We investigate hadronic molecular states with the quark contents $ccqq\overline{s}$, $bbqq\overline{s}$, and $bcqq\overline{s}$ ($q=u$, $d$) by employing the extended local hidden gauge approach. Considering that the $S$-wave meson-baryon interactions are dominated by vector meson exchange, the coupled channels scattering amplitudes are obtained by solving the Bethe-Salpeter equation in its on-shell form. We find that the poles appearing on the complex Riemann sheet are potential candidates for dynamically generated molecular pentaquark states. The results suggest the existence of a total of fourteen molecular states with quantum numbers $I(J^P)=0(1/2^{-})$, $0(3/2^{-})$, and $0(5/2^{-})$, which arise from the interactions of the $K^{(*)}{\mathrm{\Xi }}_{cc}^{(*)}$, $K^{(*)}{\mathrm{\Xi }}_{bb}^{(*)}$, $K^{(*)}{\mathrm{\Xi }}_{bc}^{(*)}$, and $K^{(*)}{\mathrm{\Xi }}_{bc}^{\prime }$ channels, respectively. Their binding energies are calculated to be about 0.1–33 MeV, and this range depends on the free parameter of the theory. Our research contributes to the spectroscopic studies of hadronic molecular pentaquark states.

A real scalar triplet with zero hypercharge offers a minimal nontrivial extension of the Standard Model (SM) with a charged Higgs and a possible dark matter or custodial symmetry breaking signature. The $Z_2$-odd inert triplet model (ITM) provides a dark matter, while the noninert Higgs triplet model (HTM) breaks the custodial symmetry, enabling rich collider signatures. Both these models also promise the viability of a first-order phase transition (FOPT). This article revisits both models under various theoretical and current experimental constraints, revealing a trade-off between DM and FOPT viability, and explores the resulting gravitational wave signals and collider prospects.

We apply the QCD sum rule method to systematically study excited light meson operators and calculate their decay constants. These operators are constructed by explicitly adding one covariant derivative to the quark-antiquark pair. In total, twelve such operators are constructed, among which ten are subjected to detailed numerical analyses. The considered quark contents include $\overline{q}q$, $\overline{q}s$, and $\overline{s}s$ ($q=u/d$), allowing the formation of various $SU(3)$ flavor nonets. For instance, our results support the interpretation that the $a_2(1320)$, $f_2(1270)$, $f_2^{\prime }(1525)$, and $K_2^{*}(1430)$ states constitute a flavor nonet with quantum numbers $J^{P(C)}=2^{+(+)}$. In addition, we predict several excited meson states, whose masses and decay constants are determined using the QCD sum rule method.

We are investigating the behavior of the fragmentation function of a gluon, denoted as $D_g(x,{\mu }^2)$, where $\mu$ represents the observable scale. This function is derived from the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations. Our objective is to evolve the fragmentation function of a gluon for heavy-quark-antiquark bound states with large transverse momentum using a Laplace transform technique. This method enables us to calculate numerical solutions for two and four quarkonium states based on the known initial fragmentation function of gluons. We examine both leading-order and higher-order approximations for the fragmentation function of a gluon, $[g\to T_{nQ}]$, by integrating the evolved fragmentation function of the gluon at the initial scale. In our computations, we utilize the initial scales for $T_g^{2c}$ from Braaten and Yuan [Phys. Rev. Lett. 71, 1673 (1993)] and for $T_g^{4c}$ and $T_g^{4b}$ from Celiberto et al. [Eur. Phys. J. C 84, 1071 (2024)] and Celiberto and Gatto [Phys. Rev. D 111, 034037 (2025)], respectively. Through comparing our predictions with existing literature results, we can accurately determine the evolution of the fragmentation function of a gluon at scale $\mu$.

QCD at nonzero isospin chemical potentials has phenomenological relevance for a series of physical systems and provides an ideal test ground for the modeling of dense, strongly interacting matter. The two-flavor quark-meson model is known to effectively describe the condensation of charged pions in QCD that occurs in this setting. In this paper, we derive a renormalization group invariant mean-field formulation of the model and demonstrate that the resulting phase diagram and equation of state are in quantitative agreement with data from lattice QCD simulations at small and intermediate isospin chemical potentials. In particular, the speed of sound from the model shows an excess over the conformal bound, as previously seen in lattice computations, in agreement with chiral perturbation theory. We then consider the speed of sound in the limit of large isospin chemical potentials and see that it approaches the conformal limit from above, in qualitative agreement with recent lattice results and in quantitative agreement with perturbation theory in the presence of a Bardeen-Cooper-Schrieffer gap. Finally, we consider the phase diagram in the approach to the chiral limit. We find that within the model, the chiral phase transition connects to the pion condensation phase boundary in the chiral limit and we discuss the implications for the properties of the chiral transition point.

We perform analysis of the near-threshold $J/\psi$ photoproduction data off the proton based on two theoretical approaches, generalized parton distribution (GPD) [Phys. Rev. D 109, 014014 (2024)] and holographic [Phys. Rev. D 106, 086004 (2022)], that represent the differential cross sections as powers of the skewness parameter with coefficients that depend only on the momentum transfer $t$. This allows us to separate kinematically the corresponding coefficient functions in much the same way as this is done for the electric and magnetic form factors using the Rosenbluth separation. We examine the independence of the extracted functions of the photon beam energy. These functions, under additional assumptions, are related to the proton’s gluon gravitational form factors (gGFFs). We compare the extracted functions with lattice calculations of the gGFFs in the region of $0.5<|t|<2{\mathrm{GeV}}^2$, where they overlap. Such analysis demonstrates the possibility of extracting some combinations of the gGFFs from the data at high $t$, complementary to the lattice calculations available in the low $t$ region. However, higher statistics are needed to more accurately check the predicted scaling behavior of the data and compare with the lattice results, thus testing and comparing the theoretical assumptions used in the GPD and holographic models.

By generalizing the construction of genuine multientropy ${\mathrm{GM}}^{(\mathtt{q})}$ for genuine multipartite entanglement proposed in the previous paper [Genuine multi-entropy and holography, Phys. Rev. D 112, 026011 (2025).], we give a prescription on how to construct ${\mathrm{GM}}^{(\mathtt{q})}$ systematically for any $\mathtt{q}$. The crucial point is that our construction naturally fits to the partition number $p(\mathtt{a})$ of integer $\mathtt{a}$. For general $\mathtt{q}$, ${\mathrm{GM}}^{(\mathtt{q})}$ contains $N(\mathtt{q})=p(\mathtt{q})-p(\mathtt{q}-1)-1$ number of free parameters. Furthermore, these give $N(\mathtt{q})+1$ number of new diagnostics for genuine $\mathtt{q}$-partite entanglement. Especially for $\mathtt{q}=4$ case, this reproduces not only the known diagnostics pointed out by Balasubramanian et al. [Multiboundary wormholes and holographic entanglement, Classical Quantum Gravity 31, 185015 (2014).], but also a new diagnostics for quadripartite entanglement. We also study these ${\mathrm{GM}}^{(\mathtt{q})}$ for $\mathtt{q}=4$, 5 in holography and show that these are of the order of $\mathcal{O}(1/G_N)$ both analytically and numerically. Our results give evidence that genuine multipartite entanglement is ubiquitous in holography. We discuss the connection to quantum error correction and the role of genuine multipartite entanglement in bulk reconstruction.

We study the essential renormalization group equation, in which inessential couplings are removed via field redefinitions, for Einstein gravity coupled to a massive scalar field in the presence of a cosmological constant. Our results indicate that perturbatively nonrenormalizable terms can be eliminated due to the cosmological term, in contrast to the case of perturbation around flat spacetime. We find a nontrivial fixed point for the Newton coupling and the cosmological term.

We study the response of an accelerated Unruh-DeWitt detector to a one-parameter family of “kappa Rindler” vacua, which generalize the standard Unruh effect. These states, parametrized by $\kappa$, continuously interpolate between the Rindler ($\kappa \to 0$) and Minkowski ($\kappa =1$) vacua. We find the detector registers a perfect thermal bath at a tunable temperature $T_{\kappa }=\kappa T_U$. This result establishes a framework for environments perceived as both “hotter” ($\kappa >1$) and “colder” ($\kappa <1$) than the standard Unruh temperature. We establish this thermality by demonstrating the Kubo-Martin-Schwinger condition for the Wightman function and by analyzing the associated particle creation process. Furthermore, we visualize the spacetime structure of the created field quanta, revealing an intuitive link between the $\kappa$-controlled symmetry of the modes and the perceived temperature. Our work provides a comprehensive framework for a modulated Unruh effect, bridging formal quantum field theory with clear visual intuition.

Symmetries are ubiquitous in modern physics. They not only allow for a more simplified description of physical systems but also, from a more fundamental perspective, can be seen as determining a theory itself. In the present paper, we propose a new definition of asymptotic symmetries that unifies and generalizes the usual notions of symmetry considered in asymptotically flat spacetimes and expanding universes with cosmological horizons. This is done by considering Bondi–Metzner–Sachs-like symmetries for “asymptotic (conformal) Killing horizons,” here defined as null hypersurfaces that are tangent to a vector field satisfying the (conformal) Killing equation in a limiting sense. The construction is theory agnostic and extremely general, for it makes no use of the Einstein equations and can be applied to a wide range of scenarios with different dimensions or hypersurface cross sections. While we reproduce the results by Dappiaggi, Moretti, and Pinamonti in the case of asymptotic Killing horizons, the conformal generalization does not yield only the Bondi–Metzner–Sachs group, but a larger group. The enlargement is due to the presence of “superdilations.” We speculate on many implications and possible continuations of this work, including the exploration of gravitational memory effects beyond general relativity, understanding antipodal matching conditions at spatial infinity in terms of bifurcate horizons, and the absence of superrotations in de Sitter spacetime and Killing horizons.

In this exploratory study, we demonstrate the capability of the numerical-relativity code bam to simulate fully relativistic black-hole binary-single and binary-binary encounters. While previous work has demonstrated the general capability of numerical-relativity frameworks to evolve spacetimes with $N$ black holes, detailed explorations of such encounters remain limited. We focus on scenarios involving initially nonspinning, equal-mass black holes that result in a variety of dynamical outcomes, including flybys, delayed or accelerated eccentric mergers, exchanges, and more complex interactions. Our results show that we can reliably simulate scattering experiments involving three and four black holes, which exhibit interesting dynamics and gravitational-wave signals. The dynamics of these systems show noticeable differences compared to analogous systems in post-Newtonian approximations up to 2.5 PN. A key result is that the gravitational waveforms exhibit remarkable features that could potentially make them distinguishable from regular binary mergers.

Given a spacetime $(ℳ,g_{ab})$ admitting a dynamical horizon segment $\mathscr{H}$, we show that there are stringent constraints on the Killing fields ${\xi }^a$ that $g_{ab}$ can admit in a neighborhood of $\mathscr{H}$: Generically, ${\xi }^a$ can only be a rotational Killing field which, furthermore, leaves each marginally trapped 2-sphere cross section $\mathcal{S}$ of $\mathscr{H}$ invariant. Finally, if ${\xi }^a$ happens to be hypersurface orthogonal near $\mathscr{H}$—as, for example, in a spacetime representing a head-on collision of nonspinning black holes—then, not only the angular momentum but also all spin multipoles vanish on every $\mathcal{S}$; the entire spin structure of these dynamical horizon segments (DHSs) is indistinguishable from that of spherically symmetric DHSs!.

We build the canonical ensemble of a hot self-gravitating matter thin shell in anti–de Sitter (AdS) space by finding its partition function through the Euclidean path integral approach with fixed temperature at the conformal boundary. We obtain the reduced action of the system by restricting the path integral to spherically symmetric metrics with given boundary conditions and with the Hamiltonian constraint satisfied. The stationary conditions, i.e., the mechanical equilibrium and the thermodynamic equilibrium, are obtained from minimizing the reduced action. Evaluating the perturbed reduced action at the stationary points yields the mechanical stability condition and the thermodynamic stability condition. The reduced action calculated at the stationary points gives the partition function in the zero-loop approximation, and from it, the thermodynamic properties of the system are acquired. Within thermodynamics alone, the only stability condition that one can establish is thermodynamic stability, which follows from the computation of the heat capacity. For given specific pressure and temperature equations of state for the shell, we obtain the solutions of the ensemble. There are four different thin shell solutions, one of them is fully stable, i.e., is stable mechanically and thermodynamically. For the equations of state given, we find a first order phase transition from the matter thermodynamic phase to the Hawking-Page black hole phase. Moreover, there is a maximum temperature above which the shell ceases to exist, presumably at these high temperatures the shell inevitably collapses to a black hole.

In spherical symmetry, gravitational collapse of dust may give rise to the so-called shell-crossing singularities, beyond which spacetime can be extended using weak solutions to the integrated version of the equations of motion. We argue that the paradigm of weak solutions is ill suited for dynamical extension beyond shell crossings through shock waves, because it is based implicitly on the assumption that the Painlevé-Gullstrand time remains continuous across the shock, and leads to the unwanted prospect of shock waves of dust particles moving faster than light.

Reference frames are crucial for describing local observers in general relativity. In quantum gravity, we have different proposals for how to understand them. There are models in which the reference frames remain classical. In other approaches, they are fundamentally quantum. Recently, two options appeared to investigate these possibilities at the level of the classical and quantum algebra of observables. One option is based on the covariant phase space approach, using gravitational edge modes. In the canonical approach, there is another option, relational clocks, built from matter or geometry itself. In this work, we extend existing results and show how to relate edge modes and geometrical clocks in linearized gravity. We proceed in three steps. First, we introduce an extension of the ADM (Arnowitt-Deser-Misner) phase space to account for covariant gauge-fixing conditions and the explicit time dependence they add to Hamilton’s equations. Second, we show how these gauge-fixing conditions recover a specific choice of geometrical clocks in terms of Ashtekar-Barbero connection variables. Third, we study the effect of the Barbero-Immirzi parameter on the generators of asymptotic symmetries. We introduce the corresponding charges and explain how this parameter, which disappears from metric gravity, modifies the generators for angle-dependent asymptotic symmetries. This modification affects the supertranslation charges, while the global charges remain unchanged.

In this work, we test for gravitational parity violation in the PSR J1141-6545 system by analyzing the orbital plane inclination precession induced by the misalignment between the white dwarf’s spin axis and the system’s total angular momentum. Using the parity-violating metric of gravity that incorporates terms from both the exterior and boundary of the field source, we calculated corrections to the relative acceleration and orbital inclination precession rates, which exhibit significant deviations from the general relativity (GR) prediction. The parity-violating contributions depend on the projection of the spin vector along the orbital angular momentum direction, contrasting with GR, where it depends on the projection within the orbital plane. The corrections are perpendicular to GR contribution, highlighting a fundamental distinction. The exterior field correction is linear in the theoretical parameter and coupled to eccentricity $e$, while the boundary term correction is quadratic. By comparing these corrections with GR and incorporating observational uncertainty, we derive the constraint on the theoretical parameter, yielding ${\dot{f}}_{\mathrm{PV}}\lesssim {10}^6\mathrm{m}$.

We investigate the relationship between a one-parameter family of (anti–)de Sitter Yang-Mills models and a model of Einstein-Palatini gravity with matter, realized through Inönü-Wigner contraction of the (A)dS algebra. By setting the group parameter $\alpha$ to zero, the gauge transformation of the potential becomes consistent with the transformation properties of the tetrad form and spin connection. We show that a sector of the Yang-Mills dynamics exists in which the equations decouple. Moreover, a subset of the gauge transformations can be related to diffeomorphisms, leading to the identification of the tetrad field. Finally, the resulting dynamics is consistent with a gravitational dynamics in the first-order formalism.

We study the counts-in-cells reduced skewness $s_3$ for dark matter, halo, and galaxy distributions in both real and redshift space, using the extended lensing physics with analytical ray tracing (elephant) suite of $N$-body simulations. We compare general relativity (GR) with two extended (EG) gravity models: $f(R)$ gravity with chameleon screening and the normal-branch Dvali–Gabadadze–Porrati (nDGP) model with Vainshtein screening. We quantify the suppression of $s_3$ by redshift-space distortions (RSD), finding that while small-scale skewness is strongly reduced, the $F5$ model retains a $\sim 4\%$ deviation from GR in galaxy samples, corresponding to a $2\sigma$ significance. We show that the ratio $s_3^{\mathrm{RSD}}/s_3^{\mathrm{real}}$ is approximately independent of the gravity model across tracers and redshifts. Our results demonstrate that real-space predictions can help reliably infer redshift-space skewness in both GR and extended gravity, providing a new tool for testing gravity with current and forthcoming galaxy redshift surveys.

We consider the possibility of a past and future eternal universe, constructing geodesically complete inflating, loitering, and bouncing spacetimes. We identify the constraints energy conditions that general relativity place on the building of eternal cosmological models. Inflationary and bouncing behavior are shown to be essential ingredients in all significant examples. Nontrivial complete spacetimes are shown to violate the null energy condition for at least some amount of time, as well as the average null energy condition, unless curvature is included. Ignoring the intractable subtleties introduced by quantum considerations, such as rare tunneling events and Boltzmann brains, we demonstrate that these universes need not have had a beginning or an end.

Physical systems are usually assumed to evolve relative to an external time parameter, which is problematic because in quantum theory that parameter is not a physical observable. Page and Wootters (1984) solved this by proposing that the Universe is in a stationary state, eliminating the need for the external time parameter. Instead, their model contains an isolated subsystem, a clock, with which other subsystems are entangled, making the latter appear to evolve relative to different states of the clock. While this resolves the problem of the time parameter, the assumption that the clock is isolated prevents it from being measured, as this requires an interaction with another system. We prove that the clock can be measured while preserving the core features of the Page-Wootters construction. We also discuss clock synchronization.