Axion-photon oscillation refers to the process of mutual conversion between photons and axions when they propagate in a magnetic field. This process depends on the strength of the background magnetic field, and magnetic white dwarfs provide a natural laboratory for testing this process. In this work, we study the behavior of axion-photon oscillation near magnetic white dwarfs: as the magnetic white dwarf rotates, its magnetic field structure rotates accordingly, causing a periodic change of the magnetic field along the path of photons. These variations affect the axion-photon oscillation process experienced by the photons emitted from the white dwarf, thereby inducing a periodic modulation in the intensity and polarization of the white dwarf’s thermal emission that we observe. Our study focuses on the impact of axion effects on the observed light curve variation and conducts a detailed investigation through numerical calculations. Using the light curve data of the white dwarf $\mathrm{PG}1015+014$ obtained from the observations by the Jacobus Kapteyn Telescope, which has a photometric precision of $\sim 1\%$, we derive the constraints on axion parameters. In the axion mass range of $\lesssim {10}^{-8}\mathrm{eV}$, the 95% credible interval upper limit of the axion-photon coupling $g_{a\gamma \gamma }$ is constrained to $<8.1\times {10}^{-12}{\mathrm{GeV}}^{-1}$.

We investigated the spin effect on the vacuum pair production by Dirac-Heisenberg-Wigner (DHW) formalism under two-color counterrotating electric fields. We primarily studied the combined effects of the field asymmetry, time delay, and frequency chirp on the particle momentum spectrum with and without considering the spin effect. We have observed that the vacuum pair production process demonstrates spin dependence even in a pure electric field and is sensitive to variations in the field parameters. The results indicate that the spin-dependent momentum spectrum exhibited distinct outcomes for various asymmetric fields with different chirp values and time delay. For an extended asymmetric field with large chirp and time delay, the particle number density can be increased by more than six orders of magnitude. The spin-up and spin-down particles are approximately comparable for a symmetric field with a small-frequency chirp and are dominated by the spin-up particles for a larger chirp. However, in the case of an asymmetric field, the increase in field asymmetry and the chirp parameter lead to a reversal of the spin asymmetry degree. For a shortened asymmetric electric field with a large-frequency chirp, the number of spin-up particles increases, leading to a spin asymmetry degree of 98.62%. Conversely, in an extended asymmetric field, the number of spin-down particles increases significantly, which corresponds to a spin asymmetry degree of 99.94%.

In the present study, we investigate the properties of an ensemble of free Dirac fermions, at finite inverse temperature $\beta$ and finite chemical potential $\mu$, undergoing rigid rotation with an imaginary angular velocity $\mathrm{\Omega }=i{\mathrm{\Omega }}_I$. Our purpose is to establish the analytical structure of such states, as well as the prospects (and dangers) of extrapolating results obtained under imaginary rotation to the case of real rotation. We show that in the thermodynamic limit, the state of the system is akin to a stationary system with modified inverse temperature ${\beta }_q=q\beta$ and the same chemical potential, where $q$ is the denominator of the irreducible fraction $\nu =\beta {\mathrm{\Omega }}_I/2\pi =p/q$. The temperature of the system becomes a fractal function of the rotation parameter, as in the case of the scalar field. The chemical potential breaks the fractalization of fermions. We also compute the thermodynamic potential $\mathrm{\Phi }$ and associated thermodynamic functions, showing that they also exhibit fractal behavior. Finally, we evaluate the axial and helical fluxes through the transverse plane, generated through the vortical effects, and show that they diverge in the thermodynamic limit, in the case when $\nu =1/q$ and $q\to \infty$.

An investigation into Schwinger pair production is presented, demonstrating that vacuum tunneling processes can be effectively controlled through electromagnetic potential modulation while maintaining the strong fields in the interaction region. This challenges the conventional paradigm that attributes exclusive governance of Schwinger processes to localized field intensities. Through comprehensive analysis of particle number, momentum spectra, and spatial distribution of created pairs, we establish that the observed modulation effects originate from electromagnetic potential—induced modifications to the quantum phase structure of virtual particles. This phenomenon reveals a profound connection between Schwinger tunneling dynamics and the geometric phase properties of the quantum vacuum state—a vacuum analog to the Aharonov-Bohm effect in charged particle systems. This discovery not only advances our understanding of electromagnetic interactions in quantum vacuum but also opens up new experimental opportunities for realizing Schwinger tunneling processes with existing facilities.

Entanglement is solely a quantum property and it can be extremely helpful to test the physics beyond the Standard Model in tabletop experiments with the advent of future quantum technologies. In this work, we provide an entanglement-based partial positive transpose witness for Yukawa-type potentials in the infrared regime between pairs of neutral/charged particles in a spatial quantum superposition. The entanglement is created by the interaction beyond the Standard Model such as axionlike particle or physics motivated by string theory such as extra dimensions in the context of gravity. We will study the constrained couplings in a few different models along with the decoherence rate to show what parameters can be searched for in near-future entanglement-driven experiments for the search of new physics.

Grand unified theory (GUT) phase transition is generally considered unobservable due to its ultrahigh energy scale, and the monopole problem associated with GUT phase transition is one motivation of inflation. We propose that if a first-order GUT phase transition happens during inflation, the induced gravitational waves (GWs) are redshifted and deformed, and might be observed today in GW observatories. We review the formalism of inflated GWs and derive the general deformation function between inflated and uninflated GW spectra in the instant-source or transitory-source application. It is valid for any e-folding number of instant or transitory source. Applying the formalism to GUT phase transition, we find that the e-folding number at 15 or 25 can shift the GWs to 10 Hz or mHz hands, respectively, which might be tested in the future ground-based or space-based interferometers. We further generalise the discussion to inflated GWs via phase transition below the GUT scale. It is worth mentioning that, due to the deformation of the spectrum, the peak of inflated GWs is not simply a redshift of the peak of uninflated GWs.

Traditional $\mathrm{SU}(N)$ lattice gauge theories (LGTs) can be formulated using an orthonormal basis constructed from the irreducible representations (irreps) $V_{\lambda }$ of the $\mathrm{SU}(N)$ gauge symmetry. On a lattice, the elements of this basis are tensor networks comprising dimer tensors on the links labeled by a set of irreps $\{{\lambda }_{\ell }\}$ and monomer tensors on sites labeled by $\{{\lambda }_s\}$. These tensors naturally define a local site Hilbert space, ${\mathcal{H}}_s^g$, on which gauge transformations act. Gauss’s law introduces an additional index ${\alpha }_s=1,2,\dots ,\mathcal{D}({\mathcal{H}}_s^g)$ that labels an orthonormal basis of the gauge-invariant subspace of ${\mathcal{H}}_s^g$. This monomer-dimer tensor-network (MDTN) basis, $|\{{\lambda }_s\},\{{\lambda }_{\ell }\},\{{\alpha }_s\}⟩$, of the physical Hilbert space enables the construction of new qubit-regularized $\mathrm{SU}(N)$ gauge theories that are free of sign problems while preserving key features of traditional LGTs. Here, we investigate finite-temperature confinement-deconfinement transitions in a simple qubit-regularized SU(2) and SU(3) gauge theory in $d=2$ and $d=3$ spatial dimensions, formulated using the MDTN basis, and show that they reproduce the universal results of traditional LGTs at these transitions. Additionally, in $d=1$, we demonstrate using a plaquette chain that the string tension at zero temperature can be continuously tuned to zero by adjusting a model parameter that plays the role of the gauge coupling in traditional LGTs.

We study multiplicities and junctions of Bogomol’nyi-Prasad-Sommerfield domain walls interpolating between different chiral vacua in $\mathcal{N}=1$ supersymmetric QCD (SQCD) with the $\mathrm{SU}(N)$ gauge group and a varying number of fundamental quarks. Depending on the number of flavors $F$, two distinct classes of degenerate domain walls emerge: (i) locally distinguishable, i.e., those which differ from each other locally, in local experiments; and (ii) those which have identical local structure and are differentiated only topologically, through judiciously chosen compactifications. In the first class, two-wall junctions exist, while in the second class, such junctions do not exist. Acharya and Vafa counted topologically distinguishable walls in pure super-Yang-Mills. Ritz, Shifman, and Vainshtein counted the locally distinguishable walls in $F=N$ SQCD. In both cases, the multiplicity of $k$ walls was the same, ${\nu }_{N,k}^{\text{walls}}=N!/[(N-k)!k!]$. We study the general case $0\le F\le N$, with mixed sets of walls from both classes (i) and (ii) simultaneously, and demonstrate that the above overall multiplicity remains intact. We argue that the growth of the quark masses exhibits no phase transition at any finite mass. The locally distinguishable walls can turn into topologically distinguishable ones only at $m=\infty$. The evolution of the low-energy wall world sheet theory in the passage from small to large $m$ is briefly discussed. We also propose a candidate for the low-energy description of wall junctions. The tools used are localization of instantons, supersymmetry enhancement on the walls, and circle compactification.

Modern neutrino-nucleus cross section computations need to incorporate sophisticated nuclear models to achieve greater predictive precision. However, the computational complexity of these advanced models often limits their practicality for experimental analyses. To address this challenge, we introduce a new Monte Carlo method utilizing normalizing flows to generate surrogate cross sections that closely approximate those of the original model while significantly reducing computational overhead. As a case study, we built a Monte Carlo event generator for the neutrino-nucleus cross section model developed by the Ghent group. This model employs a Hartree-Fock procedure to establish a quantum mechanical framework in which both the bound and scattering nucleon states are solutions to the mean-field nuclear potential. The surrogate cross sections generated by our method demonstrate excellent accuracy with a relative effective sample size of more than 98.4%, providing a computationally efficient alternative to traditional Monte Carlo sampling methods for differential cross sections.

In this work, we investigate the consistency of a perturbative definition of the S-matrix in a particular class of non-Lagrangian theories. We focus on the $p$-form theories proposed in the work by Broccoli et al. [Phys. Rev. Lett. 127, 091603 (2021)], which are fully defined by “third-way” consistent equations of motion. Using the perturbiner method, we show that the unitarity is absent even at the tree level. We then pin down a unique modification of the equations of motion that restores unitarity. The tradeoff is the reinstatement of an underlying Lagrangian, which we recognize as the higher-dimensional generalization of the Freedman-Townsend (FT) model. Finally, we discuss conserved currents in third-way theories and show they all follow from parent currents in the FT model. In particular, we point out the existence of a higher-ranked global symmetry, which signals that the FT model is compatible with the existence of branelike charged objects in higher dimensions.

The decay of asymmetric dark matter (ADM) can lead to distinct neutrino signatures characterized by an asymmetry between neutrinos and antineutrinos. In the high-energy regime, the Glashow resonant interaction ${\overline{\nu }}_e+e^{-}\to W^{-}$ yields an increase in sensitivity to the neutrino flux, and stands out as the only way of discerning the antineutrino component in the diffuse high-energy astrophysical neutrino flux. This offers a unique opportunity in the search for dark matter with masses above the PeV scale. We examine the neutrino signal stemming from ADM decay and set the first stringent constraints on ADM lifetime ${\tau }_X$. For ADM with mass $m_X\gtrsim 10\mathrm{PeV}$, we exclude ${\tau }_X\lesssim {10}^{29}\mathrm{s}$ using the data from the recent IceCube search for Glashow resonance events. Our projections further show that sensitivities at the forthcoming IceCube-Gen2 could approach ${10}^{30}\mathrm{s}$, depending on the decay channel. The current constraints on symmetric dark matter decay to neutrinos are also improved by up to a factor of 3 thanks to the Glashow resonance.

We explore semiclassical stellar collapse scenarios with pressure within the framework of effective loop quantum gravity. The objective of this work is to generalize existent models of semiclassical dust collapse and examine the role of pressure in the formation of shell-crossing singularities in a semiclassical context. Numerical investigations show that the singularity characterizing the end state of any classical stellar collapse is here resolved by quantum gravitational effects and replaced by a bounce of the star. However, they also show that shell-crossing singularities remain a general feature of these models and that the inclusion of pressure does not alter the qualitative picture emerging from semiclassical models of inhomogeneous dust collapse. Given the absence of a black hole singularity and the possibility of extending spacetime in the future of the trapped region formed by gravitational collapse, the investigation of the causal structure of the spacetime describing the semiclassical collapse of a star is inevitably tied to a better understanding of the physics of these shell-crossing singularities.

In the present study, we analyze the effects of violation of Lorentz symmetry for black-bounce solutions in a $k$-essence theory that has the form of a power law for the configuration $n=1/3$. We perform such analysis for a known model explored in previous work, ${\mathrm{\Sigma }}^2=x^2+a^2$, and complement the proposal with a new black-bounce model for the area functions, ${\mathrm{\Sigma }}_1^2=\sqrt{x^4+d^4}$. This model has the Schwarzschild–de Sitter asymptomatic behavior for $x\to -\infty$, and we investigate the scalar field, potential, and energy conditions for both models. We have shown that the violation of Lorentz symmetry can be generated through $k$-essence without the need for an additional field. These results corroborate the validation of other previously investigated wormhole solutions.

In spherical symmetry, the gravitational potential is uniquely determined by the rotational velocity profile. Numerous galaxies exhibit a universal velocity profile from which a universal gravitational profile is inferred. When treating dark matter as either an ideal gas, a Fermi gas, or a Bose gas, only the latter can produce a gravitational profile consistent with observations, along with a temperature profile that decreases outward. This requires the mass of the boson to be below a certain threshold of $43\mathrm{eV}/c^2$. Additionally, ensuring that the speed of sound is less than the speed of light yields a lower bound on the boson’s mass.

The study of the spectrum of excited states of the nucleon is vital to our understanding of how QCD is realized in the baryon spectrum. Using a simultaneous analysis of the pion nucleon scattering data up to 2 GeV as well as the results of lattice QCD calculations, we obtain new insight into the nature of the Roper resonance as well as the excited states around 1.9 GeV.

We investigate the existence of bound states and resonances in the $\varphi NN,J/\psi NN,{\eta }_{c}NN$ systems using HAL QCD interactions for $\varphi N,J/\psi N$, and ${\eta }_{c}N$. We employ the Gaussian expansion method to solve the complex-scaled Schrödinger equation and find no resonances or bound states in the $J/\psi NN$ and ${\eta }_{c}NN$ systems. We estimate the interaction between charmonium and nuclei, concluding that the $J/\psi$ or ${\eta }_c$ is likely to bind with ${}^3\mathrm{H}$, ${}^3\mathrm{He}$, ${}^4\mathrm{He}$, and heavier nuclei. For the $\varphi NN$ system, the lattice QCD $\varphi N({{}^{2}S}_{1/2})$ interaction is absent. We combine the $\varphi p$ correlation function analysis and HAL QCD results in model A. We assume the spin-spin interactions for $J/\psi N$ and $\varphi N$ systems are inversely proportional to their masses in model B. Model A predicts a stronger $\varphi N({{}^{2}S}_{1/2})$ interaction and permits a two-body bound state, whereas model B suggests the interaction is attractive but too weak to form a bound state. Both models predict bound states for the $I(J^P)=0(0^{-})$ and $0(1^{-})$ $\varphi NN$ systems. In model A, these states are deeply bound with binding energies exceeding 15 MeV and remain existent when considering parameter uncertainties. In contrast, these states are very loosely bound in model B, with binding energies below 1 MeV and an existent probability of about 60% when parameter uncertainties are considered. In both models, there exist very loosely bound $I(J^P)=0(2^{-})$ three-body states which resemble a $\varphi$-d atom with the $\varphi$ meson surrounding the deuteron, but their existence is sensitive to parameter uncertainties. No bound states or resonances are found in the isovector $I(J^P)=1(1^{-})$ $\varphi NN$ system.

Single-frequency emission from an accretion disk around a black hole is broadened into a line profile due to gravitational redshift and the motion of the disk’s particles relative to the observer. The ensemble of relativistically broadened emission frequencies from the disk elements forms the spectrum viewed by an observer. Over the past decades, the broadened spectra of accreting systems have been used to constrain the spin of the black hole, the observer’s inclination, and the astrophysical model parameters of the system. These inferences are usually made under the assumption that the accretion disk consists of particles orbiting around the black hole on stable circular orbits in the equatorial plane. Under this Standard disk model, in this work, we revisit line profile morphology, i.e., its extent, kinks, and falloff. We provide a unified analytical explanation for these line profile morphological features, which encode the black hole spin, viewing inclination, and locations of the disk’s inner and outer edges. We then show that these features, however, are model-dependent, by parametrically relaxing some of the astrophysical assumptions. In particular, we explore how allowing the disk particles to deviate from stable circular orbits rapidly degenerates the characteristic features of the line profile under the Standard disk model. Our results further demonstrate how sensitive our understanding of black hole and system properties can be to assumptions we make when interpreting these types of measurements.

We study relative motion of nearby test particles in topologically massive gravity (TMG) in three spacetime dimensions, using the equation of geodesic deviation. We show that, in a suitable reference frame, the influence of any gravitational field can be decomposed into transverse, longitudinal, and Newtonian components, which are directly related to the Cotton scalars of the Newman–Penrose type. In particular, we prove that Cotton type N spacetimes exhibit a purely transverse gravitational effect on test particles, and can thus be reasonably interpreted as specific gravitational waves with a single polarization mode in TMG. The influence of the cosmological constant manifests itself as an isotropic effect. We also discuss the physical interpretation of spacetimes of specific algebraic types, as well as the influence of various matter fields, namely the pure radiation, perfect fluid, and electromagnetic field. As an example, we provide an explicit analysis of TN-waves and pp-waves in three-dimensional TMG.

Theoretical understanding of the characteristic oscillations of a perturbed black hole, also referred to as quasinormal modes (QNMs), is crucial to interpreting the late stage of binary black hole mergers that we now routinely observe in gravitational wave detectors. In this work, we introduce a new approach, based on the generalized Sasaki-Nakamura formalism, to compute the QNM spectra and their excitation factors (QNEFs), for scalar, electromagnetic, and gravitational perturbations. Using this approach, QNM wave functions remain finite at the horizon and spatial infinity. Our results, in general, agree with previous calculations that were performed using different methods, though we further clarify that QNEFs and their scaling with the mass of the black hole depend on the spin weight of the perturbation. We show that avoided crossing is not a general phenomenon: The real or the imaginary part of the eigenvalues can cross each other but not both simultaneously, and, when crossing occurs in one part, repulsion follows in another part. Eigenvalue repulsion, originating from branch point singularities, still plays an important role in the QNM spectra, despite the fact that the spectra depend only on the real-valued black hole angular momentum.

We parametrize the equation of state of late-time dark energy as $w_{\mathrm{bin}}(z)$, with three redshift bins, characterized by a constant equation of state in each bin. Then, we constrain the parameters of the $w_{\mathrm{bin}}\mathrm{CDM}$ model using datasets from Dark Energy Spectroscopy Instrument baryon acoustic oscillations data, Planck cosmic microwave background power spectrum, ACT DR6 lensing power spectrum, and type Ia supernova distance-redshift data of Pantheon Plus/DES Y5/Union3. The significances for $w_1>-1$ are $1.9\sigma$, $2.6\sigma$ and $3.3\sigma$, and $w_2$ is consistent with $-1$ within $1\sigma$ level, while $1.6\sigma$, $1.5\sigma$ and $1.5\sigma$ for $w_3<-1$ in these three data combinations with different choices of type Ia supernova datasets, respectively. Additionally, to alleviate $H_0$ tension, we incorporate the early dark energy (EDE) model in the early-time universe and add the SH0ES absolute magnitude $M_b$ prior (or $H_0$ prior) to further constrain the $w_{\mathrm{bin}}\mathrm{EDE}$ model. In the $w_{\mathrm{bin}}\mathrm{EDE}$ model, we find a $w_{\mathrm{bin}}(z)$ pattern similar to that in the $w_{\mathrm{bin}}\mathrm{CDM}$ model. The results of the three data combinations exhibit $w_1>-1$ at $1.7\sigma$, $1.7\sigma$ and $2.9\sigma$ level, meanwhile $w_3<-1$ at $1.3\sigma$, $1.3\sigma$ and $1.3\sigma$ level, respectively. In all, our results indicate that the transition of dark energy from phantom at high redshifts to quintessence at low redshifts is not conclusive.