In this article, we have presented a completely new, well-behaved, physically acceptable and stable anisotropic fluid sphere model. For this purpose we have used a well-known Vaidya-Tikekar [J. Astrophys. Astron. 3, 325 (1982)] ansatz for metric potential $g_{rr}$ to generate the model. We have investigated the various physical aspects for our model such as energy density, pressure (radial as well as transverse), anisotropy factor, mass, compactness parameter, surface, and gravitational redshifts. Energy conditions, equilibrium, and stability analysis has been done using graphs. This ensured that our proposed solutions are well-behaved and hence represent physically acceptable models for anisotropic fluid spheres. For comparison with observational data we have considered the compact stars: Her X-1, $4\mathrm{U}1538‐52$, SAX $\mathrm{J}1808.4‐3658$, LMC X-4, SMC X-1, EXO $1785‐248$, Cen X-3, 4U $1820‐30$, PSR $\mathrm{J}1903+327$, 4U $1608‐52$, Vela X-1, PSR $\mathrm{J}1614‐2230$, Cyg X-2 and PSR $\mathrm{B}1913+16$. The calculated value of central density of each of these compact stars, using this model, is of order ${10}^{14}$ or ${10}^{15}$, which is considerably high and consistent with ultracompact stars. We have also estimated the approximate moment of inertia for each of the considered compact stars.

We describe a Bayesian formalism for analyzing individual gravitational-wave events in light of the rest of an observed population. This analysis reveals how the idea of a “population-informed prior” arises naturally from a suitable marginalization of an underlying hierarchical Bayesian model which consistently accounts for selection effects. Our formalism naturally leads to the presence of “leave-one-out” distributions which include subsets of events. This differs from other approximations, also known as empirical Bayes’ methods, which effectively double count one or more events. We design a double-reweighting postprocessing strategy that uses only existing data products to reconstruct the resulting population-informed posterior distributions. Although the correction we highlight is an important conceptual point, we find it has a limited impact on the current catalog of gravitational-wave events. Our approach further allows us to study, for the first time in the gravitational-wave literature, correlations between the parameters of individual events and those of the population.

We introduce a numerical method and python package, chimes, that simulates quantum systems initially well approximated by mean field theory using a second order extension of the classical field approach. We call this the field moment expansion method. In this way, we can accurately approximate the evolution of first and second field moments beyond where the mean field theory breaks down. This allows us to estimate the quantum break time of a classical approximation without any calculations external to the theory. We investigate the accuracy of the field moment expansion using a number of well studied quantum test problems. Interacting bosonic systems similar to scalar field dark matter are chosen as test problems. We find that successful application of this method depends on two conditions: the quantum system must initially be well described by the classical theory, and the growth of the higher order moments must be hierarchical.

In this paper, we constructed the magnetized thick disk model analytically around the static black hole in the presence of an external distribution of matter up to the quadrupole moment. This space-time is a solution to Einstein’s field equation describing the exterior of a static and axially symmetric object locally. This work aims to study this space-time and the effects of quadrupole moments via studying the properties of the equilibrium sequences of magnetized, non-self-gravitating disks in this space-time. We discussed a procedure to build the thick disk model based on a combination of two approaches previously considered in the literature. We have examined different angular momentum distributions, and we have shown the properties of this relativistic accretion disk model in this background.

Upcoming experiments on the interaction of electrons with intense laser fields are envisaged to become more and more accurate, which calls for theoretical computations of rates and probabilities with correspondingly higher precision. In strong-field QED this requires the knowledge of radiative corrections to be added to leading-order results. Here, we first derive the mass operator in momentum space of an off-shell electron in the presence of an arbitrary plane wave. By taking the average of the mass operator in momentum space over an on-shell electron state, we obtain a new representation, equivalent to but more compact than the known one computed in [V. N. Baier et al., Sov. Phys. JETP 42, 400 (1976).]. Moreover, we use the obtained mass operator to determine the electron mass shift in an arbitrary plane wave, which generalizes the already known expression in a constant crossed field. The spin-dependent part of the electron mass shift can be related to the anomalous magnetic moment of the electron in the plane wave. We show that within the locally constant field approximation it is possible to conveniently define a local expression of the electron anomalous magnetic moment, which reduces to the known expression in a constant crossed field. Beyond the locally constant field approximation, however, the interaction between the electron and the plane wave is nonlocal such that it is not possible to conveniently introduce an electron anomalous magnetic moment.

We investigate the production of QCD axion dark matter in a nonstandard cosmological era triggered by primordial black holes (PBHs) that fully evaporate before the onset of BBN. Even if PBHs cannot emit the whole axion cold dark matter abundance through Hawking radiation, they can have a strong impact on the dark matter produced via the misalignment mechanism. First, the oscillation temperature of axions reduces if there is a PBH dominated era, and second, PBH evaporation injects entropy to the standard model, diluting the axion relic abundance originally produced. The axion window is therefore enlarged, reaching masses as light as $\sim {10}^{-8}\mathrm{eV}$ and decay constants as large as $f_a\sim {10}^{14}\mathrm{GeV}$ without fine tuning the misalignment angle. Such small masses are in the reach of future detectors as ABRACADABRA, KLASH, and ADMX, if the axion couples to photons. Additionally, the axions radiated by PBHs contribute to $\mathrm{\Delta }{N}_{\mathrm{eff}}$ within the projected reach of the future CMB Stage 4 experiment.

One-loop electroweak corrections to the annihilation cross sections of dark matter in the Higgs resonance region of the inert doublet model are investigated. The procedure of how to implement the width of the Higgs in order to regularize the amplitude both at tree level and at one loop together with the renormalization of a key parameter of the model, are thoroughly scrutinized. The discussions go beyond the application to the relic density calculation and also beyond the inert doublet model so that addressing these technical issues can help in a wider context. We look in particular at the dominant channels with the $b\overline{b}$ final state and the more involved three-body final state, $Wf{\overline{f}}^{\prime }$, where both a resonance and an antiresonance, due to interference effects, are present. We also discuss how to integrate over such configurations when converting the cross sections into a calculation of the relic density.

We perform the first one-loop electroweak corrections for $2\to 3$ processes for dark matter annihilation. These are the dominant processes that enter the computation of the relic density for the low mass region of the inert doublet model (IDM) when annihilations to two on shell vector bosons are closed. The impact of the one-loop corrections are important as they involve, through rescattering effects, not only a dependence on the parameter controlling the dark sector, not present if a calculation at tree level is conducted, but also on the renormalization scale. These combined effects should be taken into account in analyses based on tree-level cross sections of the relic density calculations, as a theoretical uncertainty, which we find to be much larger than the cursory $\pm 10\%$ uncertainty that is routinely assumed, independently of the model parameters.

We examine the relic density of the light mass dark matter region in the inert doublet model (IDM) when the dominant process is due to coannihilation between the lightest neutral scalars of the model. The full one-loop electroweak corrections are computed in an on shell scheme and are found to be well approximated as an effective cross section expressed in terms of $Z$ observables. The electroweak corrections to the subdominant process, which consists of an annihilation into an on shell $W$ and an off shell $W$, that is calculated as a annihilation into a three-body final state, is also performed. In the calculation of the latter in this case of coannihilation, although the SM Higgs exchange is absent, it is induced at one loop, but the cross section does not show a peak behavior despite the crossing of the Higgs resonance. This cross section reveals an important dependence on a parameter that describes the self-interaction of the new scalars (solely within the dark sector), a parameter which is not accessible in tree-level calculations of standard model-IDM interactions.

The present paper is the first in a series that addresses the calculation of the full one-loop corrections of dark matter (DM) annihilation cross sections in the low mass region of the inert doublet model (IDM). This series is a sequel to our recent publication concerning these corrections in the high mass region. We first review the renormalization of the model both in a fully on shell (OS) scheme as well as in a mixed scheme that combines on shell (for the masses) and a $\overline{\mathrm{MS}}$ approach when the partial invisible width is closed and does not allow the use of a full OS scheme. The scale dependence introduced by the mixed scheme is shown to be tracked through an analysis of a parametrization of the tree-level cross section and the $\beta$ constant of a specific coupling; this analysis could be followed in theories. We discuss how to minimize the scale dependence. The theoretical uncertainty brought by the scale dependence leads us to introduce a new criterion on the perturbativity of the IDM. This criterion further delimits the allowed parameter space, which we investigate carefully by including a host of constraints, both theoretical and experimental, including in particular, new data from the LHC. We come up with a set of benchmark points that cover three different mechanisms for a viable relic density of DM: (i) a dominance of coannihilation into a fermion pair, (ii) annihilation into two vector bosons of which one is off shell that requires the calculation of a $2\to 3$ process, (iii) annihilation that proceeds through the very narrow standard model Higgs resonance. Since the $2\to 3$ vector boson channel features in all three channels and is essentially a buildup on the simpler annihilation to OS vector bosons, we study the latter in detail in the present paper. We confirm again that the corrected cross sections involve a parameter that can be considered as rescattering in the dark sector, which a tree-level computation is not sensitive to. The setup of the renormalization detailed in the present paper will be the backbone of the accompanying papers where each mechanism requires, calculationally, a specific treatment. One-loop corrections to $2\to 3$ processes for DM annihilation are technically challenging and have not been attempted before. We dedicate one of the accompanying papers to such a computation. The one-loop correction in the presence of a resonance will be presented separately since we need to supplement our general schemes with a complex scheme. For the coannihilation into fermions, our study will show that the annihilation cross sections can be excellently parametrized through simple effective couplings.

We present results on the isoscalar form factors including the disconnected contributions, as well as on the strange and charm quark form factors. Using previous results on the isovector form factors, we determine the flavor decomposition of the nucleon axial form factors. These are computed using an ensemble of $N_f=2+1+1$ twisted mass fermions simulated with physical values of quark masses. We investigate the SU(3) flavor symmetry and show that there is up to 10% breaking for the axial and up to 50% for the induced pseudoscalar form factors. By fitting the $Q^2$-dependence, we determined the corresponding root mean square radii. The pseudoscalar coupling of the $\eta$ meson and the nucleon is found to be $g_{\eta NN}=3.7(1.0)(0.7)$, and the Goldberger-Treiman discrepancy for the octet combination about 50%.

We present a precise calculation of the pion form factor using overlap fermions on seven ensembles of ($2+1$)-flavor domain-wall configurations with pion masses varying from 139 to $340\mathrm{MeV}$. Taking advantage of the fast Fourier transform and other techniques to access many combinations of source and sink momenta, we find the pion mean square charge radius to be $⟨r_{\pi }^2⟩=0.430(5)(13){\mathrm{fm}}^2$, which agrees well with the experimental result, and includes the systematic uncertainties from chiral extrapolation, lattice spacing and finite-volume dependence. We also find that $⟨r_{\pi }^2⟩$ depends on both the valence and sea quark masses strongly and predicts the pion form factor up to $Q^2=1.0{\mathrm{GeV}}^2$, which agrees with experiments very well.

We make a detailed study of the three-body decays $B_{(s)}\to {\chi }_{c1}h{h}^{\prime }$, where $h^{{(}^{\prime })}$ is either a pion or kaon, by taking into account the $S$-wave states in the $h{h}^{\prime }$ invariant mass distribution within the perturbative QCD approach. The two meson distribution amplitudes are introduced to capture the strong interaction related to the production of the $h{h}^{\prime }$ system. We calculate the branching ratios for the $S$-wave components and observe large values of order ${10}^{-4}$ for some Cabibbo-favored decays, which are accessible to the LHCb and Belle II experiments. The obtained branching ratio $\mathcal{B}(B\to {\chi }_{c1}{K}_0^{*}(1430)(\to K^{+}{\pi }^{-}))=({5.1}_{-0.8}^{+0.6})\times {10}^{-5}$ consistent with the data from Belle within errors. Moreover, we also predict the differential distributions in the $h{h}^{\prime }$ invariant mass for the decays under consideration, which await the future experimental test. In addition, the corresponding ${\chi }_{c1}(2P)$ channels are also investigated, which are helpful to clarify the nature of the $X(3872)$ state.

The first observation of the electroweak (EW) production of a $Z$ boson, a photon, and two forward jets ($Z\gamma \mathrm{jj}$) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. A data set corresponding to an integrated luminosity of $137{\mathrm{fb}}^{-1}$, collected by the CMS experiment at the LHC in 2016–2018 is used. The measured fiducial cross section for EW $Z\gamma \mathrm{jj}$ is ${\sigma }_{\mathrm{EW}}=5.21\pm 0.52(\mathrm{stat})\pm 0.56(\mathrm{syst})\mathrm{fb}=5.21\pm 0.76\mathrm{fb}$. Single-differential cross sections in photon, leading lepton, and leading jet transverse momenta, and double-differential cross sections in $m_{\mathrm{jj}}$ and $|\mathrm{\Delta }{\eta }_{\mathrm{jj}}|$ are also measured. Exclusion limits on anomalous quartic gauge couplings are derived at 95% confidence level in terms of the effective field theory operators ${\mathrm{M}}_0$ to ${\mathrm{M}}_5$, ${\mathrm{M}}_7$, ${\mathrm{T}}_0$ to ${\mathrm{T}}_2$, and ${\mathrm{T}}_5$ to ${\mathrm{T}}_9$.

We show that, in order to determine the equation of state of the inner crust of an accreting neutron star, one should minimize not the Gibbs free energy, as it is generally assumed in the literature, but a different thermodynamic potential $\mathrm{\Psi }$, which tends to the minimum at fixed pressure and neutron chemical potential. Once this potential is specified, one can calculate the heat-release distribution in the stellar crust due to nonequilibrium nuclear reactions induced by accretion of matter onto the neutron-star surface. The results are important for adequate modeling of the accreted crust and interpretation of the observations of accreting neutron stars in low-mass X-ray binaries.

A stochastic gravitational-wave background is expected to emerge from the superposition of numerous gravitational-wave sources of both astrophysical and cosmological origin. A number of cosmological models can have a parity violation, resulting in the generation of circularly polarized gravitational waves. We present a method to search for parity violation in the gravitational-wave data. We first apply this method to the most recent, third, LIGO-Virgo observing run. We then investigate the constraining power of future $\mathrm{A}+\mathrm{LIGO}-\mathrm{Virgo}$ detectors, including KAGRA to the network, for a gravitational-wave background generated by early universe cosmological turbulence.

Recently, P. Bargueño has commented in Phys. Rev. D 104, 088501 (2021) that the field equations obtained in the original paper [J. Harada, Phys. Rev. D 103, L121502 (2021)] have less information than those of general relativity. This reply provides clarification. The field equations obtained in the original paper have information on gravity that cannot be obtained from general relativity. For instance, the effective potential of gravity has a term that is linearly proportional to the distance. It implies that the magnitude of gravity can be stronger than that of Newton’s law of gravitation at large distances.

Recently, it has been claimed by J. Harada [Phys. Rev. D 103, L121502 (2021) that the Cotton tensor can describe the effects of gravity beyond general relativity. In this short comment, we show that the Cotton tensor is already present in general relativity. Moreover, we show that Harada’s proposal is equivalent to general relativity concerning the equation of motion both for the sources and for the trace-free part of the curvature. In essence, what remains completely free in Harada’s theory are the field equations relating the part of the curvature which is locally determined by the energy-momentum distribution.

We investigate, in the framework of linearized quantum gravity, the induced quantum gravitational interaction between two ground-state objects with permanent quadrupole moments, which are subjected to an external gravitational radiation field. Compared with the nonpolar case, there exists an additional term in the leading-order field-induced interobject interaction between two polar objects. This term arises when a real graviton is scattered by the same object center with coupling between the two objects occurring via the exchange of a single virtual graviton, and the interaction is thus relevant to the number density of gravitons, the frequency and polarization of the external gravitational field, as well as the permanent quadrupoles of the objects. Due to the existence of such an additional term, the field-induced quantum gravitational interaction between two polar objects can be significantly different from that between nonpolar ones when the interobject distance is much smaller than the wavelength of the external gravitational radiation field. Although we model the external gravitational radiation as a quantized monochromatic gravitational wave with a certain wave vector and polarization for simplicity, it is possible to generalize to more realistic situations, such as the case of a stochastic background of gravitational radiation.

We explore the Liouvillian nonintegrability criteria for long quiver gauge theories which preserve $\mathcal{N}=1$ supersymmetry in $5D$. We probe type IIB solutions with (an ${\mathrm{AdS}}_6$ factor) semiclassical strings which capture the strong coupling dynamics of $\mathcal{N}=1$ superconformal field theories (SCFTs) in $5D$. Our analysis reveals an underlying nonintegrable structure within some sub-sector of these $5D$ SCFTs. To solidify our claim, we complement our analytic results through numerics. We estimate various chaos indicators for the phase space which confirm the onset of a chaotic motion for these type IIB strings.