluza-Klein gravitons. We also show that the slingshot effect can lead to the formation of primordial black holes in observationally interesting mass ranges for dark matter and high-energy cosmic rays.

hep-ph↗

arXiv2025

The fast, the slow and the merging: probes of evaporating memory burdened PBHs

The so-called memory-burden effect implies that evaporating Primordial Black Holes (PBHs) inevitably stabilize before complete decay. This stabilization opens a new mass window for PBH Dark Matter below $10^{15}\,$g. The transition to the memory-burdened phase is not instantaneous but unfolds over cosmological timescales, with some PBHs entering this phase in the present epoch. Additionally, a fraction of PBHs undergo mergers today, forming ''young'' semiclassical black holes that evaporate at unsuppressed rates. Both processes generate fluxes of stable astrophysical particles, which are constrained by current measurements of high-energy $\gamma$-rays and neutrinos. Moreover, the steep increase in energy injection at higher redshifts perturbs the ionization history of the Universe, leading to complementary bounds from observations of the CMB temperature and polarization anisotropies. We find that the reopened window enabled by the memory-burden effect is largely within reach of detection, both locally and across cosmological distances. We further describe how our findings restrict the values of the critical exponent characterizing the memory burden phenomenon.

hep-ph↗

arXiv2025

A minimal Pati-Salam theory: from cosmic defects to gravitational waves and colliders

We discuss a minimal renormalizable Pati-Salam theory based on the $SU(4)_{\rm C}\,\times\,SU(2)_{\rm L}\,\times\,SU(2)_{\rm R}$ gauge group, with unification scale Higgs multiplets taken as $SU(2)_{\rm L}$ and $SU(2)_{\rm R}$ doublets, which lead to neutrino Dirac picture. Although a number of scalar particles could be light, even lying at the LHC energies, the unification scale is hopelessly out of reach in any foreseeable future. Moreover, phase transition in the early Universe leads to the production of magnetic monopoles and domain walls, both incompatible with the standard cosmological model. A small explicit breaking of the discrete left-right symmetry allows the domain walls to decay, and in the process possibly sweep away the monopoles, analogously to the previously discussed case of $SU(5)$ grand unified theory. This leaves an important imprint of gravitational waves, within the reach of next generation searches, correlated with monopole detection and new light particles at collider energies. The theory has a dark matter candidate in the form of an inert scalar doublet, with a mass below TeV, which can further trigger electroweak baryogenesis.

hep-ph↗

arXiv2025

Transitioning to Memory Burden: Detectable Small Primordial Black Holes as Dark Matter

Mounting theoretical evidence suggests that black holes are subjected to the memory burden effect, implying that after certain time the information stored in them suppresses the decay rate. This effect opens up a new window for small primordial black holes (PBHs) below $10^{15}\,{\rm g}$ as dark matter. We show that the smooth transition from semi-classical evaporation to the memory-burdened phase strongly impacts observational bounds on the abundance of small PBHs. The most stringent constraints come from present-day fluxes of astrophysical particles. Remarkably, currently-transitioning small PBHs are detectable through high-energetic neutrino events.

hep-ph↗

arXiv2025

$SO(10)$ theory on the plateau: the importance of being renormalizable

We revisit a minimal renormalisable $SO(10)$ grand unified theory, with the Higgs representation $45_{\rm H}$, $126_{\rm H}$ and complex $10_{\rm H}$, responsible for the unification, intermediate and the weak scale symmetry breaking, respectively. We perform the study of unification constraints and find that it allows for the Left-Right symmetric scale to be accessible even at the LHC, and the Quark-Lepton unification scale as low as its phenomenological limit around $10^5\,$GeV. Moreover, one can have neutron - anti neutron oscillations at the level of the present day sensibility in both of the above cases, while in the former case one can have simultaneously neutrinoless double beta decay induced by new light scalar states, reachable today - with both electrons emerging as left-handed, as in the neutrino exchange through its possible Majorana mass. We also discuss a recently raised issue of the fine-tuning of the light Higgs mass and its potential conflict with low intermediate mass scales.

hep-ph↗

arXiv2025

Implications of Photon Mass: Vortextrap Magnetization of Black Holes

We discuss certain astrophysical implications of the photon mass. It offers a new mechanism of black hole magnetization, described as ``vortextrap magnetization" (VTM), which can generate a near-saturated magnetic field in astrophysical black holes. The extreme magnetic field is provided by a large number of Nielsen-Olesen type vortex lines piercing a black hole. In massive photon scenario the galactic magnetic field is a densely populated forest of overlapping magnetic flux tubes. These get trapped and collected by a black hole over a cosmological time-scale. The VTM mechanism neatly fits supermassive black holes with sizes matching the phenomenologically-acceptable values of the photon mass, and has implications for magnetic-field based particle acceleration. Even in absence of surrounding plasma, the near-saturated magnetic field is expected to result into an intense electromagnetic radiation as well as gravitational waves in black hole mergers. We provide a numerical simulation of the VTM phenomenon in a prototype system.

gr-qc↗

arXiv2024

Minimal SO(10) ante portas: the importance of being effective

The minimal $SO(10)$ grand unified theory, augmented by higher-dimensional operators, is based on the following Higgs representations: adjoint $45_{\rm H}$, spinor $16_{\rm H}$ and complex vector $10_{\rm H}$. It was recently realized that, as opposed to the conventional wisdom, any intermediate mass scale has to lie close to the grand unification one. This bears profound consequences for the scalar particles mass spectrum and the proton decay lifetime. A complete analysis of the parameter space shows the following interesting correlation under the requirement of perturbativity of the theory: A color octet below approximately $5\,\rm TeV$ would imply a lower bound on neutrino mass $m_{\nu}\gtrsim 0.2\,\rm eV$, soon to be probed, a scalar weak triplet below $500\,\rm GeV$ and a scalar weak doublet, color triplet below $3\,\rm TeV$. If one were to stick to no flavor cancellations in proton decay amplitudes, one would recover a recent result of all these states being accessible at collider energies. Moreover, the proton decay lifetime would then be tantalizingly close to the present experimental bound.

hep-ph↗

arXiv2024

Ultralight Black Holes as Sources of High-Energy Particles

The \textit{memory burden} effect, the idea that the amount of information stored within a system contributes to its stabilization, is particularly relevant for systems with a large information storage capacity, such as black holes. In these objects, the evaporation process halts, at the latest, once approximately half of the initial mass has been radiated away. As a result, light primordial black holes (PBHs) with mass $m_{\rm PBH} \lesssim 10^{15}\,\mathrm{g}$, which are traditionally assumed to have fully evaporated by the present time, may instead survive and constitute viable dark matter candidates. Ongoing mergers of such PBHs would give rise to ``young'' black holes that resume their evaporation, emitting ultrahigh-energy particles potentially detectable by current experiments. The resulting emission spectrum would be thermal across all Standard Model particle species, offering a clear and distinctive signature. We demonstrate that, if the memory burden effect activates after PBHs have lost around half of their initial mass, current measurements of the neutrino flux at Earth place strong constraints on such dark matter candidates for $m_{\rm PBH} \lesssim 10^9\,\mathrm{g}$. This suggests that the memory burden must set in at earlier stages of evaporation. Unlike existing bounds, our results depend solely on the mass of the remnant, and not on model-dependent details of the stabilized phase. We also discuss the potential for refining these constraints through observations of gamma rays, cosmic rays, and gravitational waves.

astro-ph.HE↗

arXiv2024

Do neutrinos bend? Consequences of an ultralight gauge field as dark matter

An ultralight gauge boson could address the missing cosmic dark matter, with its transverse modes contributing to a relevant component of the galactic halo today. We show that, in the presence of a coupling between the gauge boson and neutrinos, these transverse modes affect the propagation of neutrinos in the galactic core. Neutrinos emitted from galactic or extra-galactic supernovae could be delayed by $\delta t = \left(10^{-8}-10^1\right)\,$s for the gauge boson masses $m_{A'} = \left(10^{-23}-10^{-19}\right)\,$eV and the coupling with the neutrino $g= 10^{-27}-10^{-20}$. While we do not focus on a specific formation mechanism for the gauge boson as the dark matter in the early Universe, we comment on some possible realizations. We discuss model-dependent current bounds on the gauge coupling from fifth-force experiments, as well as future explorations involving supernovae neutrinos. We consider the concrete case of the DUNE facility, where the coupling can be tested down to $g \simeq 10^{-27}$ for neutrinos coming from a supernova event at a distance $d = 10\,$kpc from Earth.

hep-ph↗

arXiv2024

Memory Burden Effect in Black Holes and Solitons: Implications for PBH

The essence of the \textit{memory burden} effect is that a load of information carried by a system stabilizes it. This universal effect is especially prominent in systems with a high capacity of information storage, such as black holes and other objects with maximal microstate degeneracy, the entities universally referred to as \textit{saturons}. The phenomenon has several implications. The memory burden effect suppresses a further decay of a black hole, the latest, after it has emitted about half of its initial mass. As a consequence, the light primordial black holes (PBHs), that previously were assumed to be fully evaporated, are expected to be present as viable dark matter candidates. In the present paper, we deepen the understanding of the memory burden effect. We first identify various memory burden regimes in generic Hamiltonian systems and then establish a precise correspondence in solitons and in black holes. We make transparent, at a microscopic level, the fundamental differences between the stabilization by a quantum memory burden versus the stabilization by a long-range classical hair due to a spin or an electric charge. We identify certain new features of potential observational interest, such as the model-independent spread of the stabilized masses of initially degenerate PBHs.

hep-th↗

arXiv2024

Cavity Detection of Gravitational Waves: Where Do We Stand?

High frequency gravitational waves (HFGWs) are predicted in various exotic scenarios involving both cosmological and astrophysical sources. These elusive signals have recently sparked the interest of a diverse community of researchers, due to the possibility of HFGW detection in the laboratory through graviton-photon conversion in strong magnetic fields. Notable examples include the redesign of the resonant cavities currently under development to detect the cosmic axion. In this work, we derive the sensitivities of some existing and planned resonant cavities to detect a HFGW background. As a concrete scenario, we consider the collective signals that originate from the merging of compact objects, such as two primordial black holes (PBHs) in the asteroid mass window. Our findings improve over existing work by explicitly discussing and quantifying the loss in the experimental reach due to the actual coherence of the source. We elucidate on the approach we adopt in relation with recent literature on the topic. Most notably, we give a recipe for the estimate of the stochastic background that focuses on the presence of the signal in the cavity at all times and showing that, in the relevant PBH mass region, the signal is dominated by coherent binary mergers.

gr-qc↗

arXiv2024

Minimal SU(5) theory on the edge: the importance of being effective

It is well known that the minimal renormalizable $SU(5)$ grand unified theory is ruled out: it predicts same masses of down quarks and charged leptons, the gauge couplings do not unify and neutrinos are massless. We show here that all this can be cured simultaneously by the addition of higher-dimensional effective operators. However, the theory lives on the edge since the unification scale turns out as low as roughly $10^{14}\,$GeV, threatening proton longevity. If the lower bound on the proton lifetime was to be increased by an order of magnitude, the usual desert in energies between the weak and unification scales would be populated. We also revisit two minimal extensions of this theory that offer a dynamical seesaw origin of neutrino mass, and discuss the resulting consequences.

hep-ph↗

arXiv2023

Perturbative Construction of Coherent States

The perturbative consistency of coherent states within interacting quantum field theory requires them to be altered beyond the simple non-squeezed form. Building on this point, we perform explicit construction of consistent squeezed coherent states, required by the finiteness of physical quantities at the one-loop order. Extending this analysis to two-loops, we demonstrate that a non-Gaussian alteration of squeezed coherent states is necessary. The modifications of the coherent state we propose are perturbative in $\hbar$ and may be an indication that coherence must be viewed through a nonlinearly redefined, background-dependent, degree of freedom.

hep-th↗

arXiv2023

Vortex Effects in Merging Black Holes and Saturons

Vorticity has recently been suggested to be a property of highly-spinning black holes. The connection between vorticity and limiting spin represents a universal feature shared by objects of maximal microstate entropy, so-called saturons. Using $Q$-ball-like saturons as a laboratory for black holes, we study the collision of two such objects and find that vorticity can have a large impact on the emitted radiation as well as on the charge and angular momentum of the final configuration. As black holes belong to the class of saturons, we expect that the formation of vortices can cause similar effects in black hole mergers, leading to macroscopic deviations in gravitational radiation. This could leave unique signatures detectable with upcoming gravitational-wave searches, which can thereby serve as a portal to macroscopic quantum effects in black holes.

hep-ph↗

arXiv2023

Confinement Slingshot and Gravitational Waves

In this paper, we introduce and numerically simulate a quantum field theoretic phenomenon called the gauge ``slingshot" effect and study its production of gravitational waves. The effect occurs when a source, such as a magnetic monopole or a quark, crosses the boundary between the Coulomb and confining phases. The corresponding gauge field of the source, either electric or magnetic, gets confined into a flux tube stretching in the form of a string (cosmic or a QCD type) that attaches the source to the domain wall separating the two phases. The string tension accelerates the source towards the wall as sort of a slingshot. The slingshot phenomenon is also exhibited by various sources of other co-dimensionality, such as cosmic strings confined by domain walls or vortices confined by $Z_2$ strings. Apart from the field-theoretic value, the slingshot effect has important cosmological implications, as it provides a distinct source for gravitational waves. The effect is expected to be generic in various extensions of the standard model such as grand unification.

hep-ph↗

arXiv2023

The future search for low-frequency axions and new physics with the FLASH resonant cavity experiment at Frascati National Laboratories

We present a proposal for a new experiment, the FINUDA magnet for Light Axion SearcH (FLASH), a large resonant-cavity haloscope in a high static magnetic field which is planned to probe new physics in the form of dark matter (DM) axions, scalar fields, chameleons, hidden photons, as well as high frequency gravitational waves (GWs). Concerning the QCD axion, FLASH will search for these particles as the DM in the mass range (0.49-1.49) ueV, thus filling the mass gap between the ranges covered by other planned searches. A dedicated Microstrip SQUID operating at ultra-cryogenic temperatures will amplify the signal. The frequency range accessible overlaps with the Very High Frequency (VHF) range of the radio wave spectrum and allows for a search in GWs in the frequency range (100-300) MHz. The experiment will make use of the cryogenic plant and magnet of the FINUDA experiment at INFN Frascati National Laboratories near Rome (Italy); the operations needed to restore the functionalities of the apparatus are currently underway. We present the setup of the experiment and the sensitivity forecasts for the detection of axions, scalar fields, chameleons, hidden photons, and GWs.

physics.ins-det↗