We explore new aspects of internal fermionic shifting symmetries, present in physical systems such as free Dirac spinors and $p$-form tensor-spinor fields. We propose a novel procedure to gauge these global symmetries, which also introduces a new Stückelberg mechanism to give a mass to free fermionic fields. Furthermore, we find new magnetic fermionic symmetries in these physical systems whose charged objects are disorder operators. For the case of a 4D Dirac spinor, we discuss a dual description, where the magnetic symmetry acts on the holonomies of a dual 2-form tensor-spinor. Further generalizations such as higher-group-like structures are also discussed.

We introduce a stabilizer code model with a qutrit at every edge on a square lattice and with noninvertible plaquette operators. The degeneracy of the ground state is topological as in the toric code, and it also has the usual deconfined excitations consisting of pairs of electric and magnetic charges. However, there are novel types of confined fractonic excitations composed of a cluster of adjacent faces with vanishing flux. They manifest confinement, and even larger configurations of these fractons are fully immobile although they acquire emergent internal degrees of freedom. Deconfined excitations change their nature in presence of these fractonic defects. As for instance, fractonic defects can absorb magnetic charges making magnetic monopoles exist while electric charges acquire restricted mobility. Furthermore, some generalized symmetries can annihilate any ground state and also the full sector of fully mobile excitations. All these properties can be captured via a novel type of noncommutative and non-Abelian fusion category in which the product is associative but does not commute, and can be expressed as a sum of (operator) equivalence classes. Generalized noninvertible symmetries give rise to the feature that the fusion products form a nonunital category without a proper identity. We show that a variant of this model features a deconfined fracton liquid phase and a phase where the dual (magnetic) strings have condensed.

It remains a long-standing problem, unsettled for almost two decades in the general relativity community, ever since Griffiths and Podolský demonstrated in their previous paper [J. B. Griffiths and J. Podolský, Classical Quantum Gravity 22, 3467 (2005)] that the type-D NUT $C$ metric seems to be absent from the most general family of the type-D Plebański-Demiański (P-D) solution. However, Astorino, in his recent article [M. Astorino, Phys. Rev. D 109, 084038 (2024)] presented a different form of rotating and accelerating black holes and showed that all known four-dimensional type-D accelerating black holes (without the NUT charge) can be recovered via various different limits in a definitive fashion. In particular, he provided, for the first time, the correct expressions for the type-D static accelerating black holes with a nonzero NUT charge, which was previously impossible using the traditional parametrization of the familiar P-D solution. Nevertheless, it still remains elusive how these two different forms of the four-dimensional rotating and accelerating solutions are related. In this paper, we aim to fill this gap by finding the obvious coordinate transformations and parameter identifications between the vacuum metrics after two different parametrizations of the generated solution via the inverse scattering method from the seed metric—the Rindler vacuum background. We then resolve this “missing” puzzle by providing another Möbius transformation and linear combinations of the Killing coordinates, which clearly cast the type-D NUT $C$ metric into the familiar form of the P-D solution. Additionally, we propose an alternative new routine for the normalization of the obtained metric derived via the inverse scattering method from the vacuum seed solution, which could be potentially useful for the construction of higher-dimensional solutions using the trivial vacuum background as the seed metric.

We explore scalar radiation from neutron star-black hole binaries in scalar-tensor theories with kinetic screening ($K$-essence). Using $3+1$ numerical relativity simulations in the decoupling limit, we investigate scalar dipole and quadrupole radiation for different values of the strong coupling constant $\mathrm{\Lambda }$. Our results show that kinetic screening effectively suppresses the scalar dipole radiation as $\mathrm{\Lambda }$ decreases. This is validated by comparing to analytic predictions for the screening of dipole scalar emission, with which our numerical results show good agreement. However, our numerical simulations show that the suppression of scalar quadrupole radiation is less efficient, even when the screening radius exceeds the wavelength of the emitted radiation. In fact, the dependence of the scalar quadrupole amplitude on $\mathrm{\Lambda }$ flattens out for the smallest $\mathrm{\Lambda }$ that we can simulate, and the quadrupole amplitude is suppressed only by a factor $\lesssim 3$ relative to the Fierz-Jordan-Brans-Dicke case. Overall, our study shows that scalar quadrupole radiation from mixed binaries may be used to place constraints on $K$-essence theories with next-generation gravitational-wave detectors.

For pulsar timing arrays (PTAs), the telltale signature of an isotropic stochastic background of gravitational waves is a pattern of pairwise interpulsar timing correlations approximately following the Hellings and Downs (HD) curve. Certain systematic errors and new physics processes also lead to interpulsar correlations with different patterns that can be distinguished from the HD curve to varied degrees. As evidence of HD correlations in PTA data mounts in coming years, it is important to develop principled strategies for flexibly and optimally reconstructing the pattern of interpulsar timing correlations, both to test how well the correlations track the HD pattern and to possibly detect additional effects, systematic or otherwise. To this end, we develop orthonormal basis functions that fully capture HD correlations and eliminate covariances between the HD curve and any additional correlated structure. We do this analytically and in a data-adaptive way informed by “optimal statistic” analysis techniques widely used by PTA groups. These bases are adaptive in that they will vary from PTA to PTA and from data release to data release as new pulsars of varied timing quality and baseline are added to arrays, as instrumentation advances, and as observations accrue. We discuss how the techniques we introduce can be extended to future multisignal searches by PTAs and to robust assessment of HD detection significance.

Recent studies have increasingly recognized the value of analyzing the post-reconstruction galaxy power spectrum for investigations into redshift space distortion (RSD) effects. In this paper, we present a novel theoretical model for the postreconstruction galaxy power spectrum, designed for RSD analyses. In particular, we emphasize the importance of accounting for discrete effects arising from the reconstruction displacement vector, which have been overlooked. We specifically calculate these discrete effects, i.e., shot noise terms, within the framework of standard perturbation theory at the 1-loop level. In addition, we adopt a formulation that accounts for infrared effects to accurately model the nonlinear damping of the baryon acoustic oscillation signal. Our model comprehensively integrates key physical phenomena relevant to the postreconstruction galaxy power spectrum, such as gravitational nonlinearities, RSD effects, bias effects, reconstruction effects, reconstruction-specific shot-noise effects, and the nonlinear damping of the reconstructed baryon acoustic oscillation signal, thereby making it applicable to postreconstruction RSD analyses.

We investigate the redshift dependence of the Hubble tension by comparing the luminosity distances obtained using an up-to-date BAO dataset (including the latest DESI data) calibrated with the CMB-inferred sound horizon and the $\mathrm{Pantheon}+\text{SN}$ Ia distances calibrated with Cepheids. Using a redshift tomography method. We find: (1) The BAO-inferred distances are discrepant with the $\mathrm{Pantheon}+\text{SN}$ Ia distances across all redshift bins considered, with the discrepancy level varying with redshift. (2) The distance discrepancy is more pronounced at lower redshifts ($z\in [0.1,0.8]$) compared to higher redshifts ($z\in [0.8,2.3]$). The consistency of $\mathrm{\Lambda }\mathrm{CDM}$ best fit parameters obtained in high and low redshift bins of both BAO and SN Ia samples is investigated, and we confirm that the tension reduces at high redshifts. Also a mild tension between the redshift bins is identified at higher redshifts for both the BAO and $\mathrm{Pantheon}+\text{data}$ with respect to the best fit value of $H_0$ in agreement with previous studies which find hints for an “evolution” of $H_0$ in the context of $\mathrm{\Lambda }\mathrm{CDM}$. These results confirm that the low redshift BAO and SN Ia distances can only become consistent through a reevaluation of the distance calibration methods. An $H(z)$ expansion rate deformation alone is insufficient to resolve the tension. Our findings also hint at a possible deviation of the expansion rate from the Planck18/$\mathrm{\Lambda }\mathrm{CDM}$ model at high redshifts $z\gtrsim 2$. We show that such a deformation is well described by a high redshift transition of $H(z)$ like the one expressed by ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$ even though this alone cannot fully resolve the Hubble tension due to its tension with intermediate/low $z$ BAO data.

We consider the case of axionlike particles (ALPs) during inflation. When coupled to a non-Abelian gauge sector via a Chern-Simons term, ALPs support an intriguing, testable, phenomenology with very distinctive features including chiral primordial gravitational waves. For sufficiently small values of the gauge vacuum expectation value (vev) and coupling, scalar perturbations in the gauge sector exhibit a known instability. We harness the power of such instability for primordial black hole (PBH) generation. In the case of an axion-inflaton, one is dynamically driven into a strong-backreaction regime that crosses the instability band thereby sourcing a peaked scalar spectrum leading to PBH production and the related scalar-induced gravitational waves. Remarkably, this dynamics is largely insensitive to the initial conditions and the shape of the potential, highlighting the universal nature of the sourcing mechanism.

Galaxies residing in dark matter halos exert significant gravitational effects that alter halo structure and dynamics. The complexity of these interactions escalates with the diversity of galactic structures and the variability in dark matter halo profiles under self-interacting dark matter (SIDM) models. This work extends the parametric model for dark-matter-only halos presented by Yang et al. [J. Cosmol. Astropart. Phys. 02 (2024) 032] to incorporate baryons. We adapt this model to consistently represent the SIDM halo density profile over time, highlighting the role of a gravothermal phase in characterizing the state of an SIDM halo. Given this phase, the density profile in SIDM is determined by a fictitious progenitor—consisting of a Navarro-Frenk-White halo influenced by a baryonic potential—that has evolved to its present state. In the temporal dimension, the model incorporates a form factor that rescales the evolution time in the dark-matter-only case, thereby enabling the introduction of a universal phase. In the radial dimension, the halo density profile is parametrized to reflect the influences of baryons. We calibrate the model through N-body simulations with baryon potentials to fit various stellar-to-halo mass ratios and size-mass relationships. Our parametric approach is numerically efficient, enabling the exploration of SIDM effects across a diverse set of halos, as exemplified by a case study using an illustrative sample that spans 5 orders of magnitude in the mass range. We also demonstrate that the effects of evolution history and the specific SIDM model can be separated from the current states of galaxies and halos, leaving the task of identifying consistent SIDM models to dedicated postprocessing analyses.

While dynamical tides only become relevant during the last couple of orbits for circular inspirals, orbital eccentricity can increase their impact during earlier phases of the inspiral by exciting tidal oscillations at each close encounter. We investigate the effect of dynamical tides on the orbital evolution of eccentric neutron star binaries using post-Newtonian numerical simulations and construct an analytic stochastic model that reproduces the numerical results. Our study reveals a strong dependence of dynamical tides on the pericenter distance, with the fractional energy transferred to dynamical tides over that dissipated in gravitational waves (GWs) exceeding $\sim 1\%$ at separations $r_{\mathrm{p}}\lesssim 50\mathrm{km}$ for large eccentricities. We demonstrate that the effect of dynamical tides on orbital evolution can manifest as a phase shift in the GW signal. We show that the signal-to-noise ratio of the GW phase shift can reach the detectability threshold of 8 with a single advanced Laser Interferometer Gravitational Wave Observatory detector at design sensitivity for eccentric neutron star binaries at a distance of 40 Mpc. This requires a pericenter distance of $r_{\mathrm{p}0}\lesssim 68\mathrm{km}$ ($r_{\mathrm{p}0}\lesssim 76\mathrm{km}$) at binary formation with eccentricity close to 1 for a reasonable tidal deformability and f-mode frequency of 500 and 1.73 kHz (700 and 1.61 kHz), respectively. The observation of the phase shift will enable measuring the f-mode frequency of neutron stars independently from their tidal deformability, providing significant insights into neutron star seismology and the properties of the equation of state. We also explore the potential of distinguishing between equal-radius and twin-star binaries, which could provide an opportunity to reveal strong first-order phase transitions in the nuclear equation of state.

We implemented symbolic regression techniques to identify suitable analytical functions that map various properties of neutron stars (NSs), obtained by solving the Tolman-Oppenheimer-Volkoff (TOV) equations, to a few key parameters of the equation of state (EOS). These symbolic regression models (SRMs) are then employed to perform Bayesian inference with a comprehensive dataset from nuclear physics experiments and astrophysical observations. The posterior distributions of EOS parameters obtained from Bayesian inference using SRMs closely match those obtained directly from the solutions of TOV equations. Our SRM-based approach is approximately 100 times faster, enabling efficient Bayesian analyzes across different combinations of data to explore their sensitivity to various EOS parameters within a reasonably short time.

Matched-filter-based gravitational wave search pipelines identify candidate events within seconds of their arrival on Earth, offering a chance to guide electromagnetic follow-up and observe multimessenger events. Understanding the detectors’ response to an astrophysical transient across the searched signal manifold is paramount to inferring the parameters of the progenitor and deciding which candidates warrant telescope time. We describe a framework that uses artificial neural networks to interpolate gravitational waves and, equivalently, the signal-to-noise ratio across sufficiently local patches of the signal manifold. Our machine-learning based model generates a single waveform in 6 ms on a CPU and 0.4 ms on a graphical processing unit (GPU). When using a GPU to generate batches of waveforms simultaneously, we find that we can produce ${10}^4$ waveforms in $\lesssim 1\mathrm{ms}$. This is achieved while remaining faithful, on average, to 1 part in ${10}^4$ (1 part in ${10}^5$) for binary black hole (binary neutron star) waveforms. The model we present is designed to directly utilize intermediate detection pipeline outputs in the hopes of facilitating a better real-time understanding of gravitational wave candidates.

To more precisely constrain the equation of state (EOS) of supradense neutron-rich nuclear matter, future high-precision x-ray and gravitational wave observatories are proposed to measure the radii of neutron stars (NSs) with an accuracy better than about 0.1 km. However, it remains unclear what particular aspects (other than the stiffness generally spoken of in the literature) of the EOS and to what precision they will be better constrained. In this work, within a Bayesian framework using a metamodel EOS for NSs, we infer the posterior probability distribution functions (PDFs) of incompressibility $K_0$ and skewness $J_0$ of symmetric nuclear matter (SNM) as well as the slope $L$, curvature $K_{\mathrm{sym}}$, and skewness $J_{\mathrm{sym}}$ characterizing the density dependence of nuclear symmetry energy $E_{\mathrm{sym}}(\rho )$, respectively, from mean values of NS radii consistent with existing observations and an expected accuracy $\mathrm{\Delta }R$ ranging from about 1.0 to 0.1 km. We found that (1) the $\mathrm{\Delta }R$ has little effect on inferring the stiffness of SNM at suprasaturation densities, (2) smaller $\mathrm{\Delta }R$ reveals more accurately not only the PDFs but also pairwise correlations among parameters characterizing high-density $E_{\mathrm{sym}}(\rho )$, (3) a double-peak feature of the PDF($K_{\mathrm{sym}}$) corresponding to the strong $K_{\mathrm{sym}}-J_{\mathrm{sym}}$ and $K_{\mathrm{sym}}-L$ anticorrelations is revealed when $\mathrm{\Delta }R$ is less than about 0.2 km, and the locations of the two peaks are sensitive to the maximum value of $J_{\mathrm{sym}}$ reflecting the stiffness of $E_{\mathrm{sym}}(\rho )$ above about 3 times the saturation density ${\rho }_0$ of SNM, and (4) the high-precision radius measurement for canonical NSs is more useful than that for massive ones for constraining the EOS of nucleonic matter around $(2–3){\rho }_0$.

The observations of the energy spectra of cosmic rays have revealed complicated structures. Especially, spectral hardenings in the boron-to-carbon and boron-to-oxygen ratios above $\sim 200\mathrm{GV}$ have been revealed by AMS-02 and DAMPE experiments. One scenario to account for the hardenings of secondary-to-primary ratios is the nuclear fragmentation of freshly accelerated particles around sources. In this work, we further study this scenario based on new observations of Galactic diffuse gamma rays by LHAASO and neutrinos by IceCube. We find that the spectra of cosmic ray nuclei, the diffuse ultra-high-energy gamma rays, and the Galactic component of neutrinos can be simultaneously explained, given an average confinement and interaction time of $\sim 0.2\mathrm{Myr}$ around sources. These multimessenger data thus provide evidence of non-negligible grammage of Galactic cosmic rays surrounding sources besides the traditional one during the propagation.

Radial mode stability is a necessary condition for the astrophysical viability of compact objects. In recent years, astrophysical models with two fluids have gained popularity, especially in their ability to model dark matter admixed neutron stars. Just as is the case of single-fluid stars, a stability criterion based on the background equations has been developed—the critical curve for the particle numbers of the two fluids in the two-dimensional configuration space determines a one-dimensional sequence that labels the marginally stable configurations—but its validity depends on the linear stability of radial perturbations which remains unstudied. In this paper, we establish a set of stability criteria for two perfect-fluid relativistic stars by carefully studying the radial mode perturbation equations. We prove that modes are complete, have real eigenvalues with a minimum eigenvalue (i.e., a fundamental mode), thus a configuration is stable if and only if the fundamental mode is positive. As a consequence, our work formally and rigorously proves these necessary conditions for the stability criterion based on the background equations.

We introduce the usage of equivariant neural networks in the search for violations of the charge-parity ($CP$) symmetry in particle interactions at the CERN Large Hadron Collider. We design neural networks that take as inputs kinematic information of recorded events and that transform equivariantly under a symmetry group related to the $CP$ transformation. We show that this algorithm allows one to define observables reflecting the properties of the $CP$ symmetry, showcasing its performance in several reference processes in top quark and electroweak physics. Imposing equivariance as an inductive bias in the algorithm improves the numerical convergence properties with respect to other methods that do not rely on equivariance and allows one to construct optimal observables that significantly improve the state-of-the-art methodology in the searches considered.

We consider a generalized Heitler model for a QED cascade. An exact formula for the final number of leptons is obtained by solving the kinetic equations. We demonstrate that in such a model the final number of leptons does not depend on photon and lepton mean free paths. We derive approximate formulas for the main characteristics of cascades at high energy, including the final number of leptons and the cascade depth. We show that in general the final number of leptons is asymptotically proportional to the energy of a seed particle. It is also demonstrated how the original Heitler model is reproduced as a special case.

In 2020, a di-$J/\psi$ resonance centered at around 6.9 GeV was discovered by the LHCb Collaboration and was later confirmed by the ATLAS and CMS Collaborations. In addition to the 6.9-GeV resonance, its low-energy counterpart centered at around 6552 MeV was also observed by the CMS Collaboration. They are generally considered as fully charm tetraquarks. In this paper, we calculate the inclusive decay width of molecules composed of two $J/\psi$’s and genuine fully charm tetraquarks into light hadrons and into open charms, respectively. Assuming them as $S$-wave states, we consider all possible spin configurations, namely, spin-0 and spin-2, that decay exclusively into double $J/\psi$, and find that the ratio ($\mathcal{R}$) of the decay width for the light-hadron final states to that for the charmed final states differs significantly among different spin configurations, which can help to explore the nature of the observed di-$J/\psi$ resonances.

In this paper, we study a recently discovered connection between scattering that minimally entangles and emergent symmetries. In a perturbative expansion, we have generalized the constraints of minimal entanglement scattering, beyond qubits, to general qudits of dimension $d$. Interestingly, projecting on any qubit subspaces, the constraints factorize, so that it is consistent to analyze minimal entanglement by looking at all such subspaces. We start by looking at toy models with two scalar fields, finding that minimal entanglement only allows quartic couplings which have instabilities at large field values and no symmetries. For the two Higgs doublet model, by considering $H^{+}{H}^{-}\to H^{+}{H}^{-}$ scattering, we show that minimal entanglement in this channel does not allow an interacting parameter point with enhanced symmetries. These results show that the connection between minimal entanglement and symmetries depends strongly on the scattering channels analyzed and we speculate on the potential resolutions.

In this work, we systematically analyze Feynman integrals in the ‘t Hooft-Veltman scheme. We write an explicit reduction resulting from partial fractioning the high-multiplicity integrands to a finite basis of topologies at any given loop order. We find all of these finite basis topologies at two loops in four external dimensions. Their maximal cut and the leading singularity are expressed in terms of the Gram determinant and Baikov polynomial. By performing an integration-by-parts reduction without any cut constraint on a numerical probe for one of these topologies, we show that the computational complexity drops significantly compared to the conventional dimensional regularization scheme. Formally, our work implies an upper bound on the rigidity of special functions appearing in the iterated integral solutions at each loop order in perturbative quantum field theory. Phenomenologically, the integrand-level reduction we present will substantially simplify the task of providing high-precision predictions for future high-multiplicity collider observables.