We compute the complete nonplanar integrand for the correlation function of four lightest scalar operators in $\mathcal{N}=4$ super Yang-Mills theory at five-loop order. This is equivalent to the supercorrelator of nine stress-tensor multiplets in the self-dual theory. Starting with an ansatz of $f$ graphs, we impose constraints from light-cone limits, and fix the remaining freedom by using the reformulation of the theory in twistor space. We develop an efficient GPU-based algorithm for the numerical evaluation of the twistor rules. Our result for the integrand suggests a sharpened $f$-graph genus conjecture. As an application, we extract the five-loop nonplanar anomalous dimension of the Konishi operator, whose $1/N_{\mathrm{c}}^2$ term is entirely given in terms of odd zeta values of transcendentality five and higher. Our code and result are provided in ancillary files.

What can be measured by an observer in a cosmological universe? We address this question by constructing an algebra of gravitationally dressed observables accessible to a comoving observer in Friedmann-Lemaître-Robertson-Walker spacetimes that are asymptotically de Sitter in the past, describing an inflationary epoch. The key feature of this model, compared to previous work, is that it captures the time dependence of an expanding cosmology. An essential quantized degree of freedom is the zero mode of the inflaton, which leads to fluctuations in the effective cosmological constant during inflation and prevents the existence of a maximum entropy state in the semiclassical limit. Because of the inaccessibility of measurements beyond our cosmological horizon, we demonstrate that all states are mixed with well-defined von Neumann entropy (up to a state-independent constant). For semiclassical states, the von Neumann entropy corresponds to the generalized entropy of the observer’s causal diamond, a fine-grained quantity that is sensitive to the initial conditions of the Universe.

The remnant of a black hole binary merger settles into a stationary configuration by “ringing down” through the emission of gravitational waves that consist of a superposition of damped exponentials with discrete complex frequencies—the remnant black hole’s quasinormal modes. While the frequencies themselves depend solely on the mass and spin of the remnant, the mode amplitudes depend on the merger dynamics. We investigate quasinormal mode excitation by a point particle plunging from the innermost stable circular orbit of a Kerr black hole. Our formalism is general, but we focus on computing the quasinormal mode excitation coefficients in the frequency domain for equatorial orbits, and we analyze their dependence on the remnant black hole spin. We find that higher overtones and subdominant multipoles of the radiation become increasingly significant for rapidly rotating black holes. This suggests that the prospects for detecting overtones and higher-order modes are considerably enhanced for highly spinning merger remnants.

Gravitational wave detectors produce time series of the gravitational wave strain coadded with instrument noise. For evenly sampled data, such as from laser interferometers, it has been traditional to Fourier transform the data and perform analyses in the frequency domain. The motivation being that the Fourier domain noise covariance matrix will be diagonal if the noise properties are constant in time, which greatly simplifies and accelerates the analysis. However, if the noise is nonstationary this advantage is lost. It has been proposed that the time-frequency or wavelet domain is better suited for studying nonstationary noise, at least when the time variation is suitably slow, since then the wavelet domain noise covariance matrix is, to a good approximation, diagonal. Here we investigate the conditions under which the diagonal approximation is appropriate for the case of the Wilson-Daubechies-Meyer (WDM) wavelet packet basis, which is seeing increased use in gravitational wave data analysis. We show that so long as the noise varies slowly across a wavelet pixel, in both time and frequency, the WDM noise correlation matrix is well approximated as diagonal. The off-diagonal terms are proportional to the time and frequency derivatives of the dynamic spectral model. The same general picture should apply to other discrete wavelet transforms with wavelet filters that are suitably compact in time and frequency. Strategies for handling data with rapidly varying noise that violate these assumptions are discussed.

We investigate the anomaly-induced activation of a gauge-invariant scalar degree of freedom in general relativity, the conformalon mode, directly at the level of $2\to 2$ scattering amplitudes. The analysis couples anomalous three-point functions of conformal sectors, involving gravitons $(TTT)$ and Abelian gauge currents $(TJJ)$, through single-graviton exchange derived from the quadratic expansion of the Einstein-Hilbert action. Unlike related treatments based on the nonlocal anomaly action, these interactions are suppressed by the Planck scale. We show that the conformalon, invariant under linearized diffeomorphisms, admits an interpretation as an effective scalar correction to scattering amplitudes, both in virtual exchange channels and in effective real-emission processes. Around flat space, this behavior arises from anomaly-induced nonlocal massless insertions on the external graviton and photon legs of the three-point functions, sewn through the scalar component of the graviton propagator in De Donder gauge. The resulting anomaly-mediated four-point interaction reduces to contact terms, with the Planck mass setting the suppression scale. The construction consistently matches the spin decomposition of flat-space conformal Ward identities in momentum space, which determine the vertices, with the corresponding spin decomposition of the graviton propagator. In the eikonal limit, these interactions generate contact corrections to the leading logarithmic phase in impact-parameter space. We further show that anomaly-mediated $2\to 2$ graviton amplitudes associated with the virtual exchange of such modes exhibit a characteristic double-copy structure.

During the evolution of a binary black hole, energy and angular momentum are exchanged between the orbital motion and the individual black holes through horizon absorption, modifying both the binary dynamics and the black hole masses and spins. This leaves an imprint on the emitted gravitational waves that may be relevant for the accurate modeling of signals observed by current and future detectors, while also offering a probe of the nature of compact objects. In this work, we derive, for the first time and at leading order in the post-Newtonian expansion, the effect of horizon absorption in binary black hole inspirals with both orbital eccentricity and spin-induced precession, and we incorporate these corrections into the pyefpehm waveform model. We then quantify their impact through analytical estimates of the orbital dephasing, waveform mismatches, and Bayesian parameter-estimation studies. The effect is largest for systems with large spin components (anti)aligned with the orbital angular momentum ($|{\mathit{\chi }}_i·\widehat{\mathit{l}}|\sim 1$), highly unequal mass ratios ($q=m_2/m_1\ll 1$), and long inspirals spanning a wide frequency range ($\log (f_{\max }/f_{\min })\gg 1$). For such systems, neglecting horizon absorption biases the recovered binary parameters at moderate signal-to-noise ratios. In quasicircular binaries these biases largely absorb the effect, rendering it difficult to detect. In eccentric binaries, however, the richer signal morphology breaks this degeneracy, making horizon absorption potentially measurable in high signal-to-noise-ratio events.

We introduce pyEFPEHM, a post-Newtonian (PN) inspiral waveform model for eccentric and spin-precessing compact binaries that includes higher-order modes and matter effects. Accurate and efficient waveform models capturing these effects are essential for probing compact-binary formation channels and exploiting current and future gravitational-wave (GW) observations. pyEFPEHM extends pyEFPE, significantly improving its physical content and accuracy. In particular, we show that above 2.5PN order the quasicircular contributions to the orbital phasing dominate at each PN order, and we incorporate all available higher-order quasicircular PN corrections to the phasing, including adiabatic tidal effects. We generalize the multiple-scale analysis solution of the spin-precession equations, extending it to higher PN orders and including all available quasicircular corrections. Finally, we add eccentric corrections up to 1PN order in the waveform amplitudes, including the GW multipoles $(l,|m|)=(2,2),(2,1),(2,0),(3,3),(3,2),(3,1),(3,0),(4,4),(4,2),(4,0)$. We validate pyEFPEHM against existing analytical waveform models and numerical relativity simulations, showing that it provides a robust and computationally efficient description of the inspiral, with good agreement across a broad region of parameter space and up to close to merger. The accuracy degrades in the late inspiral for systems with very unequal masses ($m_2/m_1\lesssim 0.1$), significant spins aligned with the orbital angular momentum ($|{\chi }_{\mathrm{eff}}|\gtrsim 0.5$), and high eccentricities ($e\gtrsim 0.6$), where the PN expansion is expected to break down. pyEFPEHM represents a significant step toward physically complete and efficient waveform modeling of eccentric and precessing binaries, providing a foundation for future extensions including higher-order corrections, calibration to numerical relativity, and merger-ringdown modeling.

A particular solution to the three-body problem is the circular Lagrange three-body system, where the masses move in circular orbits such that they always constitute an equilateral triangle. Such a system has been found to emit gravitational waves with a waveform similar to that of a binary system. In this work, we study the gravitational waveform degeneracy between quasicircular binary systems and Lagrange three-body systems up to 0.5PN order. Assuming we know the parameters of a given binary system, we determine the parameters of the Lagrange triple that produces the same waveform as that of the binary. We show that there exists a mass quadrupole degeneracy in both the plus and cross modes, characterized by two parameters. We also find that there are binary systems and linearly stable Lagrange three-body systems that can have the same mass quadrupole waveform up to the coalescence time. In such cases, the normalized overlap of the waveforms with respect to the power spectral density of the advanced LIGO design remains above 0.97 as long as the binary has nearly symmetric masses. Beyond the mass quadrupole, there is a unique degeneracy at the 0.5PN. However, the Lagrange triple that satisfies this degeneracy is unstable.

We computethe transmission properties of electromagnetic (EM), gravitational wave, and static gravitational perturbations through geometric throats in spherically symmetric spacetimes. On the ultrastatic Ellis-Bronnikov background, decomposition of the four-dimensional Maxwell equations into vector spherical harmonics yields an effective Schrödinger problem with centrifugal barrier $V_{\ell }^{(\mathrm{EM})}=\ell (\ell +1)/({\sigma }^2+r_0^2)$ peaked at the throat. For the lowest physical EM mode ($\ell =1$), frequencies below the barrier-top frequency ${\omega }_{\max }=\sqrt{2}/r_0$ are strongly suppressed by sub-barrier tunneling. Gravitational wave perturbations ($\ell \ge 2$) see a qualitatively similar barrier and are likewise strongly suppressed below their respective barrier-top frequencies. By contrast, the static gravitational monopole ($\ell =0$), governed by the linearized Einstein equations on the same background, satisfies the source-free conservation law $(a^2{\mathrm{\Phi }}^{\prime }{)}^{\prime }=0$ with no potential barrier, yielding the exact solution $\mathrm{\Phi }\propto \arctan (\sigma /r_0)$. We extend these results to a one-parameter family of throat geometries with varying profile shapes, and to a reflected-Schwarzschild (Damour-Solodukhin-type) wormhole, demonstrating that the qualitative asymmetry—strong sub-barrier suppression for all propagating radiation ($\ell \ge 1$) versus polynomial attenuation for the static monopole ($\ell =0$)—is universal for static, spherically symmetric throats. Numerov integration, WKB estimates, and exact analytical solutions are compared throughout. The results establish a structural constraint-wave asymmetry arising from the multipole decomposition of the field equations, independent of the matter content sourcing the geometry, on a fixed background.

We propose the jiggled interferometer (JIGI), a novel ground-based gravitational wave detector employing low-frequency noise mitigation similar to that of space-based detectors. Using rapidly repeated free-fall test masses, JIGI eliminates seismic and suspension thermal noise during free fall. Compared to the juggled interferometer, it offers improved angular stability and avoids tracking lasers. We analyze detrending—a required step to remove actuation-induced noise—and show sensitivity gains of about four orders of magnitude in the 0.1–0.3 Hz band, relative to seismic and suspension noise extrapolated from the Cosmic Explorer.

We study Bose-star formation in a Yukawa-Schrödinger-Poisson (YSP) system. A finite interaction range suppresses the infrared kinetic relaxation responsible for Bose-star condensation, modifying both the equilibrium Bose-star structure and the condensation timescale. We derive a screened kinetic condensation formula in which the ordinary gravitational Coulomb logarithm is replaced by a finite Yukawa transport logarithm. Static YSP solutions show that Yukawa screening broadens the Bose-star density profile relative to the ordinary Newtonian soliton. Fully dynamical pseudospectral simulations with homogeneous and isotropic initial conditions demonstrate that Yukawa screening systematically delays Bose-star condensation, in good agreement with the screened kinetic prediction after fitting a single overall normalization parameter.

We present an alternative measurement of the Baryon Acoustic Oscillation (BAO) using the Legendre multipole representation of the Lyman-$\alpha$ forest correlation functions from the second data release (DR2) of the Dark Energy Spectroscopic Instrument survey. Compressing the autocorrelation and cross-correlation functions into Legendre multipoles yields a positive-definite covariance matrix without any smoothing—unlike the baseline DR2 analysis—thanks to a significantly reduced data vector size. We introduce the statistical corrections required to debias the finite-sample covariance matrix estimate and demonstrate that monopole and quadrupole terms for both autocorrelations and cross-correlations can be used even when the correlation functions are distorted by continuum errors and contaminated by metals. This formalism has slightly diminished the constraining power of the BAO scale, while considerably weakening constraints on nuisance parameters. We measure the isotropic BAO scale with 0.93% precision at $z_{\mathrm{eff}}=2.35$, the Hubble parameter $H(z_{\mathrm{eff}})=(239.5\pm 3.4)(147.09\mathrm{Mpc}/r_d)\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$, and the transverse comoving distance $D_M(z_{\mathrm{eff}})=(5.80\pm 0.10)(r_d/147.09\mathrm{Mpc})\mathrm{Gpc}$ for a given value of the sound horizon ($r_d$). Our BAO results are entirely consistent with the baseline DR2 analysis.

The early dark energy resolution of Hubble tension seems to be suggesting a scale-invariant Harrison-Zeldovich spectrum of primordial scalar perturbation, i.e., $n_s=1$ [$|n_s-1|\sim \mathcal{O}(0.001)$] for $H_0\sim 73\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$. In this work, we propose a possibility to acquire $n_s=1$ in single field slow-roll models of inflation. In our consideration, the potential of inflaton during inflation still preserve the shape of well-known single field inflation models in deep slow-roll region, but inflation ends suddenly due to a large step of inflaton potential. In particular, we investigate the implication of our scheme for chaotic inflation and Starobinski inflation, and show how they can be compatible with the observation for $n_s=1$.

We study a modified cosmological scenario for the late Universe, involving an evolutionary dark energy model associated with the dynamics of a self-interacting scalar field in a potential-dominated regime. Through the analogy with a fluid energy-momentum tensor, we introduce a viscous contribution to the scalar dynamics, accounting for effective nonequilibrium behavior of the self-interacting scalar cluster. The resulting picture is that of an intrinsic quintessence contribution that, due to the bulk viscosity, admits an effective equation of state parameter that can also take values below $-1$. Within this framework, we set up the diagnostic tool of the so-called “effective running Hubble constant,” which allows us to trace possible deviations from a standard $\mathrm{\Lambda }\mathrm{CDM}$ model. We then compare this theoretical function with binned data from the master sample of Supernovae Ia [1], constructed assuming a $\mathrm{\Lambda }\mathrm{CDM}$ model in the Markov Chain Monte Carlo procedure performed in each bin. We show that the self-interacting scalar field corresponding to the best fit satisfies a slow-rolling condition, since the kinetic energy remains small compared to the potential contribution throughout the redshift interval. The key finding is that, when limiting the model to specific regions of the parameter space and fitting it to the data, the transition only occurs at redshifts significantly lower than the value $z\sim 0.5$ identified by the DESI Collaboration [2,3]. Furthermore, for the parameter values ensuring the best fit, no quintessence-to-phantom transition occurs (i.e., the effective equation of state parameter remains below $-1$ across the whole redshift domain). In other words, supernova data alone provide no indication of a change in the nature of the dark energy.

We report the first results of a subsolar mass compact binary search using the data from the first part of the fourth observing run (O4a) of the Advanced LIGO detectors. Subsolar mass neutron stars and black holes are not expected to form via standard stellar evolution, and their observation would signify a new class of astrophysical objects or the discovery of a component of dark matter. Our search covers binaries with primary masses 0.1 to $2M_{\odot }$ and secondary masses 0.1 to $1M_{\odot }$. We explicitly incorporate tidal effects up to $7\times {10}^5$ for extremely low mass neutron stars. Due to the recent development of efficient ratio filter dechirping frameworks, this search consisting of 25 million templates is now computationally feasible. No statistically significant candidates are identified. We place a 90% confidence upper limit on the merger rate ${\mathcal{R}}_{90}$ for subsolar mass black holes to be $<2.5\times {10}^4{\mathrm{Gpc}}^{-3}{\mathrm{yr}}^{-1}$ for a chirp mass of $0.2M_{\odot }$. We place the first constraints for binary neutron stars with tidal deformabilities up to $\sim 7\times {10}^5$ and improve the merger rate estimate by a factor $\sim 3$ in comparison to previous O3 tidal searches for tidal deformabilities $<{10}^4$. The advanced sensitivity of the O4a run enables an improvement in the subsolar mass black hole merger rate limits by more than $2\times$ over the previous three observing runs (O1–O3) combined. We constrain the effective local dark matter fraction to be ${\tilde{f}}_{\mathrm{PBH}}<0.5\%$ for $M_{\mathrm{PBH}}=0.4M_{\odot }$, approximately 2 times lower than the previous O1–O3 constraints. Given our model assumptions, our local dark matter fraction constraints are 2–10 times lower than the OGLE microlensing survey for $M_{\mathrm{PBH}}\ge 0.25M_{\odot }$.

Following the previous work by us [Phys. Rev. D 113, 023007 (2026)], here we consider early thermal evolution of hot strange stars made of color superconducting quarks in two different pairing states: two-flavor color superconductor and color-flavor-locked (CFL) phases, taking into account cooling by neutrinos and electron-positron pair creation due to the Schwinger process. We show that Schwinger luminosity in the electrosphere is a universal function of temperature, independent of quark matter phase for quark chemical potential ${\mu }_q>280\mathrm{MeV}$. The surface of a strange star in all the cases cools faster than its interior. This leads to a fast decrease of pair luminosity with time, so it does not exceed ${10}^{46}\mathrm{erg}/\mathrm{s}$ at 1 sec after strange star formation. Neutrino luminosity dominates over pair luminosity in all the cases except for the CFL phase with a large gap parameter $\mathrm{\Delta }>60\mathrm{MeV}$, where there is a strong suppression of neutrino emission. The total energy emitted in electron-positron pairs is always smaller than the energy emitted in neutrinos, but they become comparable for the large gap parameter.

Under ideal conditions, the shock acceleration theory of cosmic rays predicts that the spectral indices (γ) of different elements after acceleration should be consistent. However, studies of the spectra of elements with $\mathrm{A}/\mathrm{Z}\approx 2$, as measured by the AMS-02 experiment, confirm the existence of differences in spectral indices among these elements. In this work, based on a spatially dependent propagation model, we utilize observational data from AMS-02 and DAMPE to constrain $\gamma$. To avoid the influence of solar modulation and due to the lack of precise, high-energy component-resolved spectra, this study utilizes data only within the energy range of 3 GeV/n to 10 TeV/n. We determine that for elements with $\mathrm{A}/\mathrm{Z}\approx 2$, $\gamma$ is positively correlated with both Z and A, likely due to A- or Z-dependent fragmentation cross sections. We anticipate that the observed spectra of Ni and Zn will be consistent with that of Fe, while their injection spectra are expected to be slightly softer than that of Fe. We look forward to further measurements from AMS-02, DAMPE, and HERD to verify these findings, and we also hope for theoretical frameworks that can systematically explain this phenomenon.

Compact astrophysical objects, such as neutron stars, can provide a unique environment where the interplay between strongly interacting nuclear matter and dark matter (DM) can yield possible observable signatures. We investigate here the impact of fermionic DM interacting with nucleons via a vector mediator ($Z^{\prime }$) portal inside neutron stars using the relativistic mean-field framework. Unlike scalar portal DM models, which primarily modify the effective nucleon mass through scalar interactions, vector mediators ($Z^{\prime }$) introduce additional repulsive interactions that directly affect the baryonic chemical potential and the pressure of dense matter. We show that the precise measurements of neutron-star properties, including the mass-radius relation and tidal deformability from gravitational wave observations and x-ray and radio observations of pulsars, can shed light on properties of DM. We study the gross structural properties of a neutron star using the Tolman-Oppenheimer-Volkoff equations, employing an equation of state (EOS) for neutron-star matter in the presence of vector portal-assisted DM. The resulting stellar configurations, consistent with observational bounds from gravitational wave observations (GW170817) in LIGO/Virgo and x-ray observations of pulsar PSR $\mathrm{J}0030+0451$ in NICER, are shown to constrain the vector portal DM parameters. It is observed that, while large portal mass can soften the EOS of the DM-admixed neutron-star matter, the light portal mass can make the EOS stiffer at large densities, resulting in distinct mass-radius relation and the tidal deformability between the two scenarios. The vector portal DM scenario, with DM interaction with quarks via the $Z^{\prime }$ vector boson, can establish a direct connection to terrestrial searches, including direct and indirect detection and collider searches for the $Z^{\prime }$ boson. Taken together, these constitute a comprehensive framework that bridges neutron-star astrophysics with particle physics, enabling a multimessenger exploration of DM properties.

We report the direct detection of gamma-ray emission from the Galactic Center in the 150–600 keV band using the electron-tracking Compton camera (ETCC), which has a wide field of view of 3.1 sr. This represents the first application of this linear, imaging-spectroscopy method to observations of the Galactic Center. Measurements in a one-day flight over Australia yielded significant gamma-ray detection in the light curve and revealed a $7.9\sigma$ excess over the background in the image map from the Galactic Center region. These results, obtained through a simple and unambiguous analysis, demonstrate the high reliability and sensitivity of the ETCC and establish its potential for future high-precision MeV gamma-ray observations. The measured intensity and spatial distribution were tested against three emission models: a single pointlike source, a multicomponent structure, and a symmetric two-dimensional Gaussian. All three were found to be statistically consistent with the data. The positronium-related flux provided by the multicomponent model is $(3.2\pm 1.4)\times {10}^{-2}$ photons ${\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$, consistent with the value reported by INTEGRAL within $1\sigma$. These results establish the potential of the ETCC for future high-precision MeV gamma-ray surveys.

Ultra-high-energy neutrinos and cosmic rays are excellent probes of astroparticle physics phenomena. For astroparticle physics analyses, robust and accurate reconstruction of signal parameters such as arrival direction and energy is essential. Radio detection is an established detector concept explored by many observatories; however, current reconstruction methods ignore bin-to-bin noise correlations, which limits reconstruction resolution and, so far, has prevented calculations of event-by-event uncertainties. In this work, we present a likelihood description of neutrino or cosmic-ray signals in radio detectors with correlated noise, as present in all neutrino and cosmic-ray radio detectors. We demonstrate, with simulation studies of both neutrinos and cosmic-ray radio signals, that signal parameters such as energy and direction, including event-by-event uncertainties with correct coverage, can be obtained. This method reduces reconstruction uncertainties and biases compared to previous approaches. Additionally, the Likelihood can be used for event selection and enables differentiable end-to-end detector optimization. The reconstruction code is available through the open-source software NuRadioReco.