arXiv subjects

Salvatore Capozziello

Publications and source records attributed to Salvatore Capozziello.

At least 19 recordsLinked to original sources

arXiv2026

Rotating Weyssenhoff fluids in linearized Einstein-Cartan theory

The Weyssenhoff fluid expands the ordinary perfect-fluid description of general relativity by taking into account the intrinsic spin of its constituent particles. Within the linearized regime of Einstein-Cartan theory, we investigate the exterior geometry produced by isolated slowly rotating Weyssenhoff fluids, i.e., sources endowed with both macroscopic and microscopic angular momenta. Our work represents an extension of the foundational analysis of Arkuszewski, Kopczy{ń}ski and Ponomariev, which was restricted to the static fluid configuration. Under the assumptions of stationarity and axial symmetry, we derive the explicit expression for the linearized stress-energy tensor of the source and obtain the corresponding metric through a multipole expansion. The ensuing solution exhibits a generalized Lense-Thirring structure, with both the gravitoelectric and gravitomagnetic sectors affected by the quantum spin and macroscopic rotation. We also discuss some phenomenological implications of the model, including the gyroscope precession and the Sagnac effect, along with potential experimental probes of the predicted corrections.

gr-qc↗

arXiv2026

Elastic toroidal vector dark matter through a dark photon in the LUX-ZEPLIN high recoil window

The 2026 LUX-ZEPLIN search reports one nuclear recoil candidate at $248\pm23_{\rm stat}\pm23_{\rm sys}~\mathrm{keV}$ in an extended window reaching about $270~\mathrm{keV}$. We consider elastic scattering of neutral complex vector dark matter through its dimension-six toroidal electromagnetic moment and find appreciable spectral weight in this recoil region. The nonrelativistic reduction correlates $\mathcal O_{17}$ and $\mathcal O_{20}$, relating a coherent charge branch to a transverse spin tensor branch. For $m_X=1~\mathrm{TeV}$, natural xenon exhibits a broad high recoil maximum at $204.8$ to $206.6~\mathrm{keV}$ and retains $80.4$ to $85.4\%$ of this maximum at $248~\mathrm{keV}$. Resolving the interaction through a dark photon relates the high-to-low recoil ratio to the mediator mass. A renormalizable $SU(2)_X\times U(1)_D$ realization stabilizes the complex vector by a residual $Z_3$ gauge symmetry and generates the toroidal current through vectorlike messengers carrying a physical CP phase. For a benchmark with $m_X=0.998~\mathrm{TeV}$ and $m_{A'}=0.450~\mathrm{GeV}$, $R(248)/R(50)=1.43$ for GCN and $1.21$ for JJ55, while the odd $A$ xenon fraction remains above $99.9\%$. The response level ratio between the $350$ to $590~\mathrm{keV}$ and $100$ to $270~\mathrm{keV}$ intervals is about $0.46$ at this benchmark. The tensor branch is absent for spin zero argon, whereas annual modulation remains at the few percent level. The resulting spectral, isotope, target, timing, mediator, and high energy dependences give correlated tests of an elastic tensor interpretation of the LZ recoil.

hep-ph↗

arXiv2026

DESI and Dynamical Dark Energy from Extended Pre-geometric Gravity

We consider the simplest quadratic extension of MacDowell--Mansouri pre-geometric gravity that preserves the topological pre-volume-form symmetry. Upon symmetry breaking, the theory reduces to $(\mathrm{Lovelock})^2$ gravity and admits a Galileon-like Horndeski scalar-tensor representation. The gravitational Higgs mechanism relates the Gauss--Bonnet coupling to the bare cosmological constant, while the quadratic correction elevates the gravitational $θ$-angle to a dynamical gravi-axion whose ultra-light mass scale can drive late-time acceleration. We confront the Jordan-frame background with DESI DR2 baryon-acoustic-oscillation measurements and an auxiliary six-point compressed growth diagnostic. A transient dark-energy response localized near $H\simeq m_b$ ($m_b$ the effective gravi-axion mass) reproduces the fitted expansion and its BAO-distance predictions and becomes negligible at high redshift. For the full linear calculation, we combine a smooth positive-density representative of this response class with explicitly imposed GR-like tensor and local sectors, together with the parameterized post-Friedmann prescription. The resulting gravi-axion benchmark exhibits a transient effective phantom crossing and admits a regular full linear CAMB evolution. Its separate likelihood contributions are promising relative to those obtained from the flat-$Λ$CDM baseline for the same data set. These results establish the dynamical gravi-axion framework, dual to MacDowell--Mansouri pre-geometric gravity, as a viable effective quantum-gravity inspired description of late-time cosmology, motivating further investigation into its fundamental origin and perturbative consistency.

gr-qc↗

arXiv2026

Parametrized beyond-Teukolsky framework in the time domain

Modifications to General Relativity can significantly alter the perturbative response of black holes, leaving imprints on quasinormal-mode spectra, waveform amplitudes and phases, and late-time tails. The parametrized beyond-Teukolsky framework was introduced to capture possible deviations from Kerr dynamics, but the ringdown has so far only been explored as an eigenvalue problem. We present the first time-domain implementation of this framework and perform (2+1)-dimensional scattering experiments with Gaussian wave packets. This approach provides the full linear evolution of the perturbation, from the initial prompt response through the ringdown and into the late-time regime. Using frequency-domain eigenvalue results as benchmarks, we find excellent agreement for low azimuthal numbers, while higher azimuthal numbers are affected by mode mixing, which limits the precision of the extracted modes. We further use the time-domain waveforms to estimate quadratic and mixed coefficients within the linearized modified-potential model, providing a diagnostic for the regime of validity of the linear approximation. Beyond mode frequencies, we show that the deformation parameters can strongly affect the ringdown amplitude and phase, with trends that can be understood from the near-horizon structure of the modified potential. We also analyze the late- time behavior, finding that near-horizon deformations leave the tail exponent unchanged but can substantially shift the onset of the power-law decay. These results demonstrate that time-domain evolutions provide a complementary and flexible framework for testing parametrized deviations from General Relativity in black-hole perturbation theory.

gr-qc↗

arXiv2026

Probing dynamics of extreme galaxies I. Dark matter content in ultra-diffuse galaxies

We investigate the internal structure of two galaxies from the LEWIS sample: the ultra-diffuse galaxy UDG-1 and the extended dwarf LSB-6. Both show coherent stellar rotation combined with a non-negligible fraction of random motion, with no signs of ongoing disturbance. This is the first attempt to constrain the dynamics and dark matter physics of rotation-supported UDGs through integral-field stellar kinematics. We model the galaxies as stellar spheroids with typical dwarf-like thickness embedded in spherical dark matter halos, deriving two-dimensional velocity fields that we compare with the observations in a Bayesian framework. Besides cold dark matter, we test fuzzy, self-interacting, and non-minimally coupled dark matter. The data prefer a cuspy halo in UDG-1 and a cuspless one in LSB-6. All the alternative models remain viable, although current data cannot conclusively discriminate among them. For fuzzy dark matter we obtain mutually consistent boson masses, $m_α= 4.7^{+1.8}_{-1.1} \times 10^{-22}$ eV for UDG-1 and $m_α= 6.3^{+0.4}_{-0.4} \times 10^{-22}$ eV for LSB-6. For self-interacting dark matter, LSB-6 yields a robust constraint on the velocity-weighted cross section, $\langle σv\rangle/m = 14.3^{+2.0}_{-1.9}$ cm$^2$ km g$^{-1}$ s$^{-1}$. For non-minimally coupled dark matter we derive upper bounds on the coupling length, implying marginal deviations from $Λ$CDM. Regardless of the model, both galaxies exhibit a dark matter content comparable with halos of typical dwarf galaxies with similar stellar masses. Together with stellar population analyses and globular cluster information, these results support a scenario in which UDG-1 and LSB-6 originate from puffed-up dwarfs. This work is the first in a series exploiting kinematic data of extremely low-surface-brightness galaxies to test fundamental physics, from dark matter to modified theories of gravity.

astro-ph.GA↗

arXiv2026

A New Window for Testing the PPN in the Strong-Field Regime: Stellar Rotation of S301

The recently discovered S301 star, with an orbital period of 8.7 years and eccentricity $e = 0.982$, reaches a pericenter of just $140\,R_{\mathrm{s}}$ --- approximately nine times closer than S2's $\sim 1200R_{\mathrm{s}}$ --- offering an unprecedented laboratory for testing strong-field gravity. We demonstrate that S301's stellar spin precession provides a novel probe of the PPN parameter $γ$, scaling as $(2γ_{\mathrm{PPN}} + 1)/3$ relative to general relativity (GR). For maximum projected velocity shifts of $46.1~\mathrm{km\,s^{-1}}$, next-generation spectrographs could constrain $γ_{\mathrm{PPN}}$ to $\sim 10\%$ precision. When combined with S301's orbital precession --- a substantial $\sim 1.95^\circ$ pericenter advance per orbit (GR prediction), approximately an order of magnitude larger than S2's $\sim 0.2^\circ$, constraining $(2β_{\mathrm{PPN}} + 2γ_{\mathrm{PPN}} - 1)/3$ --- the spin measurement breaks the $β$-$γ$ degeneracy. A MCMC analysis of projected S2 and S301 observations yields $σ_β\approx 2.3 \times 10^{-4}$, with the $γ$ precision limited by the spin precession measurement to $σ_γ\approx 0.1$. While the spin precession provides an independent consistency check, its true significance lies in probing gravity at $ϕ/c^2 \sim 10^{-4}$ and $v/c \sim 0.08$ --- four orders of magnitude stronger than Solar System tests and an order of magnitude stronger than current S-star constraints. This complementary approach opens a new window for testing the PPN framework in the strong-field regime and demonstrates the power of combining multiple stellar probes at the Galactic Center.

gr-qc↗

arXiv2026

Nuclear interference versus dark sector excitation in the 248 keV LUX-ZEPLIN recoil candidate

The 2026 LUX-ZEPLIN (LZ) high energy nuclear recoil search reports one event at $248\pm23_{\rm stat}\pm23_{\rm sys}~\mathrm{keV}$ and finds the elastic isovector interaction $\mathcal L_6^v$ locally favored at about $3.3σ$ in the heavy dark matter regime. We examine whether this recoil scale can arise from resolved nuclear response within the elastic interaction and compare its spectral, target, and annual modulation behavior with endothermic dark sector excitation. Covariant matching correlates four Galilean operators, removes the longitudinal spin response algebraically, and fixes interference between density and orbital spin orbit amplitudes. The GCN and JJ55 xenon shell model calculations give a second natural xenon cancellation at $211$ and $214~\mathrm{keV}$. In the heavy mass regime, its position changes by less than $0.01~\mathrm{keV}$ from a dark matter mass of $200~\mathrm{GeV}$ to the asymptotic limit. A curvature weighted isotope centroid reproduces the position and residual depth of the natural xenon minimum. Direct $^{40}$Ar calculations shift the nuclear feature to about $350$ and $425~\mathrm{keV}$, whereas endothermic excitation follows reduced mass scaling set by the dark state splitting. At a dark matter mass of $1~\mathrm{TeV}$, the endothermic Ar to Xe scale ratio is $1.082$, compared with $1.63$ to $2.01$ for the nuclear calculations. Elastic scattering gives a few percent annual modulation in the adopted halo model, while endothermic solutions near the maximum laboratory halo speed show much larger seasonal variation. These scaling and timing behaviors provide tests of a target-dependent nuclear cancellation against an excitation energy set by dark sector kinematics.

hep-ph↗

arXiv2026

The Pre-geometric Origin of Geometric Trinity of Gravity

The so-called Geometric Trinity of Gravity is based on three distinct geometric features of spacetime, i.e.\ curvature, torsion and non-metricity, which give rise to equivalent dynamics for General Relativity (GR), Teleparallel Equivalent of General Relativity (TEGR) and Symmetric Teleparallel Equivalent of General Relativity (STEGR). Pre-geometric gravity, on the other hand, offers a unifying framework from which all metric-affine theories can emerge. Starting from a gauge formulation \textit{à la} Yang--Mills with a Higgs-like field, a mechanism of spontaneous symmetry breaking can give rise to an effective metric as well as to the classical dynamics of the gravitational field. In particular, the emergence of gravity in the spontaneously broken phase is shown to be consistent with all the different formulations of the Geometric Trinity of Gravity, in terms both of actions and of gauge choices for the affine connection. This general result is achieved by deriving and analysing suitable expressions in the unbroken phase for pre-geometric actions and for pre-geometric gauge-fixing conditions respectively.

gr-qc↗

arXiv2026

CMB Test of the Higgs Origin of Dark-Photon Dark Matter

Laboratory searches determine the mass and kinetic mixing of dark-photon dark matter. The CMB isocurvature probes how its abundance depends on inflationary initial conditions. We formulate this dependence through the logarithmic response $q_{\rm eff}=\partial\ln n_{A'}/\partial\ln r_i$ of the final vector number to the primordial dark-Higgs displacement. For a smooth local abundance map, the separate-universe relation connects $q_{\rm eff}$ to the CDM isocurvature. The uncorrelated Planck limit applies when the dark Higgs is a light and energetically subdominant spectator with weak inflaton mixing. In the quadratic conserved-number branch displacement-independent transfer gives $q_{\rm eff}=2$. The all-dark-matter bound then requires $r_i/H_*>3.5\times10^4$. We calculate the dynamical map by evolving the radial mode and its tangent response through a smooth Abelian-Higgs crossover. The post-transition orbit gives the comoving action. The map contains positive, negative, and near-zero responses at finite transferred action. Tanh and error-function crossovers retain these branches. A thermal-mass profile and finite inflationary quartics shift their locations continuously. Stochastic duration and radiative stability then determine realization regions. Early symmetry breaking and momentum redshift add the remaining conditions. Low-energy measurements and the CMB response can distinguish Higgsed-vector cosmologies with identical present-day $(m_{A'},ε)$ and relic abundance.

hep-ph↗

arXiv2026

Constraints on the Modified Emergent Dark Energy Model Using DESI DR2 BAO

In this work, we investigate the modified emergent dark energy (MEDE) model using baryon acoustic oscillation measurements from the Dark Energy Spectroscopic Instrument Data Release 2 (DESI DR2), together with CMB information from the {\tt LoLLiPoP} (low-$\ell$) and {\tt HiLLiPoP} (high-$\ell$) likelihoods based on the latest Planck NPIPE PR4 release, Planck PR4 lensing, ACT DR6 lensing, and three Type Ia supernova samples (Pantheon$+$, DES-Dovekie, and Union3). We find that the MEDE model remains largely consistent with the standard $Λ$CDM cosmology. Although small departures from $Λ$CDM are allowed, the inclusion of SNe~Ia data drives the model parameters toward the standard cosmological scenario, with the parameter $α$ remaining consistent with $α=0$ at the $1σ$ level. The model does not significantly alleviate the $H_0$ or $S_8$ tensions: the inferred $H_0$ values remain below the SH0ES measurement, the sound horizon $r_d$ is nearly unchanged, and the predicted $S_8$ values remain close to those of $Λ$CDM. The reconstructed cosmological evolution closely follows the $Λ$CDM prediction, with deviations generally below the $0.5σ$ level. While the CMB + DESI DR2 dataset favors a full phantom regime, the inclusion of SNe~Ia shifts the evolution toward a full quintessence regime. Finally, although the $Δχ^2_{\rm MAP}$ and $Δ{\rm AIC}$ criteria indicate a marginally better fit than $Λ$CDM, the logarithmic Bayes factor provides only inconclusive evidence in favor of the MEDE model. Overall, the MEDE model remains compatible with current observations but does not exhibit the phantom-crossing behavior suggested by recent DESI DR2 analyses.

physics.gen-ph↗

arXiv2026

Primordial black hole induced gravitational waves in $f(R)$ gravity

Ultra-light primordial black holes (PBHs) with masses $M_\mathrm{PBH}<5\times 10^{8}\mathrm{g}$ can trigger an early matter-dominated (eMD) era before Big Bang Nucleosynthesis (BBN) and reheat the Universe through their evaporation. Notably, the initial isocurvature in nature PBH energy density fluctuations can induce abundantly gravitational waves (GWs) due to second-order gravitational effects. In this work, we study this induced GW signal within the context of $f(R)$ gravity investigating the effect of $f(R)$ gravity on the behaviour of scalar perturbations during the PBH-driven eMD era as well as on the source of the second-order induced tensor modes. In particular, we focus on two minimal $f(R)$ models, that is $R^2$ and $R^{1+ε}$, with $ε\ll 1$, gravity theories as illustrative examples, finding at the end that $R^2$ gravity presents very small deviations from general relativity (GR) at the level of both the scalar and tensor perturbations. However, $R^{1+ε}$ gravity features a different behaviour, exhibiting in particular an exponential growth of scalar perturbations during a matter-dominated era. This unique feature leads ultimately to an enhanced induced GW signal even for very small initial PBH abundances, being characterized by a linear frequency scaling on large infrared scales away from the peak frequency, namely $Ω_\mathrm{GW}(k)\propto f$ for $f\ll f_\mathrm{peak}$ and a very peaky behaviour with a $f^{35/2}$ frequency scaling close to the non-linear cut-off scale below which perturbation theory breaks down. Interestingly, one finds as well that the induced GW signal can be well within the sensitivity curves of GW detectors, namely that of LISA, ET, BBO and SKA.

astro-ph.CO↗

arXiv2026

Conformal Killing Gravity: New Constraints from DESI DR2 BAO datasets

We investigate a geometric approach referred to as the Conformal Killing Gravity (CKG), in which the dark energy sector emerges naturally from the conformal Killing symmetry of the Robertson--Walker space-time. Within this framework, the divergence-free conformal Killing tensor behaves as an effective perfect fluid, giving rise to a dynamical dark-energy component whose density, pressure, and equation of state are uniquely determined by the underlying geometry, without introducing any empirical dark-energy parametrization. The resulting CKG model extends the standard $Λ$CDM cosmology through a single additional parameter while recovering the $Λ$CDM limit in the absence of the geometric contribution. We constrain the model using Planck PR4 (NPIPE) CMB temperature, polarization, and lensing observations, ACT DR6 CMB lensing, DESI DR2 baryon acoustic oscillation measurements, and the Pantheon$+$, DES-Dovekie, and Union3 Type Ia supernova compilations. The analysis shows that the CKG favors a quintessence-like dark-energy evolution with no evidence for phantom crossing, while the reconstructed equation of state rapidly approaches the cosmological constant at earlier cosmic times. Furthermore, the model predicts a future critical redshift in the range $-0.8 \lesssim z_c \lesssim -0.7$, indicating that the present cosmic expansion eventually reaches a turning point before the formal singular limit at $z=-1$. Since the geometric contribution modifies only the post-recombination expansion history, the sound horizon remains essentially unchanged and the model does not provide a complete solution to the $H_0$ tension. Our results demonstrate that the CKG provides a simple, physically motivated, and observationally favored framework for describing the late-time accelerated expansion of the Universe.

astro-ph.CO↗

arXiv2026

Cosmological constraints and standard sirens forecasts for non-dynamical dark energy in Horndeski gravity

We investigate an analytically tractable sector of the Extended Cuscuton model, a non-dynamical dark-energy realization within the framework of viable Horndeski gravity. We focus on four benchmark submodels and constrain them with current background probes, namely cosmic chronometers, Type-Ia supernovae, and BAO, while imposing theoretical viability, Lunar Laser Ranging, and Big Bang Nucleosynthesis bounds. We then forecast third-generation bright-standard-siren constraints with Einstein Telescope and Cosmic Explorer networks, considering prompt-emission, afterglow, and kilonova counterparts. Current data already restrict the viable parameter space to small departures from $Λ$CDM and do not remove the calibration-driven offset between the CC+SN and CC+BAO determinations of $H_0$. In principle, future bright sirens substantially sharpen the constraints, especially for kilonova catalogues and extended detector networks. Across the forecast configurations, the relative uncertainty on $H_0$ remains below $13.18\%$ and can reach $0.21\%$ in the most constraining cases, while $Ω_Λ$ is recovered at the percent level in the best cases. These results show that third-generation standard sirens can provide a precise complementary test of non-dynamical dark energy beyond $Λ$CDM.

astro-ph.CO↗

arXiv2026

No preference for generalized emergent dark energy from current cosmological data

In this work, we revisit the generalized emergent dark energy model by confronting it with DESI DR2 baryon acoustic oscillation measurements, in combination with joint CMB data from ACT, SPT, and Planck, as well as Type Ia supernova samples including Pantheon$^+$, DES-Dovekie, and Union3. We find that the GEDE model remains compatible with the $Λ$CDM paradigm, with no statistically significant preference for deviations when all datasets are combined. In particular, the key model parameter $Δ$ is consistent with the $Λ$CDM value $Δ= 0$ within $2σ$ once SNe Ia data are included. Despite this overall agreement, the GEDE model does not exhibit the phantom crossing suggested by DESI DR2. Instead, the evolution of the dark energy equation of state $w(z)$ indicates that the model behaves either as a full phantom ($w < -1$) or quintessence ($w > -1$), depending on the dataset combination, without a clear transition across $w = -1$. When Pantheon$^+$ data are included, the model converges closely to $Λ$CDM with $w \simeq -1$. The GEDE model does not alleviate the existing cosmological tensions. The inferred values of $H_0$ remain in the range $67.9$-$69.8\ \mathrm{km,s^{-1},Mpc^{-1}}$, while the sound horizon $r_d$ and clustering parameter $S_8$ remain consistent with $Λ$CDM, failing to resolve the $H_0$ and $S_8$ tensions. Finally, both Gaussian significance levels ($<2σ$) and Bayesian evidence ($\ln B_{i,j} < 1$) indicate no statistically significant preference for GEDE over $Λ$CDM. We conclude that, although DESI DR2 hints at dynamical dark energy, the GEDE model remains observationally indistinguishable from $Λ$CDM and does not support the Quintom-B-type behavior suggested by DESI DR2.

astro-ph.CO↗

arXiv2026

Testing the Anton-Schmidt dark energy model with the DESI DR2 measurements

We present a comparative cosmological analysis of the Anton-Schmidt, $Λ$CDM, and CPL models using baryon acoustic oscillation measurements from the Dark Energy Spectroscopic Instrument Data Release 2, combined with the Planck PR4 (NPIPE) CamSpec Cosmic Microwave Background likelihoods and three Type Ia supernova catalogues: Pantheon$+$, DES-Dovekie, and Union3. We use Markov Chain Monte Carlo analyses to constrain the parameters of the Anton-Schmidt model against each dataset combination. We find that the Anton-Schmidt model provides a good fit to current cosmological observations. The Anton-Schmidt model provides a good fit to the current cosmological observations but does not provide a significant alleviation of either the $H_0$ or the $S_8$ tensions. The Anton-Schmidt parameter is tightly constrained to $B \simeq -0.38$, indicating that the logarithmic correction becomes relevant only at late times. The Anton-Schmidt and CPL models predict quintessence-like present-day dark-energy equations of state and shows Quintom-B evolution, with their dark-energy equation-of-state parameters crossing the phantom divide at approximately $z \approx 0.5$. The characteristic density scale is constrained to be $ρ_\ast/ρ_{c,0}\sim4\text{--}5$, substantially smaller than the large density scales typically assumed in logotropic-inspired scenarios, indicating that the Anton-Schmidt correction mainly affects the late-time expansion history. Finally, Bayesian evidence shows moderate-to-strong preference for the Anton-Schmidt model over the $Λ$CDM model and strong-to-decisive preference over the CPL parametrization. Although the Anton-Schmidt model does not alleviate the current cosmological tensions, it emerges as a statistically favored dynamical dark-energy scenario whose cosmological implications deserve further tested with forthcoming Stage-IV large-scale structure observations.

physics.gen-ph↗

arXiv2026

Conformal dark matter and MHz gravitational waves

A localized enhancement of the primordial curvature spectrum can leave two distinct relics: gravitationally produced conformal-fermion dark matter and a scalar-induced stochastic gravitational-wave background. We show that the dark-matter abundance fixes the scalar normalization through the cubic moment of the curvature spectrum, while the induced tensor signal probes its quadratic convolution. This closes the usual normalization freedom in scalar-induced gravitational-wave templates and ties the MHz signal directly to the dark-matter mass, peak scale, and spectral width. A concrete single-field realization demonstrates this mechanism: a Mukhanov--Sasaki evolution produces a broad MHz background that sits safely below the Gaussian primordial-black-hole threshold. In this construction, a null high-frequency search becomes a lower bound on the conformal-fermion mass, while a detection has to reproduce the relic abundance, peak frequency, amplitude, and width from one primordial feature. The result is a testable link between small-scale inflationary structure, superheavy dark matter, and laboratory MHz gravitational-wave searches

astro-ph.CO↗

arXiv2026

Parametric Resonance of Higgsed Vector Dark Matter: Inflationary Initial Conditions and Sourced Displacements

Parametric resonance in a Higgsed Abelian sector provides an efficient mechanism for producing vector dark matter, but its viability depends crucially on the origin of the initial dark-Higgs displacement that seeds the resonance. In this work, we investigate this initial-condition problem in a weakly coupled Abelian-Higgs theory with potential $V=λ_4(ϕ^2-v^2)^2/4$, using the calibrated nonlinear broad-resonance relic map together with a stochastic inflationary analysis of the dark-Higgs condensate. We show that a minimal light-spectator realization fails under standard inflationary duration: while broad resonance and isocurvature constraints require $ ϕ_0/H_I \gtrsim 3.3\times10^4, $ the stochastic equilibrium and finite-duration random walk produce only $ ϕ/H_I=\mathcal O(1). $ This large displacement mismatch is robust against order-of-magnitude variations in the resonance efficiency and broadness threshold, establishing a model-independent obstruction to the stochastic branch. We then identify a distinct classically sourced branch, generated by a negative Hubble-induced mass, in which the condensate tracks a time-dependent minimum, $ ϕ_0=κH_*/\sqrt{λ_4}, $ and the radial fluctuation remains heavy during inflation. In this case, the fixed-$e/λ_D$ relic scaling shifts from $ m_X\propto λ_4^{5/8}H_I^{-3/2} $ to $ m_X\propto κ^{-3/2}λ_4 H_*^{-3/2}. $ We derive the simultaneous consistency conditions for this sourced branch, including broad resonance, adiabatic tracking, perturbativity, sub-Planckian displacement, thermal non-erasure, spectator backreaction, and control of inflationary vector fluctuations. Our results establish that Higgsed-vector resonance is not merely a dark-matter production mechanism, but a sensitive probe of the inflationary and reheating dynamics that determine its initial conditions.

hep-ph↗

arXiv2026

Vacuum stability in Geometric Trinity of Gravity

The decay of a metastable (false) vacuum plays a crucial role in constraining Standard Model and beyond the Standard Model physics. In particular, it has been shown that gravity can have a significant impact on the calculation of the decay rate. In this context, it is natural to ask whether different but classically equivalent formulations of gravity lead to the same physical predictions. The aim of this paper is to analyze vacuum decay in teleparallel and symmetric teleparallel equivalent formulations of General Relativity (GR), namely TEGR and STEGR. Although these theories describe the same classical dynamics, it is of paramount importance to understand whether this equivalence persists also at the quantum level. In this respect, the analysis of vacuum stability may provide a particularly sensitive testing ground. The central question is whether the decay rate of a false vacuum computed within TEGR or STEGR coincides with the corresponding result obtained in GR. Our analysis shows that the tunneling exponent remains unchanged, offering a non-trivial example in which the equivalence between different formulations of gravity extends beyond classical dynamics.

gr-qc↗