We introduce an updated To&Krause2021 model for joint analyses of cluster abundances and large-scale two-point correlations of weak lensing and galaxy and cluster clustering (termed $\mathrm{CL}+3\times 2\mathrm{pt}$ analysis) and validate that this model meets the systematic accuracy requirements of analyses with the statistical precision of the final Dark Energy Survey (DES) Year 6 (Y6) dataset. The validation program consists of two distinct approaches, (i) identification of modeling and parametrization choices and impact studies using simulated analyses with each possible model misspecification and (ii) end-to-end validation using mock catalogs from customized Cardinal simulations that incorporate realistic galaxy populations and DES-Y6-specific galaxy and cluster selection and photometric redshift modeling, which are the key observational systematics. In combination, these validation tests indicate that the model presented here meets the accuracy requirements of DES-Y6 for $\mathrm{CL}+3\times 2\mathrm{pt}$ based on a large list of tests for known systematics. In addition, we also validate that the model is sufficient for several other data combinations: the $\mathrm{CL}+\mathrm{GC}$ subset of this data vector (excluding galaxy–galaxy lensing and cosmic shear two-point statistics) and the $\mathrm{CL}+3\times 2\mathrm{pt}+\mathrm{BAO}+\mathrm{SN}$ (combination of $\mathrm{CL}+3\times 2\mathrm{pt}$ with the previously published Y6 DES baryonic acoustic oscillation and Y5 supernovae data).

Dark photons are one of the promising candidates of light dark matter and could be detected by using their interaction with standard model particles via kinetic mixings. Here, we propose a feasible approach to detect the dark photons by nondestructively probing these mixing-induced quantum state transitions of atomic ensembles. Specifically, we show that the dark photons, in both centimeter- and millimeter-wave bands, could be detected by using the artificial atomic ensemble detector, generated by surface-state electrons on liquid helium. It is estimated that, with the detectable transition probability of ${10}^{-4}$, the experimental surface state of $N={10}^8$ trapped electrons might provide a feasible approach to search for the dark photons in $18.61–82.71\mathrm{\mu }\mathrm{eV}$ and $496.28–909.84\mathrm{\mu }\mathrm{eV}$ mass ranges, within about five months. The confidence level can exceed 95% for the achievable sensitivities, i.e., the value of the kinetic mixing parameter between dark photons and ordinary photons, being ${10}^{-14}–{10}^{-13}$ and ${10}^{-12}–{10}^{-11}$, respectively. In principle, the proposal could also be applied to the other atomic ensemble detections of dark photons in the other frequency bands.

The $\alpha$-attractor models of inflation have remained one of the preferred inflationary models for nearly a decade now. The unique attractor nature of these models in the $n_s-r$ plane have put these models in the sweet spot of the $n_s-r$ measurement of Planck observations. In this article, we analyze the behavior of such attractor models in a warm inflation setup to investigate whether the attractor nature of these models can be retained even when the dynamics deviates from the standard cold inflationary dynamics. We have chosen to analyze these models in a strongly dissipative warm inflation setup, namely the minimal warm inflation, as in such a setup the inflationary dynamics significantly departs from the standard cold inflation dynamics. We observe that the departure from the standard cold inflation dynamics destroys the unique attractor nature of such models. The analysis clearly indicates that the attractor nature of these $\alpha$-attractor models is quite unique to the standard cold inflationary dynamics. However, on a positive note, the analysis indicates that the $\alpha$-attractor models may be made in tune with the recent Atacama Cosmology Telescope results in warm inflation for certain parameter ranges.

Recent measurements made by the Alpha Magnetic Spectrometer (AMS) have detected accurate positron flux for an energy range of 1–1000 GeV. The energy spectrum can be best described by two source terms: the low-energy background diffusion term and an unknown high-energy source term. In this article, we discuss the possibility of the emission of positrons originating from dark matter annihilation in two nearby black hole X-ray binaries A0620-00 and XTE $\mathrm{J}1118+480$. We show that the dark matter density spikes around these two black holes can best produce the observed AMS-02 high-energy positron flux due to dark matter annihilation with rest mass $m_{\mathrm{DM}}\approx 8000\mathrm{GeV}$ via the $W^{+}{W}^{-}$ annihilation channel. This initiates a new proposal to account for the unknown high-energy source term in the AMS-02 positron spectrum.

The origin of merging binary black holes detected through gravitational waves remains a fundamental question in astrophysics. While stellar evolution imposes an upper mass limit of $\sim 50M_{\odot }$ for black holes, some observed mergers—most notably GW190521—involve significantly more massive components, suggesting alternative formation channels. Here we investigate the maximum masses attainable by black hole mergers within active galactic nucleus (AGN) disks. Using a comprehensive semianalytic model incorporating 27 binary and environmental parameters, we explore the role of AGN disk conditions in shaping the upper end of the black hole mass spectrum. We find that an AGN disk lifetime is the dominant factor, with high-mass mergers ($\gtrsim 200M_{\odot }$) only possible if disks persist for $\gtrsim 40\mathrm{Myr}$. The joint electromagnetic observation of an AGN-assisted merger could therefore lead to a direct measurement of the age of an AGN disk.

Ultralight scalars can form superradiant clouds around rotating black holes. These may alter the dynamics of compact binaries and the ensuing waveform through orbital resonances and cloud ionization. We reexamine resonances involving states with nonzero decay width, deriving an effective treatment for resonances that are wider than the binary’s frequency chirp. We demonstrate the utility of this approach by calculating an upper bound for the cloud’s mass surviving up to the latest stages of the inspiral. Next, we study the accumulation of resonances with high-energy bound states. When these infinitely many, increasingly weak resonances are properly taken into account, they smooth out the “sharp features” in the binary’s evolution that had been attributed to the ionization of the cloud. We compare our Newtonian results with recent relativistic calculations, highlighting common features as well as discrepancies. Our conclusions emphasize the need to carefully incorporate resonances in boson cloud waveform modeling.

In this work, the fragmentation production mechanism of ground state heavy tetraquarks is studied at lowest order of perturbative QCD using the diquark-antidiquark model. Through this model, we assume that heavy tetraquarks are composed of a pair of heavy diquark-antidiquarks bound by strong force so the two stage fragmentation is considered for their production, i.e., fragmentation of a heavy quark into a heavy diquark followed by its fragmentation into a heavy tetraquark. Our analytical results are compared with those obtained in a various approach where heavy tetraquarks are assumed as the compact four-quark states; tightly compact picture. To assess the prospects for experimental studies of heavy tetraquarks in the present and future high energy $e^{+}{e}^{-}$ colliders as well as hadron colliders, we will also approximate the production rate of ground state heavy tetraquarks in the pair annihilation process and proton-proton collision at lowest order of perturbative QCD.

The couplings of axionlike particles (ALPs) to Standard Model fermions are proportional to the fermion masses, making the interaction with the top quark particularly significant. In this study, we consider an ALP that is a mixture of $CP$-even and $CP$-odd components, thereby introducing $CP$ violation. This $CP$ violation, in turn, gives rise to electric dipole moments (EDMs) of quarks and leptons, as well as chromoelectric dipole moments (CEDMs) of quarks. We compute the one-loop and two-loop contributions to the top quark CEDM induced by the ALP. In our calculation, we treat the external gluon as off shell with momentum $q^2\ne 0$, derive the analytical results, and finally evaluate the top quark CEDM at $q^2=m_t^2$, corresponding to the top quark pole mass. This value is relevant for subsequent calculations of the EDMs of the neutron and mercury. By applying current experimental bounds on EDMs and CEDMs, we derive constraints on the ALP-top quark coupling, with the strongest limit coming from the neutron EDM.

While charged lepton-flavor-violating tau decays to strange mesons provide powerful probes of the underlying $\tau \to \ell d\overline{s}$ transition, the corresponding decay modes involving hyperons are kinematically forbidden. To address this gap, we propose the quasielastic scattering processes $e^{-}N\to {\tau }^{-}Y$. Within a general low-energy effective Lagrangian, we perform a comprehensive analysis of the final-state polarizations of both the $\tau$ lepton and the hyperon $Y$, systematically addressing the theoretical uncertainty driven by the model dependence of form factors. Our analysis demonstrates that while this uncertainty leads to large variations in predicted rates, the polarization observables can potentially distinguish between the form factor models, and help to determine the chiral nature of the vectorial new physics interaction. Finally, we forecast the event rates for future facilities, revealing a strong dependence on the form factor models, with predicted yields ranging from potentially observable levels to rates far below current detection thresholds.

In previous work [D. Giusti, et al., Methods for high-precision determinations of radiative-leptonic decay form factors using lattice QCD, Phys. Rev. D 107, 074507 (2023)], we showed that form factors for radiative leptonic decays of pseudoscalar mesons can be determined efficiently and with high precision from lattice QCD using the “three-dimensional (3D) method,” in which three-point functions are computed for all values of the current insertion time and the time integral is performed at the data-analysis stage. Here, we demonstrate another benefit of the 3D method: the form factors can be extracted for any number of nonzero photon virtualities from the same three-point functions at no extra cost. We present results for the $D_s\to \ell \nu {\gamma }^{*}$ vector form factor as a function of photon energy and photon virtuality, for both positive and negative virtuality, for a single ensemble with 340 MeV pion mass and 0.11 fm lattice spacing. In our analysis, we separately consider the two different time orderings and the different quark flavors in the electromagnetic current. We discuss in detail the behavior of the unwanted exponentials contributing to the three-point functions, as well as the choice of fit models and fit ranges used to remove them for various values of the virtuality. While positive photon virtuality is relevant for decays to multiple charged leptons, negative photon virtuality suppresses soft contributions and is of interest in QCD-factorization studies of the form factors.

We introduce a novel methodology for addressing systematic uncertainties in unbinned inclusive cross-section measurements and related collider-based inference problems. Our approach incorporates known analytic dependencies on parameters of interest, including signal strengths and nuisance parameters. When these dependencies are unknown, as is frequently the case for systematic uncertainties, dedicated neural network parametrizations provide an approximation that is trained on simulated data. The resulting machine-learned surrogate captures the complete parameter dependence of the likelihood ratio, providing a near-optimal test statistic. As a case study, we perform a first-principles inclusive cross-section measurement of $\mathrm{H}\to \tau \tau$ in the single-lepton channel, utilizing simulated data from the FAIR universe Higgs uncertainty challenge. Results in Asimov data, from large-scale toy studies, and using the Fisher information demonstrate significant improvements over traditional binned methods. Our computer code guaranteed optimal log-likelihood-based unbinned method (GOLLUM) for machine-learning and inference is publicly available.

We study fluctuations of rotating viscous stars, using the causal relativistic hydrodynamics of Bemfica, Disconzi, Kovtun, and Noronha. We derive, in a slow-rotation approximation, a coupled system of equations describing the propagation of axial gravitational waves through the star, which couple to internal viscous modes. We show that rotating viscous stars amplify incoming low-frequency gravitational waves, a phenomenon which we argue to be universal. Superradiant amplification does not seem to trigger an instability for uniformly rotating stars, even if the object is compact enough to have light rings.

We numerically evaluate, for slab entangling geometries, the mutual information and the holographic entanglement entropy between strongly interacting fields in different spatial regions for two different conformal holographic models at finite temperature and $R$-charge density. The $1R$-Charge Black Hole (1RCBH) model describes a strongly interacting fluid with a critical point in its phase diagram, while the $2R$-Charge Black Hole model has no critical point. In both models, we find that the mutual information tends to be overall reduced by increasing the value of $\mu /T$ at larger values of the separation length $x$ between two disjoint spatial regions of the medium, while the opposite tendency is observed at lower values of $x$. We also observe that, very close to the critical point of the 1RCBH model, the mutual information tends to increase with increasing $\mu /T$ in the stable branch of black hole solutions. Moreover, the mutual information between the fields in the two disjoint regions is observed to be enhanced by increasing the characteristic size $\ell$ of these regions, with such an enhancement asymptotically saturating, thus suggesting the existence of a finite field correlation length between the disjoint regions of the system. The finite part of the entanglement entropy may change sign depending on the values of $\mu /T$ and $\ell$, and it correctly detects the critical point of the 1RCBH model, a feature that is also adequately detected by the mutual information.

An explicit derivation of the four-dilatino scattering amplitude from type II superstring theory is presented. This is obtained by using the Kawai-Lewellen-Tye relations for closed string scattering amplitudes in terms of the product of two open string scattering amplitudes. We also investigate its Regge limit.

We investigate the linear static response of three covariant loop quantum black holes, namely, the two models proposed by Zhang, Lewandowski, Ma, and Yang (ZLMY) and the Alonso-Bardaji, Brizuela, and Vera (ABV) model, to an external tidal field. Using effective spacetime description, we uniquely extract the tidal Love numbers (TLNs) using perturbative solutions derived from the Green’s function technique. Our findings reveal that, in contrast to the classical Schwarzschild black hole, the TLNs for loop quantum black holes are generally nonzero. The sign and magnitude of the TLNs depend on the spin of the external tidal field, the multipole number, and the details of the loop quantized model. The magnitude of the TLNs is found to be Planck scale suppressed for all three models, implying a stronger tidal deformability for black holes with Planckian mass. Additionally, for the same black hole mass, the magnitude of the TLNs for the ABV model is larger than the ZLMY models. We also find that the TLNs exhibit logarithmic running behavior at the leading order, even for low multipole numbers, in response to scalar and vector field perturbations. These distinct features of the TLNs can serve as a potential tool to differentiate between various quantization ambiguities arising in loop quantum black holes. We briefly discuss the potential phenomenological and theoretical implications of nonzero TLNs for black hole physics.

We study the 4D Einstein-Hilbert action extension based on the square of the curvature tensors. Analyses of gauge and perturbation modes are often done considering the Teyssandier gauge condition. Although this approach can be useful for other higher-order extensions of quadratic gravity, a generalized transverse (or Lorentz) gauge is clear and sufficient for the present case, as explained here. We provide a detailed analysis of the generalized transverse gauge condition, its residual gauge symmetry, the physical modes, the induced energy-momentum tensor (EMT) of the massive spin-2 mode (which is gauge-dependent), and a comparison with the Teyssandier gauge. The derivation is valid for any EMT. We also compare the induced EMT in quadratic gravity with the massive spin-2 Fierz-Pauli EMT, which is different from the previous cases. The comparison is further developed by considering a spherical isothermal sphere, which works as an approximation to virialized spherical systems.

An algebraic framework was introduced in our previous works to address the covariance issue in spherically symmetric effective quantum gravity. This paper extends the framework to the electrovacuum case with a cosmological constant. After analyzing the notion of covariance in the classical theory, we propose an effective Hamiltonian for the electromagnetic field. The effective Hamiltonian together with the effective Hamiltonian constraint of gravity determines an effective dynamical model of gravity coupled to the electromagnetic field. The resulting model is covariant with respect to both the effective metric and the effective vector potential. By solving the equations of motion derived from the effective Hamiltonian constraint, we obtain several quantum-corrected solutions. Notably, some of these solutions reveal quantum gravity effects manifesting not only in spacetime metrics but also in the electromagnetic field. Finally, the covariance of coupling models with general matter fields is discussed.

An extreme mass ratio inspiral (EMRI), which corresponds to small compact object inspirals around a massive black hole in the center of a galaxy, is one of the most important sources for future space-borne gravitational-wave (GW) detectors such as TianQin and LISA. By analyzing the emitted GW signals, we can probe the theory of gravity and the nature of black holes in the strong field region. To achieve these objectives, the second-order self-force effect should be considered in the waveform modeling. Up to now, the waveform of EMRIs including the second-order self-force effect is only achieved for the circular orbit on the Schwarzschild background. In this work, we generalized the calculation of the second-order self-force to the eccentric orbits on Schwarzschild spacetime. We calculated the puncture field, and give the form of two-timescale expansion for the field equations. The corresponding numerical calculation and programming can be performed based on these results.

Measuring quasinormal modes (QNMs) during the ringdown phase of binary black hole coalescences provides key insights into merger dynamics and enables tests of the no-hair theorem. The QNM rational filter has recently been introduced as a technique to identify specific QNMs in ringdown signals without sampling over mode amplitudes and phases. In this work, we extend the QNM rational filter framework to quantify the statistical confidence of subdominant mode detections in real gravitational wave (GW) observations. We employ a frequentist approach to estimate false-alarm probabilities and propose a workflow for robust identification of specific QNMs. We first validate our methodology using synthetic signals generated from numerical relativity waveforms. We then reanalyze the first GW event, GW150914, finding a marginal detection of an overtone, but at time when the applicability of constant amplitude QNM fits is not fully understood. This extended methodology provides a systematic approach to improving the reliability of QNM detections, paving the way for more precise tests of strong-field gravity with current and future GW observations.

This paper develops a renormalized perturbation theory framework for nonlinear structure formation in a broad class of modified gravity models that exhibit Vainshtein screening, with a focus on a viable subclass of Horndeski theories. We extend earlier perturbative methods, originally applied to the Dvali–Gabadadze–Porrati model, to construct a self-consistent treatment that captures both the linear modifications to gravity at large scales and the nonlinear screening effects at small scales. In the framework, the response of the gravitational potential to matter density fluctuations is characterized by renormalized propagators, leading to the definition of a nonlinear (or renormalized) effective gravitational constant. This paper details several numerical strategies to compute this renormalized gravitational constant. Numerical examples illustrate how the effective gravitational constant evolves with scale and redshift. These results are key to accurately predicting cosmological observables such as the matter power spectrum and bispectrum in modified gravity scenarios.