We derive the phase acquired by a neutral scalar particle propagating along Reissner-Nordström geodesics. Considering two flavors propagating on different trajectories which intersect, we plot the interference pattern induced by gravitational lensing from the charged compact object. Although the effect of the charge is subdominant in the metric, it proves to be significant in the phase, and shifts the interference pattern, compared to the Schwarzschild case. This pattern is characterized by two oscillation lengths which, if known, would allow the determination of both eigenmasses independently.

High-precision measurements of the lepton’s electromagnetic dipole moments provide a powerful probe for testing the Standard Model. A nonzero value of the $\tau$ lepton’s electric(weak) dipole moment ($d_{\tau }^{\gamma }$, $d_{\tau }^Z$) would serve as a smoking gun of the new physics. On the one hand, current and future high energy colliders offer an ideal environment for such measurements. On the other hand, it is essential to investigate the optimal measurement method for extracting not only $d_{\tau }^{\gamma }$ and $d_{\tau }^Z$, but also the anomalous magnetic dipole moment ($a_{\tau }$). In this work, we analyze the precision of observables, particularly optimal observables, for determining these physics quantities through the process $e^{+}{e}^{-}\to {\gamma }^{*}/Z\to {\tau }^{+}{\tau }^{-}$ with $\tau$ leptons undergoing (semi)leptonic and hadronic decays at the center-of-mass energies at the Z pole mass and significantly below $m_Z$. By considering the full kinematic information of the decay products, we find that the sensitivities to the weak dipole moments, $\mathrm{Im}[d_{\tau }^Z]$ and $\mathrm{Re}[d_{\tau }^Z]$, can reach ${10}^{-21}e\mathrm{cm}$ at CEPC with $\sqrt{s}=m_Z$. This compares to sensitivities for the electric dipole moments, $\mathrm{Im}[d_{\tau }^{\gamma }]$ and $\mathrm{Re}[d_{\tau }^{\gamma }]$, of ${10}^{-20}e\mathrm{cm}$ at Belle-II $\mathrm{\Upsilon }(4S)$ resonance and ${10}^{-17}e\mathrm{cm}$ at BEPCII $\psi (2S)$ resonance. For $a_{\tau }$, we find that precisions of ${10}^{-5}$ for $\mathrm{Im}[a_{\tau }]$ and $\mathrm{Re}[a_{\tau }]$ can be attained at Belle-II $\sqrt{s}=10.58\mathrm{GeV}$.

In this work, we study flavor-violating scalars (flavons) in a range of large masses that have not been explored previously. We model the interactions with an effective field theory formulation where the flavon is heavier than the top quark. In addition, we assume that the flavon only couples to fermions of the standard model in a flavor-changing way, making it easier to escape experimental constraints. As the flavon couples strongly to top quarks, same-sign and opposite-sign top-quark pair signals can be explored in the search for those particles. We investigate the possibility of probing flavons through their interactions with a top quark plus up and charm quarks for effective couplings of order ${10}^{-2}\mathrm{TeV}$ and masses in the $\sim 200–1400\mathrm{GeV}$ range in the 14 TeV LHC in scenarios with up to $3000/\mathrm{fb}$.

We have studied the chiral-odd generalized parton distributions (GPDs) for the octet baryons within the framework of diquark spectator model, emphasizing the difference arising from different quark flavors of proton $p$ and light hyperons ${\mathrm{\Sigma }}^{+}$ and ${\mathrm{\Xi }}^0$. The equation of quark-quark correlator for the tensor current has been solved to investigate the transversely polarized quark dynamics using light-cone wave functions. In the forward limit, transversity distributions of all the constituent quark flavors of proton, ${\mathrm{\Sigma }}^{+}$ and ${\mathrm{\Xi }}^0$, have been studied. Additionally, the first moment of GPD $H_T$ and the combination of GPDs $E_T$ and ${\tilde{H}}_T$ have also been investigated. Our results are comparable with other available model predictions and lattice data for the proton. Furthermore, we have presented a comparative analysis of tensor charges and anomalous tensor magnetic moments for all the constituent quark flavors of the considered baryons, comparing them with available data obtained from different approaches.

The spectral form factor is believed to exhibit a special type of behavior called “dip-ramp-plateau” in chaotic quantum systems that originates from random matrix theory. This suggests that the shape of the spectral form factor could serve as an indicator of chaos in various quantum systems. It has been shown recently that the dip-ramp-plateau structure appears in the spectral form factor when the normal modes of a massless scalar field theory in the brick-wall model of the Bañados-Teitelboim-Zanelli black hole are treated as eigenvalues of a quantum Hamiltonian. At the same time, the level spacing distribution of these normal modes differs from that associated with random matrix theory ensembles if no averaging over randomly distributed boundary conditions is taken into account. In this paper, we extend the results for BTZ background to the case of a nonzero mass of the field, study the generalized spectral form factor, and consider the same context for another nontrivial background—de Sitter space. We compare the generalized spectral form factor for simple integrable quantum systems and for backgrounds with a horizon to the behavior predicted by random matrix theory. As a result, we confirm that BTZ and de Sitter brick-wall models without averaging exhibit the dip-ramp-plateau structure of the spectral form factor but differ in the structure of the three-level generalized spectral form factor from the one predicted by random matrix theory.

The superconducting cosmic strings (SCS) are a special case of cosmic strings that have a core carrying a charged field. When SCS passes through magnetized regions, the charged particles in the string experience a Lorentz force, which can produce radiation on the entire electromagnetic spectrum. This radiation can inject energy into the surrounding plasma, resulting in a modification of the thermal and ionization evolution of the intergalactic medium (IGM) and, subsequently, the global 21-cm signal. The signatures of SCS in the postrecombination era have been primarily studied in the low-frequency (radio) regime, which does not impact the state of the IGM. In this work, we study the effect of decaying SCS on the dark ages global 21-cm signal $(\delta T_b)$, considering both the ionizing and radio radiation. The dark ages signal can provide pristine cosmological information free from astrophysical uncertainties, as the Universe was primarily homogeneous during this era in the absence of baryonic structure formation. Considering a change in the $\delta T_b$ at redshift $z\sim 89$ from the Lambda Cold Dark Matter ($\mathrm{\Lambda }$CDM) framework, we derive an upper bound on the decay efficiency parameter, $g\equiv g(I,G{\mu }_s)$, to be $\lesssim 5.1\times {10}^{14}{\mathrm{GeV}}^2$, where, $I$ and $G{\mu }_s$ represent the loop current and string tension of SCS, respectively.

We generalize a recent prescription for the relaxation time approximation for the relativistic Boltzmann equation for systems with multiple particle species at finite temperature. This is performed by adding counter-terms to the traditional Anderson-Witting ansatz for each particle species. Our approach allows for the use of momentum-dependent relaxation times and the obedience of local conservation laws regardless of the definition of the local equilibrium state. As an application, we derive the first order Chapman-Enskog corrections to the equilibrium distribution and display results for the hadron-resonance gas. We also demonstrate that our collision term ansatz obeys the second law of thermodynamics.

A novel measurement technique of strong-phase differences between the decay amplitudes of $D^0$ and ${\overline{D}}^0$ mesons is introduced which exploits quantum-correlated $D\overline{D}$ pairs produced by $e^{+}{e}^{-}$ collisions at energies above the $\psi (3770)$ production threshold, where $D\overline{D}$ pairs are produced in both even and odd eigenstates of the charge-conjugation symmetry. Employing this technique, the first determination of a $D^0–{\overline{D}}^0$ relative strong phase is reported with such data samples. The strong-phase difference between $D^0\to K^{-}{\pi }^{+}$ and ${\overline{D}}^0\to K^{-}{\pi }^{+}$ decays, ${\delta }_{K\pi }^D$, is measured to be ${\delta }_{K\pi }^D={({192.8}_{-12.4-2.4}^{+11.0+1.9})}^{\circ }$, using a dataset corresponding to an integrated luminosity of $7.13{\mathrm{fb}}^{-1}$ collected at center-of-mass energies between 4.13–4.23 GeV by the BESIII experiment.

At finite temperature, the coupling of an axion to non-Abelian gauge fields causes dissipation due to sphaleron heating. This mechanism has been considered as ideal for realizing warm inflation, since it can lead to large thermal friction while preserving the flatness of the potential. We show, however, that requiring standard properties of an axion—in particular, a discrete shift symmetry—excludes the strong regime of warm slow-roll inflation, in which thermal friction dominates. The present argument, which does not rely on any phenomenological input, leaves room for the weak regime of warm axion inflation, but in this case a super-Planckian decay constant represents a well-known issue. Finally, we discuss nonminimal and axionlike models as a way out.

We study scalar field theory on biregular trees, as a new model for discrete holography. Biregular trees are discrete symmetric spaces associated with the bulk isometry group $\mathrm{SU}(3)$ over the unramified quadratic extension of a nonarchimedean field. The bulk-to-bulk and bulk-to-boundary propagators exhibit distinct features absent on the regular tree or continuum AdS spaces, arising from the semihomogeneous nature of the bulk space. We compute the two- and three-point correlators of the putative boundary dual. The three-point correlator exhibits a nontrivial “tensor structure” via dependence on the homogeneity degree of a unique bulk point specified in terms of boundary insertion points. The computed operator product expansion coefficients show dependence on zeta functions associated with the unramified quadratic extension of a nonarchimedean field. This work initiates the formulation of holography on a family of discrete holographic spaces that exhibit features of both flat space and negatively curved space.

In this manuscript we examine the high energy channeling radiation datasets from the CERN-NA63 experiment using ultrarelativistic synchrotron emission. To incorporate recoil, we examine the standard quasiclassical formalism as well as develop a formalism that includes the Unruh effect by utilizing a hyperbolic recoil acceleration, based on conservation of momentum, in the classical synchrotron trajectory. We also perform an asymptotic radiation timescale analysis that predicts a photon energy threshold, beyond which the Unruh effect dominates. We then compare the classical, quasiclassical, and Unruh synchrotron theories to the data. We find that above threshold, the Unruh effect saturates the spectrum of all datasets.

Relativistic microcausality is the statement that local field operators commute outside the light cone. This condition is known to break down in low-energy effective theories, such as $P(X)$ models with a derivative interaction term of the “wrong sign.” Despite their Lorentz-invariant form, these theories can exhibit superluminal propagation on Lorentz-breaking backgrounds. We approach this phenomenon by computing the full operator-valued commutator in position space, perturbatively in interaction picture. After testing this formalism on a $\lambda {\varphi }^4$ theory, we apply it to a $P(X)$ model. There, we show that the perturbative corrections to the free-theory commutator contain derivatives of $\delta$ functions with support on the standard Minkowski light cone. While these corrections vanish on Lorentz-invariant states, they become “activated” on states where Lorentz symmetry is spontaneously broken. In this case, they approximate the new “sound cone” by means of a Taylor expansion. By applying linear response theory to an extended source, we show that deviations from standard causality are already present at first order in this expansion. Finally, we try to understand what goes wrong with the standard argument according to which Lorentz invariance implies microcausality.

In this paper, we present a method for estimating the validity range of the quantum Markovian master equation as applied to the Unruh-DeWitt (UDW) detector within a broader context, particularly without necessitating an exact solution for the detector’s evolution. We propose a relaxed van Hove limit (i.e., late-time limit) and offer a perturbative estimate of the error order resulting from the standard derivation procedure of open quantum dynamics. Our primary findings include reliability criteria for the Markov approximation and conditions for the applicability of the rotating wave approximation. Nevertheless, the specific forms of these validity conditions rely on the details of the detector-field system, such as the spacetime background, the trajectory of the detector, and the type of quantum field being analyzed. Finally, we illustrate our results by reexamining the open dynamics of an accelerating UDW detector undergoing the Unruh effect, where the validity conditions narrow the parameter space to ensure the solution’s reliability regarding the quantum Markovian master equation.

We combine the ghost-free bimetric theory of gravity with the concept of local Weyl invariance, realized in the framework of Einstein-Cartan gravity. The gravitational sector, characterized by two independent metrics and two independent connections, is coupled to a scalar field that can in principle develop a nonvanishing expectation value through radiative corrections. The spectrum of the model, apart from the massless standard graviton and a pair of axionlike pseudoscalars, associated with the presence of the Holst invariants in the action, includes an additional spin-2 state of a nonvanishing Fierz-Pauli mass proportional to the scalar field vacuum expectation value. We analyze the phenomenology of the model and specify the conditions under which the massive spin-2 state could be a primary dark matter candidate.

LISA data analysis represents one of the most challenging tasks ahead for gravitational wave (GW) astronomy. Characterizing the instrument’s noise properties while fitting for all the other detectable sources is a key requirement of any robust inference pipeline. Noise estimation will also play a crucial role in searches and parameter estimation of cosmological and astrophysical stochastic signals. Previous studies have tackled this topic by assuming perfect knowledge of the spectral shape of the instrumental noise and of different possible types of stochastic GW backgrounds (SGWBs), usually resorting to parametrized templates. Recently, various works that employ template-agnostic methods have been presented. In this work, we take an additional step further, introducing flexible spectral shapes in both the instrumental noise and the stochastic signals. We account for the lack of knowledge of the exact shape of the individual contributions to the overall power spectral density by using splines to represent arbitrary perturbations of the noise and signal spectral densities. We implement a data-driven reversible jump Markov chain Monte Carlo algorithm to fit different components simultaneously and to infer the level of flexibility required under different scenarios. We test this approach on simulated LISA data produced under different assumptions. We investigate the impact of this increased flexibility on the reconstruction of both the injected signal and the noise level, and we discuss the prospects for claiming a successful SGWB detection.

Instead of assuming that they depend only on the background variables, we investigate the hypothesis that counterterms appearing in the deformed algebra approach to loop quantum cosmology depend on the full phase-space variables. We derive the associated anomalies and solve the entire system in several specific cases. New restrictions on the generalized holonomy corrections are obtained.

Functions of bound Kerr geodesic motion play a central role in many calculations in relativistic astrophysics, ranging from gravitational-wave generation to self-force and radiation-reaction modeling. Although these functions can be expressed as a Fourier series using the geodesic fundamental frequencies, reconstructing them in coordinate time is challenging due to the coupling of the radial and polar motions. In this paper, we compare two strategies for performing such reconstructions and their ability to estimate high-order coordinate-time derivatives of the orbital functional. The first method maps Fourier coefficients from Mino to coordinate time; the second method fits a sampled time series of the function to a truncated coordinate-time Fourier series. While the latter method is prone to overfitting, it yields more accurate reconstructions and derivatives than the mapping, but completely misrepresents the harmonic content of the orbital functional. For the purpose of accurate coordinate-time derivative estimation, we propose a hybrid method: fit for the Mino-time coefficients, differentiate with respect to Mino time, then convert to coordinate time. Applied to the mass quadrupole of a generic Kerr geodesic, this hybrid method recovers the sixth derivative with a fractional residual $\sim {10}^{-6}$ using only two harmonics. For orbital functionals that depend explicitly on the geodesic orbit expressed in Boyer-Lindquist coordinates, we also provide a recursive procedure for computing coordinate-time derivatives using exact analytic expressions. These results offer a general framework for accurately evaluating high-order time derivatives along Kerr geodesic worldlines, with direct relevance to applications such as extreme-mass-ratio inspiral kludge waveform modeling, where such derivatives are key ingredients for precise gravitational-wave predictions.

Scalar fields with a nontrivial kinetic term derived from a nonlinear sigma model are motivated by UV completions of gravity such as string theory. We discuss the $\mathrm{SL}(2,\mathbb{R})$ and O(3) sigma models with interacting potentials and simulate their full nonlinear dynamics on black hole spacetimes. We study the properties of the field as a function of the curvature of the sigma model with respect to the free massive scalar case. In the accretion process, the $\mathrm{SL}(2,\mathbb{R})$ model behaves as a self-interacting field with attractive interaction, while the O(3) one exhibits a repulsive phenomenology. In the case of a binary black hole system, these models cause a positive or negative dephasing of the gravitational waveform, respectively, when compared to the noninteracting case and as long as the field’s Compton wavelength is larger than the binary separation. We observe no bosenova emission, which suggests that nonlinearities tend to suppress this phenomenon. Our results highlight how the kinetic and potential terms are both relevant in determining the field dynamics.

The equilibrium configurations of slowly rotating anisotropic self-gravitating fluids are computed using the extended Hartle structure equations, including anisotropic effects, derived in our previous paper. We focus on the so-called $\mathcal{C}$-star, whose anisotropic pressure follows a fully covariant equation of state (EOS), while a standard polytrope describes the radial pressure. We determine surface and integral properties, such as the moment of inertia, mass change, mass quadrupole moment, and ellipticity. Notably, for certain values of the compactness parameter, highly anisotropic $\mathcal{C}$-stars exhibit a prolate shape rather than the typical oblate form—an intriguing behavior also observed in other anisotropic systems like Bowers-Liang spheres and stars governed by a quasilocal EOS. Although the $\mathcal{C}$-stars considered in this study are limited by stability criteria and cannot sustain compactness beyond $M/R\approx 0.38$, we found indications that certain rotational perturbations exhibit similarities to those observed in other ultracompact systems approaching the black hole limit.

Future space-based gravitational wave (GW) observatories beyond LISA aim to explore the sub-millihertz to microhertz frequency band, targeting massive binary black hole (MBBH) coalescences across cosmic distances. In this work, we evaluate the detection and localization capabilities of such missions, taking into account the full galactic foreground. We show that signal-to-noise ratios (SNRs) can reach several thousand over a wide redshift range. Using ASTROD-GW as a representative mission concept, we consider three orbital configurations—nonprecessing and precessing with varying inclinations—and assess their performance across different MBBH populations. In the absence of precession, we find that the dominant quadrupole mode alone results in a two-hemisphere degeneracy, which is resolved by including higher-order harmonics. These harmonics equalize localization performance across configurations, reducing the relative advantage of orbital precession. Operating in the $10\mu \mathrm{Hz}–10\mathrm{mHz}$ band, sub-mHz detectors partially overlap with LISA’s sensitivity while extending significantly into lower frequencies, enabling more precise localization of high-mass MBBHs. The resulting high SNRs open new opportunities for multimessenger astronomy, cosmological inference, and tests of gravitational theory. Our results highlight the complementary strengths of sub-mHz missions in advancing the next frontier of GW astrophysics.