Binary black hole simulations become increasingly more computationally expensive with smaller mass ratios, partly because of the longer evolution time, and partly because the lengthscale disparity dictates smaller time steps. The program initiated by Dhesi et al. [Phys. Rev. D 104, 124002 (2021)] explores a method for alleviating the scale disparity in simulations with mass ratios in the intermediate astrophysical range (${10}^{-4}\lesssim q\lesssim {10}^{-2}$), where purely perturbative methods may not be adequate. A region (“worldtube”) much larger than the small black hole is excised from the numerical domain, and replaced with an analytical model approximating a tidally deformed black hole. Here we apply this idea to 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. This is a first implementation of the worldtube excision method in full $3+1$ dimensions. We demonstrate the accuracy and efficiency of the method, and discuss the steps toward applying it for evolving orbits and, ultimately, in the binary black-hole scenario. Our implementation is publicly accessible in the spectre numerical relativity code.

We study the dynamics of the field equations in a four-dimensional isotropic and homogeneous spatially flat Friedmann-Lemaître-Robertson-Walker geometry in the context of Einstein-Gauss-Bonnet theory with a matter source and a scalar field coupled to the Gauss-Bonnet scalar. In this theory, the Gauss-Bonnet term contributes to the field equations. The mass of the scalar field depends on the potential function and the Gauss-Bonnet term. For the scalar field potential, we consider the exponential function and the coupling function between the scalar field and the Gauss-Bonnet scalar is considered to be the linear function. Moreover, the scalar field can have a phantom behavior. We consider a set of dimensionless variables and write the field equations into a system or algebraic-differential equations. For the latter, we investigate the equilibrium points and their stability properties. We use compactified variables to perform a global analysis of the asymptotic dynamics. This gravitational theory can explain the Universe’s recent and past acceleration phases. Therefore, it can be used as a toy model for studying inflation or as a dark energy candidate.

Over the last few years, there has been a large momentum to ensure that the third-generation era of gravitational wave detectors will find its realisation in the next decades, and numerous design studies have been ongoing for some time. Some of the main factors determining the cost of the Einstein Telescope lie in the length of the interferometer arms and its shape; L-shaped detectors versus a single triangular configuration. Both designs are further expected to include a xylophone configuration for improvement on both ends of the frequency bandwidth of the detector. We consider binary neutron star sources in our study, as examples of sources already observed with the current-generation detectors and ones which hold most promise given the broader frequency band and higher sensitivity of the third-generation detectors. We estimate parameters of the sources, with different kinds of configurations of the Einstein Telescope detector, varying arm lengths, as well as shapes and alignments. Overall, we find little improvement with respect to changing the shape, or alignment. However, there are noticeable differences in the estimates of some parameters, including tidal deformability, when varying the arm length of the detectors. In addition, we also study the effect of changing the laser power, and the lower limit of the frequency band in which we perform the analysis.

The impact of a strong electromagnetic background field on otherwise perturbative QED processes is studied in the momentum-space formulation. The univariate background field is assumed to have finite support in time, thus being suitable to provide a model for a strong laser pulse in plane-wave approximation. The usually employed Furry picture in position space must be equipped with some regularizing procedure, also to ensure the Ward identity. The momentum space formulation allows generically for an easy and systematic account of such expressions, both globally and order-by-order in the weak-field expansion. In the limit of an infinitely long-acting (monochromatic) background field, these terms become gradually suppressed, and the standard perturbative QED Feynman diagrams are recovered in the leading-order weak-field limit. A few examples of three- and four-point amplitudes are considered to demonstrate the application of our Feynman rules which employ free Dirac spinors, the free photon propagator, and the free fermion propagator, while the external field impact is solely encoded in the fermion-fermion-photon vertex function. Properties of the latter vertex function are elaborated in some detail. The appearance of on/off shell contributions, singular structures, and Oleinik resonances is pointed out.

We study the role of the Schwinger phase (SP) that appears in the propagator of a charged particle in the presence of a static and uniform magnetic field $\overrightarrow{B}$. We first note that this phase cannot be removed by a gauge transformation; far from this, we show that it plays an important role in the restoration of the symmetries of the system. Next, we analyze the effect of SPs in the one-loop corrections to charged pion and rho meson self-energies. To carry out this analysis we consider first a simple form for the meson-quark interactions, and then we study the ${\pi }^{+}$ and ${\rho }^{+}$ propagators within the Nambu-Jona-Lasinio model, performing a numerical analysis of the $B$ dependence of meson lowest energy states. For both ${\pi }^{+}$ and ${\rho }^{+}$ mesons, we compare the numerical results arising from the full calculation—in which SPs are included in the propagators, and meson wave functions correspond to states of definite Landau quantum number—and those obtained within alternative schemes in which SPs are neglected (or somehow eliminated) and meson states are described by plane waves of definite four-momentum.

Massive vector particles are minimal dark matter candidates that motivate a wide range of laboratory searches, primarily exploiting a postulated kinetic mixing with the photon. However, depending on the high energy field content, the dominant vector dark matter (VDM) coupling to visible particles may arise at higher operator dimension, motivating efforts to predict direct detection rates for more general interactions. Here, we present the first calculation of VDM absorption through its coupling to electron electric (EDM) or magnetic (MDM) dipole moments, which can be realized in minimal extensions to the Standard Model and yield the observed abundance through a variety of mechanisms across the eV–MeV mass range. We compute the absorption rate of the MDM and EDM models for a general target and then derive direct detection constraints from targets currently in use: Si and Ge crystals and Xe and Ar atoms. We find that current experiments are already sensitive to VDM parameter space corresponding to a cosmological freeze-in scenario, and future experiments will be able to completely exclude MDM and EDM freeze-in models with reheat temperatures below the electroweak scale. Additionally, we find that while constraints on the MDM interaction can be related to constraints on axionlike particles, the same is not true for the EDM model, so the latter absorption rate must be computed from first principles. To achieve this, we update the publicly available program $\mathsf{EXCEED-}\mathsf{DM}$ to perform these new calculations.

We entertain the novel possibility that long-range forces may lead to violations of accidental symmetries, in particular baryon number. Employing an ultralight scalar, with a mass $\ll \mathrm{eV}$, we illustrate that this scenario can lead to vastly disparate nucleon lifetimes, in different astronomical objects. Such a long range interaction can yield a number of potentially observable effects, such as a flux of neutrinos at $\gtrsim 10\mathrm{MeV}$ from the Sun and heating of old neutron stars. We examine the prospects for constraining this scenario, with current and future astrophysical data, and find that neutron star heating provides the strongest present and near term bounds. Simple extensions of our setup allow for the ultralight scalar to constitute the dark matter of the Universe. This suggests that matter-enhanced baryon-number violation can be a signal of ultralight dark matter, which has apparently been overlooked, so far.

We investigate the possibilities of probing the electroweak scale seesaw scenarios such as type-I, type-II, and type-III seesaw at $e^{-}\gamma$ and $\gamma \gamma$ colliders. For the case of type-I seesaw, the heavy neutrinos can be produced at $e^{-}\gamma$ colliders in association with a $W$ boson. We study a variety of final states in this case, including single and multilepton modes in association with jets to estimate bounds on the light-heavy neutrino mixing angle. In case of type-II seesaw, doubly charged multiplets of the $\mathrm{SU}(2{)}_L$ triplet scalar can be produced in pair at $\gamma \gamma$ collider. We study the multileptonic decay modes coming from this pair production of doubly charged Higgs and show how one can probe neutrino mass hierarchy. We also study same-sign $W$ boson production from the doubly charged Higgs to study multilepton modes in association with missing energy. From the type-III seesaw, we study same-sign $\mathrm{dilepton}+\text{jets}$ and $\mathrm{trilepton}+\text{jets}$ modes at $e^{-}\gamma$ collider which are coming from the neutral and charged component of the triplet fermion in association with a $W$ boson and a $Z$ boson, respectively. Due to the existing limits on the triplet fermions from the LHC we choose heavier mass so that the gauge boson originating from the decay of a neutral multiplet can be sufficiently boosted producing a fat-jet signature in association with same-sign dilepton and trilepton. Finally, we estimate bounds on the light neutrino-heavy triplet fermion mixing angle and compare them with the existing bounds.

We demonstrate that the Ising model on a general triangular graph with three distinct couplings $K_1$, $K_2$, and $K_3$ corresponds to an affine transformed conformal field theory (CFT). Full conformal invariance of the $c=1/2$ minimal CFT is restored by introducing a metric on the lattice through the map $\sinh (2K_i)={\ell }_i^{*}/{\ell }_i$ which relates critical couplings to the ratio of the dual hexagonal and triangular edge lengths. Applied to a 2D toroidal lattice, this provides an exact lattice formulation in the continuum limit to the Ising CFT as a function of the modular parameter. This example can be viewed as a quantum generalization of the finite element method applied to the strong coupling CFT at a Wilson-Fisher IR fixed point and suggests a new approach to conformal field theory on curved manifolds based on a synthesis of simplicial geometry and projective geometry on the tangent planes.

In the framework of the Born-Oppenheimer effective field theory, the hyperfine structure of heavy quarkonium hybrids at leading order in the $1/m_Q$ expansion is determined by two potentials. We estimate those potentials by interpolating between the known short-distance behavior and the long-distance behavior calculated in the QCD effective string theory. The long-distance behavior depends, at leading order, on two parameters which can be obtained from the long-distance behavior of the heavy quarkonium potentials (up to sign ambiguities). The short-distance behavior depends, at leading order, on two extra parameters, which are obtained from a lattice calculation of the lower-lying charmonium hybrid multiplets. This allows us to predict the hyperfine splitting both of bottomonium hybrids and of higher multiplets of charmonium hybrids. We carry out a careful error analysis and compare with other approaches.

We present a new derivation of Israel-Stewart-like relativistic second-order dissipative spin hydrodynamic equations using the entropy current approach. In our analysis, we consider a general energy-momentum tensor with symmetric and antisymmetric parts. Moreover, the spin tensor, which is not separately conserved, has a simple phenomenological form that is antisymmetric only in the last two indices. Apart from the evolution equations for energy density, fluid flow, and spin density, we also find relaxation-type dynamical equations for various dissipative currents. The latter are consistently derived within the second-order theory as gradient corrections to the energy-momentum and spin tensors. We argue that this approach correctly reproduces the corresponding Navier-Stokes limit of spin hydrodynamic equations. Throughout our analysis, the spin chemical potential is considered an $\mathcal{O}(\partial )$ quantity in the hydrodynamic gradient expansion and reduces to thermal vorticity in the global equilibrium. New coefficients appearing in the generalized spin hydrodynamic equations are undetermined and can only be evaluated within a proper underlying microscopic theory of a given system.

Glueballs remain an experimentally undiscovered expectation of QCD. Lattice QCD (As well as other theoretical approaches) predicts a spectrum of glueballs, with the tensor ($J^{PC}=2^{++}$) glueball being the second lightest, behind the scalar glueball. Here, using a chiral hadronic model, we compute decay ratios of the tensor glueball into various meson decay channels. We find the tensor glueball to primarily decay into two vector mesons, dominated by $\rho \rho$ and $K^{*}{K}^{*}$ channels. These results are compared to experimental data of decay rates of isoscalar tensor mesons. Based on this comparison, we make statements on the eligibility of these mesons as potential tensor glueball candidates: the resonance $f_2(1950)$ turns out to be, at present, the best match as being predominantly a tensor glueball.

We describe a new data sample of IceCube DeepCore and report on the latest measurement of atmospheric neutrino oscillations obtained with data recorded between 2011–2019. The sample includes significant improvements in data calibration, detector simulation, and data processing, and the analysis benefits from a sophisticated treatment of systematic uncertainties, with significantly greater level of detail since our last study. By measuring the relative fluxes of neutrino flavors as a function of their reconstructed energies and arrival directions we constrain the atmospheric neutrino mixing parameters to be ${\sin }^2{\theta }_{23}=0.51\pm 0.05$ and $\mathrm{\Delta }{m}_{32}^2=2.41\pm 0.07\times {10}^{-3}{\mathrm{eV}}^2$, assuming a normal mass ordering. The errors include both statistical and systematic uncertainties. The resulting 40% reduction in the error of both parameters with respect to our previous result makes this the most precise measurement of oscillation parameters using atmospheric neutrinos. Our results are also compatible and complementary to those obtained using neutrino beams from accelerators, which are obtained at lower neutrino energies and are subject to different sources of uncertainties.

Measurements of $CP$ asymmetry in charmless $B\to PV$ decays are presented, where $P$ and $V$ denote a pseudoscalar and a vector meson, respectively. Five different $B\to PV$ decays from four final states, $B^{\pm }\to {\pi }^{\pm }{\pi }^{+}{\pi }^{-}$, $B^{\pm }\to K^{\pm }{\pi }^{+}{\pi }^{-}$, $B^{\pm }\to K^{\pm }{K}^{+}{K}^{-}$ and $B^{\pm }\to {\pi }^{\pm }{K}^{+}{K}^{-}$ are analyzed. The measurements are based on a method that does not require full amplitude analyses, and are performed using proton-proton collision data at a center-of-mass energy of 13 TeV collected by LHCb between 2015 and 2018, corresponding to an integrated luminosity of $5.9{\mathrm{fb}}^{-1}$. In the ${\pi }^{+}{\pi }^{-}$ $P$-wave, in the region dominated by the $B^{\pm }\to \rho (770{)}^0{K}^{\pm }$ decay, a $CP$ asymmetry of $A_{CP}=+0.150\pm 0.019\pm 0.011$ is measured, where the first uncertainty is statistical and the second is systematic. This is the first observation of $CP$ violation in this process. For the other four decay channels, in regions dominated by the $B^{\pm }\to \rho (770{)}^0{\pi }^{\pm }$, $B^{\pm }\to \stackrel{(¯)}{K}{}^{*}(892{)}^0{\pi }^{\pm }$, $B^{\pm }\to \stackrel{(¯)}{K}{}^{*}(892{)}^0{K}^{\pm }$ and $B^{\pm }\to \varphi (1020)K^{\pm }$ decays, $CP$ asymmetries in the $P$-wave compatible with zero are measured.

We propose antiferromagnets as optimal targets to hunt for sub-MeV dark matter with spin-dependent interactions. These materials allow for multimagnon emission even for very small momentum transfers and are therefore sensitive to dark matter particles as light as the keV. We use an effective theory to compute the event rates in a simple way. Among the materials studied here, we identify nickel oxide (a well-assessed antiferromagnet) as an ideal candidate target. Indeed, the propagation speed of its gapless magnons is very close to the typical dark matter velocity, allowing the absorption of all its kinetic energy, even through the emission of just a single magnon.

In effective field theory, the positivity bounds of higher-derivative operators are derived from analyticity, causality, and unitarity. We show that the positivity bounds on some operators of the effective field theory, e.g., the dimension-eight term of a single massless scalar field, the Standard Model effective field theory dimension-eight $SU(N)$ gauge bosonic operators, and higher-derivative operators in the Einstein-Maxwell theory, generated by interactions between heavy and light degrees of freedom can be derived by the non-negativity of relative entropy. For such effective field theories, we prove that the interactions increase thermodynamic entropy at a fixed charge and an extremal point of energy, which is intimately connected with the extremality relations of black holes exhibiting the weak gravity conjecture. These arguments are applicable when corrections from the interactions involving higher-derivative operators of light fields are not dominant in the effective field theories. The entropy constraint is a consequence of the Hermiticity of Hamiltonian, and any theory violating the non-negativity of entropy would not respect the second law of thermodynamics.

We reduce the study of perturbations of rotating black holes in higher-derivative extensions of general relativity to a system of decoupled radial equations that stem from a set of universal Teukolsky equations. We detail a complete computational strategy to obtain these decoupled equations in general higher-derivative theories. We apply this to six-derivative gravity to compute the shifts in the quasinormal mode frequencies with respect to those of Kerr black holes in general relativity. At linear order in the angular momentum we reproduce earlier results obtained with a metric perturbation approach. In contrast with this earlier work, however, the method given here applies also to postmerger black holes with significant spin, which are of particular observational interest.

It was demonstrated by Comisso and Asenjo that the magnetic reconnection in the ergosphere is a promising mechanism to extract energy from the rotating Kerr black hole. In this work, we investigate the role of the Comisso-Asenjo mechanism in energy extraction from the newly suggested rotating hairy black holes which have an extra hair due to the additional surrounding sources, such as dark matter or dark energy. We examine how the hairy parameters characterized the hair affect the magnetic reconnection process in addition to other important variables of the Comisso-Asenjo process, including the parameter spaces that permit energy extraction, the power, efficiency and power ratios with respect to the Blandford-Znajek mechanism.

Recent interest in new early dark energy (NEDE), a cosmological model with a vacuum energy component decaying in a triggered phase transition around recombination, has been sparked by its impact on the Hubble tension. Previous constraints on the model parameters were derived in a Bayesian framework with Markov-chain Monte Carlo (MCMC) methods. In this work, we instead perform a frequentist analysis using the profile likelihood in order to assess the impact of prior volume effects on the constraints. We constrain the maximal fraction of NEDE $f_{\mathrm{NEDE}}$, finding $f_{\mathrm{NEDE}}=0.076_{-0.035}^{+0.040}$ at 68% CL with our baseline dataset and similar constraints using either data from SPT-3G, ACT or full-shape large-scale structure, showing a preference over $\mathrm{\Lambda }\mathrm{CDM}$ even in the absence of a SH0ES prior on $H_0$. While this is stronger evidence for NEDE than obtained with the corresponding Bayesian analysis, our constraints broadly match those obtained by fixing the NEDE trigger mass. Including the SH0ES prior on $H_0$, we obtain $f_{\mathrm{NEDE}}=0.136_{-0.026}^{+0.024}$ at 68% CL. Furthermore, we compare NEDE with the early dark energy (EDE) model, finding similar constraints on the maximal energy density fractions and $H_0$ in the two models. At 68% CL in the NEDE model, we find $H_0=69.56_{-1.29}^{+1.16}\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ with our baseline and $H_0=71.62_{-0.76}^{+0.78}\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ when including the SH0ES measurement of $H_0$, thus corroborating previous conclusions that the NEDE model provides a considerable alleviation of the $H_0$ tension.

The quantum cosmology of the flat Friedmann-Lemaître-Robertson-Walker universe, filled with a scalar field, is considered in the de Broglie–Bohm (dBB) interpretation framework. A stiff-matter quantum bounce solution is obtained. The bouncing and subsequent pre-inflationary and inflationary dynamics are studied in details. We consider some representative primordial inflation models as examples, for which analytical expressions characterizing the dynamical quantities can be explicitly derived. The dependence of the inflationary dynamics on the quantum bounce parameters is then analyzed. The parameters emerging from our description are constrained by requiring the produced dynamics to be in accordance with some key cosmological quantities. The constraining conditions are also illustrated through regions of parameter space in terms of the bounce quantities.