Models of “modified-inertia” formulation of MOND are described and applied to nonrelativistic many-body systems. Whereas the interbody forces are Newtonian, the expression for their inertia is modified from the Newtonian $m\mathbf{a}$ to comply with the basic tenets of MOND. This results in time-nonlocal equations of motion. Momentum, angular momentum, and energy are (nonlocally) defined for bodies, and the total values are conserved for isolated many-body systems. The models make all the salient MOND predictions. Yet, they differ in important ways from existing “modified-gravity” formulations in their second-tier predictions. Indeed, the heuristic value of the model is in limelighting such possible differences. The models describe correctly the motion of a composite body in a low-acceleration field even when the internal accelerations of its constituents are high (e.g., a star in a galaxy). They exhibit a MOND external field effect (EFE) that shows some important differences from what we have come to expect from modified-gravity versions: in one, simple example of the models, what determines the EFE, in the case of a dominant external field, is $\mu (\theta ⟨a_{ex}⟩/a_0)$, where $\mu (x)$ is the MOND “interpolating function” that describes rotation curves, compared with $\mu (a_{ex}/a_0)$ for presently known modified-gravity formulations. The two main differences are that, while $a_{ex}$ is the momentary value of the external acceleration, $⟨a_{ex}⟩$ is a certain time average of it and that $\theta >1$ is an extra factor that depends on the frequency ratio of the external- and internal-field variations. Only ratios of frequencies enter, and $a_0$ remains the only new dimensioned constant. For example, for a system on a circular orbit in a galaxy (such as the vertical dynamics in a disk galaxy), the first difference disappears, since $⟨a_{ex}⟩=a_{ex}$. But the $\theta$ factor can appreciably enhance the EFE in quenching MOND effects, over what is deduced in modified gravity. This $\theta$ enhancement is important in most applications of the EFE. Some exact solutions are also described, such as for rotation curves, for an harmonic force, and the general, two-body problem, which in the deep-MOND regime reduces to a single-body problem.

Using the Bragg-Williams construction of an off-shell free energy, we calculate the topological charge of the Hawking-Page transition point for black holes in anti–de Sitter. A computation following from a related off-shell effective potential in the boundary gauge dual matches the value of topological charge obtained in the bulk. We also work out the topological charges of the equilibrium phases of these systems, which follow from the saddle points of the appropriate free energy. The locally stable and unstable phases turn out to have topological charges opposite to each other, with the total being zero, in agreement with the result obtained from a recent construction [S.-W. Wei, Y.-X. Liu, and R. B. Mann, arXiv:2208.01932].

In this present work, we study the observational appearance of Kerr-Melvin black hole (KMBH) illuminated by an accretion disk. The accretion disk is assumed to be located on the equatorial plane and to be thin both geometrically and optically. Considering the fact that outside the innermost stable circular orbit (ISCO) the accretion flow moves in prograde or retrograde circular orbit and falls toward the horizon along plunging orbit inside the ISCO, we develop the numerical backward ray-tracing method and obtain the images of KMBH accompanying with the accretion disk for various black hole spins, strengths of magnetic fields, and inclination angles of observers. We present the intensity distribution horizontally and longitudinally and show the profiles of the redshift for the direct and lensed images. Our study suggests that the inner shadow and critical curves can be used to estimate the magnetic field around a black hole without degeneration.

We study the quasinormal modes of the charged scalar perturbations in the background of the Einstein-Maxwell-aether black hole through three methods (WKB method, continued fraction method, generalized eigenvalue method). Then we propose the specific treatment for the generalized effective potential with $\omega$-dependence and the complete procedure of transforming calculation continued fraction method into finding the zero point of the corresponding complex function numerically. These methods are valid because the results from different methods are consistent. We also investigate the allowed region of the second kind aether black hole among the system parameters ($c_{13},c_{14},Q$). Finally we show the existence of quasiresonances of massive perturbation for Einstein-Maxwell-aether black hole even with large aether parameter.

Binaries of relatively massive black holes like GW190521 have been proposed to form in dense gas environments, such as the disks of active galactic nuclei (AGNs), and they might be associated with transient electromagnetic counterparts. The interactions of this putative environment with the binary could leave a significant imprint at the low gravitational wave frequencies observable with the Laser Interferometer Space Antenna (LISA). We show that LISA will be able to detect up to ten GW190521-like black hole binaries, with sky position errors $\lesssim 1{\mathrm{deg}}^2$. Moreover, it will measure directly various effects due to the orbital motion around the supermassive black hole at the center of the AGN, especially the Doppler modulation and the Shapiro time delay. Thanks to a careful treatment of their frequency domain signal, we were able to perform the full parameter estimation of Doppler and Shapiro-modulated binaries as seen by LISA. We find that the Doppler and Shapiro effects will allow for measuring the AGN parameters (radius and inclination of the orbit around the AGN, central black hole mass) with up to percent-level precision. Properly modeling these low-frequency environmental effects is crucial to determine the binary formation history, as well as to avoid biases in the reconstruction of the source parameters and in tests of general relativity with gravitational waves.

The Hubble constant estimated from the cosmic microwave background measurements shows large disagreement with the locally measured value. This inconsistency is called the Hubble tension and is vastly studied in recent years. Early dark energy (EDE) gives a few percent contribution to the total energy density of the universe only at an epoch before the recombination, and it is considered as a promising solution to the tension. A simple realization of EDE is given by dynamics of a scalar field, called the EDE scalar, and models including the EDE scalar are extensively studied in the literature. In this paper, we present a novel EDE scenario based on higher-dimensional gauge theories. An extra component of gauge fields associated with a compact extra dimension behaves as the EDE scalar at low-energy and has a periodic potential, which has a similar form as potentials for pseudo Nambu-Goldstone bosons (PNGB). In a five-dimensional $U(1)$ gauge theory, we show that a scalar field that originates from the gauge field can give EDE through its dynamics in a PNGB type potential with a suitable choice of parameters in the theory. We focus on the scenario where EDE is explained by the scalar field and clarify constraints on the fundamental parameters of the gauge theory, such as the gauge coupling, the compactification scale, and the mass parameters for matter fields. We also find that a sufficient dilution of EDE requires nontrivial relations among $U(1)$ charges of matter fields with degenerate bulk masses. The required bulk matter contents and $U(1)$ charges can be given by hand and may be realized more naturally through underlying mechanisms such as flavor symmetries. With specific matter contents, we numerically solve the time evolution of the scalar field and confirm that its energy density behaves as an EDE. In our scenario, the parameters of the gauge theory and predicted properties of EDE are related to each other. Thus, the cosmological restrictions on the EDE properties provide insights into higher-dimensional gauge theories.

Neutrinos are expected to freestream (i.e., not interact with anything) since they decouple in the early Universe at a temperature $T\sim 2\mathrm{MeV}$. However, there are many relevant particle physics scenarios that can make neutrinos interact at $T<2\mathrm{MeV}$. In this work, we take a global perspective and aim to identify the temperature range in which neutrinos can interact given current cosmological observations. We consider a generic set of rates parametrizing neutrino interactions and by performing a full $Planck$ cosmic microwave background (CMB) analysis we find that neutrinos cannot interact significantly for redshifts $2000\lesssim z\lesssim {10}^5$, which we refer to as the freestreaming window. We also derive a redshift dependent upper bound on a suitably defined interaction rate ${\mathrm{\Gamma }}_{\mathrm{nfs}}(z)$, finding ${\mathrm{\Gamma }}_{\mathrm{nfs}}(z)/H(z)\lesssim 1-10$ within the freestreaming window. We show that these results are largely model independent under some broad assumptions, and contextualize them in terms of neutrino decays, neutrino self-interactions, neutrino annihilations, and Majoron models. We provide examples of how to use our model independent approach to obtain bounds in specific scenarios, and demonstrate agreement with existing results. We also investigate the reach of upcoming cosmological data finding that CMB Stage-IV experiments can improve the bound on ${\mathrm{\Gamma }}_{\mathrm{nfs}}(z)/H(z)$ by up to a factor 10. Moreover, we comment on large-scale structure observations, finding that the ongoing DESI survey has the potential to probe uncharted regions of parameter space of interacting neutrinos. Finally, we point out a peculiar scenario that has so far not been considered, and for which relatively large interactions around recombination are still allowed by $Planck$ data due to some degeneracy with $n_s$, $A_s$, and $H_0$. This scenario can be fully tested with CMB-S4.

While primordial black holes (PBHs) with masses $M_{\mathrm{PBH}}\gtrsim {10}^{-11}{M}_{\odot }$ cannot comprise the entirety of dark matter, the existence of even a small population of these objects can have profound astrophysical consequences. A subdominant population of PBHs will efficiently accrete dark matter particles before matter-radiation equality, giving rise to high-density dark matter spikes. We consider here the scenario in which dark matter is comprised primarily of weakly interacting massive particles (WIMPs) with a small subdominant contribution coming from PBHs, and revisit the constraints on the annihilation of WIMPs in these spikes using observations of the isotropic gamma-ray background (IGRB) and the cosmic microwave background (CMB), for a range of WIMP masses, annihilation channels, cross sections, and PBH mass functions. We find that the constraints derived using the IGRB have been significantly overestimated (in some cases by many orders of magnitude), and that limits obtained using observations of the CMB are typically stronger than, or comparable to, those coming from the IGRB. Importantly, we show that $\sim \mathcal{O}(M_{\odot })$ PBHs can still contribute significantly to the dark matter density for sufficiently low WIMP masses and p-wave annihilation cross sections.

The spin precession of binary black holes (BBHs) that originate from isolated high-mass binary stars is determined by the interplay of phenomena such as tides, winds, accretion, common-envelope evolution, natal kicks, and stellar core-envelope coupling. In previous work, we identified regions of the parameter space that may produce BBHs with large misalignments from natal kicks and high spin magnitudes from three mechanisms—tides, accretion, or inheritance via minimal core-envelope coupling. Here, we explore the spin precession of such BBHs using five parameters that describe the amplitude and frequency with which the orbital angular momentum precesses and nutates about the total angular momentum, modulating the gravitational-wave emission. Precession is generally possible for sufficiently strong natal kicks provided at least one of the black holes is spinning. Nutation is a consequence of spin-spin coupling and depends on the three spin-up mechanisms. Tidal synchronization can leave a distinct correlation between the aligned effective spin and the nutation frequency, but does not produce large nutations. When a black hole accretes $\gtrsim 20\%$ of its companion’s envelope, the precession frequency and amplitude are large. A much smaller amount of accretion, e.g., $\approx 2\%$, is needed to provide a large precession frequency and amplitude when the accretor is a Wolf-Rayet (WR) star. The inheritance of high natal WR spins ($\gtrsim 5\%$ of their maximum breakup value) via minimal core-envelope coupling is the most promising mechanism for producing nutating BBHs, implying that a measurement of nutation from gravitational-wave observations may suggest isolated-binary origin with minimal core-envelope coupling.

The characteristics of the cosmic microwave background provide circumstantial evidence that the hot radiation-dominated epoch in the early Universe was preceded by a period of inflationary expansion. Here, we show how a measurement of the stochastic gravitational wave background can reveal the cosmic history and the physical conditions during inflation, subsequent pre- and reheating, and the beginning of the hot big bang era. This is exemplified with a particularly well-motivated and predictive minimal extension of the Standard Model, which is known to provide a complete model for particle physics—up to the Planck scale—and for cosmology—back to inflation.

In this work, the cross sections of $\varphi$ photoproduction are systematically investigated with the two gluon exchange model and the Pomeron model. The results obtained show that the theoretical values of the two models agree well with the experimental data. Since the mass radius and mechanical properties of the proton are encoded in the scalar gravitational form factor of the momentum energy tensor, based on the differential cross sections of $\varphi$ photoproduction at near-threshold predicted by the two gluon exchange model, the average mass radius of the proton is derived as $\sqrt{{⟨r^2⟩}_{\mathrm{m}}}=0.78\pm 0.06\mathrm{fm}$. As a comparison, we directly extract the proton mass radius from the experimental data of $\varphi$ photoproduction to obtain an average value of $0.80\pm 0.05\mathrm{fm}$, which is very close to the result given by the two gluon exchange model. Taking a similar approach, we extracted the average value of $m_D$ to obtain the distribution of the pressure and shear force contributed within the proton, and compared the results with other groups. The results of this paper may provide necessary theoretical information for the subsequent in-depth study of the internal structure and properties of proton.

We reconsider the two-flavor version of the massive chiral Gross-Neveu model in $1+1$ dimensions. Its phase diagram as a function of baryon chemical potential, isospin chemical potential, and temperature has previously been explored. We recapitulate the results, adding the missing tricritical curves. They can be determined exactly by extending the standard stability analysis, using fourth-order almost degenerate perturbation theory. Results for three different bare masses are presented and discussed.

Recently, a nice work about the understanding of one-loop integrals has been given by Arkani-Hamed and Yuan [arXiv:1712.09991] using the language of the projective space associated to their Feynman parametrization. We find this language is also very suitable to deal with the reduction problem of one-loop integrals with general tensor structures as well as propagators having arbitrary higher powers. In this paper, we show how to combine Feynman parametrization and embedding formalism to give a universal treatment of reductions for general one-loop integrals, even including the degenerated cases, such as the vanishing Gram determinant. Results from this method can be written in a compact and symmetric form.

We study the allowed parameter space of the scalar sector in the superweak extension of the standard model (SM). The allowed region is defined by the following conditions: (i) stability of the vacuum, (ii) perturbativity up to the Planck scale, and (iii) the pole mass of the Higgs boson falling into its experimentally measured range. We employ renormalization group equations and quantum corrections at two-loop accuracy. We study the dependence on the Yukawa couplings of the sterile neutrinos at selected values. We also check the exclusion limit set by the precise measurement of the mass of the $W$ boson. Our method for constraining the parameter space using two-loop predictions can also be applied to simpler models such as the singlet scalar extension of the SM in a straightforward way.

In this paper, a novel discrete algebra is presented which follows by combining the SU(2) Lie-Poisson bracket with the discrete Frenet equation. Physically, the construction describes a discrete piecewise linear string in ${\mathbb{R}}^3$. The starting point of our derivation is the discrete Frenet frame assigned at each vertex of the string. Then the link vector that connects the neighboring vertices is assigned the SU(2) Lie-Poisson bracket. Moreover, the same bracket defines the transfer matrices of the discrete Frenet equation which relates two neighboring frames along the string. The procedure extends in a self-similar manner to an infinite hierarchy of Poisson structures. As an example, the first descendant of the SU(2) Lie-Poisson structure is presented in detail. For this, the spinor representation of the discrete Frenet equation is employed, as it converts the brackets into a computationally more manageable form. The final result is a nonlinear, nontrivial, and novel Poisson structure that engages four neighboring vertices.

Liquid xenon-based direct detection dark matter experiments have recently expanded their searches to include high-energy nuclear recoil events as motivated by effective field theory dark matter and inelastic dark matter interaction models, but few xenon recoil calibrations above 100 keV are currently available. In this work, we measured the scintillation and ionization yields of xenon recoils up to 426 keV. The experiment uses 14.1 MeV neutrons to scatter off xenon in a compact liquid xenon time projection chamber and produce quasimonoenergetic xenon recoils between 39 and 426 keV. We report the xenon recoil responses and their electric field dependence for recoil energies up to 306 keV; due to the low event statistics and the relatively mild field dependence, the yield values at higher energies are reported as the average of xenon responses for electric fields between 0.2 and $2.0\mathrm{kV}/\mathrm{cm}$. This result will enable xenon-based dark matter experiments to significantly increase their high-energy dark matter sensitivities by including energy regions that were previously inaccessible due to lack of calibrations.

Symmetric and antisymmetric structure functions from electromagnetic deep inelastic scattering of charged leptons off spin-$1/2$ hadrons are investigated in the framework of a top-down holographic dual description. We consider the Brower-Polchinski-Strassler-Tan Pomeron, type IIB superstring theory scattering amplitudes, and type IIB supergravity on ${\mathrm{AdS}}_5\times S^5$. In all cases, the hard-wall prescription is used. Different kinematic regions of the Bjorken variable $x$, as well as the squared momentum of the virtual photon $Q^2$, are studied in detail for $F_2^P$ and $g_1^P$ structure functions of the proton. Also, the virtual Compton scattering asymmetry of the proton $A_1^P$ is investigated. Comparison with data from several experimental collaborations is presented. In addition, the holographic Pomeron leads to predictions for the mentioned observables for very small $x$ values. In particular, we present predictions for $g_1^P$ at $Q^2$ around $10{\mathrm{GeV}}^2$, for data expected to be measured in a future electron-ion collider. Limitations of this holographic dual approach are discussed.

We show how causal relativistic Navier-Stokes equations arise from the relativistic Boltzmann equation: the causality is preserved via a judicious choice of the zero modes of the collision operator. A completely analogous procedure may be used to extract causal hydrodynamics from the fluid-gravity correspondence: again, causality of the hydrodynamic equations is preserved by a suitable choice of zero modes of the corresponding differential operators in the bulk. We give examples of zero modes which give rise to causal hydrodynamic equations for nonconformal fluids with a conserved U(1) global symmetry current.

For a massive scalar field with general curvature coupling we evaluate the Wightman function in the geometry of two parallel branes perpendicular to the AdS boundary. On the separate branes, the field operator is constrained by Robin boundary conditions, in general, with different coefficients. In the region between the branes their contribution to the Wightman function is explicitly separated. By using this decomposition, the brane-induced effects on the vacuum expectation values for the field squared and energy-momentum tensor are investigated. The behavior of those expectation values is studied in various asymptotic regions of the parameters. The vacuum energy-momentum tensor in addition to the diagonal components has a nonzero off-diagonal stress. Depending on the boundary conditions and also on the distance from the branes, the vacuum energy density can be either positive or negative. The Casimir forces acting on the branes have two components. The first one corresponds to the standard normal force and the second one is parallel to the branes and presents the vacuum shear force. Unlike to the problem of parallel plates in the Minkowski bulk, the normal Casimir forces acting on separate branes differ if the boundary conditions on the branes are different. They can be either repulsive or attractive. In a similar way, depending on the coefficients in the boundary conditions, the shear force is directed toward or from the AdS boundary. The separate components may also change their signs as functions of the interbrane separation. At large proper separations between the branes, compared to the AdS curvature radius, both of the components of the Casimir forces exhibit a power-law decay. For a massive scalar field this behavior is in contrast to that for the Minkowski bulk, where the decrease is exponential.

Black holes in Lorentz violating gravity, such as Einstein-Aether or Hořava-Lifshitz gravity, are drastically different from their general relativistic siblings. Although they allow for superluminal motion in their vicinity, they still exhibit an absolute causal boundary in the form of a universal horizon. By working in the tunneling picture for a gravitating scalar field, we show that universal horizons emit Hawking radiation in a manner akin to standard results in general relativity, with a temperature controlled by the high-energy behavior of the dispersion relation of the gravitating field, and in agreement with alternative derivations in the literature. Our results substantiate the link between the universal horizon and thermodynamics in Lorentz violating theories.