We investigate rare special dileptonic decays of ${\mathrm{\Lambda }}_b$, ${\mathrm{\Sigma }}_b$, and ${\mathrm{\Xi }}_b$ baryons in the standard model and context of the general two-Higgs-doublet model with Type III. Specifically, we consider the decays ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }{\ell }^{+}{\ell }^{-}$, ${\mathrm{\Sigma }}_b\to \mathrm{\Sigma }{\ell }^{+}{\ell }^{-}$, and ${\mathrm{\Xi }}_b\to \mathrm{\Xi }{\ell }^{+}{\ell }^{-}$, where $\ell$ represents $\mu$ or $\tau$ lepton. By studying these rare decays, we aim to assess the impact of the two-Higgs-doublet model with Type III on various observables, such as the differential decay width, the total decay width, the differential branching ratio, the total branching ratio, and lepton forward-backward asymmetries using the decay amplitude and the transition matrix elements in terms of form factors calculated via light cone QCD in full theory. We compare our results to those of the standard model, as well as existing lattice QCD predictions and experimental data, to assess the agreement and viability of the two-Higgs-doublet model with Type III. Furthermore, we highlight the potential for experimental investigations of these decay channels in the near future. The soon-to-be updated LHCb and/or Belle II detectors, renowned for their capabilities in studying rare decays, present excellent opportunities for probing the predicted branching ratios.

The low-lying orbital excitations of ${\mathrm{\Xi }}_c^{(\prime )}$ baryons are studied within the chiral quark model combined with the ${}^3{P}_0$ decay mechanism. Motivated by the LHCb observation that ${\mathrm{\Xi }}_c(3055)$ is a $\lambda$-mode $1D$ state with $J^P=3/2^{+}$, we take it as a reference to constrain model parameters and perform a systematic analysis of states below 3.1 GeV. Our results provide a consistent interpretation of the observed ${\mathrm{\Xi }}_c$ spectrum: ${\mathrm{\Xi }}_c(2790)$ and ${\mathrm{\Xi }}_c(2815)$ are well described as a $\lambda$-mode $1P$ doublet, the structures around 2.9 GeV can be interpreted as $P$-wave excitations with mixed $\lambda /\rho$ modes, and ${\mathrm{\Xi }}_c(2970)$ is consistent with a $2S$ assignment. Furthermore, ${\mathrm{\Xi }}_c(3055)$ together with ${\mathrm{\Xi }}_c(3080)$ forms a $\lambda$-mode $D$-wave doublet, while ${\mathrm{\Xi }}_c(3123)$ favors a $1D$ assignment. These results provide a coherent picture of the low-lying ${\mathrm{\Xi }}_c$ spectrum and call for further experimental tests.

We compute the spectrum of gluons emitted by a highly energetic quark inside a flowing QCD medium, focusing on the soft gluon limit at first order in the opacity expansion. Specifically, we derive the leading energy-suppressed corrections to the double differential final parton distribution, and show that they are substantial for both static and flowing matter. In particular, we demonstrate that the corrections due to the transverse flow become large even at moderate energies and flow velocities, affecting drastically both the shape and magnitude of the spectrum. We observe that the final transverse momentum of the emitted gluon tends to align along the flow direction, resulting in a nontrivial azimuthal distribution. These results can be directly implemented into the estimation of multiple observables to get a better understanding of the jet-medium interaction processes in heavy-ion collisions.

In this work, we investigate the phenomenological implications of ultralight scalar dark matter (ULDM) coupled to neutrinos. We focus on a large homogeneous liquid scintillator detector, analyzing the regime where ULDM oscillations lead to time-averaged distortions in neutrino oscillation probabilities. We derive sensitivity limits on the modulation parameters ${\eta }_{{\mathrm{\Delta }}_{21}}$ and ${\eta }_{{\mathrm{\Delta }}_{31}}$, which quantify a ULDM-induced smearing effect in oscillations driven by solar ($\mathrm{\Delta }{m}_{21}^2$) and atmospheric ($\mathrm{\Delta }{m}_{31}^2$) mass-squared differences. We further demonstrate that ULDM interactions could produce a mild impact on both the determinations of the neutrino oscillation parameters and the neutrino mass-ordering sensitivity. These results showcase the benefits of a large liquid scintillator detector as a powerful probe of neutrino-ULDM interactions via neutrino oscillations.

This paper illustrates a generic method for multidimensional reweighting of $\mathcal{O}(1)\mathrm{GeV}$ neutrino interaction Monte Carlo samples. The reweighting is based on a boosted decision tree algorithm trained on high-dimensional space in detector final-state observables. This enables one generator’s events to be reweighted so that its reconstructed particle content and kinematics distributions, as well as detector efficiency, match those of a target model. The approach establishes an efficient way to reuse legacy Monte Carlo data, avoiding regeneration. As an example, we test its use in a measurement of transverse kinematic imbalance of the ${\mu }^{-}$ and proton in charged-current quasielastic like ${\nu }_{\mu }$ events from the MINERvA experiment.

In this Letter, we develop a numerically efficient framework for evaluating parameters in metric theories of gravity, and apply it to constrain the horizon-scale magnetic field in the Kerr-Bertotti-Robinson spacetime using the latest Event Horizon Telescope observations. The method’s adaptive ray-tracing strategy achieves near-linear computational efficiency without loss of numerical accuracy. This efficiency allows for high-precision black hole shadow modeling at a minimal computational cost and, for the first time, supports statistically robust parameter inference for arbitrary stationary black holes from horizon-scale observations. Applying the framework to the exact magnetized and rotating Kerr-Bertotti-Robinson solution [Phys. Rev. Lett. 135, 181401 (2025)], we evaluate the horizon-scale magnetic fields of M87* and Sgr A*. The analysis yields a field strength of ${93.3}_{-23.8}^{+14.7}\mathrm{G}$ for Sgr A*, consistent with the 71 G equipartition estimate from polarized Atacama Large Millimeter/submillimeter Array observations, thereby supporting the predictions of Einstein’s gravity.

We present a new constraint on the effective number of relativistic species in the early universe, $N_{\mathrm{eff}}$, by combining recent primordial helium abundance measurements from the Large Binocular Telescope $Y_p$ Project with primordial deuterium abundance data, CMB observations from Planck, the Atacama Cosmology Telescope, and the South Pole Telescope, and baryon acoustic oscillation (BAO) data from the Dark Energy Spectroscopic Instrument, yielding $N_{\mathrm{eff}}=2.990\pm 0.070$ (68% CL). This is the tightest constraint on $N_{\mathrm{eff}}$ to date, and is in excellent agreement with the standard model prediction of $N_{\mathrm{eff}}=3.044$. Furthermore, we constrain excess contributions to $N_{\mathrm{eff}}$ beyond the three neutrino species, finding $\mathrm{\Delta }{N}_{\mathrm{eff}}<0.107$ (95% CL). This bound nearly approaches the minimum contribution to $\mathrm{\Delta }{N}_{\mathrm{eff}}$ from a light spin-$3/2$ particle that decoupled at any time after inflation ended. Our baseline analysis does not include large-scale Planck polarization information, enabling a fully consistent combination of state-of-the-art CMB and BAO measurements. As a byproduct, we show that current $N_{\mathrm{eff}}$ bounds are essentially insensitive to the inclusion or exclusion of optical depth constraints inferred from large-scale CMB polarization data, making $N_{\mathrm{eff}}$ highly robust in this regard. Our constraints place stringent limits on light particles in the early Universe and on a broad range of models aimed at increasing the CMB-inferred value of the Hubble constant.

Sterile neutrinos are compelling dark matter (DM) candidates, yet the minimal production mechanism solely based on active-sterile (${\nu }_a-{\nu }_s$) oscillations is robustly excluded by astrophysical observations. Nonstandard self-interactions in either the active (${\nu }_a-{\nu }_a$) or sterile (${\nu }_s-{\nu }_s$) sector are known to alter the sterile neutrino DM production in the early Universe, which could alleviate the tension with astrophysical constraints. Here, we propose a new solution where scalar-mediated nonstandard interactions between active and sterile neutrinos (${\nu }_a-{\nu }_s$) lead to new production channels for sterile neutrino DM, independent of the active-sterile mixing and without the need for any fine-tuned resonance or primordial lepton asymmetries. This framework enables efficient sterile neutrino DM production even at vanishingly small mixing angles and opens up new viable regions of parameter space that can be tested with future x-ray and gamma-ray observations. It also provides a new mechanism for observable neutrino-DM interactions while being consistent with DM relic density and has broad phenomenological implications for astrophysical neutrinos and beyond.

The memory effect is known to introduce a permanent displacement in the gravitational wave (GW) detectors after the passage of a GW signal. While the linear memory adheres to the source properties, the nonlinear memory is a secondary effect sourced by the GW itself. In the present work, we discuss GW signals with both these kinds of memory effects, while focusing on the parabolic limit of an encounter. This special case is theoretically intriguing and emerges as a limiting situation for both eccentric and hyperbolic events. However, in this paper, we argue that a simple extrapolation of memory calculations for eccentric or hyperbolic cases to the parabolic case may lead to incorrect estimations. Therefore, we treat the parabola as a special case and use an intrinsic parametrization, with which we calculate gravitational wave signals and their energy spectrum via an effective field theory formalism. Unlike the hyperbolic case, which is known to have linear memory, we notice that parabolic encounters bring out new features in the zero frequency limit. The exactly parabolic case is studied here primarily as an idealized separatrix between bound and unbound motion, and our analysis highlights some of the key challenges and salient aspects of GW memory in this regime.

We introduce a new type of generating theorems in general relativity for anisotropic, static, spherically symmetric solutions of the Einstein field equations. The results are used to derive a class of solutions that can serve as new models for the interiors of compact stars. Their geometric and thermodynamic properties are studied in detail, and we show that some of the new spacetimes contain, as particular cases, other well-known solutions. Focusing on a constant-density solution, we assess the relevance of the newly found geometry as a candidate for the incompressible limit of anisotropic compact stellar objects, comparing its features with those of the Bowers-Liang spacetime.

We study hierarchical triple systems formed by a compact binary orbiting a supermassive black hole (SMBH), focusing on the role of relativistic magnetic tidal interactions. Extending previous analyses of precession resonances to 0.5 post-Newtonian order, we incorporate quadrupolar magnetic tidal moments, which have no Newtonian counterpart. We find that magnetic tides introduce new resonances absent at lower order, leading to additional eccentricity excitations and significantly modifying the binary’s long-term evolution. Numerical solutions of the Lagrange planetary equations confirm these analytical predictions and reveal how resonance strength depends on orbital eccentricity and inclination. The resulting dynamics accelerates the binary merger and imprints distinctive signatures on gravitational waves, potentially observable by LISA. Our findings identify magnetic tidal coupling as a novel strong-gravity effect and establish its importance for the resonant dynamics of compact-object binaries near SMBHs.

Physical aspects of a static solution to the Einstein equations with two black holes of equal mass are studied via ray tracing. The exact solution for this double Schwarzschild solution is known in explicit form. The black holes are separated by a singularity called Weyl strut. The effect of this strut on null geodesics is shown to be defocusing, in contrast to the focusing effect of the black holes. It is shown that black holes with a large separation essentially lead to similar behavior of the null geodesics as a single black hole, whereas nearby holes display widely changed behavior due to the Weyl strut.

We present thermal Sunyaev-Zel’dovich (tSZ) Compton-$y$ parameter maps constructed from two years (2019–2020) of observations with the South Pole Telescope (SPT) third-generation camera, SPT-3G, combined with data from the Planck satellite. Using a linear combination pipeline, we obtain a suite of reconstructions that explore different trade-offs between statistical sensitivity and suppression of astrophysical contaminants, including minimum-variance, CMB-deprojected, and cosmic infrared background (CIB)-deprojected $y$ maps. We validate these maps through different statistical techniques such as auto- and cross-power spectra with large-scale structure tracers as well as stacking on cluster locations. These tests are used to understand the balance between noise and astrophysical foreground residuals (such as the CIB) in combination with the recovery of the tSZ signal for different maps. For example, results from stacking at the location of clusters confirm the robustness of the recovered tSZ signal over the $\sim 1500{\mathrm{deg}}^2$ SPT-3G survey field used in this analysis. The high-resolution and low-noise maps produced here provide an important cosmological tool for future studies, including measurements of the Compton-$y$ map power spectrum, cross-correlations with other tracers of the large-scale structure, detailed modeling of cluster pressure profiles, and study of the thermodynamic state of the baryons in the Universe.

Numerical relativity (NR), solving Einstein equations numerically, plays an important role in source modeling for gravitational wave astronomy. Traditional methods for NR including the finite difference method, spectral method, and finite element method have been well developed. But newly developed neural network methods for partial differential equations (PDE) have not been well studied yet for NR. We present a physics-informed neural network (PINN) method to solve the Hamiltonian constraint equation for binary black hole (BBH) initial data in NR. This equation is a highly nonlinear elliptic PDE, posing significant challenges for conventional PINN approaches. To overcome these difficulties, we introduce a set of new techniques. We show that our PINN together with these techniques can successfully solve the Hamiltonian constraint equation for generic BBH systems. Validation against the traditional results demonstrates the high accuracy and robustness of our method, revealing the immense potential of constructing a PINN-based initial data solution to all BBH systems for NR.

The spatiotemporal content of a black hole movie is set jointly by source variability and by the distribution of light-travel times across the image. In the slow-light prescription, an image evaluated at fixed observer time contains photons emitted at different source times, whereas in fast light all rays sample a single source emission time. In this work we compare these light-propagation prescriptions through the lensing-band structure of Kerr geodesic delays in a controlled semianalytic setting. For a given emitting geometry, black hole spin, and observer inclination, we show how the coordinate-time delay distributions of Kerr null geodesics, decomposed by image order across lensing bands, can be compared with the source correlation time to quantify differences between light-propagation prescriptions. We find that when the intrinsic variability timescale is comparable to, or shorter than, the relevant delay spread, the high-inclination mismatch between fast- and slow-light curves can reach several tens of percent. Motivated by this geometric structure, we introduce brisk light, an intermediate prescription that compresses each lensing-band delay map to its dominant temporal interval rather than collapsing the full image to a single source time. The proposed methodology provides both a practical criterion for when slow light matters and an efficient route to black hole movies that retain the leading temporal imprint of strong lensing, a regime of direct relevance for future space-based very-long-baseline interferometry targeting photon-ring observables.

We reconsider the classical 1 bit absorption model of black hole (BH) growth as a discrete recursion rather than a continuum equation. Here “1 bit” denotes one elementary absorption unit in natural logarithmic units. For a Schwarzschild-Tangherlini BH, the discrete treatment yields the expected area scaling together with a logarithmic correction whose coefficient is fixed by the dimensional dependence of the mass step. We then extend the construction to the Reissner-Nordström case at fixed charge and show that the logarithmic coefficient acquires an explicit charge dependence. The fixed charge sector can be read as the asymptotic neutral growth stage after a charged seed has already been formed, so realistic charged absorption affects the initial cutoff rather than the large-mass recursion for weakly charged final states. Ordered charged, oppositely charged, and neutral labels define a formal history ensemble. In a unitary description, two different histories may lead to the same reduced macroscopic state $(M,Q,S)$ while remaining different in hidden or environmental degrees of freedom. Adding a mass or energy label reduces the end point degeneracy, but it does not remove it in the ensembles studied here. The corrected interpretation separates dynamical entropy, state entropy, history entropy, and hidden conditional entropy. It also clarifies that the multinomial formula is a restricted history-counting result rather than a proof of unique or identical microscopic BH states.

Current multiton detectors put stringent constraints on the GeV-scale galactic dark matter, pushing the allowed cross section almost toward the neutrino fog, yet remain mostly insensitive to the light dark matter. Cosmic rays can upscatter the nonrelativistic halo dark matter particles, making a subpopulation of them gain sufficient kinetic energy to be discernible in current direct search experiments. In this work, we explore this alternate strategy to probe sub-MeV electrophilic dark matter boosted by cosmic rays with the latest data of LZ 2025 (WS2024 run). We also incorporate the attenuation effect on the boosted dark matter flux during its propagation through the Earth and perform a full numerical treatment to obtain the resulting event rate. Our result shows LZ 2025 data improve the constraint on the MeV scale dark matter by almost $\sim \mathcal{O}(1)$ compared to the previous XENONnT limit for the energy-independent cross section. Using realistic energy-dependent cross sections, we also analyze such a scenario, where the associated mediator mass plays a crucial role in governing the event rate and hence the expected limits too. With energy-dependent cross sections, our obtained limits also remain stronger than the existing constraints from the XENONnT experiment. Even compared to the limits from neutrino detectors with much larger target masses, LZ 2025 can place stringent constraints in certain regions of the mediator parameter space, particularly in the light-mediator regime, excluding previously unexplored regions.

We explore Cherenkov radiation in anisotropic chiral matter within the framework of Carroll-Field-Jackiw electrodynamics, where the axion angle exhibits a linear dependence on position. By deriving closed-form expressions for the polarization modes of electromagnetic fields in cylindrical coordinates and the space-frequency domain, we solve the modified Maxwell’s equations. To enforce causality, we impose outgoing wave boundary conditions at a cylindrical surface at infinity, which yields the dispersion relations. Our analysis uncovers the specific angles and frequency ranges that allow for zero, one, or two Cherenkov cones. We also obtain the spectral energy distribution of the radiation in all cases. Notably, one sector of the model exhibits a novel phenomenon: Cherenkov radiation can be generated by slowly moving charges without a threshold, but only within a specific frequency range. This behavior is not observed in standard materials. Using our exact calculations, we also investigate the reliability of an approximate method previously proposed based on the calculation of the Green’s function for the system.

We discuss charm associated production of the pseudoscalar Higgs boson $h^{\prime \prime }$ in the Maximally CP symmetric Model’ (MCPM’). In our analysis we assume $m_{h^{\prime \prime }}=95.4\mathrm{GeV}$, which corresponds to an enhancement observed by the CMS collaboration in the $\gamma \gamma$ channel. As discussed recently, the MCPM’ is consistent with the CMS enhancement. In this model the $h^{\prime \prime }$ Higgs boson of this mass decays dominantly into $c\overline{c}$ jets. The cross section for the associated $h^{\prime \prime }$ production in $pp\to h^{\prime \prime }c\overline{c}$ is found to be almost as big as that for the Drell-Yan (DY) $c\overline{c}\to h^{\prime \prime }$ production, much larger than that for two-gluon fusion $gg\to h^{\prime \prime }$. Since in the MCPM’ the dominant $h^{\prime \prime }$ decay is into the $c\overline{c}$ channel we have to deal with the $pp\to c\overline{c}c\overline{c}$ process with $c$ and $\overline{c}$ jets. In addition to the signal processes, we have sizeable single parton scattering (SPS) and double parton scattering (DPS) nonresonant background. In our analysis we include diagrams of gluon-gluon fusion $gg\to h^{\prime \prime }$ which lead to the $c\overline{c}c\overline{c}$ final state. We discuss also the possible role of the reaction $pp\to h^{\prime \prime }{h}^{\prime \prime }$. Assuming 100% c and $\overline{c}$ jet tagging we discuss in detail how to improve the signal-to-background ratio. Our analysis shows promising resonance-like enhancements and relatively large cross sections in the $c\overline{c}c\overline{c}$ channel within the MCPM’. In an Appendix we discuss the total cross section for $h^{\prime \prime }$ production at the LHC. We also compare distributions for the reactions $pp\to h^{\prime \prime }X$ and $pp\to ZX$ with $h^{\prime \prime }$ and $Z$ decaying to $c\overline{c}$ and ${\mu }^{+}{\mu }^{-}$. We hope that the LHC collaborations will in the future perform the experimental studies corresponding to the theoretical studies discussed here.

We investigate the phenomenology of a TeV-scale doubly charged scalar from the right-handed sector within the framework of left-right symmetric models. Focusing on its flavor-diagonal couplings to right-handed electrons and muons, we assess probes from both high-energy colliders and low-energy precision experiments. High-energy processes include Bhabha scattering at LEP and future circular electron-positron colliders, direct production at the LHC, and dedicated searches and precision measurements at proposed muon colliders and $\mu \mathrm{TRISTAN}$. Low-energy observables encompass parity-violating Møller scattering, muon anomalous magnetic moment, and muonium-antimuonium oscillations. Our combined analysis indicates that, for a doubly charged scalar in the 1–3 TeV range, the flavor-diagonal Yukawa couplings to electrons and muons as small as ${10}^{-2}$ are accessible. Observations of such a doubly charged scalar would potentially point toward the type-I seesaw mechanism of neutrino masses in the left-right symmetric model with $D$-parity breaking.