This is a third installment in a program to develop a method for alleviating the scale disparity in binary black hole simulations with mass ratios in the intermediate astrophysical range, where simulation cost is prohibitive while purely perturbative methods may not be adequate. The method is based on excising a “worldtube” around the smaller object, much larger than the object itself, replacing it with an analytical model that approximates a tidally deformed black hole. Previously [N. A. Wittek et al., Worldtube excision method for intermediate-mass-ratio inspirals: Scalar-field model in $3+1$ dimensions, Phys. Rev. D 108, 024041 (2023)] we have tested the idea in a toy model of a scalar charge in a fixed circular geodesic orbit around a Schwarzschild black hole, solving for the massless Klein-Gordon field in $3+1$ dimensions on the spectre platform. Here we take the significant further step of allowing the orbit to evolve radiatively, in a self-consistent manner, under the effect of back-reaction from the scalar field. We compute the inspiral orbit and the emitted scalar-field waveform, showing a good agreement with perturbative calculations in the adiabatic approximation. We also demonstrate how our simulations accurately resolve postadiabatic effects (for which we do not have perturbative results). In this work we focus on quasicircular inspirals. Our implementation is publicly accessible in the spectre numerical relativity code.

In the black hole perturbation theory framework, two different physical pictures for echoes in compact objects have been proposed. The first mechanism interprets echoes as repeated reflections of gravitational waves within a potential well, where the echo period is defined by twice the distance related to the spatial displacement operator that separates two local maxima of the effective potential. The second mechanism associates echoes with a discontinuity in the effective potential, potentially associated with specific accretion processes, without necessarily introducing a second local maximum in the effective potential. This discontinuity leads to echo signals that are typically attenuated over time more quickly, with their period dictated by the characteristics of the transfer amplitudes. In both scenarios, the echoes correspond to a new category of quasinormal modes with minor real parts, with their period connected to the spacing between successive modes in the frequency domain. This work elaborates on a unified framework in compact stars that encompasses both echo mechanisms. It suggests that these two types of echoes derive from different physical origins and can be independently triggered. The occurrence and interplay between these two types of echoes are demonstrated through numerical simulations.

We study the effects on particle production of a Planck-suppressed coupling between the inflaton and a scalar dark matter candidate, $\chi$. In the absence of this coupling the dominant source for the relic density of $\chi$ is the long wavelength modes produced from the scalar field fluctuations during inflation. In this case, there are strong constraints on the mass of the scalar and the reheating temperature after inflation from the present-day relic density of $\chi$ (assuming $\chi$ is stable). When a coupling $\sigma {\varphi }^2{\chi }^2$ is introduced, with $\sigma =\tilde{\sigma }{m}_{\varphi }^2/M_P^2\sim {10}^{-10}\tilde{\sigma }$, where $m_{\varphi }$ is the inflaton mass, the allowed parameter space begins to open up considerably even for $\tilde{\sigma }$ as small as $\gtrsim {10}^{-7}$. For $\tilde{\sigma }\gtrsim \frac{9}{16}$, particle production is dominated by the scattering of the inflaton condensate, either through single graviton exchange or the contact interaction between $\varphi$ and $\chi$. In this regime, the range of allowed masses and reheating temperatures is maximal. For $0.004<\tilde{\sigma }<50$, constraints from isocurvature fluctuations are satisfied, and the production from parametric resonance can be neglected.

The angular correlation of pulsar residuals observed by NANOGrav and other pulsar timing array collaborations show evidence in support of the Hellings-Downs correlation expected from stochastic gravitational wave background (SGWB). In this paper, we offer a nongravitational wave explanation of the observed pulsar timing correlations as caused by an ultralight $L_{\mu }-L_{\tau }$ gauge boson dark matter (ULDM). ULDM can affect the pulsar correlations in two ways. The gravitational potential of vector ULDM gives rise to a Shapiro time delay of the pulsar signals and a nontrivial angular correlation (as compared to the scalar ULDM case). In addition, if the pulsars have a nonzero charge of the dark matter gauge group, then the electric field of the local dark matter causes an oscillation of the pulsar and a corresponding Doppler shift of the pulsar signal. We point out that pulsars carry a significant charge of muons, and thus the $L_{\mu }-L_{\tau }$ vector dark matter contributes to both the Doppler oscillations and the time delay of the pulsar signals. The synergy between these two effects provides a better fit to the shape of the angular correlation function, as observed by the NANOGrav collaboration, compared to the standard SGWB explanation or the SGWB combined with time delay explanations. Our analysis shows that, in addition to the SGWB signal, there may potentially be excess timing residuals attributable to the $L_{\mu }-L_{\tau }$ ULDM.

We analyze the long-term evolution of hierarchical triple systems in Newtonian gravity to second order in the fundamental quadrupolar perturbation parameter, and to sixth order in $\epsilon =a/A$, the ratio of the semimajor axes of the inner and outer orbits. We apply the “two-timescale” method from applied mathematics to the Lagrange planetary equations for the inner and outer orbits, in which each osculating orbit element is split into an orbit averaged part that evolves on the long perturbative timescale, and an “average-free” part that is oscillatory in the orbital timescales. Averages over the two orbital timescales are performed using the well-known “secular approximation,” carefully adapted to account for the time integrals that produce the oscillatory solutions. We also incorporate perturbative corrections to the relation between time and the orbital phases, or “anomalies.” We place no restrictions on the masses of the three bodies, on the relative orbit inclinations or on the eccentricities, beyond the requirement that the quadrupolar perturbation parameter and $\epsilon$ both be “small.” The result is a complete set of long-timescale evolution equations for the averaged elements of the inner and outer orbits. At first order in perturbation theory, we obtain the dotriacontapole contributions explicitly at order ${\epsilon }^6$, augmenting earlier well-known results at quadrupole, octupole, and hexadecapole orders. At second order in perturbation theory, i.e. quadratic in the quadrupole perturbation amplitude, we find contributions that scale as ${\epsilon }^{9/2}$ (found in earlier work), ${\epsilon }^5$, ${\epsilon }^{11/2}$, and ${\epsilon }^6$. At first perturbative order and dotriacontapole order, the two averaged semimajor axes are constant in time (and we prove that this holds to arbitrary multipole orders); but at second perturbative order, beginning at $O({\epsilon }^5)$, they are no longer constant. Nevertheless we verify that the total averaged energy of the system is conserved, and we argue that this behavior is not incompatible with classical theorems on secular evolution of the semimajor axes.

Torsional oscillations of magnetized neutron stars have been well studied since they may be relevant to the physical interpretation of some of the observed quasiperiodic oscillations in the magnetar giant flares. In the crustal region of a magnetar, the strong magnetic field can alter the equation of state and composition due to the Landau-Rabi quantization of electron motion. In this paper, we study this effect on the crust-confined, torsional oscillation modes of neutron stars with mixed poloidal-toroidal magnetic fields in general relativity under the Cowling approximation. Furthermore, the inner and outer crusts are treated consistently based on the nuclear-energy density functional theory. Depending on the magnetic-field configurations, we find that the Landau-Rabi quantization of electrons can change the frequencies of the fundamental torsional oscillation mode of $1.4M_{\odot }$ neutron star models with a normal fluid core by about 10% when the magnetic field strength at the pole reaches the order of ${10}^{16}\mathrm{G}$. The shift can even approach 20% at a field strength of ${10}^{15}\mathrm{G}$ for neutron stars with a simple model of superconducting core where the magnetic field is assumed to be expelled completely.

In this work we investigate the phenomenological implications of several nontrivial Higgs-boson- axion couplings, which cover most of the possible nonperturbative scenarios. Specifically we consider the combination of having higher-order nonrenormalizable Higgs-boson-axion couplings originating from a weakly coupled effective theory combined with nonperturbative couplings of the form $\sim \epsilon {\mathrm{\Lambda }}_c^2|H{|}^2\cos (\frac{\varphi }{f_a})$. Since we consider the misalignment axion, the nonperturbative couplings can be expanded in the form of a perturbation expansion in powers of $\varphi /f_a$, thus after the electroweak symmetry breaking, the effective potential of the axion is drastically affected by these terms. We investigate the phenomenological implications of these terms for various values of the mass scale ${\mathrm{\Lambda }}_c$, and some scenarios are theoretically disfavored, while other scenarios with nonperturbative Higgs-boson-axion couplings of the form $\sim \epsilon {\mathrm{\Lambda }}_c^2|H{|}^2\cos (\frac{\varphi }{f_a})$ with ${\mathrm{\Lambda }}_c\sim {10}^{-10}\times m_a$ and $m_a\sim {10}^{-10}\mathrm{eV}$, lead to a characteristic pattern in the stochastic gravitational wave background via the deformation of the background equation of state parameter occurring at frequencies probed by the Einstein Telescope. We also consider loop effects from the Higgs sector caused by the term $\sim \epsilon {\mathrm{\Lambda }}_c^2|H{|}^2\cos (\frac{\varphi }{f_a})$ if we close the Higgs in one loop.

We study the high-energy behavior of the elastic scattering amplitude using two distinct unitarization schemes: the eikonal and the $U$-matrix. Our analysis begins with a formalism involving solely Pomerons, incorporating pion-loop insertions in the Pomeron trajectory representing the nearest singularity generated by $t$-channel unitarity. Subsequently, we explore a scenario that includes the presence of an Odderon. In our analyses, we explore the tension between the TOTEM and the ATLAS measurements for ${\sigma }_{\mathrm{tot}}$ and $d\sigma /dt$ at 7, 8, and 13 TeV and the subsequent implications for the properties of both the Pomeron and Odderon. Our results show that the Odderon phase factor ${\xi }_{\mathbb{O}}=-1$ is favored in both unitarization schemes, supporting an Odderon with a phase opposite to that of other crossing-odd components of the scattering amplitude. More interestingly, this specific phase factor stands as the sole one that aligns with results consistent with a nonzero Odderon coupling.

Motivated by the recent experimental measurements, we have investigated the Cabibbo-favored process ${\mathrm{\Lambda }}_c^{+}\to p{\overline{K}}^0\eta$, where the $N(1535)$ resonance is dynamically generated from the $S$-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach. The contributions from the intermediate $N(1650)$ and the predicted low-lying baryon ${\mathrm{\Sigma }}^{*}(1/2^{-})$ are also considered. In addition, a Breit-Wigner amplitude for the $N(1535)$ resonance is checked. By comparing with the measured $\eta p$, ${\overline{K}}^0\eta$, and $p{\overline{K}}^0$ invariant mass squared distributions, our results support the interpretation of $N(1535)$ as a dynamically generated state. Furthermore, we demonstrate that, with the contribution from ${\mathrm{\Sigma }}^{*}(1/2^{-})$ taken into account, the calculated invariant mass distributions agree with the Belle measurements. Future precise measurements of the ${\mathrm{\Lambda }}_c^{+}\to p{\overline{K}}^0\eta$ process can further elucidate the existence of the low-lying baryon ${\mathrm{\Sigma }}^{*}(1/2^{-})$.

In high-energy particle physics, the study of particle-particle correlations in proton-proton and heavy-ion collisions constitutes a pivotal frontier in the effort to understand the fundamental dynamics of the strong force. To the best of our knowledge, we employ for the first time the Balitsky-Fadin-Kuraev-Lipatov dynamics implemented in a Monte Carlo code in momentum space to compute final-state correlations in proton-proton collisions. Our present work aims to investigate whether the particular dynamics of the high-energy limit of QCD can contribute to the long-range rapidity correlations and the enigmatic ridge effect in proton-proton collisions.

The SPICE/HeRALD collaboration is performing research and development to enable studies of sub-GeV dark matter models using a variety of target materials. Here we report our recent progress on instrumenting a superfluid ${}^4\mathrm{He}$ target mass with a transition-edge sensor based calorimeter to detect both atomic signals (scintillation) and ${}^4\mathrm{He}$ quasiparticle (phonon and roton) excitations. The sensitivity of HeRALD to the critical “quantum evaporation” signal from ${}^4\mathrm{He}$ quasiparticles requires us to block the superfluid film flow to the calorimeter. We have developed a heat-free film-blocking method employing an unoxidized Cs film, which we implemented in a prototype “HeRALD v0.1” detector of $\sim 10\mathrm{g}$ target mass. This article reports initial studies of the atomic and quasiparticle signal channels. A key result of this work is the measurement of the quantum evaporation channel’s gain of $0.15\pm 0.01$, which will enable ${}^4\mathrm{He}$-based dark matter experiments in the near term. With this gain the HeRALD detector reported here has an energy threshold of 145 eV at $5\sigma$, which would be sensitive to dark matter masses down to $220\mathrm{MeV}/{\mathrm{c}}^2$.

We perform an angular analysis of the $B\to K^{*}{e}^{+}{e}^{-}$ decay for the dielectron mass squared, $q^2$, range of $0.0008–1.1200{\mathrm{GeV}}^2/c^4$ using the full Belle dataset in the $K^{*0}\to K^{+}{\pi }^{-}$ and $K^{*+}\to K_S^0{\pi }^{+}$ channels, incorporating new methods of electron identification to improve the statistical power of the dataset. This analysis is sensitive to contributions from right-handed currents from physics beyond the Standard Model by constraining the Wilson coefficients ${\mathcal{C}}_7^{(\prime )}$. We perform a fit to the $B\to K^{*}{e}^{+}{e}^{-}$ differential decay rate and measure the imaginary component of the transversality amplitude to be $A_T^{\mathrm{Im}}=-1.27\pm 0.52\pm 0.12$, and the $K^{*}$ transverse asymmetry to be $A_T^{(2)}=0.52\pm 0.53\pm 0.11$, with $F_L$ and $A_T^{\mathrm{Re}}$ fixed to the Standard Model values. The resulting constraints on the value of ${\mathcal{C}}_7^{\prime }$ are consistent with the Standard Model within a $2\sigma$ confidence interval.

The results of the search for the $e^{+}{e}^{-}\to {\eta }^{\prime }\gamma$ process in the center-of-mass energy range from 1.075 to 2 GeV are presented. We analyze data with an integral luminosity of $746{\mathrm{pb}}^{-1}$ accumulated with the SND detector at the $e^{+}{e}^{-}$ collider VEPP-2000 in 2010–2024. The ${\eta }^{\prime }\to \eta {\pi }^0{\pi }^0$ decay is used in the analysis, with the subsequent $\eta$ and ${\pi }^0$ decays into $\gamma \gamma$. Upper limits not exceeding 13 pb have been set on the $e^{+}{e}^{-}\to {\eta }^{\prime }\gamma$ cross section at the 90% confidence level.

All independent interaction vertices involving massless (Fang-Fronsdal) fermions in three dimensions are classified, completing the classification of interactions of massless fields of any spin. Similar to the bosonic case, we get no independent vertices at quartic or higher order in the fields involving fields with spin $s\ge 3/2$ and cubic vertices only for spins satisfying triangle inequalities, apart from the cases involving (matter) fields with spin $s\le 1$. Different from the bosonic cases, we get only one vertex for each triple of spins with two Majorana fermions and one boson, which is parity even (odd) when the sum of the spins of all fields involved is odd (even). When the two Majorana fermions are identical, their coupling to an odd-spin boson is trivialized. We comment on the nontrivial holographic dictionary relating these vertices to conformal field theory correlators in two dimensions.

The $S$-matrix formulation of gravity suggests that the $\theta$-vacuum structure must not be sustained by the theory. We point out that, when applied to the vacuum of general relativity, this criterion hints to supersymmetry. The topological susceptibility of gravitational vacuum induced by Eguchi-Hanson instantons can be eliminated neither by spin-$1/2$ fermions nor by an axion coupled via them since such fermions do not provide instanton zero modes. Instead, the job is done by a spin-$3/2$ fermion, hence realizing a local supersymmetry. This scenario also necessitates the spontaneous breaking of supersymmetry and predicts the existence of axion of $R$ symmetry which gets mass exclusively from the gravitational instantons. The $R$ axion can be a viable dark matter candidate. Matching between the index and the anomaly imposes a constraint that spin-$1/2$ fermions should not contribute to the chiral gravitational anomaly.

We study stationary rotating topological solitons in a ($2+1$)-dimensional $\mathbb{C}{P}^2$ nonlinear sigma model with a stabilizing potential term. We find families of $U(1)\times U(1)$ symmetric solutions with topological degrees equal or larger than 1, which have two angular frequencies and are labeled by two (one topological and the other nontopological) winding numbers $k_1\ge k_2$. We discuss properties of these solitons and investigate the domains of their existence.

Mixing between ultralight bosons and the Standard Model photon may allow access to the hitherto invisible Universe. In the presence of plasma, photons are dressed with an effective mass which will influence the conversion between the two. We study this phenomenon, known as in-medium suppression, in the context of black hole physics. We consider both axion-photon mixing around charged black holes and dark photon-photon mixing around neutral black holes. We find that the presence of plasma indeed influences the conversion rate, possibly quenching it altogether for large plasma densities, and discuss implications for superradiance and observational signatures.

We present the proof of renormalization of the Hořava theory in the nonprojectable version. We obtain a form of the quantum action that exhibits a manifest Becchi-Rouet-Stora-Tyutin–symmetry structure. Previous analysis has shown that the divergences produced by irregular loops cancel completely between them. The remaining divergences are local. The renormalization is achieved by using the approach developed by Barvinsky et al. with the background-field formalism.

Aether scalar-tensor theory is a modification of general relativity proposed to explain galactic and cosmological mass discrepancies conventionally attributed to dark matter. The theory is able to fit the cosmic microwave background and the linear matter power spectrum. In this work, we derive the Tolman-Oppenheimer-Volkoff equation in this theory and solve it for realistic nuclear equations of state to predict the mass-radius relation of neutron stars. We find solutions that are compatible with all current observations of neutron stars.

We present cosmology results obtained from a blind joint analysis of the abundance, projected clustering, and weak lensing of galaxy clusters measured from the Sloan Digital Sky Survey (SDSS) redMaPPer cluster catalog and the Hyper-Suprime Cam (HSC) Year 3 shape catalog. We present a full-forward model for the cluster observables, which includes empirical modeling for the anisotropic boosts on the lensing and clustering signals of optical clusters. We validate our analysis via mock cluster catalogs which include observational systematics, such as the projection effect and the effect of baryonic feedback, and find that our analysis can robustly constrain cosmological parameters in an unbiased manner without any informative priors on our model parameters. The joint analysis of our observables in the context of the flat $\mathrm{\Lambda }\mathrm{CDM}$ model results in cosmological constraints for $S_8\equiv {\sigma }_8\sqrt{{\mathrm{\Omega }}_{\mathrm{m}}/0.3}={0.816}_{-0.039}^{+0.041}$. Our result is consistent with the $S_8$ inference from other cosmic microwave background- and large scale structure-based cosmology analyses, including the result from the Planck 2018 primary CMB analysis.