We critically reconsider the argument based on ’t Hooft anomaly matching that aims at proving chiral symmetry breaking in confining four-dimensional quantum chromodynamics-like theories with $N_c>2$ colors and $N_f$ flavors. The main line of reasoning relies on a property of the solutions of the anomaly matching and persistent mass equations called $N_f$-independence. In previous works, the validity of $N_f$-independence was assumed based on qualitative arguments, but it was never proven rigorously. We provide a detailed proof and clarify under which (dynamical) conditions it holds. Our results are valid for a generic spectrum of massless composite fermions including baryons and exotics.

Enhancements in the invariant mass distribution or scattering cross section are usually associated with resonances. However, the nature of exotic signals found near hadron-hadron thresholds remain a puzzle today due to the presence of experimental uncertainties. In fact, a purely kinematical triangle diagram is also capable of producing similar structures, but do not correspond to any unstable quantum state. In this paper, we report for the first time, that a deep neural network can be trained to distinguish triangle singularity from pole-based enhancements with a reasonably high accuracy of discrimination between the two seemingly identical line shapes. We also identify the type of triangle enhancement that can be misidentified as a dynamic pole structure. We apply our method to confirm that the $P_{\psi }^N(4312{)}^{+}$ state is not due to a triangle singularity, but is more consistent with a pole-based interpretation, as determined solely through pure line-shape analysis. Lastly, we explain how our method can be used as a model-selection framework useful in studying other exotic hadron candidates.

The leading Fock-state light-front wave functions of heavy quarkonia and $D$ and $B$ mesons are obtained from the projections of their Bethe-Salpeter wave functions on the light front. We compute their leading-twist time-reversal even transverse momentum distributions and parton distribution functions. Mirroring the behavior of parton distribution amplitudes, the support of both distributions is increasingly narrower and shifted toward larger $x$ as a function of the meson mass. The dependence of $x$ and ${\mathit{k}}_{\perp }^2$ of the transverse distributions does not factorize into separate functions, and their falloff with ${\mathit{k}}_{\perp }^2$ is much slower than that of light mesons.

We apply the 3D glasma simulation method using Milne coordinates, proposed in our previous work [H. Matsuda and X.-G. Huang, [Phys. Rev. D 108, 114008 (2023)] ], to the early stage of the Au-Au collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$. The nucleus model prior to the collisions, which offers the initial condition for the 3D glasma simulation, is constructed to account for the longitudinal structure of the nucleus, the finite thickness of nucleons, and their random positions along the collision axis. We investigate rapidity profiles for a wide range of physical quantities of the glasma, including energy, pressure, fluctuations of topological charge, eccentricity, and angular momentum. In particular, we elucidate the behavior of eccentricity and angular momentum, which are physical quantities dependent on the geometric shape of the glasma, across a wide range of impact parameter regions.

We investigate the exclusive rare semileptonic decays $B(B_c)\to K(D_{(s)})l\overline{l}/{\nu }_l\overline{{\nu }_l}$ ($l=\mu$, $\tau$) in the framework of relativistic independent quark model based on an average flavor independent confining potential in equally mixed scalar-vector harmonic form. The invariant weak form factors, parametrizing the matrix elements between participating meson states, are calculated in the parent meson rest frame. The momentum transfer dependence of the form factors is reliably determined in the whole accessible kinematical range $q_{\min }^2\le 0\le q_{\max }^2$. Our predicted branching fractions for $B\to K{\mu }^{+}{\mu }^{-}/{\tau }^{+}{\tau }^{-}({\nu }_l\overline{{\nu }_l})$, $B_c\to D(D_s){\mu }^{+}{\mu }^{-}$, $B_c\to D(D_s){\tau }^{+}{\tau }^{-}$, and $B_c\to D(D_s){\nu }_l\overline{{\nu }_l}$, obtained in order of ${10}^{-7}({10}^{-6})$, ${10}^{-9}({10}^{-7})$, ${10}^{-9}({10}^{-8})$, and ${10}^{-8}({10}^{-7})$, respectively, are in reasonable agreement with other Standard Model predictions and Lattice QCD results. The averaged values of the lepton polarization asymmetries for decay modes are obtained as $⟨P_L(B\to K{\mu }^{+}{\mu }^{-})⟩=-0.97$, $⟨P_L(B_c\to D_{(s)}{\mu }^{+}{\mu }^{-})⟩=-0.972$, $⟨P_L(B\to K{\tau }^{+}{\tau }^{-})⟩=-0.224$, $⟨P_L(B_c\to D{\tau }^{+}{\tau }^{-})⟩=-0.275$, and $⟨P_L(B_c\to D_s{\tau }^{+}{\tau }^{-})⟩=-0.194$.

This article shows that the approach to generalized curvature and torsion pioneered by Poláček and Siegel [Natural curvature for manifest T-duality, J. High Energy Phys. 01 (2014) 026.] is a generalization of Cartan geometry—rendering latter natural from the point of view of $\mathrm{O}(d,d)$-generalized geometry. We present this approach in the generalized metric formalism and show that almost all parts of the additional higher generalized tensors appearing in this approach correspond to covariant derivatives of the generalized Riemann tensor. As an application, we use this framework to phrase $\sigma$-model dynamics in an explicitly covariant way—both under generalized diffeomorphisms and local gauge transformations.

Recently, a class of Gauss-Bonnet extended Starobinsky gravity was proposed, allowing black holes to carry ghost-free massive scalar hair for the first time without requiring additional matter fields. This intriguing feature offers a new perspective for understanding higher-curvature pure gravity and highlights the importance of further studying the potential effects of Gauss-Bonnet extensions in gravitational systems beyond black holes. In this study, we investigate the properties of neutron stars within this model, focusing on how the higher-curvature terms, particularly the coupling between the Gauss-Bonnet term and the curvature-squared term, impact the stellar structure. We present a detailed analysis of these effects and compute the moment of inertia for rotating neutron stars under the slow-rotation approximation. The substantial differences in the moment of inertia between general relativity and Gauss-Bonnet extended Starobinsky gravity are expected to be detectable through future high-precision observations.

We carried out long-term monitoring of the LIGO/Virgo/KAGRA binary black hole (BBH) merger candidate S230922g in search of electromagnetic emission from the interaction of the merger remnant with an embedding active galactic nuclei (AGN) accretion disk. Using a dataset primarily composed of wide-field imaging from the Dark Energy Camera and supplemented by additional photometric and spectroscopic resources, we searched $\sim 70\%$ of the sky area probability for transient phenomena and discovered six counterpart candidates. One especially promising candidate—AT 2023aagj—exhibited temporally varying asymmetric components in spectral broad line regions, a feature potentially indicative of an off-center event such as a BBH merger. This represents the first live search and multiwavelength, photometric, and spectroscopic monitoring of a gravitational wave BBH optical counterpart candidate in the disk of an AGN.

We study neutrino flavor evolution in the quantum many-body approach using the full neutrino-neutrino Hamiltonian, including the usually neglected terms that mediate nonforward scattering processes. Working in the occupation number representation with plane waves as single-particle states, we explore the time evolution of simple initial states with up to $N=10$ neutrinos. We discuss the time evolution of the Loschmidt echo, one body flavor and kinetic observables, and the one-body entanglement entropy. For the small systems considered, we observe “thermalization” of both flavor and momentum degrees of freedom on comparable time scales, with results converging towards expectation values computed within a microcanonical ensemble. We also observe that the inclusion of nonforward processes generates a faster flavor evolution compared to the one induced by the truncated (forward) Hamiltonian.

Measuring gravitational interactions on $\mathrm{sub}\text{−}100\text{−}\mathrm{\mu }\mathrm{m}$ length scales offers a window into physics beyond the Standard Model. However, short-range gravity experiments are limited by the ability to position sufficiently massive objects to within small separation distances. Here we propose mass-loaded silicon nitride ribbons as a platform for testing the gravitational inverse square law at separations currently inaccessible with traditional torsion balances. These microscale torsion resonators benefit from low thermal noise due to strain-induced dissipation dilution while maintaining compact size ($<100\mathrm{\mu }\mathrm{g}$) to allow close approach. Considering an experiment combining a $40\mathrm{\mu }\mathrm{g}$ torsion resonator with a source mass of comparable size ($130\mathrm{\mu }\mathrm{g}$) at separations down to $25\mathrm{\mu }\mathrm{m}$, and including limits from thermomechanical noise and systematic uncertainty, we predict these devices can set novel constraints on Yukawa interactions within the $1–100\mathrm{\mu }\mathrm{m}$ range.

High energy collider neutrinos have been observed for the first time by the $\mathrm{FASER}\nu$ experiment. The detected spectrum of collider neutrinos scattering off nucleons can be used to probe neutrinophilic mediators with GeV-scale masses. We find that constraints on the pseudoscalar (axial vector) neutrinophilic mediator are close to the scalar (vector) case since they have similar cross section in the neutrino massless limit. We perform an analysis on the measured muon spectra at $\mathrm{FASER}\nu$, and find that the bounds on the vector mediator from the current $\mathrm{FASER}\nu$ data are comparable to the existing bounds at $m_{Z^{\prime }}\approx 0.2\mathrm{GeV}$. We also study the sensitivities to a neutrinophilic mediator at future Forward Physics Facilities including FLArE and $\mathrm{FASER}\nu 2$ by using both the missing transverse momentum and the charge identification information. We find that FLArE and $\mathrm{FASER}\nu 2$ can impose stronger bounds on both the scalar and vector neutrinophilic mediators than the existing bounds. The constraints on the scalar mediator can reach 0.08 (0.1) for $m_{\varphi }\lesssim 1\mathrm{GeV}$ with (without) muon charge identification at $\mathrm{FASER}\nu 2$.

We propose an explanation for the observed excesses around 95 GeV in the diphoton and ditau invariant mass distributions, as reported by the CMS collaboration at the Large Hadron Collider. These findings are complemented by a long-standing discrepancy in the $b\overline{b}$ invariant mass at the Large Electron-Positron Collider. Additionally, the ATLAS collaboration has reported a corroborative excess in the diphoton final state within the same mass range, albeit with slightly lower significance. Our approach involves the superposition of $CP$-even and $CP$-odd Higgs bosons within the type-III two-Higgs doublet model to simultaneously explain these excesses at $1\sigma$ confidence level, while remaining consistent with current theoretical and experimental constraints.

The hadroproduction of single isolated photon at high energies is studied within the framework of the next-to-leading order (${\mathrm{NLO}}^{\star }$) approximation of the parton Reggeization approach based on the modified multi-Regge limit of the hard scattering quantum chromodynamics (QCD) amplitudes. The contribution from the LO subprocess $Q\overline{Q}\to \gamma$ and the NLO tree-level corrections $QR\to \gamma q$ and $Q\overline{Q}\to \gamma g$ are considered. To avoid specific double counting in rapidity between tree-level corrections to the hard scattering coefficient and unintegrated PDFs, a corresponding subtraction scheme is proposed. We demonstrated self-consistency of the parton Reggeization approach using the subtraction scheme. The results of calculations are compared with data from various collaborations in the wide energy range $\sqrt{S}=24\mathrm{GeV}–13\mathrm{TeV}$. We obtained a quite satisfactory agreement with data up to $p_T^{\gamma }/\sqrt{S}\simeq 0.2–0.3$. Predictions for the future SPD NICA experiment were discussed.

We present a methodology to streamline implementation of massive-quark radiative contributions in calculations with a variable number of active partons in proton-proton collisions. The methodology introduces subtraction and residual heavy-quark parton distribution functions (PDFs) to implement calculations in the Aivazis–Collins–Olness–Tung (ACOT) factorization scheme and its simplified realization in various processes up to the next-to-the-next-to-leading order in the QCD coupling strength. Interpolation tables for bottom-quark subtraction and residual distributions for CT18 NLO and NNLO PDF ensembles are provided in the common LHAPDF6 format. A numerical calculation of $Z$-boson production with at least one $b$ jet at the Large Hadron Collider beyond the lowest order in QCD is considered for illustration purposes.

In this work, we conduct a three-coupled-channel analysis of the $Z_c(3900)$ structure, focusing on the $D{\overline{D}}^{*}$, $J/\psi \pi$, and $\rho {\eta }_c$ channels, based on the one-boson exchange model. Drawing from previous study on the exotic state $T_{cc}$, we only utilize one more parameter to construct the interactions between the channels. Our model successfully reproduces the experimental line shapes of the invariant mass distribution at $\sqrt{s}=4.23$ and 4.26 GeV for the three channels. Additionally, the finite-volume energy levels in our model show agreement with current lattice QCD conclusion. Detailed analysis suggests that the $Z_c(3900)$ peaks in the $\pi J/\psi$ and $\rho {\eta }_c$ distributions primarily arise from the triangle loop involving the $D_1\overline{D}{D}^{*}$ intermediate system. In the $D{\overline{D}}^{*}$ distribution, the threshold peak is generated by the cascade decay mechanism enhanced by a triangle diagram. Moreover, we find a virtual pole located far from the threshold, indicating that $Z_c(3900)$ peaks are not associated with a physical pole. We conclude that the $Z_c(3900)$ peaks are predominantly caused by the threshold cusp.

Color coherence effects play a crucial role in the description of jet evolution at collider experiments. It is well known that the stimulated gluon emission suffered by energetic jets traversing deconfined QCD matter is also affected by color coherence effects. Through multiple soft scatterings with the medium constituents, an antenna will lose its color correlation, causing its legs to behave as independent emitters after the so-called decoherence time. In this work, we provide the first computation of the properties of the recoils produced as a result of these soft scatterings between a color coherent dipole and the medium constituents. Our findings reveal that the angular phase-space of these soft recoils is strongly restricted by the opening angle of the dipole itself due to quantum interference effects. In this long wavelength limit, one can effectively consider that interactions take place with each of the legs of the dipole separately, provided that the angular constraints dictated by the corresponding color flow topologies are respected. This is in complete analogy with the case of soft gluon emission in vacuum, where the recoil quark plays the role of the emitted gluon. As a direct phenomenological application, we estimate the collisional energy loss rate of a color antenna. Importantly, these results indicate the way in which color coherence effects can be implemented in jet quenching models that account for the recoils from elastic scatterings, improving in this way our description of medium response physics in heavy-ion collisions.

We propose a new bottom up method to construct tree amplitudes of nonlinear sigma model (NLSM) and special Galileon theory (SG), based on assuming the universality of soft behaviors and the double copy structure. We extend the on-shell amplitudes to off-shell ones with two off-shell external legs, which allow the numbers of external legs to be odd. Then the 3-point and 4-point off-shell amplitudes can be bootstrapped, and the soft behaviors of 4-point NLSM and SG amplitudes can be derived from them. The universality of soft behaviors allows us to invert the resulted soft theorems to construct higher-point off-shell amplitudes recursively, and express them as expansions to tree amplitudes of biadjoint scalar theory. In our construction, the exact forms of universal soft behaviors are derived, rather than assumed. Back to the on-shell limit, amplitudes with odd numbers of external legs vanish automatically, and the enhanced Adler zero emerges. From the perspective without the aid of a Lagrangian, the enhanced Adler zero is understood as, the soft behavior vanishes faster than the degree expected from the naive power counting of soft momentum in our expansion formula. Interestingly, such “zero” have explicit formulas and can be interpreted naturally. For tree amplitudes of Born-Infeld and Dirac-Born-Infeld theories, our method of construction does not make sense, but the enhanced Adler zero can be studied similarly.

We derive areal inequalities for five types of attractive gravity probe surfaces, which were proposed by us in order to characterize the strength of gravity in different ways including weak gravity region, taking into account of contributions of electric and magnetic charges, angular momentum, gravitational waves, and matters. These inequalities are generalizations of the Riemannian Penrose inequality for minimal surfaces and lead to the concept of extremality for a given surface whose condition is given in terms of the gravitational mass and the electromagnetic charges. This means that the extremality is a characteristic property not only of black hole horizons or minimal surfaces but also of surfaces in weak gravity region. We also derive areal inequalities and extremality conditions for surfaces in asymptotically locally anti-de Sitter spacetimes.

The construction of local escape cones and their complementary cones, related to the locally nonrotating frames (LNRFs) orbiting superspinars with the external field described by the Kerr–de Sitter (KdS) naked singularity (NS) spacetimes, is described for all possible classes of the KdS NS spacetimes and all possible positions of the photon emitter. The notion of the local escape cones is then applied to construct the shadow of the KdS superspinars related to the distant static observers represented by the LNRFs located near the so-called static radius where the spacetime is close to the asymptotically flat region of the Kerr spacetimes. The shadow construction is focused on the KdS superspinars limited by the cosmological and astrophysical restrictions on the spacetime parameters, namely, the superspinar dimensionless spin and the dimensionless cosmological parameter relating the cosmological constant and the superspinar’s mass.