The detection of intermediate-mass black hole (IMBHs) i.e., those with mass $\sim 100–{10}^5{\mathrm{M}}_{\odot }$, is an emerging goal of gravitational-wave (GW) astronomy with wide implications for cosmology and tests of strong-field gravity. Current PyCBC-based searches for compact binary mergers, which match filtered the detector data against a set of template waveforms, have so far detected or confirmed several GW events. However, the sensitivity of these searches to signals arising from mergers of IMBH binaries is not optimal. Here, we present a new optimized PyCBC-based search for such signals. Our search benefits from using a targeted template bank, stricter signal-noise discriminators, and a lower matched-filter frequency cut-off. In particular, for a population of simulated signals with isotropically distributed spins, we improve the sensitive volume-time product over previous PyCBC-based searches at an inverse false alarm rate of 100 years, by a factor of 1.5 to 3 depending on the total binary mass. We deploy this new search on Advanced LIGO-Virgo data from the first half of the third observing run. The search does not identify any new significant IMBH binaries but does confirm the detection of the short-duration GW signal, GW190521, with a false alarm rate of 1 in 727 years.

Aromatic organic compounds, because of their small excitation energies $\sim \mathcal{O}(\mathrm{few}\mathrm{eV})$ and scintillating properties, are promising targets for detecting dark matter of mass $\sim \mathcal{O}(\mathrm{few}\mathrm{MeV})$. Additionally, their planar molecular structures lead to large anisotropies in the electronic wave functions, yielding a significant daily modulation in the event rate expected to be observed in crystals of these molecules. We characterize the daily modulation rate of dark matter interacting with an anisotropic scintillating organic crystal such as trans-stilbene, and show that daily modulation is an $\sim \mathcal{O}(1)$ fraction of the total rate for small DM masses and comparable to, or larger than, the $\sim 10\%$ annual modulation fraction at large DM masses. As we discuss in detail, this modulation provides significant leverage for detecting or excluding dark matter scattering, even in the presence of a non-negligible background rate. Assuming a nonmodulating background rate of $1/\min /\mathrm{kg}$ that scales with total exposure, we find that a $100\mathrm{kg}·\mathrm{yr}$ experiment is sensitive to the cross section corresponding to the correct relic density for dark matter masses between 1.3–14 MeV (1.5–1000 MeV) if dark matter interacts via a heavy (light) mediator. This modulation can be understood using an effective velocity scale $v^{*}=\mathrm{\Delta }E/q^{*}$, where $\mathrm{\Delta }E$ is the electronic transition energy and $q^{*}$ is a characteristic momentum scale of the electronic orbitals. We also characterize promising future directions for the development of scintillating organic crystals as dark matter detectors.

We study a pseudoscalar dark-matter model arising from a complex singlet extension of the standard model (SM), and show that the dark-matter nucleon scattering is suppressed when two $CP$-even scalars are degenerate. In such a degenerate-scalar scenario we explore the model parameter space which satisfies constraints from the direct detection experiments and the relic density of dark matter. In addition, we discuss a possibility to verify such a scenario by using the recoil-mass technique at the International Linear Collider. We find that a pair of states separated by 0.2 GeV can be distinguished from the single SM-like Higgs state at $5\sigma$ with an integrated luminosity of $2{\mathrm{ab}}^{-1}$.

During the expansion of a heavy ion collision, the system passes close to the $O(4)$ critical point of QCD, and thus the fluctuations of the order parameter $(\sigma ,\overrightarrow{\pi })$ are expected to be enhanced. Our goal is to compute how these enhanced fluctuations modify the transport coefficients of QCD near the pseudocritical point. We also make a phenomenological estimate for how chiral fluctuations could effect the momentum spectrum of soft pions. We first formulate the appropriate stochastic hydrodynamic equations close to the $O(4)$ critical point. Then, working in mean field, we determine the correlation functions of the stress tensor and the currents which result from this stochastic real-time theory, and use these correlation functions to determine the scaling behavior of the transport coefficients. The hydrodynamic theory also describes the propagation of pion waves, fixing the scaling behavior of the dispersion curve of soft pions. We present scaling functions for the shear viscosity and the charge conductivities near the pseudocritical point and estimate the absolute magnitude of the critical fluctuations to these parameters and the bulk viscosity. Using the calculated pion dispersion curve, we estimate the expected critical enhancement of soft pion yields, and this estimate provides a plausible explanation for the excess seen in experiment relative to ordinary hydrodynamic computations. Our results motivate further phenomenological and numerical work on the implications of chiral symmetry on real-time properties of thermal QCD near the pseudocritical point.

The quark contribution to the QCD pressure, $P_q$, is evaluated up to next-to-leading order (NLO) within the renormalization group optimized perturbation theory (RGOPT) resummation approach. To evaluate the complete QCD pressure we simply add the perturbative NLO contribution from massless gluons to the resummed $P_q$. Despite this unsophisticated approximation our results for $P=P_q+P_g$ at the central scale $M\sim 2\pi T$ show a remarkable agreement with lattice predictions for $0.25\lesssim T\lesssim 1\mathrm{GeV}$. We also show that by being imbued with RG properties, the RGOPT produces a drastic reduction of the embarrassing remnant scale dependence that plagues both standard thermal perturbative QCD and hard thermal loop perturbation theory applications.

We present an analysis of excited-state solutions for a gravitationally localized system consisting of a filled shell of high-angular-momentum fermions, using the Einstein-Dirac formalism introduced by Finster, Smoller, and Yau [Phys. Rev. D 59, 104020 (1999). We show that, even when the particle number is relatively low ($N_f\ge 6$), the increased nonlinearity in the system causes a significant deviation in behavior from the two-fermion case. Excited-state solutions can no longer be uniquely identified by the value of their central redshift, with this multiplicity producing distortions in the characteristic spiraling forms of the mass-radius relations. We discuss the connection between this effect and the internal structure of solutions in the relativistic regime.

Recently it was proposed that microscopic models of braneworld cosmology could be realized in the context of anti–de Sitter/conformal field theory ($\mathrm{AdS}/\mathrm{CFT}$) correspondence using black hole microstates containing an end-of-the-world brane. Motivated by a desire to establish the microscopic existence of such microstates, which so far have been discussed primarily in bottom-up models, we have studied similar microstates in a simpler version of $\mathrm{AdS}/\mathrm{CFT}$. On one side, we define and study boundary states in the charged Sachdev-Ye-Kitaev model and show that these states typically look thermal with a certain pattern of symmetry breaking. On the other side, we study the dimensional reduction of microstates in Einstein-Maxwell theory featuring an end-of-the-world brane and show that they have an equivalent description in terms of 2D Jackiw-Teitelboim gravity coupled to an end-of-the-world particle. In particular, the same pattern of symmetry breaking is realized in both sides of the proposed duality. These results give significant evidence that such black hole microstates have a sensible microscopic realization.

We investigate the interaction between a moving detector and a quantum field, especially about how the trajectory of the detector would affect the vacuum fluctuations when the detector moves in a quantum field (the Unruh effect). We focus on two moving detectors system for future application in quantum teleportation. We find that the trajectory of a uniformly accelerated detector in Rindler space cannot be extended to a trajectory in which a detector moves at constant velocity. Based on our previous work, we redo the calculations and find that a term is missing from past calculations, and we also find that there are some restrictions on the values for the parameters in the solutions. In addition, without inclusion of the missing term, the variance from the quantum field for the inertial detector will be zero and is unlikely in such a system. When all these points are combined, there is a difference in the two-point correlation function between the inertial detector and the accelerated detector in the early-time region. The influence of proper acceleration can be seen in the two-point correlation functions. This might play a role in the quantum teleportation process and be worth studying thoroughly.

Bayesian parameter estimation of gravitational waves from compact binary coalescence (CBC) typically requires the generation of millions of computationally expensive template waveforms. We propose a technique to reduce the cost of waveform generation by exploiting the chirping behavior of CBC signal. Our technique does not require waveforms at all frequencies in the frequency range used in the analysis, and does not suffer from the fixed cost due to the upsampling of waveforms. Our technique speeds up the parameter estimation of typical binary neutron star signal by a factor of $\mathcal{O}(10)$ for the low-frequency cutoff of 20 Hz, and $\mathcal{O}({10}^2)$ for 5 Hz. It does not require any offline preparations or accurate estimates of source parameters provided by detection pipelines.

In this paper, we investigate the deflection of a charged particle moving in the equatorial plane of Kerr-Newman spacetime, focusing on weak field limit. To this end, we use the Jacobi geometry, which can be described in three equivalent forms, namely the Randers-Finsler metric, the Zermelo navigation problem, and the ($n+1$)-dimensional stationary spacetime picture. Based on Randers data and Gauss-Bonnet theorem, we utilize the osculating Riemannian manifold method and the generalized Jacobi metric method, respectively, to study the deflection angle. In the ($n+1$)-dimensional spacetime picture, the motion of charged particle follows the null geodesic, and thus we use the standard geodesic method to calculate the deflection angle. The three methods lead to the same second-order deflection angle, which is obtained for the first time. The result shows that the black hole spin $a$ affects the deflection of charged particles both gravitationally and magnetically at the leading order [$\mathcal{O}([M{]}^2/b^2)$]. When $qQ/E<2M$, $a$ will decrease (or increase) the deflection of prograde (or retrograde) charged signal. If $qQ/E>2M$, the opposite happens, and the ray is divergently deflected by the lens. We also show that the effect of the magnetic charge of the dyonic Kerr-Newman black hole on the deflection angle is independent of the particle’s charge.

We develop a simple toy model for polarized images of synchrotron emission from an equatorial source around a Kerr black hole by using a semianalytic solution of the null geodesic equation and conservation of the Penrose-Walker constant. Our model is an extension of Narayan et al., which presented results for a Schwarzschild black hole, including a fully analytic approximation. Our model includes an arbitrary observer inclination, black hole spin, local boost, and local magnetic field configuration. We study the geometric effects of black hole spin on photon parallel transport and isolate these effects from the complicated combination of relativistic, gravitational, and electromagnetic processes in the emission region. Expanding in $1/r_{\mathrm{s}}$, we find an analytic approximation, consistent with previous work, for the geometric effect of spin on observed face-on polarization rotation in the direct image: $\mathrm{\Delta }\mathrm{EVPA}\sim -2a/r_{\mathrm{s}}^2$, where $a$ is the black hole spin and $r_{\mathrm{s}}$ is the emission radius. We further show that spin introduces an order unity effect on face-on subimages: $\mathrm{\Delta }\mathrm{EVPA}\sim \pm a/\sqrt{27}$. We also use our toy model to analyze polarization “loops” observed during flares of orbiting hot spots. Our model provides insight into polarimetric simulations and observations of black holes such as those made by the EHT and GRAVITY.

In the framework of the Einstein-Maxwell-axion-aether theory we establish the model, the Lagrangian of which contains the sin-type generalization of the term describing the axion-photon coupling, and the axionically induced cosine-type modification of the term attributed to the dilaton-photon interactions. The extension of the axion-dilaton-aether electrodynamics is inspired by the Jackson’s idea concerning the internal symmetry of the equations of electromagnetism. The application of the extended theory to the anisotropic homogeneous cosmological model of the Bianchi-I type is considered. The exact solutions to the model evolutionary equations are obtained for the case, when the axionic dark matter is in the state of equilibrium, which is characterized by vanishing potential of the pseudoscalar field and its first derivative. The state of the axion-photon system, which is of a new type and is indicated as a dynamic equilibrium, is studied in the framework of electrodynamics with axionic nonlinearity. We show that the nonlinear axion-photon interactions can mimic the dilaton-photon coupling. We discuss the stability of the model with respect to homogeneous fluctuations of the axion field.

We investigate what the orbits of globular clusters (GCs) in the Fornax dwarf spheroidal (dSph) galaxy can teach us about dark matter (DM). This problem was recently studied for ultralight dark matter (ULDM). We consider two additional models: (i) fermionic degenerate dark matter (DDM), where Pauli blocking should be taken into account in the dynamical friction computation; and (ii) self-interacting dark matter (SIDM). We give a simple and direct Fokker-Planck derivation of dynamical friction, new in the case of DDM and reproducing previous results in the literature for ULDM and cold DM. ULDM, DDM and SIDM were considered in the past as leading to cores in dSphs, a feature that acts to suppress dynamical friction and prolong GC orbits. For DDM we derive a version of the cosmological free streaming limit that is independent of the DM production mechanism, finding that DDM cannot produce an appreciable core in Fornax without violating Ly-$\alpha$ limits. If the Ly-$\alpha$ limit is discounted for some reason, then stellar kinematics data does allow a DDM core which could prolong GC orbits. For SIDM we find that significant prolongation of GC orbits could be obtained for values of the self-interaction cross section considered in previous works. In addition to reassessing the inspiral time using updated observational data, we give a new perspective on the so-called GC timing problem, demonstrating that for a cuspy cold DM profile dynamical friction predicts a $z=0$ radial distribution for the innermost GCs that is independent of initial conditions. The observed orbits of Fornax GCs are consistent with this expectation with a mild apparent fine-tuning at the level of $\sim 25\%$.

When searching for new gravitational-wave or electromagnetic sources, the $n$ signal parameters (masses, sky location, frequencies,...) are unknown. In practice, one hunts for signals at a discrete set of points in parameter space, with a computational cost that is proportional to the number of these points. If that is fixed, the question arises, where should the points be placed in parameter space? The current literature advocates selecting the set of points (called a “template bank”) whose Wigner–Seitz (also called Voronoï) cells have the smallest covering radius ($\equiv$ smallest maximal mismatch). Mathematically, such a template bank is said to have “minimum thickness”. Here, for realistic populations of signal sources, we compute the fraction of potential detections which are “lost” because the template bank is discrete. We show that at fixed computational cost, the minimum thickness template bank does not maximize the expected number of detections. Instead, the most detections are obtained for a bank which minimizes a particular functional of the mismatch. For closely spaced templates, the fraction of lost detections is proportional to a scale-invariant “quantizer constant” $G$, which measures the average squared distance from the nearest template, i.e., the average expected mismatch. This provides a straightforward way to characterize and compare the effectiveness of different template banks. The template bank which minimizes $G$ is mathematically called the “optimal quantizer”, and maximizes the expected number of detections. We review optimal quantizer and minimum thickness template banks that are built as $n$-dimensional lattices, showing that even the best of these offer only a marginal advantage over template banks based on the humble cubic lattice.

We investigate the dependence of the $\rho$ meson-nucleon coupling constant on the temperature of the medium using the soft-wall model of AdS/QCD. The finite temperature profile functions for the vector and fermion fields are applied to the model having a thermal dilaton field. The interaction Lagrangian in the bulk between these fields is written as in the zero temperature case and includes minimal- and magnetic-type interactions. The temperature dependence of the $g_{\rho NN}(T)$ coupling constant and its terms are plotted. We observe that the coupling constant and its separate terms become zero at the medium temperature near the Hawking temperature of the phase transition.

In many extensions of the Standard Model, the Higgs boson can decay into two light scalars, each of which then subsequently decay into two photons. The underlying event is $h\to 4\gamma$, but the kinematics from boosted light scalar decays combined with realistic detector resolutions may fail to register the events in straightforward categories and thus may be lost. In this article, we investigate the phase space for highly boosted diphoton events from these exotic Higgs decays and discuss search strategies that aim to capture and label events in this difficult region. In the process, we develop a new category, $\xi$ jets, which identifies with high selectivity highly collimated diphoton decay modes of the Higgs boson.

We provide a 0.8%-accurate determination of $V_{cs}$ from combining experimental results for the differential rate of $D\to K$ semileptonic decays with precise form factors that we determine from lattice QCD. This is the first time that $V_{cs}$ has been determined with an accuracy that allows its difference from 1 to be seen. Our lattice QCD calculation uses the highly improved staggered quark (HISQ) action for all valence quarks on gluon field configurations generated by the MILC Collaboration that include the effect of $u$, $d$, $s$, and $c$ HISQ quarks in the sea. We use eight gluon field ensembles with five values of the lattice spacing ranging from 0.15 fm to 0.045 fm and include results with physical $u/d$ quarks for the first time. Our calculated form factors cover the full $q^2$ range of the physical decay process and enable a Standard Model test of the shape of the differential decay rate as well as the determination of $V_{cs}$ from a correlated weighted average over $q^2$ bins. We obtain $|V_{cs}|=0.9663(53{)}_{\mathrm{latt}}(39{)}_{\exp }(19{)}_{{\eta }_{\mathrm{EW}}}(40{)}_{\mathrm{EM}}$, where the uncertainties come from lattice QCD, experiment, short-distance electroweak, and electromagnetic corrections, respectively. This last uncertainty, neglected for $D\to K\ell \nu$ hitherto, now needs attention if the uncertainty on $V_{cs}$ is to be reduced further. We also determine $V_{cs}$ values in good agreement using the measured total branching fraction and the rates extrapolated to $q^2=0$. Our form factors enable tests of lepton flavor universality violation. We find the ratio of branching fractions for $D^0\to K^{-}$ with $\mu$ and $e$ in the final state to be $R_{\mu /e}=0.9779(2{)}_{\mathrm{latt}}(50{)}_{\mathrm{EM}}$ in the Standard Model, with the uncertainty dominated by that from electromagnetic corrections.

Quantum technologies offer the prospect to efficiently simulate sign-problem afflicted regimes in lattice field theory, such as the presence of topological terms, chemical potentials, and out-of-equilibrium dynamics. In this work, we derive the $(3+1)\mathrm{D}$ topological $\theta$-term for Abelian and non-Abelian lattice gauge theories in the Hamiltonian formulation, paving the way toward Hamiltonian-based simulations of such terms on quantum and classical computers. We further study numerically the zero-temperature phase structure of a $(3+1)\mathrm{D}$ U(1) lattice gauge theory with the $\theta$-term via exact diagonalization for a single periodic cube. In the strong coupling regime, our results suggest the occurrence of a phase transition at constant values of $\theta$, as indicated by an avoided level crossing and abrupt changes in the plaquette expectation value, the electric energy density, and the topological charge density. These results could in principle be cross-checked by the recently developed $(3+1)\mathrm{D}$ tensor network methods and quantum simulations, once sufficient resources become available.

The relativistic charged spinor matter field is quantized in the background of a straight cosmic string with nonvanishing transverse size. The most general boundary conditions ensuring the impossibility for matter to penetrate through the edge of the string core are considered. The role of discrete symmetries is elucidated, and analytic expressions for the temporal and spatial components of the induced vacuum current are derived in the case of either $P$ or CT invariant boundary condition with two parameters varying arbitrarily from point to point of the edge. The requirement of physical plausibility for the global induced vacuum characteristics is shown to remove completely an arbitrariness in boundary conditions. We find out that a magnetic field is induced in the vacuum and that a sheath in the form of a tube of the magnetic flux lines encloses a cosmic string. The dependence of the induced vacuum magnetic field strength on the string flux and tension, as well as on the transverse size of the string and on the distance from the string, is unambiguously determined.