We study the nonperturbative properties of the nucleon’s chiral-odd generalized parton distributions (transversity GPDs) in the large-$N_c$ limit of QCD. This includes the parametric ordering of the spin-flavor components, the polynomiality property of the moments, and the sum rules connecting the GPDs with the tensor form factors. A multipole expansion in the transverse momentum transfer is used to enumerate and interpret the structures in the nucleon matrix element of the chiral-odd partonic operator, including monopole, dipole and quadrupole terms. The $1/N_c$ expansion of the GPDs is performed using the abstract mean-field picture of baryons in the large-$N_c$ limit and its symmetries. We derive a large-$N_c$ relation between the flavor-nonsinglet GPDs $E_T^{u-d}$ and ${\tilde{H}}_T^{u-d}$ and test it with recent lattice QCD results. We show that the polynomiality property and sum rules of the GPDs are fulfilled with the restricted realization of translational and rotational invariance in the mean-field picture. The results provide a basis for the phenomenological analysis of chiral-odd GPDs and hard exclusive processes in the large-$N_c$ limit, and for calculations in specific dynamical models.

Charged Higgs bosons produced either in top-quark decays or in association with a top quark, subsequently decaying via $H^{\pm }\to {\tau }^{\pm }{\nu }_{\tau }$, are searched for in $140{\mathrm{fb}}^{-1}$ of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$ recorded with the ATLAS detector. Depending on whether the top quark is produced together with the $H^{\pm }$ decays hadronically or semileptonically, the search targets $\tau +\text{jets}$ or $\tau +\mathrm{lepton}$ final states, in both cases with a $\tau$-lepton decaying into a neutrino and hadrons. No significant excess over the Standard Model background expectation is observed. For the mass range of $80\le m_{H^{\pm }}\le 3000\mathrm{GeV}$, upper limits at 95% confidence level are set on the production cross section of the charged Higgs boson times the branching fraction $\mathcal{B}(H^{\pm }\to {\tau }^{\pm }{\nu }_{\tau })$ in the range 4.5 pb–0.4 fb. In the mass range 80–160 GeV, assuming the Standard Model cross section for $t\overline{t}$ production, this corresponds to upper limits between 0.27% and 0.02% on $\mathcal{B}(t\to b{H}^{\pm })\times \mathcal{B}(H^{\pm }\to {\tau }^{\pm }{\nu }_{\tau })$.

In this paper we report the first scientific result based on antineutrinos emitted from the BR2 reactor at SCK CEN. The SoLid experiment uses a novel type of highly granular detector whose basic detection unit combines two scintillators, polyvinyl toluene (PVT) and ${}^6\mathrm{Li}\mathrm{F}:\mathrm{ZnS}(\mathrm{Ag})$, to measure antineutrinos via their inverse-$\beta$-decay products. An advantage of PVT is its highly linear response as a function of deposited particle energy. The full-scale detector comprises 12 800 voxels and operates over a very short 6.3–8.9 m baseline from the reactor core. The detector segmentation and its three-dimensional imaging capabilities facilitate the extraction of the positron energy from the rest of the visible energy, allowing the latter to be utilized for signal-background discrimination. We present a result obtained from 280 reactor-on days (55 MW mean power) and 172 reactor-off days, respectively, of live data taking. A total of $29479\pm 603$ (stat) antineutrino candidates have been selected, corresponding to an average rate of 105 events per day and a signal-to-background ratio of 0.27. A search for disappearance of antineutrinos to a sterile state has been conducted using complementary model-dependent frequentist and Bayesian fits, providing constraints on the allowed region of the reactor antineutrino anomaly.

Deep learning-based object detection algorithms enable the simultaneous classification and localization of any number of objects in image data. Many of these algorithms are capable of operating in real-time on high resolution images, attributing to their widespread usage across many fields. We present an end-to-end object detection pipeline designed for rare event searches for the Migdal effect, at real-time speeds, using high-resolution image data from the scientific CMOS camera readout of the MIGDAL experiment. The Migdal effect in nuclear scattering, critical for sub-GeV dark matter searches, has yet to be experimentally confirmed, making its detection a primary goal of the MIGDAL experiment. The Migdal effect forms a composite rare event signal topology consisting of an electronic and nuclear recoil sharing the same vertex. Crucially, both recoil species are commonly observed in isolation in the MIGDAL experiment, enabling us to train YOLOv8, a state-of-the-art object detection algorithm, on real data. Topologies indicative of the Migdal effect can then be identified in science data via pairs of neighboring or overlapping electron and nuclear recoils. Applying selections to real data that retain 99.7% signal acceptance in simulations, we demonstrate our pipeline to reduce a sample of 20 million recorded images to fewer than 1000 frames, thereby transforming a rare search into a much more manageable search. More broadly, we discuss the applicability of using object detection to enable data-driven machine learning training for other rare event search applications such as neutrinoless double beta decay searches and experiments imaging exotic nuclear decays.

We propose to introduce the intrinsic transversal momentum distribution functions (iTMDs), in conjunction with the light-cone distribution amplitudes, to elucidate the probability amplitude of encountering a meson state wherein the partons swiftly traverse along the longitudinal axis while gently oscillating in the transversal plane. The primary motivation stems from the oversight of soft transverse dynamics within the $k_T$ factorization formalism of an exclusive QCD process, which confines perturbative QCD (pQCD) predictions to scenarios involving large-momentum transfers. We meticulously investigate the $\pi$ and $K$ electromagnetic form factors using the iTMD-improved pQCD calculation at next-to-leading order. By analyzing data in the timelike physical regions, we obtain the transversal size parameters ${\beta }_{\pi }^2=0.51\pm 0.04{\mathrm{GeV}}^{-2}$ and ${\beta }_K^2=0.30\pm 0.05{\mathrm{GeV}}^2$. We then extract the chiral mass of pions to be $m_0^{\pi }(1\mathrm{GeV})=1.84\pm 0.07\mathrm{GeV}$ and explain the precise measurements of kaon form factors in the perturbative timelike region. As a remarkable byproduct, we found that the incorporation of iTMDs improves the pQCD predictions for electromagnetic form factors, extending the applicable range to a few ${\mathrm{GeV}}^2$. This improvement allows for direct comparison with existing measurements and lattice QCD evaluations.

The so-called two-vertex model of loop quantum gravity has been analytically studied in the past within a $\mathrm{U}(N)$ symmetry-reduced sector leading to a cosmological interpretation. In this work we study the simplest nontrivial two-vertex model (with four edges, i.e., $N=4$), using the spinorial formalism and twisted geometries to isolate the degrees of freedom and derive a canonical parametrization. We identify eight geometric parameters describing the polyhedral configurations and four twist angles characterizing the system’s dynamics. Going beyond the U($N$) symmetry-reduced sector which can be interpreted as homogeneous and isotropic, we find three additional stable symmetry-reduced sectors: the privileged-direction sector, the bi-twist sector, and the inhomogeneous bi-twist sector. Each sector introduces degrees of anisotropy or inhomogeneity and expand the potential cosmological interpretations of the two-vertex model.

In this work, we investigate the particle creation rate in a dynamical (Vaidya) spacetime using Feynman’s path integral formalism within the framework of the effective action approach. We examine three distinct cases involving the following mass functions, each representing dynamical geometries: (i) $m(v,r)=\mu v$, (ii) $m(v,r)=\mu v+\nu r$, and (iii) $m(v,r)=\mu v-\frac{{\mu }^2{v}^2}{2r}$, where $\mu$ and $\nu$ are positive constants that satisfy all known energy conditions. We analyze particle production rates in the region of dynamical horizons, revealing an initial high rate followed by a rapid decline in all cases. Additionally, we explore the thermodynamic properties by calculating the surface gravity and corresponding Hayward-Kodama temperatures for each scenario. Graphical representations show the variation of surface gravity over time for the three cases, offering insights into the system’s thermodynamic evolution. Our research investigates the connection between background geometry and the particle creation process, placing it within the broader context of quantum field theory in curved spacetime. The nonstationary nature of Vaidya geometry is highlighted as a valuable framework for examining the dynamic aspects of particle creation. This in-depth analysis enhances our understanding of quantum processes in curved spacetime and may offer insights relevant to thermodynamics and studies of gravitational collapse.

As an extension of our previous work [H. Ovcharenko et al. Phys. Rev. D 111, 024038 (2025)], we study a complete family of type D black holes with Kerr-like rotation, Newman-Unti-Tamburino (NUT) twist, acceleration, electric and magnetic charges, and any value of the cosmological constant $\mathrm{\Lambda }$. We relate various metric forms of these spacetimes, namely those found by Plebański-Demiański, Griffiths-Podolský, and most recently Astorino. By explicit coordinate transformations and proper identification of the physical parameters we show that these representations are locally equivalent, and cover the entire class of type D solutions of the Einstein-Maxwell-$\mathrm{\Lambda }$ equations, such that the (non-null) electromagnetic field is aligned with both the (double-degenerate) principal null directions of the Weyl tensor. In particular, we concentrate on the subclass which describes accelerating NUT black holes without the Kerr-like rotation.

The motion of an extended, but still weakly gravitating body in general relativity can often be determined by a set of conserved quantities. Much like for geodesic motion, a sufficient number of conserved quantities allows the motion to be solved by quadrature. Under the gravitational self-force (relaxing the “weakly gravitating” assumption), the motion can then be described in terms of the evolution these “conserved quantities.” This evolution can be calculated using the (local) self-force on the body, but such an approach is computationally intensive. To avoid this, one often uses flux-balance laws: relationships between the average evolution (capturing the dissipative dynamics) and the values of the field far away from the body, which are far easier to compute. In the absence of spin, such a flux-balance law has been proven in Isoyama et al. [“Flux-balance formulae” for extreme mass-ratio inspirals, Prog. Theor. Exp. Phys. 2019, 013E01 (2019).] for any of the conserved action variables appearing in a Hamiltonian formulation of geodesic motion in the Kerr spacetime. In this paper, we derive a corresponding flux-balance law, to linear order in spin, directly relating average rates of change to the flux of a conserved current through the horizon and out to infinity. In the absence of spin, this reproduces results consistent with those in Isoyama et al. [“Flux-balance formulae” for extreme mass-ratio inspirals, Prog. Theor. Exp. Phys. 2019, 013E01 (2019).]. To linear order in spin, we construct flux-balance laws for four of the five constants of motion for spinning bodies in the Kerr spacetime, although not in a practical form. However, this result provides a promising path toward deriving the flux-balance law for the (generalized) Carter constant.

We discuss boson stars and black holes with scalar hair in a model where the complex scalar field forming the boson star and the hair on the black hole, respectively, interacts with a real scalar field via a Hénon-Heiles-type potential. We demonstrate that black holes and boson stars carrying only a real scalar field with cubic self-interaction are possible and that black holes with both real and complex scalar field branch off from these solutions for sufficiently large interaction between the two fields and/or sufficiently large horizon radius $r_h$. The latter possess lower mass for the same choice of coupling constants than the former, however seem to be thermodynamically preferred only for high enough temperature.

We estimate the global signal in the redshifted hyperfine structure line 21 cm of hydrogen atoms formed during the dark ages and cosmic dawn epochs. The evolution of the brightness temperature in this line was computed to study its dependence on the physical conditions in the intergalactic medium. We show that the profile of this line crucially depends on the temperature and ionization of baryonic matter, as well as the spectral energy distribution of radiation from the first sources. The cosmological models with self-annihilating and decaying dark matter with allowable parameters by current observational data were considered, as well as the modeling of first light, which is consistent with the observational data on reionization. The results show that the dark ages part of the profile is very sensitive to the parameters of self-annihilating and decaying dark matter particles, while the cosmic dawn part of the profile is very sensitive also to the spectral energy distribution of radiation from the first sources. It was concluded that only compatible observations of the redshifted 21-cm line in the decameter and meter wavelength range, formed during the dark ages and cosmic dawn, will make it possible to constrain the parameters of dark matter models and astrophysical models of the first sources based on the radio tomography of the young Universe.

The Page time marks the moment when the von Neumann entropy of the emitted Hawking radiation equals the Bekenstein-Hawking entropy of an evaporating black hole, which is assumed to quantify its degrees of freedom as seen from the outside. Beyond this point, from unitarity we would expect that the entropy of the radiation begins to decrease, ensuring that information is eventually recovered. In this work, we investigate the dependence of the Page time on black hole properties and the particle content of nature. Specifically, we analyze its sensitivity to the Standard Model (SM) and potential beyond-the-SM degrees of freedom, incorporating the effects of particle masses. We find that a Schwarzschild primordial black hole (PBH) with an initial mass of $\sim 6.23\times {10}^{14}\mathrm{g}$ would have a Page time equal to the age of the Universe, assuming the emission of SM particles only. We further explore the impact of a non-negligible PBH angular momentum, finding that light spin-2 particles are predominantly emitted before the Page time. Specifically, for initial angular momentum values exceeding $a_{\star }>0.5$, approximately 70% of the total graviton emission occurs prior to the Page time for PBHs with an initial mass $M_{\mathrm{BH}}\lesssim {10}^{10}\mathrm{g}$. Finally, we discuss the implications for PBH phenomenology, particularly regarding potential constraints from $\mathrm{\Delta }{N}_{\mathrm{eff}}$ measurements.

We study the $P$-wave bottom baryons of the $SU(3)$ flavor antitriplet and systematically calculate their strong decay properties, including their $D$-wave decays into ground-state bottom baryons with light pseudoscalar mesons and $S$-wave decays into ground-state bottom baryons with light vector mesons. Together with [W. H. Tan et al., Predicted ${\mathrm{\Xi }}_b(6087{)}^0$ and further predictions, Eur. Phys. J. C 84, 382 (2024)., H. M. Yang et al., Decay properties of $P$-wave bottom baryons within light-cone sum rules, Eur. Phys. J. C 80, 80 (2020)., H. M. Yang and H. X. Chen, $P$-wave bottom baryons of the $SU(3)$ flavor ${\mathbf{6}}_F$ Phys. Rev. D 101, 114013 (2020)., and X. Luo, H. M. Yang, and H. X. Chen, Radiative decays of $P$-wave bottom baryons from light-cone sum rules, arXiv:2407.04433.], a rather complete investigation has been performed to study their mass spectra and strong/radiative decay properties, through the methods of quantum chromodynamics (QCD) sum rules and light-cone sum rules within the framework of heavy quark effective theory. Among various possibilities, we identify four ${\mathrm{\Lambda }}_b$ and four ${\mathrm{\Xi }}_b$ baryons, with limited decay widths and so capable of being observed in experiments. Their masses, mass splittings within the same multiplets, and strong/radiative decay widths are summarized in Table II for future experimental searching.

Stringent constraints from the dark matter (DM) direct detection experiments can be naturally evaded for a pseudo-Nambu-Goldstone boson (pNGB) DM. We propose a realization of pNGB DM in the context of a left-right symmetric model, wherein the neutrinos are pseudo-Dirac in nature. The Dirac mass term for neutrinos arises from two-loop quantum corrections, whereas the Majorana mass terms are generated from Planck-induced corrections. This class of model also provides a parity solution to the strong $CP$ problem without the need for an axion. We show an interesting correlation between the lifetime of the DM and the mass-squared differences between active and sterile neutrinos while maintaining a solution to the strong $CP$ problem.

We study the complete parameter space of a bulk axion in flat and warped extra spacetime dimensions. We characterize in detail the regimes where no single KK mode is produced along the canonical QCD axion line, and instead, it is maximally deviated along with several other axions that constitute a multiple solution to the strong $CP$ problem. In both flat and Randall-Sundrum scenarios, and assuming that all Peccei-Quinn breaking comes from QCD, we find that these solutions are however subject to tight phenomenological constraints. In light of these results, we expect that only KK canonical patterns (with the zero-mode close to the standard QCD line) can emerge from a bulk axion in one or more extra spacetime dimensions. As a byproduct, we generalize the axions eigenvalue and eigenvector equations for an arbitrary number of spacetime dimensions and compactifications.

We examine the new physics sensitivity of the rare decay ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }\nu \overline{\nu }$, which can be accessible at future $Z$-pole machines like Future Circular Collider and Circular Electron Positron Collider. We find that the longitudinal polarization of ${\mathrm{\Lambda }}_b$ baryons produced in $Z$ decays introduces a novel observable, the forward-backward asymmetry $A_{\mathrm{FB}}^{\uparrow }$ in the angle between the outgoing $\mathrm{\Lambda }$ momentum and the ${\mathrm{\Lambda }}_b$ spin. We provide Standard Model predictions for the ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }\nu \overline{\nu }$ branching ratio and $A_{\mathrm{FB}}^{\uparrow }$, and show that future precision measurements of these observables are complementary and probe new physics scales comparable to other $b\to s\nu \overline{\nu }$ and $b\to s{\ell }^{+}{\ell }^{-}$ processes. We also show that the zero crossing of the forward-backward asymmetry offers a robust test of form factor calculations independent of new physics.

The Schwinger model with two massive fermions is a nontrivial theory for which no analytical solution is known. The strong coupling limit of the theory allows for different semiclassical approximations to extract properties of its low-lying spectrum. In particular, analytical results exist for the fermion condensate, the fermion mass dependence of the pseudoscalar meson mass or its decay constant. These approximations, nonetheless, are not able to quantitatively predict isospin breaking effects in the light spectrum, for example. In this paper we use lattice simulations to test various analytical predictions and study isospin breaking effects from nondegenerate quark masses. We also introduce a low-energy effective field theory based on a nonlinear $\sigma$ model with a dilaton field, which leads to the correct fermion mass dependence of the pion mass, the correct $\sigma$-to-$\pi$ mass ratio and a prediction of the isospin breaking effects, which we test numerically.

Quantum chromodynamics in two spacetime dimensions is investigated with the Functional Renormalization Group. We use a functional formulation with covariant gauge fixing and derive Renormalization Group flow equations for the gauge coupling, quark mass and an algebraically complete set of local fermion-fermion interaction vertices. The flow, based on a convenient Callan–Symanzik-type regularization, shows the expected behavior for a super-renormalizable theory in the ultraviolet regime and leads to a strongly coupled regime in the infrared. Through a detailed discussion of symmetry implications, and variations in the gauge group and flavor numbers, the analysis sets the stage for a more detailed investigation of the bound state spectrum in future work.

QCD calculations for collider physics make use of perturbative solutions of renormalization group equations. Ambiguities related to these solutions can contribute significantly to systematic uncertainties of theoretical predictions for physical observables. We propose a general method to estimate these systematic effects using techniques inspired by soft-gluon and transverse-momentum resummation approaches. We first discuss the cases of the evolution of strong coupling ${\alpha }_s$, collinear parton-distribution functions, and transverse-momentum-dependent distributions. We then study the implications for precision observables in hadron-collider processes, such as the deep-inelastic scattering structure functions and the transverse-momentum distribution of the lepton pair in Drell-Yan production.

Among three leptonic mixing angles, ${\theta }_{23}$, which characterizes the fractional contribution of two flavor eigenstates ${\nu }_{\mu }$ and ${\nu }_{\tau }$ to the third mass eigenstate ${\nu }_3$, is known to be the largest but least precisely measured. The work investigates the possible reach of ${\theta }_{23}$ precision with two forthcoming gigantic accelerator-based long-baseline neutrino experiments, namely, Hyper-Kamiokande (T2HK) and the Deep Underground Neutrino Experiment (DUNE), as well as a possible joint analyses of future neutrino facilities. Our simulation yields that each experiment will definitely establish the octant of ${\theta }_{23}$ for all values within a $1\sigma$ parameter interval, while considering the current limitation. However, if the actual value is $0.48\le {\sin }^2{\theta }_{23}\le 0.54$, it becomes challenging for these two experiments to reject the maximal (${\theta }_{23}=\pi /4$) hypothesis and conclude its octant. This octant-blind region can be further explored with the proposed facilities European Spallation Source Neutrino Super Beam and Neutrino Factory. The accurate determination of the mixing angle ${\theta }_{23}$, as well as the accuracy of ${\delta }_{CP}$, is crucial for examining a certain category of discrete non-Abelian leptonic flavor models. Specifically, if $CP$ is conserved in the leptonic sector, the combined analysis of T2HK and DUNE will rule out the majority of these models. However, if the $CP$ is maximally violated, a higher precision of ${\delta }_{CP}$ is necessary to test these flavor models.