We study the possibility that four $\mathrm{\Xi }$ resonances $(\mathrm{\Xi }(1620)$, $\mathrm{\Xi }(1690)$, $\mathrm{\Xi }(1820)$, and $\mathrm{\Xi }(1950))$ could correspond to pentaquark states, in the form of meson-baryon bound systems. We also explore the possible existence of doubly strange pentaquarks with hidden charm $(P_{css})$ and find two candidates structured in a similar form, at energies of 4493 and 4630 MeV. The meson-baryon interaction is built from t-channel meson exchange processes, which are evaluated using effective Lagrangians. Moreover, we analyze the ${\mathrm{\Xi }}_b\to \mathrm{\Xi }J/\psi \varphi$ decay process, which permits exploring the existence of the heavy double strange pentaquark, as well as other exotic hadrons, in the three different two-body invariant mass spectra of the emitted particles. In the $J/\psi \varphi$ mass spectrum, we analyze the nature of the $X(4140)$ and $X(4160)$ resonances. In the $J/\psi \mathrm{\Xi }$ invariant mass spectrum, we study the signal produced by the double strange pentaquark, where we conclude that it has a good chance to be detected in this reaction if its mass is around 4580–4680 MeV. Finally, in the $\varphi \mathrm{\Xi }$ spectrum, we study the likelihood to detect the $\mathrm{\Xi }(2500)$ state.

We calculate the electromagnetic polarizabilities of the spin-$\frac{1}{2}$ singly heavy baryons in the heavy baryon chiral perturbation theory up to $\mathcal{O}(p^3)$. We estimate the low-energy constants using the magnetic moments of singly charmed baryons from lattice QCD simulations and the experimental decay widths of ${\mathrm{\Sigma }}_c$ and ${\mathrm{\Sigma }}_c^{*}$. Our results indicate that the long-range chiral corrections make significant contributions to the polarizabilities. Additionally, the magnetic dipole transitions ${\mathcal{B}}_6^{*}\to {\mathcal{B}}_6+\gamma$ also provide large contribution to the magnetic polarizabilities.

Recently, a charmonium $X(3960)$ in $B$ decays in the $D_s^{+}{D}_s^{-}$ invariant-mass spectrum is discovered by the LHCb collaboration with the quantum number $J^{PC}=0^{++}$. Motivated by the discovery, in this work, we systematically investigated the $c\overline{c}s\overline{s}$ tetraquark states with the quantum numbers $J^{PC}=0^{++},1^{++},1^{+-},2^{++}$ in the framework of the chiral quark model. In our calculations, we considered the meson-meson structure of the tetraquark states and the diquark-antidiquark structure, as well as the channel coupling of all channels of these two configurations are considered in this work. For example, all color structures including color singlet, hidden color channel, and the mixing of them are also taken into account. The numerical results indicate that no bound states were found in our model. There exist several resonant states by using the stabilization method, the so-called real scaling method. Among these states, the $0^{++}$ resonant state with mass 3927 MeV matches very well with the energy of the newly discovered exotic state $X(3960)$ reported by the LHCb collaboration. As a result, our calculations suggest that $X(3960)$ can be interpreted as a $c\overline{c}s\overline{s}$ tetraquark state with quantum number $J^{PC}=0^{++}$. Apart from that, we also find several resonance states with mass 4179 and 4376 MeV with $0^{++}$. For $1^{++}$, there is likely one resonance state in the energy range of $\sim 4310–4336\mathrm{MeV}$, along with two resonance states at the energy of 4395 and 4687 MeV, respectively. Besides, two resonance states at 4300 and 4355 MeV for $1^{+-}$, as well as one state at 4788 MeV for $2^{++}$, are found, which are likely to be new exotic states. More experimental data is needed to confirm the existence of these resonance states.

We calculate the elastic production of dijets from electron collisions with a longitudinally polarized proton target at small values of the Bjorken $x$ variable. Building on the pioneering proposals of Hatta et al. [Gluon orbital angular momentum at small-$x$, Phys. Rev. D 95, 114032 (2017).] and Bhattacharya et al. [Signature of the gluon orbital angular momentum, Phys. Rev. Lett. 128, 182002 (2022)., Probing the quark orbital angular momentum at electron-ion colliders using exclusive $\pi 0$ production, Phys. Rev. Lett. 133, 051901 (2024)., and Exploring orbital angular momentum and spin-orbit correlation for gluons at the Electron-Ion Collider, arXiv:2404.04209.] for measuring the quark and gluon orbital angular momentum (OAM) distributions, our focus is on both the longitudinal double spin asymmetry (DSA) and longitudinal single spin asymmetry (SSA). We compute the numerators of these asymmetries in the small-$x$ formalism of the light-cone operator treatment. Utilizing the small-$x$ expressions for the OAM distributions derived earlier in Kovchegov and Manley [Orbital angular momentum at small x revisited, J. High Energy Phys. 02 (2024) 060.], we demonstrate that the DSA provides a robust probe for both the quark and gluon OAM distributions within the proton. In contrast, we find that while the SSA is also sensitive to the OAM distributions, extraction of the latter from the SSA would require new developments in small-$x$ theory and phenomenology, and is probably not feasible at this point in time. These findings highlight the potential of DSA measurements in elastic dijet production at the future Electron-Ion Collider to provide the first-ever direct access to the quark and gluon OAM distributions at small $x$, paving the way for new insights into the proton spin puzzle.

In this work, we investigate the heavy-flavor conserving weak decays of charmed baryons, specifically the processes ${\mathrm{\Xi }}_c\to {\mathrm{\Lambda }}_c\pi$ and ${\mathrm{\Omega }}_c\to {\mathrm{\Xi }}_c\pi$, where the pole model is employed to account for the nonfactorizable contributions. Additionally, the nonperturbative parameters involved are determined within the framework of the nonrelativistic quark model, utilizing exact baryon wave functions obtained by solving the Schrödinger equation with a nonrelativistic potential. By considering the mixing angle $\theta \in (24.4°,32.4°)$ for ${\mathrm{\Xi }}_c-{\mathrm{\Xi }}_c^{\prime }$ mixing, we find that the experimental data can be effectively reproduced. Furthermore, we estimate the branching ratios: $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Lambda }}_c^{+}{\pi }^0)=(8.69–9.79)\times {10}^{-3}$, $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Xi }}_c^{+}{\pi }^{-})=(11.3–12.1)\times {10}^{-3}$, and $\mathcal{B}({\mathrm{\Omega }}_c^0\to {\mathrm{\Xi }}_c^0{\pi }^0)=(4.67–5.23)\times {10}^{-3}$. These predictions can be tested in ongoing experiments at LHCb, Belle II, and BESIII.

We introduce the first generative model trained on the jetclass dataset. Our model generates jets at the constituent level, and it is a permutation-equivariant continuous normalizing flow (CNF) trained with the flow matching technique. It is conditioned on the jet type, so that a single model can be used to generate the ten different jet types of jetclass. For the first time, we also introduce a generative model that goes beyond the kinematic features of jet constituents. The jetclass dataset includes more features, such as particle-ID and track impact parameter, and we demonstrate that our CNF can accurately model all of these additional features as well. Our generative model for jetclass expands on the versatility of existing jet generation techniques, enhancing their potential utility in high-energy physics research, and offering a more comprehensive understanding of the generated jets.

Water-based liquid scintillator (WbLS) is a hybrid detector medium which has been proposed as a fill material for future large-volume rare event searches, including $\nu -$ detectors. This family of scintillating suspensions promises waterlike attenuation and scattering behavior, while offering scintillation light yield for sub-Cherenkov-threshold events. These features may allow for improved vertex and energy resolution, and concomitant improvements in background rejection and particle identification. While subscale measurements of light yield, timing and pulse-shape have been performed in several WbLS formulations, detailed measurements of the attenuation and scattering properties of WbLS remain a critical, unresolved step along the pathway to deployment. In pursuit of a better understanding of these parameters, a “long-arm” attenuation and scattering instrument has been developed at Lawrence Livermore National Laboratory, dubbed LASE (Livermore Attenuation and Scattering Experiment). Optical property measurements have been performed using LASE in DI water, Gd-water, WbLS and Gd-WbLS. Measurements of the optical properties of WbLS (1% LAB-PPO scintillator) provided by Brookhaven National Laboratory demonstrate an attenuation minimum of $4.87\times {10}^{-4}\pm 1.42\times {10}^{-4}{\mathrm{cm}}^{-1}$ at 450 nm, while Gd-loaded WbLS (1% LAB-PPO scintillator, 0.1% Gd) demonstrated a minimum attenuation coefficient of $4.77\times {10}^{-4}\pm 1.27\times {10}^{-4}{\mathrm{cm}}^{-1}$ at the same wavelength. Measurements of scattering in WbLS show a scattering coefficient of $3.39\times {10}^{-4}\pm 1.98\times {10}^{-5}{\mathrm{cm}}^{-1}$ at the 450 nm attenuation minimum, while Gd-WbLS has a scattering coefficient of $2.8\times {10}^{-4}\pm 1.63\times {10}^{-5}{\mathrm{cm}}^{-1}$ at that wavelength. These scattering and attenuation coefficients are significantly larger than measured for DI water at similar wavelengths ($8.8\times {10}^{-5}{\mathrm{cm}}^{-1}\pm 3.8\times {10}^{-5}$ attenuation at 430 nm, $2.2\times {10}^{-5}\pm 1.28\times {10}^{-6}{\mathrm{cm}}^{-1}$ scattering). Though the WbLS attenuation and scattering coefficients measured are lower than the corresponding values published for ultrapure oils and LAB-PPO liquid scintillator, the material tested attenuates significantly more than water across the blue and green portions of the visible spectrum. This attenuation is markedly stronger at wavelengths under 430 nm.

Understanding the internal structure of nucleons and nuclei has been a topic of enduring interest in high-energy physics. Gravitational form factors (GFFs) provide an important portal for us to probe the energy-momentum/mass distribution of nucleons and nuclei. This paper presents the study of the photon and gluon momentum GFFs, also known as the A-GFFs, of relativistic hadrons using the Weizsäcker-Williams method. To begin, we express the photon A-GFFs in terms of charge form factors and discuss the corresponding photon radius. Furthermore, an integral relation between the gluon A-GFF and the Laplacian of dipole scattering amplitude is derived in the small-$x$ framework, and it allows us to unravel the gluon energy momentum distribution inside hadrons through measurements at the upcoming Electron-Ion Collider. In addition, we generalize the analysis to study the A-GFF of nuclei and propose employing the nuclear gluon mean square radius, together with the charge distribution, to constrain the neutron distribution for large nuclei. This work provides an interesting perspective into the fundamental structure of high-energy hadrons.

Using $e^{+}{e}^{-}$ collision data collected with the BESIII detector at the BEPCII collider at 32 center-of-mass energies from 3.50 to 4.95 GeV, corresponding to an integrated luminosity of $25{\mathrm{fb}}^{-1}$, we measure the Born cross section of the $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ reaction and the effective form factor for the first time. No significant charmonium(-like) state, i.e., $\psi (3770)$, $\psi (4040)$, $\psi (4160)$, $\psi (4230)$, $\psi (4360)$, $\psi (4415)$, or $\psi (4660)$, decaying into the ${\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ final state is observed by fitting the $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ dressed cross section. The upper limits for the product of the branching fraction and the electronic partial width at the 90% confidence level are provided for each assumed charmonium(-like) state for the first time. In addition, the ratios of the Born cross section and the effective form factor between the $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ and the $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^{+}{\overline{\mathrm{\Sigma }}}^{-}$ reactions are provided, which can be used to validate the prediction of the vector meson dominance model.

Utilizing $4.5{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 4.600 and 4.699 GeV, the first observation of the singly Cabibbo-suppressed decay ${\mathrm{\Lambda }}_c^{+}\to p{\pi }^0$ is presented, with a statistical significance of $5.4\sigma$. The ratio of the branching fractions of ${\mathrm{\Lambda }}_c^{+}\to p{\pi }^0$ and ${\mathrm{\Lambda }}_c^{+}\to p\eta$ is measured as $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{\pi }^0)/\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p\eta )=(0.120\pm 0.026_{\mathrm{stat}}\pm 0.007_{\mathrm{syst}})$. This result resolves the longstanding discrepancy between earlier experimental searches, providing both a decisive conclusion and valuable input for QCD-inspired theoretical models. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish the signal from the prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

The spectroscopic study of black hole quasinormal modes in gravitational-wave ringdown observations is hindered by our ignorance of which modes should dominate astrophysical signals for different binary configurations, limiting tests of general relativity and astrophysics. In this work, we present a description of the quasinormal modes that are excited in the ringdowns of comparable mass, quasicircular precessing binary black hole coalescences—a key region of parameter space that has yet to be fully explored within the framework of black hole spectroscopy. We suggest that the remnant perturbation for precessing and nonprecessing systems is approximately the same up to a rotation, which implies that the relative amplitudes of the quasinormal modes in both systems are also related by a rotation. We present evidence for this by analyzing an extensive catalog of numerical relativity simulations. Additional structure in the amplitudes is connected to the system’s kick velocity and other asymmetries in the orbital dynamics. We find that the ringdowns of precessing systems need not be dominated by the $(\ell ,m,n)=(2,\pm 2,0)$ quasinormal modes, and that instead the $(2,\pm 1,0)$ or (2, 0,0) quasinormal modes can dominate. Our results are consistent with a ringdown analysis of the LIGO-Virgo gravitational wave signal GW190521, and may also help in understanding phenomenological inspiral-merger-ringdown waveform model systematics.

In general relativity with vector and scalar fields given by the Lagrangian $\mathcal{L}(F,\varphi ,X)$, where $F$ is a Maxwell term and $X$ is a kinetic term of the scalar field $\varphi$, we study the linear stability of static and spherically symmetric objects without curvature singularities at their centers. We show that the background solutions are generally described by either purely electrically or magnetically charged objects with a nontrivial scalar-field profile. In theories with the Lagrangian $\tilde{\mathcal{L}}(F)+K(\varphi ,X)$, which correspond to nonlinear electrodynamics with a $k$-essence scalar field, angular Laplacian instabilities induced by vector-field perturbations exclude all the regular spherically symmetric solutions including nonsingular black holes. In theories described by the Lagrangian $\mathcal{L}=X+\mu (\varphi )F^n$, where $\mu$ is a function of $\varphi$ and $n$ is a constant, the absence of angular Laplacian instabilities of spherically symmetric objects requires that $n>1/2$, under which nonsingular black holes with apparent horizons are not present. However, for some particular ranges of $n$, there are horizonless compact objects with neither ghosts nor Laplacian instabilities in the small-scale limit. In theories given by $\mathcal{L}=X\kappa (F)$, where $\kappa$ is a function of $F$, regular spherically symmetric objects are prone to Laplacian instabilities either around the center or at spatial infinity. Thus, in our theoretical framework, we do not find any example of linearly stable nonsingular black holes.

Effective-one-body (EOB) models are based on analytical building blocks that, mathematically, are truncated Taylor series with logarithms. These functions are usually resummed using Padé approximants obtained first assuming that the logarithms are constant, and then replacing them back into the resulting rational functions. A recent study [A. Nagar et al., Effective-one-body waveform model for non-circularized, planar, coalescing black hole binaries: The importance of radiation reaction, Phys. Rev. D 110, 084001 (2024)] pointed out that this procedure introduces spurious logarithmic terms when the resummed functions are reexpanded. We therefore explore analytically more consistent resummation schemes. Here we update the TEOBResumS-Dalí waveform model for spin-aligned, noncircularized coalescing black hole binaries by systematically implementing new (still Padé based) resummations for all EOB functions (that is, the metric potentials $A$, $D$ and the residual waveform amplitude corrections ${\rho }_{\ell m}$ up to $\ell =8$). Once the model is informed by 50 numerical relativity (NR) simulations (with the usual two flexibility parameters, one in the orbital and one in the spin sector), this new approach proves key in lowering the maximum effective-one-body (EOB)/numerical relativity (NR) unfaithfulness ${\overline{\mathcal{F}}}_{\mathrm{EOBNR}}^{\max }$ for the $\ell =m=2$ mode (with the Advanced LIGO noise in the total mass range $10–200M_{\odot }$) over 530 spin-aligned waveforms of the Simulating eXtreme Spacetimes catalog. A median unfaithfulness equal to $3.09\times {10}^{-4}$ is achieved, which is a marked improvement over the previous value, $1.06\times {10}^{-3}$. The largest value, $\mathrm{Max}[{\overline{\mathcal{F}}}_{\mathrm{EOBNR}}^{\max }]=6.80\times {10}^{-3}$, is found for an equal-mass, equal-spin simulation with dimensionless spins $\sim +0.998$; only five configurations have ${\overline{\mathcal{F}}}_{\mathrm{EOBNR}}^{\max }>5\times {10}^{-3}$ (four of which equal mass and with equal spins larger than $\sim +0.98$). Results for eccentric binaries are similarly excellent (well below ${10}^{-2}$ and mostly around ${10}^{-3}$). For scattering configurations, we find an unprecedented EOB/NR agreement ($\lesssim 1\%$) for relatively small values of the scattering angle, though differences progressively increase as the threshold of immediate capture is approached. Our results thus prove that an improved treatment of (apparently) minor analytical details is crucial to obtain highly accurate waveform models for next generation detectors.

This study explores the influence of the Kalb-Ramond (KR) field, characterized by Lorentz-violating effects, on the structure, thermodynamics, and observational phenomena of Reissner-Nordström-like black holes. By introducing a modified Einstein-Hilbert action incorporating the KR field’s nonminimal coupling with the īRicci tensor, we derive a spherically symmetric black hole solution. The Lorentz-violating parameter $L$ alters the black hole’s horizon structure, curvature invariants, and thermodynamic properties, such as Hawking temperature and entropy, with exponential quantum corrections offering deeper insights into high-energy phenomena. Photon dynamics in both vacuum and plasma environments reveal refractive effects due to the KR field, with weak gravitational lensing analyzed using the Gauss-Bonnet theorem and perturbative methods, including higher-order deflection corrections. Observational signatures like modified photon spheres, lensing angles, and shadows are discussed, providing potential avenues for experimental validation.

Recent developments in post-Minkowskian (PM) calculations have led to a fast-growing body of weak-field perturbative information. As such, there is major interest within the gravitational wave community as to how this information can be used to improve the accuracy of theoretical waveform models. In this work, we build on recent efforts to validate high-order PM calculations using numerical relativity simulations. We present a new set of high-energy scattering simulations for equal-mass, nonspinning binary black holes, further expanding the existing suite of numerical relativity (NR) simulations. We outline the basic features of three recently proposed resummation schemes (the $\mathcal{L}$-resummed model, the $w^{\mathrm{eob}}$ model and the SEOB-PM model) and compare the analytical predictions to our NR data. All of the models struggle to accurately capture the behavior at high energies, with common features including PM hierarchical shifts and divergences. The NR data are used to calibrate pseudo-5PM corrections to the scattering angle and to inform the effective one-body radial potentials. In each case, we argue that including higher-order information improves the agreement between the analytical models and NR, though the extent of improvement depends on how this information is incorporated and the choice of analytical baseline. Finally, we demonstrate that further resummation of the effective one-body radial potentials could be an effective strategy to improving the model agreement.

We present a classical theory of gravity, which is singularity-free at short distances and reduces to general relativity at large distances. We discuss its implications.

Exact solutions describing multiple, electrically charged black holes (BHs) in a model of nonlinear electrodynamics (NLE) minimally coupled to Einstein’s gravity are presented. The NLE model is ModMax theory, that has attracted much attention due to its duality and conformal invariance, features shared with standard (linear) electrodynamics. In the nonextremal case, the solution has conical singularities, similarly to the multi Reissner-Nordström solution in Einstein-Maxwell theory. In the extremal case the solution is regular on and outside the event horizon; it is isometric to the Majumdar-Papapetrou solution, although the individual BHs have a nonunitary charge to mass ratio, due to screening effects. Using the ModMax electromagnetic duality invariance, magnetically charged and dyonic generalizations are also obtained. Finally, we construct multi-BH solutions with a positive cosmological constant.

Standard quantum theory admits naturally statistical ensembles that are both preselected and postselected, i.e., they involve both an initial and a final state. We argue that there is no compelling physical reason to preclude a probability assignment with a final quantum state at the cosmological level. We therefore analyze the implications of a final state in the probability assignment for quantum cosmology. To this end, we derive effective classical equations of motion for systems subject to both initial and final conditions. Remarkably, these effective equations do not depend on the details of the quantum theory, but only on the geometric features of the classical state space. When applied to Friedman-Robertson-Walker cosmological models, these effective equations generically describe cosmic acceleration in the absence of a cosmological constant, dark energy, or modified gravitational dynamics. Therefore, cosmic acceleration emerges as a quantum postselection effect, that is, a macroscopic quantum phenomenon.

We consider the linear response of a near-equilibrium charged relativistic gas in the presence of electromagnetic and gravitational field in a generic stationary spacetime up to the second order of relaxation time and calculate the tensorial kinetic coefficients introduced by the presence of the strong electromagnetic and/or gravitational field. Using the covariant transfer equations thus developed, a covariant heat equation governing the relativistic heat conduction is derived, which, in Minkowski spacetime, reduces into a form which is remarkably similar to the well-known Cattaneo equation but with a different sign in front of the second-order time derivative term. We also perform a comparative analysis on the different behaviors of our heat equation and the Cattaneo equation in Minkowski spacetime. Furthermore, the effect of gravity on the heat conduction predicted by our heat equation is illustrated around Schwarzschild black hole, which makes a sharp contrast to the Minkowski case.

We present various post-Newtonian (PN) models for the phase evolution of compact objects moving along quasispherical orbits in Kerr spacetime. The models are derived by using the 12PN analytic formulas of the energy, angular momentum and their averaged rates of change calculated in the framework of the black hole perturbation theory. To examine the convergence of time-domain PN models (TaylorT families), we evaluate the dephasing between approximants with different PN orders. We found that the TaylorT1 model shows the best performance and the performance of the TaylorT2 model is the next best. To evaluate the convergence of frequency-domain PN models (TaylorF families), we evaluate the mismatch between approximants with different orders. We found that the performance of the TaylorF2 model is comparable with the TaylorT2 model. Although the TaylorT2 and TaylorF2 models are not so accurate as the TaylorT1 model, the fully analytical expressions give us easy-to-handle templates and are useful to discuss effects beyond general relativity.