We nonperturbatively examine the emission rate of acceleration-induced radiation from a uniformly accelerated gapless qudit-type Unruh-DeWitt detector. We find that the emission rate can be written as Larmor’s formula multiplied by a factor that depends on the detector’s initial state. In particular, certain initial states of integer-spin detectors do not produce radiation. Although the appearance of Larmor’s formula may suggest a classical phenomenon, we argue that the resulting radiation is fundamentally distinct from that of structureless classical sources, as it evolves into a multimode coherent state correlated with the detector’s internal degree of freedom. Thus, gapless detectors cannot be treated as structureless sources, as previously proposed.

Analog models of black holes typically have collective excitations with a dispersion relation that breaks the effective Lorentz symmetry at high energy. We investigate the consequences of such Lorentz violations on the quasinormal modes (QNMs) of the system, that is, the modes of energy dissipation. The model involves low frequency capillary-gravity waves (whose dispersion relation can be adjusted between sub- and superluminal modifications) around a draining vortex, which mimics a rotating black hole spacetime. For a subluminal/superluminal modification, the frequency and decay rate of corotating modes can be reduced/increased substantially, while counterrotating modes are barely affected. A further consequence of the superluminal modification is that there are no corotating QNMs above a critical rotation and no counterrotating ones below a critical rotation for strong enough Lorentz violations.

We show that Laser Interferometer Space Antenna can uniquely identify the sites of intermediate-mass binary black hole (IMBBH) mergers if they occur in active galactic nuclei (AGN) disks with a gas density $\rho \ge {10}^{-12}\mathrm{g}/\mathrm{cc}$ via measurement of dynamical friction effect in the gravitational waveform. We find that even a single observation of a gravitational wave source with a total mass of ${10}^3{M}_{\odot }$ and a mass ratio of 2 at a luminosity distance of 3 Gpc is sufficient to confidently associate the merger to be in an AGN disk with a density $\sim {10}^{-12}\mathrm{g}/\mathrm{cc}$, as it allows estimation of the density with an error bar $\mathcal{O}(100\%)$. This provides a new way of inferring AGN disk densities that complement traditional x-ray observations. Further, we find that neglecting the presence of environmental effects in the waveform models used for parameter estimation can bias the chirp mass, mass ratio, and arrival time of a merger. If not corrected, this can significantly impact our ability to carry out multiband data analysis of IMBBHs that combines information from LISA and ground-based gravitational wave detectors.

A scalar field coupled conformally and disformally to matter affects both the linear memory effect for binary systems on hyperbolic orbits, as well as the kick velocity for binaries on bound or unbound orbits. We study these corrections in detail, their order of magnitude, and discuss their detectability. In particular, we find that the disformal interaction does not contribute to the memory effect and the emitted power spectrum at zero frequency. The conformal interaction corrects the GR linear memory and the quadrupole emitted power at zero frequency resulting in a breaking of the GR memory-power spectrum relationship. On the other hand, disformal interactions give rise to a change of momentum for the center of mass. Hence, measuring both the linear memory effect and the kicks for hyperbolic orbits would give access to the conformal and disformal couplings of nearly massless scalars to matter.

A new version of the modified theory of gravity is formulated in which two physical metrics are constructed out of two vierbeins connected with each other by the duality condition including the flat metric of the prior geometry. The duality condition plays a crucial role in this theoretical scheme, and thus gives the name to the whole approach: the theory of dual relativity (TDR). The energy-momentum tensor density of a closed system is defined, and the conservation law for this tensor density is deduced. In the TDR it is assumed that there exist two kinds of matter governed by two physical metrics connected to each other by the duality relations, and it is shown that the interaction between these kinds of matter has antigravitational character. A cosmological limit of the field equations of the TDR is considered. In this limit, there are two types of solutions; with positive and with negative energy density. The first type admits the existence of a stable Universe as a whole. The second type gives the oscillations of the cosmological scale factor within the finite limits excluding the zero point, that can be treated as a solution for a certain domain of the Universe. For this type of solutions, the model formula for the dependence of the Hubble parameter $H$ on the redshift $z$ has been obtained. The values of the parameters of this formula are found from the fit to the available $H(z)$ data. It is obtained that the TDR gives a better description of the $H(z)$ data as compared to the flat $\mathrm{\Lambda }\mathrm{CDM}$ model. The important consequences of the obtained results are, first, their incompatibility with the standard big bang model and, second, the existence of two critical values of the scale factor determining the points of its sharp change in the course of oscillations in the solutions of the second type.

We introduce a framework based on short Fourier transforms (SFTs) to analyze long-duration gravitational wave signals from compact binaries. Targeted systems include binary neutron stars observed by third-generation ground-based detectors and massive black hole binaries observed by the LISA space mission. In short, ours is an extremely fast, scalable, and parallelizable implementation of the gravitational wave inner product, a core operation of gravitational wave matched filtering. By operating on disjoint data segments, SFTs allow for efficient handling of noise nonstationarities, data gaps, and detector-induced signal modulations. We present a pilot application to early warning problems in both ground- and space-based next-generation detectors. Overall, SFTs reduce the computing cost of evaluating an inner product by three to five orders of magnitude, depending on the specific application, with respect to a nonoptimized approach. We release public tools to operate using the SFT framework, including a vectorized and hardware-accelerated reimplementation of a time-domain waveform. The inner product is the key building block of all gravitational wave data treatments; by speeding up this low-level element so massively, SFTs provide an extremely promising solution for current and future gravitational wave data-analysis problems.

Local-type primordial non-Gaussianity (PNG), predicted by many nonminimal models of inflation, creates a scale-dependent contribution to the power spectrum of large-scale structure tracers. Its amplitude is characterized by the product $b_{\varphi }{f}_{\mathrm{NL}}^{\mathrm{loc}}$, where $b_{\varphi }$ is an astrophysical parameter dependent on the properties of the tracer. However, $b_{\varphi }$ exhibits significant secondary dependence on halo concentration and other astrophysical properties, which may bias and weaken the constraints on $f_{\mathrm{NL}}^{\mathrm{loc}}$. In this work, we demonstrate that incorporating knowledge of the relation between Lagrangian bias parameters and $b_{\varphi }$ can significantly enhance PNG constraints. We employ the hybrid effective field theory approach at the field level and a linear regression model to seek a connection between the bias parameters and $b_{\varphi }$ for halo and galaxy samples, constructed using the abacussummit simulation suite and mimicking the luminous red galaxies and quasistellar objects of the Dark Energy Spectroscopic Instrument survey. For the fixed-mass halo samples, our full bias model reduces the uncertainty by more than 70%, with most of that improvement coming from $b_{\nabla }$, which we find to be an excellent proxy for concentration. For the galaxy samples, our model reduces the uncertainty on $b_{\varphi }$ by 80% for all tracers. By adopting Lagrangian-bias informed priors on the parameter $b_{\varphi }$, future analyses can thus constrain $f_{\mathrm{NL}}^{\mathrm{loc}}$ with less bias and smaller errors.

We assess the impact of accurate, self-consistent modeling of thermal effects in neutron-star merger remnants in the context of third-generation gravitational-wave detectors. This is done through the usage, in Bayesian model selection experiments, of numerical-relativity simulations of binary neutron star (BNS) mergers modeled through (i) nuclear, finite-temperature (or “tabulated”) equations of state (EOSs), and (ii) their simplifed piecewise (or “hybrid”) representation using seven or ten polytropic pieces. These cover four different EOSs, namely SLy4, DD2, HShen and LS220. Our analyses make direct use of the Newman-Penrose scalar ${\psi }_4$ outputted by numerical simulations. Considering a detector network formed by three Cosmic Explorers, we show that differences in the gravitational-wave emission predicted by the two models are detectable with a natural logarithmic Bayes factor $\log \mathcal{B}\ge 5$ at average distances of $d_L\simeq 50\mathrm{Mpc}$, reaching $d_L\simeq 100\mathrm{Mpc}$ for source inclinations $\iota \le 0.8$, regardless of the EOS. This impact is most pronounced for the HShen EOS. For low inclinations, only the DD2 EOS prevents the detectability of such modeling differences at $d_L\simeq 150\mathrm{Mpc}$. Our results suggest that the usage a self-consistent treatment of thermal effects is crucial for third-generation gravitational-wave detectors.

Quantum kinetics of neutrinos are known to potentially change the classical neutrino radiation field in high-energy astrophysical sources such as core-collapse supernovae and binary neutron-star mergers. However, the mixing phenomena still have open issues in the nonlinear dynamics and the asymptotic states, particularly for recently discovered collision-induced flavor conversion. In this paper, we investigate linear and nonlinear dynamics of collisional neutrino-flavor conversion (CFC) with multienergy neutrino gases through numerical simulations, demonstrating that the asymptotic states dramatically change depending on unstable modes dominating the system. In one unstable mode, high-energy neutrinos reach a flavor equipartition, but low-energy neutrinos return back to almost their initial states. In contrast, in the other one, rather low-energy neutrinos achieve a full flavor swap, but high-energy neutrinos undergo less flavor conversion. We clarify the distinct spectral behaviors in two different ways based on stability analysis and flavor pendulum. Our result suggests that CFC with flavor swap can become crucial at deeper radii with low electron fraction and requires more detailed theoretical modeling of neutrino quantum kinetics.

We perform spherically symmetric simulations of core-collapse supernovae with the aid of heavy axionlike particles (ALPs) which interact with photons and redistribute energy within supernova matter. We explore a wide ALP parameter space that includes MeV-scale ALP mass $m_a$ and the ALP-photon coupling constant $g_{a\gamma }\sim {10}^{-10}{\mathrm{GeV}}^{-1}$, employing three progenitor models with zero-age main-sequence mass of $11.2M_{\odot }$, $20.0M_{\odot }$, and $25.0M_{\odot }$. We find a general trend that, given $m_a\lesssim 300\mathrm{MeV}$, heavier ALPs are favorable for the shock wave to be successfully revived, aiding the onset of the neutrino-driven explosion. However, if ALPs are heavier than $\sim 400\mathrm{MeV}$, the explosion is failed or weaker than that for the models with smaller $m_a$, because of an insufficient temperature inside the supernova core to produce heavy ALPs. The maximum temperature in the core depends on the initial progenitor structure. Our simulations indicate that the high-temperature environment in the collapsing core of massive progenitors leads to a significant impact of ALPs on the explodability.

Hidden sector supersymmetry (SUSY) breaking where charged hidden sector fields obtain SUSY breaking vacuum expectation values once seemed common in dynamical SUSY breaking (DSB). In such a case, scalars can obtain large masses but gauginos and $A$-terms gain loop-suppressed anomaly-mediated contributions which may be smaller by factors of $1/16{\pi }^2\sim 1/160$. This situation leads to models such as PeV or minisplit supersymmetry with $m_{\mathrm{scalars}}\sim 160m_{\mathrm{gaugino}}$. In order to generate a light Higgs mass $m_h\simeq 125\mathrm{GeV}$, the scalar mass terms are required in the 10–100 TeV range, leading to large, unnatural contributions to the weak scale. Alternatively, in gravity mediation with singlet hidden sector fields, then $m_{\mathrm{scalars}}\sim m_{\mathrm{gauginos}}\sim A$-terms and the large $A$-terms lift $m_h\to 125\mathrm{GeV}$ even for natural values of $m_{{\tilde{t}}_1}\sim 1–3\mathrm{TeV}$. Requiring naturalness, which seems probabilistically preferred by the string landscape, then the measured Higgs mass seems to favor singlets in the hidden sector, which can be common in metastable and retrofitted DSB models.

The one loop matching kernels between parton distribution functions (PDFs) for parton $i=u$, $d$, $s$, $g$ and their corresponding quasi-PDFs are computed at one loop in the hybrid-ratio scheme. We found that, in addition to the conservation of the quasiquark number for each flavor, the second moment $⟨x{⟩}_{\tilde{i}}=⟨x{⟩}_i$ of quasi-PDF of parton $i$ (denoted as $\tilde{i}$) and PDF of parton $i$ is the same in our approach. This is demonstrated numerically using the CTEQ14 global analysis as input.

We investigate the possibility of reproducing the continuum physics of 2D $SU(N)$ gauge theory coupled to a single flavor of massless Dirac fermion using qubit regularization. The continuum theory is described by $N$ free fermions in the ultraviolet (UV) and a coset Wess-Zumino-Witten (WZW) model in the infrared (IR). In this work, we first explore how well these features can be reproduced using the Kogut-Susskind (KS) Hamiltonian with a finite-dimensional link Hilbert space and a generalized Hubbard coupling. We do this by analyzing the renormalization group (RG) flow diagram of the continuum theory and identifying important phases of the theory. Using strong coupling expansions, we show that our lattice model exhibits a gapped dimer phase and a spin-chain phase. Furthermore, for $N=2$, using tensor network methods, we show that there is a second-order phase transition between these two phases, which we identify as the critical surface of the continuum theory that connects the IR and UV fixed points. In the IR, we identify the critical theory at the transition as the expected $SU(2{)}_1$ WZW model. Lastly, we argue that modifications of our model may allow the study of the UV physics of free fermions.

The mass spectrum of the charmed mesons is investigated by considering the coupled channel effects within the nonrelativistic potential model. The predicted masses of the charmed mesons are in agreement with experimental data. The strong decay properties are further analyzed within the ${}^3{P}_0$ model by using numerical wave functions obtained from the nonrelativistic potential model. Based on the predicted masses and decay properties, we give a classification of the recently observed charmed states. Especially, we have effectively explained the masses and decay properties of the $D_1^{*}(2600)$ and $D_1^{*}(2760)$ by considering the $S-D$ mixing. Furthermore, the predicted masses and decay properties of the $2P$ wave states are helpful to search for them experimentally in future.

It has previously been demonstrated that the mesonic fields in chiral Lagrangians can be related to the quark-level operators of QCD sum-rules via energy-independent (constant) scale factor matrices constrained by chiral symmetry. This leads to universal scale factors for each type of chiral nonet related to quark-antiquark ($q\overline{q}$) operators and four-quark ($qq\overline{q}\overline{q}$) operators. Motivated by these successful demonstrations of scale-factor universality for the $K_0^{*}$ isodoublet and $a_0$ isotriplet scalar mesons, a revised Gaussian QCD sum rule methodology is developed that enables the extension to higher-dimensional isospin sectors, including the possibility of mixing with glueball components. Moreover, to extract nonperturbative information about a resonance stemming from the final state interactions of its decay products, a background-resonance interference approximation is developed and shown to provide an excellent description of both $\pi K$ scattering amplitude data and $\pi \eta$ scattering calculations. This background-resonance interference approximation inspires new resonance models as ingredients in the scale-factor analysis connecting chiral Lagrangians and QCD Gaussian sum rules. Using the revised Gaussian QCD sum rule methodology, key properties of the scale factors are examined for the $K_0^{*}$ isodoublet and $a_0$ isotriplet scalar mesons for a sequence of increasingly sophisticated resonance models. Gaussian sum rules are demonstrated to have sufficient resolution to distinguish between different resonance models, and it is shown that the background-resonance interference approximation not only describes $\{\pi K,\pi \eta \}$ scattering, but leads to the best universality and energy-independence properties of the scale factors.

In this study, we propose using the $Z_c(3900)$ pole position to constrain the existence of the $DD{D}^{*}$ three-body bound state within the one-boson-exchange (OBE) model. The existence of the $DD{D}^{*}$ bound state remains uncertain due to significant variations in the OBE interaction, particularly in the strength of scalar-meson-exchange interactions, which can differ by a factor about 20 between two commonly used OBE models. This discrepancy renders the $DD{D}^{*}$ system highly model-dependent. To address this issue, we constrain the scalar-meson-exchange interaction using the $Z_c(3900)$ pole position, where the pseudoscalar-meson coupling is well-determined, and the $\rho$- and $\omega$-exchange interactions nearly cancel each other out, leaving the coupling constant of the $\sigma$-exchange as the only unknown parameter. Our results indicate that the isospin-$\frac{1}{2}$ $DD{D}^{*}$ bound states exist when $Z_c(3900)$ is a virtual state of $D{\overline{D}}^{*}/\overline{D}{D}^{*}$ located within approximately $-15\mathrm{MeV}$ of the threshold. However, the three-body bound state is gone when the $Z_c(3900)$ virtual state pole is more than 20 MeV away from the threshold. Each experimental progress, either on the $DD{D}^{*}$ state or the $Z_c(3900)$, can shed light on the nature of the other state. Another significant outcome is a refined set of OBE model parameters calibrated using the pole positions of $X(3872)$, $T_{cc}(3875)$, and $Z_c(3900)$, rigorously addressing the cutoff dependence. These parameters provide a valuable resource for more accurate calculations of systems involving few-body $D$, $D^{*}$, and their antiparticles. Additionally, we find no evidence of the $DD{D}^{*}$ three-body resonances after extensive search using a combination of the Gaussian expansion method and the complex scaling method.

In a perturbation theory approach, the gravitational waveform is obtained by the convolution of the Green’s function and the source of radiation. Hence, the ringdown properties of black hole spacetimes, namely its start time, depend on both functions. The unknown time shift encoded in the Green’s function introduces a “time-shift problem” for ringdown. We study the ringdown time-shift problem by reconstructing a waveform via the excitation factors of quasinormal modes (QNMs) of a spinning black hole. For the first time, we reconstruct ringdown with a significant number of QNMs weighted with their excitation factors and find excellent convergence. We then precisely identify the ringdown starting time. We also find (i) that for moderate or large spins and $\ell =m=2$, QNMs should be included up to around the 20th prograde overtones and around fifth retrograde overtones to reconstruct the ringdown waveform for the delta-function source with a mismatch threshold $\mathcal{M}<\mathcal{O}({10}^{-3})$. For higher angular modes, a more significant number of QNMs are necessary to reconstruct it: (ii) that the time shift of ringdown caused by the Green’s function is the same for different $(\ell ,m,n)$ modes but that nontrivial sources can change this conclusion. Finally, we demonstrate (iii) that the graybody factor can be reconstructed with the superposed QNM spectrum in the frequency domain.

The anticipated observation of the gravitational microlensing of gravitational waves (GWs) promises to shed light on a host of astrophysical and cosmological questions. However, extracting the parameters of the lens from the modulated GWs requires accurate modeling of the lensing amplification factor, accounting for wave-optics effects. Analytic solutions to the lens equation have not been found to date, except for a handful of simplistic lens models. While numerical solutions to this equation have been developed, the time and computational resources required to evaluate the amplification factor numerically make large-scale parameter estimation of the lens (and source) parameters prohibitive. On the other hand, surrogate modeling of GWs has proven to be a powerful tool to accurately, and rapidly, produce GW templates at arbitrary points in parameter space, interpolating from a finite set of available waveforms at discrete parameter values. In this work, we demonstrate that surrogate modeling can also effectively be applied to the evaluation of the time-domain microlensing amplification factor $\tilde{F}(t)$. We show this by constructing $\tilde{F}(t)$ for two lens models, viz. point-mass lens, and singular isothermal sphere, which notably includes logarithmic divergence behavior. We find both surrogates reproduce the original lens models accurately, with mismatches $\lesssim 5\times {10}^{-4}$ across a range of plausible microlensed binary black hole sources observed by the Einstein Telescope. This surrogate is between 5 and ${10}^3$ times faster than the underlying lensing models, and can be evaluated in about 100 ms. The accuracy and efficiency attained by our surrogate models will enable practical parameter estimation analyses of microlensed GWs.