In this work, we investigate hot, isentropic compact stars in the limiting cases of static and maximally rotating configurations, focusing on how variations in the symmetry energy of the equation of state derived from covariant density functional theory affect stellar properties. We consider both nucleonic and hyperonic matter with systematically varied symmetry energy slopes, fixed entropies per baryon $s/k_B=1$ and 3, and electron fractions $Y_e=0.1$ and $Y_e=0.4$, representative of conditions in binary neutron star mergers and proto-neutron stars. We compute and analyze mass–radius and moment-of-inertia-mass relations, as well as the dependence of the Keplerian (mass-shedding) frequency on mass, angular momentum, and the ratio of kinetic to gravitational energy. Furthermore, we show that several universal relations between global properties remain valid across both nucleonic and hyperonic equations of state with varying symmetry energy, both in the static and Keplerian limit, and for various combinations of the fixed entropy and electron fraction.

We investigate axionlike particles coupled to gravity through a parity-violating Chern-Simons (CS) interaction. In this framework, axion dark matter (DM) can decay into pairs of circularly polarized gravitons, producing a persistent, nearly monochromatic gravitational wave signal. We compute the expected signal at Earth assuming a Navarro-Frenk-White Galactic halo model with the corresponding velocity distribution, and compare it with the narrow-band sensitivities of the LIGO O4 run and the projected reach of the Einstein Telescope. The resulting bounds on the axion-graviton coupling $\alpha$ improve upon the cosmological stability requirement for axion masses $m_{\varphi }\lesssim {10}^{-11}\mathrm{eV}$, excluding values up to four orders of magnitude below the stability limit. This constitutes a robust direct terrestrial constraint on the axion-gravity CS coupling. We also discuss distinctive observational signatures, such as circular polarization asymmetries, annual modulation, and potential enhancements from DM substructures, which could serve as smoking-gun evidence for parity-violating gravitational interactions.

We perform fully general-relativistic hydrodynamics simulations of binary neutron star mergers over 100 ms postmerger to investigate the dynamics of remnant massive neutron stars (NSs). Our focus is mainly on the analysis of convective stability and mode characteristics of the massive NSs. We derive stability criteria for hot, differentially rotating relativistic stars that account for both buoyant and rotational restoring forces, and apply them for the first time to the postmerger massive NSs. Our results show no evidence of large-scale convective instability, as both angle-averaged specific entropy and specific angular momentum increase outward within the massive NSs. Rotational effects significantly enhance stability for local regions that would be otherwise unstable by the Schwarzschild criterion. Additionally, our mode analysis of matter fields and gravitational waves reveals no excitation of observable inertial modes after the damping of quadrupolar $f$-modes in the massive NSs, contrasting with previous studies. As in many previous works, we observe the excitation of an $m=1$ one-armed mode. However, we also find that the growth of the $m=1$ mode amplitude after the merger may correlate strongly with the violation of linear momentum conservation, indicating that we cannot reject the possibility that the excitation of the one-armed mode has a numerical origin.

We present a framework for dark matter halo formation based on a kinetic theory of self-gravitating fermions together with a solid connection to thermodynamics. Based on maximum entropy arguments, this approach predicts a most likely phase-space distribution which takes into account the Pauli exclusion principle, relativistic effects, and particle evaporation. The most general equilibrium configurations depend on the particle mass and develop a degenerate compact core embedded in a diluted halo, both linked by their fermionic nature. By applying such a theory to the Milky Way we analyze the stability of different families of equilibrium solutions with implications on the dark matter distribution and the mass of the dark matter particle candidate. We find that stable core-halo profiles, which explain the dark matter distribution in the Galaxy, exist only in the range $m{c}^2\approx 194–387\mathrm{keV}$. The lower bound is a consequence of imposing thermodynamical stability on the core–halo solutions having a $4.2\times {10}^6{M}_{\odot }$ quantum core mass alternative to the black hole hypothesis at the Galaxy center. The upper bound is solely an outcome of general relativity when the quantum core reaches the Oppenheimer-Volkoff limit and undergoes gravitational collapse toward a black hole. We demonstrate that stable core-halo profiles exist which are astrophysically relevant in the sense that their total mass is finite, do not suffer from the gravothermal catastrophe, and agree with observations. The morphology of the halo tail is described by a polytrope of index $\raisebox{1ex}{$5$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$, developing a sharp decline of the density beyond 25 kpc in excellent agreement with the latest Gaia DR3 rotation curve data. Moreover, we obtain a total Milky Way mass of about $2\times {10}^{11}{M}_{\odot }$ including baryons and a local dark matter density of about $0.4\mathrm{GeV}{\mathrm{c}}^{-2}{\mathrm{cm}}^{-3}$ in line with recent independent estimates.

Since the first direct detection of a gravitational wave signal in 2015, advancements in technology have resulted in incremental improvements to the current detector network. Future detectors will exploit new technologies to deliver an order of magnitude improvement in performance by increasing their scale and directly targeting thermal and other noise sources. With many next-generation gravitational wave detectors planning to implement crystalline materials as replacements for fused silica, there is an increasing need for novel techniques in suspension jointing. This work will report on the development and characterisation of a repeatable and repairable laser welding technique for crystalline sapphire. Utilizing a ${\mathrm{CO}}_2$ laser within a crystal growth machine, specifically designed for laser-heated pedestal growth, we established a reliable method for laser welding sapphire stock pieces of various millimetre scale diameters. Experimental characterisation revealed an upper limit of the weld region to be $\le 200\mathrm{\mu }\mathrm{m}$, and no measurable detriment to the thermal conductivity or tensile strength due to a welded joint. A thermal conductivity of $4587{\text{Wm}}^{-1}{\mathrm{K}}^{-1}$ at 20 K and a minimum unbroken tensile strength of 1.1 GPa were measured on a welded sample. In addition, cryogenic mechanical loss measurements produced a lowest loss of $3.2\times {10}^{-7}$ at 14 K, allowing a weld loss estimate of $5.1\times {10}^{-6}$. These initial findings indicate significant potential for sapphire welding as a viable concept in next-generation cryogenic detector suspensions and provide a strong justification for further development of this jointing method.

Results are presented from numerical simulations of the flat-space nonlinear Maxwell-Klein-Gordon-Dirac equations. The introduction of a boson-fermion interaction allows a scalar vortex to act as a harmonic trap that can confine massive Dirac bound states. A parametric analysis is performed to understand the range of boson-fermion coupling strengths, Ginzburg-Landau parameters, and fermion effective masses that support the existence of bound state solutions; results are shown to be comparable to quasiparticle bound states in gapped Dirac materials. Solutions are time evolved and are observed to be stable until the fermion field $\psi$ becomes large enough to collapse the spontaneously broken vacuum of the condensate. Head-on scattering simulations are performed, and traditional vortex right-angle scattering is shown to break down with increased fermion field strength. For sufficiently large $\psi$ and low velocity, the collision of two $m=1$ vortices results in a pseudostable $m=2$ bound state that eventually becomes unstable and decays back into two $m=1$ vortices. For large $\psi$ and collision velocity, vortex scattering is observed to produce nontopological (zero winding number) scalar bound states that are ejected from the collision. The scalar bubbles contain coherent fermion bound states in their interiors and interpolate between the spontaneously broken vacuum of the bulk and the modified vacuum induced by the boson-fermion interaction.

The quantum property of nonstabilizerness, also known as magic, plays a key role in designing quantum computing systems. How to produce, manipulate, and enhance magic remains mysterious, such that concrete examples of physical systems that manifest magic behavior are sought after. In this paper, we study two-particle scattering of gluons and gravitons in Yang-Mills theory and general relativity, as well as their supersymmetric extensions. This provides an interesting case of two-qubit systems, differing only in the physical spin of the qubits. We show that magic is generically produced in both theories, and also show that magic typically decreases as the spin of the qubits increases. The maximal magic in each case is found to be substantially less than the known upper bound. Differences in the profile of magic generation can be traced to the known physics of each theory, as manifested in relations between their respective scattering amplitudes. Our case study may provide useful insights into understanding magic in other systems.

We develop a procedure to analytically calculate higher-order contributions to the high-temperature real-time static potential in QCD. It is based on the introduction of a semihard external scale, which lies between the hard scale (the temperature) and the soft scale (the screening mass), and the method of integration by regions. We calculate the leading and next-to-leading corrections in the region where bound states transit from narrow resonances to wide ones. The calculation involves both loop diagrams calculated in the hard thermal loop (HTL) effective theory and power corrections to the HTL Lagrangian calculated in QCD. We also calculate the thermal corrections to the heavy quarkonium spectrum, and estimate the dissociation temperatures. We compare our results with recent lattice data and discuss their usefulness to guide lattice inputs in inverse problems.

Using the QCD sum rule method, we investigate the mass splitting for the spin-orbit partner states of the $\mathrm{\Omega }(2012)$ baryon assuming that it is a $P$-wave excitation with $J^P=3/2^{-}$. This study is an extension of the previous work [N. Su et al.Phys. Rev. D 110, 034007 (2024)] in which the masses of these states were estimated with uncertainties too large to extract the reliable mass splitting. In the present study, by directly formulating a sum rule for the mass splitting, we obtain an improved prediction, $\delta M=M_{3/2^{-}}-M_{1/2^{-}}=-{18.0}_{-17.1}^{+33.6}\mathrm{MeV}$. This result provides a more quantitative insight into the spectrum of $P$-wave $\mathrm{\Omega }$ baryons and serves as a useful reference for future experiments.

In the frame of conformal Killing gravity cosmology, we performed a Bayesian analysis on two different datasets of baryon acoustic oscillations (DESI and SDSS DR16), two datasets of SNeIa ($\mathrm{Pantheon}+\text{and}\mathrm{Union}3$), and using the cosmic microwave background (CMB) Planck likelihood. The results for $H_0$ and ${\mathrm{\Omega }}_M$ in a spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) background are consistent with the $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) scenario. We obtain a non-negligible negative value for the novel density of dark sector, ${\mathrm{\Omega }}_D$, and its relevance in the evolution of the cosmological observables, thus finding quantitatively what its contribution is on real data to match the standard scenario. The results confirm the dynamical character of dark energy. We also calculate the deceleration parameter $q_0$ and the present time dark energy equation of state parameter $w_0$: the latter belongs to the quintessence regime. The evaluation of the first acoustic peak of CMB places it near to the best value provided by the Planck Collaboration. In this scenario, we can conclude that late time and early time data can be successfully matched under the same standard.

We perform an in-depth comparative analysis of unintegrated parton distribution function (UPDF) models for isolated prompt diphoton production in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ within the $k_T$-factorization framework. Predictions are obtained with three UPDF approaches: parton branching (PB), NLO-MRW, and modified KMRW (MKMRW). Tree-level $q+\overline{q}\to \gamma +\gamma$, $q+\overline{q}\to \gamma +\gamma +g$, and $q+g\to \gamma +\gamma +q$ subprocesses are generated with katie using off shell initial states; the loop-induced $g+g\to \gamma +\gamma$ channel is evaluated independently. We compare differential cross sections with ATLAS measurements across a broad set of observables, including the photon transverse momenta, diphoton invariant mass and transverse momentum, the Collins-Soper angle, acoplanarity, ${\varphi }_{\eta }^{*}$, and a transverse thrust-related variable. This comparative study quantifies the impact of the UPDF choice on the diphoton spectra. We find that the PB model provides the most consistent agreement over all distributions, whereas NLO-MRW tends to overshoot in regions correlated with larger factorization scales and MKMRW generally undershoots due to stronger Sudakov suppression. With standard scale variations, our results indicate that $k_t$-factorization with PB UPDFs can accurately describe diphoton production, while fixed-order collinear predictions typically require higher-order corrections together with parton-shower effects to achieve a comparable description.

In this work we focus on the evaluation of the leading-order hadronic vacuum polarization contribution from the $\pi \pi$ channel to the muon anomalous magnetic moment $a_{\mu }$ by using the experimental $\tau \to \pi \pi {\nu }_{\tau }$ data. The isospin breaking corrections play the decisive role in this approach of computing $a_{\mu }$. One of such important isospin breaking sources is the long-distance electromagnetic correction factor $G_{\mathrm{EM}}$ of the $\tau \to \pi \pi {\nu }_{\tau }$ process from the real photon radiation. The latter effect can be calculated from the $\tau \to \pi \pi {\nu }_{\tau }\gamma$ amplitude, which is revised in this work within the resonance chiral theory by simultaneously including the even-intrinsic-parity and odd-intrinsic-parity resonance operators. We update the determination of the only unknown resonance coupling through the $\omega \to {\pi }^0{\pi }^0\gamma$ decay by including contributions from both the vector and scalar resonances. By taking other remaining contributions from the muon $g-2$ White Paper 2025, we further revise the complete value of $a_{\mu }$, which turns out to deviate from the newest world average result after Fermilab’s measurement at the level of $2.7\sigma$.

Dileptons serve as a clean and penetrating probe of the quark-gluon plasma created in high-energy heavy-ion collisions. In this work, we investigate thermal dilepton spectra and their elliptic flow through the dynamical conductivity that governs the production rate. The conductivity is obtained from the trace of the spectral function within relativistic kinetic theory using the relaxation time approximation. This allows us to derive for the first time an analytical expression for the dilepton rate with explicit dependence on the relaxation time of quark-antiquark interactions. We find a nonmonotonic dependence of the dilepton rate on the relaxation time and compare the resulting transverse momentum, invariant mass spectra, and elliptic flow with previous quantum field theory results. The spectra and elliptic flow are obtained by integrating the rate over the full spacetime volume of the evolving medium, using temperature and flow profiles from realistic music hydrodynamic simulations without considering the effect of magnetic fields in the profiles itself. However, we study the role of an external space-time-dependent magnetic field by making the conductivity anisotropic. At small relaxation times, magnetic fields have negligible impact, while for larger relaxation times and stronger initial fields, modifications of up to $\sim 20\%$ appear in both spectra and elliptic flow. Assuming instead a constant magnetic field of $\sim 1m_{\pi }^2$ at large relaxation times yields more modest effects, with changes of about 10% in spectra and 5% in elliptic flow.

The flux of cosmic ray muons at the Earth’s surface exhibits seasonal variations due to changes in the temperature of the atmosphere affecting the production and decay of mesons in the upper atmosphere. Using 1473 live days of data collected by the NuMI Off-axis ${\nu }_e$ Appearance (NOvA) Near Detector during 2018–2022, we studied the seasonal pattern in the multiple-muon event rate. The data confirm an anticorrelation between the multiple-muon event rate and effective atmospheric temperature, consistent across all the years of data. Previous analyses from MINOS and NOvA saw a similar anticorrelation but did not include an explanation. We find that this anticorrelation is driven by altitude–geometry effects as the average muon production height changes with the season. This has been studied with a CORSIKA cosmic ray simulation package by varying atmospheric parameters, and provides an explanation to a longstanding discrepancy between the seasonal phases of single and multiple-muon events.

The global symmetry data of a $D$-dimensional absolute quantum field theory (QFT) can sometimes be packaged in terms of a ($D+1$)-dimensional bulk system obtained by extending along an interval, with a relative ${\mathrm{QFT}}_D$ at one end and suitable gapped or free boundary conditions at the other end. The partition function of the ${\mathrm{QFT}}_D$ can then be interpreted as a wave function depending on background fields. However, in some cases, it is not possible or simply cumbersome to fix an absolute form of the symmetry data. Additionally, it is also of interest to consider entangled and mixed states of relative QFTs as well as entangled and mixed states of gapped or free boundary conditions. We argue that Wigner’s quasiprobabilistic function on phase space provides a physical interpretation of the symmetry data in all such situations. We illustrate these considerations in the case of string compactifications and holographic systems.

We study topological properties of a quantum mechanical system with $U(1)$ symmetry within the functional renormalization group approach. These properties include the vacuum energy structure and the topological susceptibility. Our approach works with a complexification of the flow equation, and specifically, we embed the original symmetry into the complex plane, $U(1)\to \mathbb{C}$. We compute the effective potential of a given topological sector by restricting ourselves to field configurations with given generalized nontrivial Chern-Simons numbers. The full potential is directly constructed from these sector potentials. Our results compare well with the benchmark results obtained from solving the corresponding Schrödinger equation.

Quantum uncertainty is deeply linked to quantum correlations and relativistic motion. The entropic uncertainty relation with quantum memory (QMA-EUR) offers a powerful way to study how shared entanglement affects measurement precision. However, under acceleration, the Unruh effect can degrade quantum correlations, raising questions about the reliability of QMA-EUR in such settings. Here, we investigate the QMA-EUR for two uniformly accelerating Unruh–DeWitt detectors coupled to a massless scalar field. Using the Kossakowski–Lindblad master equation, we calculate the entropic uncertainty, its lower bound, and the tightness of the relation under different Unruh temperatures. We find that acceleration does not always increase the lower bound on the uncertainty relation. Depending on the initial correlations between the detectors, it may either increase or decrease. This behavior results from the interplay between quantum discord and minimal missing information. Interestingly, a higher quantum discord does not necessarily lead to lower uncertainty.

We describe gauge theories that allow one to retrieve a large class of gravitational theories, including MacDowell-Mansouri gravity and its topological extension to loop quantum gravity via the Pontryagin characteristic class involving the Nieh-Yan term. Considering symmetric spaces parametrized by mutations allows one to naturally obtain a bare cosmological constant that in particular cases gives rise to a positive effective cosmological constant while having an anti–de Sitter (AdS) spacetime. Two examples are studied, Lorentzian geometry (including dS and AdS spacetimes) and Lorentz $\times$ Weyl geometry. In the latter case, we prove that adding a term dependent on torsion and dilations makes the equations of motion exhibit a secondary source for curvature in addition to the usual energy-momentum tensor. This additional source is expressed in terms of the spin density of matter, torsion, and their variations. Finally, we show that the $\mathrm{gauge}+\mathrm{matter}$ actions constructed from invariant polynomials are asymptotically topological if one assumes a vanishing bare cosmological constant together with gauge and matter fields having compact support.

We introduce imrphenomtehm, a new phenomenological time-domain model for eccentric aligned-spin binary black holes. Building upon the accurate quasicircular (QC) imrphenomthm model, imrphenomtehm integrates the eccentric post-Newtonian (PN) dynamics and introduces eccentric corrections into the waveform multipoles up to 3PN including spin effects. The model incorporates the dominant $(2,\pm 2)$ spherical harmonic mode, as well as the subdominant modes $(2,\pm 1),(3,\pm 3),(4,\pm 4)$, and $(5,\pm 5)$, with the assumption that the binary has circularized by the time of merger. This approach ensures a smooth transition to the noneccentric limit, and it is shown to provide an accurate QC limit against the imrphenomthm model. When comparing against 28 public eccentric numerical relativity (NR) simulations from the Simulating eXtreme Spacetimes catalog, imrphenomtehm achieves lower than 2% unfaithfulness, confirming its accurate description without calibration to numerical relativity eccentric datasets. imrphenomtehm provides a reliable description of the evolution of eccentric black hole binaries with aligned spins and eccentricities lower than $e=0.4$ at a frequency of 10 Hz, making it suitable for upcoming gravitational-wave observing runs. We validate the model’s accuracy through parameter estimation studies, recovering injected parameters within 90% credible intervals for four NR eccentric simulations and reanalyzing GW150914 and GW190521, obtaining results consistent with the literature.