We compute the expectation value of the energy-momentum tensor of a real scalar field in an approximation which accounts for spacetime gradients of the hydrodynamical variables in local thermodynamical equilibrium. We show that the energy-momentum tensor receives corrections with respect to the standard local-equilibrium result. Notably, the relation between the energy density and pressure, i.e., the equation of state, is modified with respect to the one in global equilibrium. The obtained corrections might be relevant for systems created in relativistic hadron and heavy-ion collisions.

We investigate new physics effects on coherent elastic neutrino nucleus scattering within the framework of nonstandard interactions and generalized neutrino interactions. Additionally, we examine the possibility of light mediators from a simplified model that includes all possible Lorentz-invariant interactions of vector, axialvector, scalar, pseudoscalar, and tensor types. Constraints and allowed regions at the 90% CL for masses and couplings in each new physics scenario have been obtained through the analysis of TEXONO data, which includes two datasets from a high-purity $n$-type point contact germanium detector in 2016 and an advanced $p$-type point contact Ge detector in 2025. The results are presented in comparison with other reactor and accelerator-based neutrino experiments for complementarity.

We propose a GeV-scale self-interacting dark matter (SIDM) candidate within a dark $U(1{)}_D$ gauged extension of the Standard Model (SM), addressing small-scale structure issues in $\mathrm{\Lambda }\mathrm{CDM}$ while predicting an observable contribution to $\mathrm{\Delta }{N}_{\mathrm{eff}}$ in the form of dark radiation. The model introduces a fermionic DM candidate $\chi$ and a scalar $\varphi$, both charged under an unbroken $U(1{)}_D$ gauge symmetry. The self-interactions of $\chi$ are mediated by a light vector boson $X^{\mu }$, whose mass is generated via the Stueckelberg mechanism. The relic abundance of $\chi$ is determined by thermal freeze-out through annihilations into $X^{\mu }$, supplemented by a nonthermal component from the late decay of $\varphi$. Crucially, $\varphi$ decays after the big bang nucleosynthesis (BBN) but before the cosmic microwave background (CMB) epoch, producing additional $\chi$ and a dark radiation species (${\nu }_S$). This late-time production compensates for thermal underabundance due to efficient annihilation into light mediators, while remaining consistent with structure formation constraints. The accompanying dark radiation yields a detectable $\mathrm{\Delta }{N}_{\mathrm{eff}}$, compatible with Planck 2018 bounds and within reach of next-generation experiments such as SPT-3G, CMB-S4, and CMB-HD.

We study the Hamiltonian formulation of SU(2) Yang-Mills theory with staggered fermions in a ($2+1$)-dimensional small lattice system. We construct a gauge-invariant and finite-dimensional Hilbert space for the theory by applying the loop-string-hadron formulation and specifically map the model to a spin system. We classically emulate digital quantum simulation and observe the real-time evolution of the single-site entanglement entropy, the fermion entanglement entropy, and the fermion pair production.

We perform a systematic analysis of the low-lying ${\mathrm{\Omega }}_c$ structures in a coupled-channel approach. The couplings between meson-baryon channels, ${\mathrm{\Xi }}_c\overline{K}$, ${\mathrm{\Xi }}_c^{\prime }\overline{K}$, ${\mathrm{\Xi }}_c^{*}\overline{K}$, ${\mathrm{\Omega }}_c\eta$, and ${\mathrm{\Omega }}_c^{*}\eta$, and three-quark bare states ${\mathrm{\Omega }}_c(1P_{\lambda })$ are considered. We predict a bound state ${\mathrm{\Omega }}_c(2954)$ below the ${\mathrm{\Xi }}_c\overline{K}$ threshold with $(J^P,j)=(1/2^{-},0)$, which can be studied in the final states of ${\mathrm{\Omega }}_c^{(*)}\pi$ and ${\mathrm{\Omega }}_c^{(*)}\gamma$. Also, the resonances ${\mathrm{\Omega }}_c(3000)$ and ${\mathrm{\Omega }}_c(3050)$ can be classified as the lower $(J^P,j)=(1/2^{-},1)$ and $(J^P,j)=(3/2^{-},1)$ states, respectively. Our present assignments based on this coupled-channel perspective are significantly different from those of the traditional three-quark picture and of the molecular scenario. The future BelleII and LHCb experiments can search for the bound state ${\mathrm{\Omega }}_c(2954)$ and measure the spin-parities of particles ${\mathrm{\Omega }}_c(3000)$ and ${\mathrm{\Omega }}_c(3050)$ to test our predictions.

It has been found that the gluon density inside the proton grows rapidly at small momentum fractions. Quantum chromodynamics (QCD) predicts that this growth can be regulated by nonlinear effects, ultimately leading to gluon saturation. Within the color glass condensate framework, nonlinear QCD effects are predicted to suppress and broaden back-to-back angular correlations in collisions involving heavy nuclei. While suppression has been observed in various experiments in $d/p+\mathrm{A}$ collisions compared to $p+p$ collisions, the predicted broadening remains unobserved. This study investigates the contributions of intrinsic transverse momentum ($k_T$), which is associated with saturation physics, as well as parton showers and transverse motion from fragmentation ($p_T^{\mathrm{frag}}$), which are not saturation dependent, to the width of the correlation function. Our findings show that the non-saturation dependent effects, especially the initial-state parton shower and $p_T^{\mathrm{frag}}$, which occur independently of the collision system, smear the back-to-back correlation more than gluon saturation does, making the broadening phenomenon difficult to observe.

We study the impact of the pointlike $q{\overline{q}}^{\prime }WH$ interactions originating from a subset of dimension-six operators of the Standard Model effective field theory (SMEFT) on the Higgs boson associated production $pp\to W^{+}H$ at the LHC. For consistency, we also take into account the corresponding $q{\overline{q}}^{\prime }W$ vertices implied by these operators. We compute the next-to-next-to-leading order quantum chromodynamics (QCD) corrections to this process and compare these corrections in the Standard Model and SMEFT production mechanisms.

We present a method to measure time-dependent $CP$ violation in $B^0$ decays produced in $\mathrm{\Upsilon }(4S)\to B^0{\overline{B}}^0$ events at $B$ factories without reconstructing the signal decay vertex. The method exploits the sensitivity of the tag ${\overline{B}}^0$ decay time to $CP$ violation in the $B^0$ signal. It relies on a compact $e^{+}{e}^{-}$ interaction region and excellent vertex resolution, which enable precise measurement of the displacement between production and decay vertices of the tag meson. We study an application to $B^0\to {\pi }^0{\pi }^0$ decays using a simplified simulation that approximates the conditions of the Belle II experiment at the SuperKEKB collider. Our approach achieves a sensitivity on mixing-induced $CP$ violation that would require 20 times larger samples with standard approaches. When incorporated into the $B\to \pi \pi$ isospin analysis, the expected results would reduce the degeneracy of ${\varphi }_2$ solutions and significantly increase precision. This work opens a path to previously inaccessible $CP$-violation studies enhancing and accelerating the reach of Belle II and future flavor physics programs.

Superradiance, the phenomenon enabling energy extraction through radiation amplification, is not universal to all black holes. We show that semiclassical backreaction can induce superradiance, even when absent at the classical level. Specifically, we compute the quasinormal modes of a massless scalar field probing a family of rotating “quantum” black holes in three-dimensional anti-de Sitter space, accounting for all orders of backreaction due to quantum conformal matter. A subset of these modes is identified as superradiant, leading to the formation of quantum black hole “bombs.” Further, we find all thermally unstable black holes exhibit modal linear instabilities, though the converse does not hold generally. Our findings thus suggest a semiclassical version of the Hollands-Wald conjecture on black hole stability. This motivates us to propose a stability criterion for quantum black holes.

When excited states decay with energy $E_0-i\mathrm{\Gamma }$ the time evolution operator $U(t)=e^{-iHt}$ does not obey $U^{†}(t)U(t)=I$. Nonetheless, probability conservation is not lost if one includes both decay and excitation with energy $E_0+i\mathrm{\Gamma }$, though it takes a different form. Specifically, if the eigenspectrum of a Hamiltonian is complete, then due to $CPT$ symmetry, a symmetry that holds for all physical systems, there must exist an operator $V$ that effects $VH{V}^{-1}=H^{†}$, so that $V^{-1}{U}^{†}(t)VU(t)=I$. In consequence, because of probability conservation the time delay associated with decay must be accompanied by an equal and opposite time advance for excitation. Thus when a photon excites an atom the spontaneous emission of a photon from the excited state must occur without any decay time delay at all. An effect of this form together with an associated negative time delay has recently been reported by Sinclair et al. [PRX Quantum 3, 010314 (2022)] and Angulo et al. [arXiv:2409.03680].

We develop, in the AdS/CFT correspondence, a method to compute correlation functions when the conformal field theory (CFT) is governed by the Lindblad equation for open quantum systems, via the anti–de Sitter (AdS) theory. Using a simple example in ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$, we demonstrate that the predictions of the AdS theory based on our method match the direct computations in the dual CFT. We also briefly discuss the relaxation problem and the holographic entropy in this example.

We discuss unusual $\theta$ terms that can appear in field theories that allow global vortices. These “Cheshire $\theta$ terms” induce Aharonov-Bohm effects for some particles that move around vortices. For example, a Cheshire $\theta$ term can appear in QCD coupled to an axion and induces Aharonov-Bohm effects for baryons and leptons moving around axion strings.

We revisit the general analytic solution space for relativistic ($1+1$)-dimensional hydrodynamics for a perfect fluid flowing along the longitudinal direction. We work out the explicit one-parameter family of interpolating flows between boost-invariant and boost-noninvariant regimes, where a direct and simple dialing of the parameter at the level of solutions is possible. We also discuss the construction of generalized rapidity distribution of entropy for such interpolating flows at the level of potentials.

Classical linearized gravity admits a dual formulation in terms of a higher-rank tensor field. However, proposing a prescription for the instanton sectors of linearized gravity and its dual, we show that they may be quantum inequivalent. The duality anomaly is obtained by resolving the dual graviton theories into vector-valued $p$-form electrodynamics and is controlled by three topological invariants: the Reidemeister torsion, Ray-Singer torsion, and twisted Euler characteristic. Under the proposed instanton prescription, the duality anomaly vanishes for an odd number of spacetime dimensions as a consequence of the celebrated Cheeger-Müller theorem. In the presence of a gravitational $\theta$-term, the partition function is a modular form in direct analogy to Abelian S-duality for Maxwell theory.

Semianalytical waveform models for black hole binaries require calibration against numerical relativity waveforms to accurately represent the late inspiral and merger, where analytical approximations fail. After the fitting coefficients contained in the model are optimized, they are typically held fixed when the model is used to infer astrophysical parameters from real gravitational-wave data. Though point estimates for the fitting parameters are adequate for most applications, they provide an incomplete description of the fit, as they do not account for either the quality of the fit or the intrinsic uncertainties in the numerical relativity data. Using the imrphenomd model, we illustrate how to propagate these uncertainties into the inference by sampling the fitting coefficients from a prior distribution and marginalizing over them. The prior distribution is constructed by ensuring that the model is compatible with a training set of numerical relativity surrogates, within a predefined mismatch threshold. This approach demonstrates a pathway to mitigate systematic bias in high signal-to-noise events, particularly when envisioned for the next generation of semianalytical models.

We present a group field theory (GFT) quantization of the Husain-Kuchar (HK) model formulated as a noninteracting GFT. We demonstrate that the path-integral formulation of this HK-GFT provides a complete spinfoam model and a unique Fock representation that describes the quantum three-geometries of the HK model. These results provide a link to the canonical quantization of the HK model and demonstrate how GFTs can bridge distinct quantization schemes.

We solve the Schrödinger-Newton problem of Newtonian gravity coupled to a nonrelativistic scalar particle for solutions with axial symmetry. The gravitational potential is driven by a mass density assumed to be proportional to the probability density of the scalar. Unlike related calculations for condensates of ultralight dark matter or boson stars, no assumption of spherical symmetry is made for the effective gravitational potential. Instead, the potential has only axial symmetry, consistent with the axial symmetry of the particle’s probability density for eigenstates of $L_z$. With total angular momentum no longer a good quantum number, there are, in general, contributions from a range of partial waves. This permits us to study the partial-wave content of self-consistent solutions of the Schrödinger-Newton system.

The issue of general covariance in effective quantum gravity models within the Hamiltonian framework is addressed. The previously proposed equations for the covariance condition in spherically symmetric models are explicitly derived. By solving this equation, a new effective Hamiltonian constraint is obtained, incorporating free functions that can account for quantum gravity effects. The resulting spacetime structure is analyzed by specifying the free functions. Remarkably, in this model, the classical singularity is replaced by a region where the metric asymptotically approaches a Schwarzschild-de Sitter one with negative mass. Thus, this new quantum-corrected black hole model avoids the Cauchy horizons presented typically in previously studied models. The covariant approach is also applicable to matter coupling in the models.

Wide classes of new fundamental physics theories cause apparent variations in particle mass ratios in space and time. In theories that violate the weak equivalence principle (EP), those variations are not uniform across all particles and may be detected with atomic and molecular clock frequency comparisons. In this work we explore the potential to detect those variations with near-future clock comparisons. We begin by searching published clock data for variations in the electron-proton mass ratio. We then undertake a statistical analysis to model the noise in a variety of clock pairs that can be built in the near future according to the current state of the art, determining their sensitivity to various fundamental physics signals. Those signals are then connected to constraints on fundamental physics theories that lead directly or indirectly to an effective EP-violating, including those motivated by dark matter, dark energy, the vacuum energy problem, unification or other open questions of fundamental physics. This work results in projections for tight new bounds on fundamental physics that could be achieved with atomic and molecular clocks within the next few years. Our code for this work is packaged into a forecast tool that translates clock characteristics into bounds on fundamental physics.

In our paper we pay attention to the problem of uniqueness (classification) of higher-dimensional electro-magnetic static, asymptotically flat, nonextremal solutions of multidimensional Einstein (n-2)-form gauge field gravity theory, which possess a photon sphere. The photon sphere is uniquely described by its asymptotic data. Conformal positive energy theorem is the key tool in the proof.