arXiv subjects

Christopher Ewasiuk

Publications and source records attributed to Christopher Ewasiuk.

7 recordsLinked to original sources

arXiv2026

Ghost Degrees of Freedom Without Quantum Runaway: Exact Moment Bounds from an Operator Conservation Law

We prove an exact quantum conservation law for a harmonic oscillator coupled to a ghost degree of freedom: a second classical conserved quantity lifts to a quantum operator that commutes with the Hamiltonian with no hbar corrections, yielding a rigorous, state-independent upper bound on the mean squared phase-space radius for all time and every quantum state with finite initial second moments. The proof uses only canonical commutation relations and the Leibniz rule; it requires no confining potential, no spectral assumptions, and no perturbative expansion. The interaction studied here is bounded and vanishes at large separations, the generic situation in effective field theory, yet this suffices to guarantee quantum stability in the sense of bounded second moments. Three independent numerical frameworks (Heisenberg picture, Schrodinger picture, and Fock-space diagonalization) confirm wavepacket confinement below the analytic bound, a real energy spectrum, and Poisson level statistics numerically consistent with an integrable structure. The absence of a confining potential means the proof is silent on spectral discreteness and the existence of a ground state; those questions, addressed for polynomial confining interactions in concurrent work, remain open for the interaction class studied here and represent the sharpest targets for future work. Ghost quantum instability is therefore not an inevitable consequence of a wrong-sign kinetic term but depends critically on the interaction structure.

quant-ph↗

arXiv2026

High-frequency gravitational wave transients from superradiance

Ultralight bosons can form macroscopic gravitational-atom clouds around rotating black holes via superradiance, sourcing quasi-monochromatic gravitational waves through level transitions and annihilation. Primordial black holes provide a natural setting for such systems in a frequency range relevant for resonant-cavity experiments. We present a unified treatment of gravitational-wave emission from both isolated and binary-perturbed gravitational atoms in this regime. For isolated systems, we derive analytic expressions for the time- and frequency-domain strain from transition and annihilation channels, emphasizing their narrow-band structure. For binaries, we model resonantly driven level transitions using the Landau--Zener formalism and compute the resulting transient signals. We find that, while binary-driven transitions generically yield signals with durations compatible with detector response times, their characteristic strain lies well below the sensitivity of current experiments at astrophysically plausible distances, and event rates further suppress detectability by requiring sources at unrealistically small separations. We quantify the improvements in sensitivity, bandwidth, and response needed to render these signals observable, and identify gravitational-atom systems around primordial black holes as a theoretically well-motivated target for future high-frequency gravitational-wave searches.

gr-qc↗

arXiv2026

Quantum Tunneling of Primordial Black Holes to White Holes: Rates, Constraints, and Implications for Fast Radio Bursts

We calculate the present-day and cosmological volumetric rate of primordial black hole (PBH) quantum tunneling events to white holes, incorporating the competition between Hawking evaporation and tunneling, cosmological depletion, realistic mass-dependent abundance constraints, extended mass functions, and the alternative memory-burden scenario. The burst rate is maximized along a narrow ridge in the mass--tunneling-parameter plane where the effective PBH lifetime is comparable to the age of the Universe. Within the canonical Planck-star range of tunneling timescales, FRB-level rates arise only in two highly restricted regions: a low-mass window near the evaporation boundary, and a narrow sequential window where evaporation precedes tunneling; broadening the PBH mass function does not qualitatively alter this conclusion. We further assess observational constraints from FRB repetition statistics, radio spectral properties, prompt and diffuse gamma-ray limits, host-galaxy demographics, and gravitational-wave signatures. All current observations are consistent with a subdominant white-hole contribution to the FRB population but strongly disfavor a dominant origin. The rate calculation does not generically support FRB-level event densities, and any viable FRB interpretation requires narrow, fine-tuned, and strongly assumption-dependent corners of parameter space.

gr-qc↗

arXiv2025

Precision gravity constraints on large dark sectors

General relativity, treated as a low energy effective field theory, predicts quantum corrections to Newtons law of gravitation arising from loops of matter and graviton fields. While these corrections are negligible for the Standard Model particle content, the situation changes dramatically in the presence of a hidden or dark sector containing a very large number of light degrees of freedom. In such cases, loop induced modifications to the Newtonian potential can accumulate to levels testable in laboratory and astrophysical probes of gravity at short distances. In this work we systematically derive and constrain the impact of large dark sectors on precision tests of Newtons law, translating effective field theory predictions into the experimental language of Yukawa type deviations and inverse square law deformations. By mapping precision fifth force constraints onto bounds on species multiplicities and masses, we show that current and forthcoming experiments already impose nontrivial constraints on the size and structure of hidden sectors coupled only gravitationally. For truly massless hidden states, present data still permit multiplicities as large as 1e61, with modest spin dependence; for finite masses the constraints reduce to the familiar short range Yukawa parameterization. Our results provide a model independent framework for confronting dark sector scenarios with precision gravity data and clarify how non minimal scalar couplings, potential higher derivative poles at large species number, and Kaluza Klein towers fit within this picture. The approach is complementary to cosmological probes: Big Bang Nucleosynthesis and the Cosmic Microwave Background constrain relic abundances under specified production histories, whereas laboratory tests constrain the spectrum of light states irrespective of their cosmological population.

hep-ph↗

arXiv2025

Dark-sector modifications to Kerr and Reissner-Nordstrom black hole evaporation

We present a comprehensive comparative analysis of the evaporation dynamics of Schwarzschild, Kerr, and Reissner- Nordstrom black holes, focusing on the evolution of their mass, charge, and angular momentum, using detailed calculations of the corresponding Page factors. We investigate the evolution of black holes during the evaporation process, emphasizing how these quantities evolve relative to one another. Our study incorporates the effects of greybody factors, near-extremal conditions, and the introduction of additional particle species beyond the Standard Model. We demonstrate that the addition of particle degrees of freedom may significantly alter the evaporation hierarchy, potentially leading to scenarios in which the effective black hole charge increases during evaporation. Additionally, we examine the impact of Schwinger pair production and of super-radiance on charged, spinning black hole evaporation. These findings offer new insights into the complex interplay between different black hole parameters during evaporation and highlight the importance of considering additional particle species in the process.

gr-qc↗

arXiv2024

The Maximal Gravitational Wave Signal from Asteroid-Mass Primordial Black Hole Mergers At Resonant Microwave Cavities

Primordial black holes can be the entirety of the dark matter in a broad, approximately five-orders-of-magnitude-wide mass range, the ``asteroid mass range'', between $10^{-16}\ M_{\rm Sun}$ -- where constraints originate from evaporation -- and $10^{-11}\ M_{\rm Sun}$ -- from microlensing. A direct detection in this mass range is very challenging with any known observational or experimental methods. Here we update the calculation of the sight distance for narrow-band detectors such as resonant microwave cavities, and the resulting maximal event rate. We find that the largest detection rates are associated with binaries from non-monochromatic mass functions in early-formed three-body systems. Even in the most optimistic setup, these events are anticipated to be extremely rare.

astro-ph.HE↗

arXiv2024

Constraints on the maximal number of dark degrees of freedom from black hole evaporation, cosmic rays, colliders, and supernovae

A dark sector with a very large number of massive degrees of freedom is generically constrained by radiative corrections to Newton's constant. However, there are caveats to this statement, especially if the degrees of freedom are light or mass-less. Here, we examine in detail and update a number of constraints on the possible number of dark degrees of freedom, including from black hole evaporation, from perturbations to systems including an evaporating black hole, from direct gravitational production at colliders, from high-energy cosmic rays, and from supernovae energy losses.

hep-ph↗