Cohen and Glashow argued that very special conformal field theories of a particular kind [i.e., with HOM(2) or SIM(2) invariance] cannot be constructed within the framework of local field theories. We, however, show examples of local construction by using nonlinear realization. We further construct linear realization from the topological twist at the cost of unitarity. To demonstrate the ubiquity of our idea, we also present corresponding holographic models.

The technique for constructing conformally invariant theories within the coset space construction is developed. It reproduces all consequences of the conformal invariance and Lagrangians of widely known conformal field theories. The method of induced representations, which plays the key role in the construction, allows us to reveal a special role of the Nambu-Goldstone fields for special conformal transformations. Namely, their dependence on the coordinates turns out to be fixed by the symmetries. This results in the appearance of the constraints on possible forms of Lagrangians, which ensure that discrete symmetries are indeed symmetries of the theory.

We consider a real, massive scalar field both on the $n$-dimensional anti–de Sitter (${\mathrm{AdS}}_n$) spacetime and on its universal cover ${\mathrm{CAdS}}_n$. In the second scenario, we extend the recent analysis on ${\mathrm{PAdS}}_n$, the Poincaré patch of ${\mathrm{AdS}}_n$, first determining all admissible boundary conditions of Robin type that can be applied on the conformal boundary. Most notably, contrary to what happens on ${\mathrm{PAdS}}_n$, no bound state mode solution occurs. Subsequently, we address the problem of constructing the two-point function for the ground state satisfying the admissible boundary conditions. All these states are locally of Hadamard form being obtained via a mode expansion which encompasses only the positive frequencies associated to the global timelike Killing field on ${\mathrm{CAdS}}_n$. To conclude we investigate under which conditions any of the two-point correlation functions constructed on the universal cover defines a counterpart on ${\mathrm{AdS}}_n$, still of Hadamard form. Since this spacetime is periodic in time, it turns out that this is possible only for Dirichlet boundary conditions, though for a countable set of masses of the underlying field, or for Neumann boundary conditions, though only for even dimensions and for one given value of the mass.

Detections of gravitational waves emitted by binary black holes allow for tests of general relativity in the strong-field regime. In particular, deviations from general relativity can be observed by comparing incoming signals to waveform templates that include parametrized deviations from general relativity. However, it is essential that the general relativity sector of these templates accounts for all predictable physics. Otherwise, missing physics might be mimicked by the “beyond general relativity” sector of the templates, leading the analysis to report apparent deviations from general relativity. Current parametrized tests implement templates that omit physical phenomena such as orbital eccentricity and higher-order modes. In this paper, we show how the omission of higher modes can lead to false deviations from general relativity when these effects are strong enough. We study the extent of these deviations as a function of the mass ratio and the orbital orientation. We find that significant false deviations can arise when current tests are performed on signals emitted by asymmetric binaries whose orbital angular momentum is orthogonal to the line of sight. We estimate that the Advanced LIGO-Virgo network operating at its design sensitivity can observe false violations with a significance above $5\sigma$ as often as once per year. Similar results are expected for other tests of general relativity that compare the data to waveforms where some physical effects are omitted.

We give the formulation and the general analysis of the rotational accretion problem on $D$-dimensional spherical spacetime and investigate sonic points and critical points. First, we construct the simple two-dimensional rotating accretion flow model in general $D$-dimensional static spherically symmetric spacetime and formulate the problem. The flow forms a two-dimensional disk lying on the equatorial plane, and the disk is assumed to be geometrically thin and has uniform distribution in the polar angle directions. Analyzing the critical point of the problem, we give the conditions for the critical point and its classification explicitly and show the coincidence with the sonic point for the generic equation of state (EOS). Next, adopting the EOS of ideal photon gas to the analysis, we reveal that there always exists a correspondence between the sonic points and the photon spheres of the spacetime. Our main result is that the sonic point of the rotating accretion flow of ideal photon gas must be on (one of) the unstable photon sphere(s) of the spacetime in arbitrary spacetime dimensions. This paper extends this correspondence for spherical flows shown in the authors’ previous work to rotating accretion disks.

We show that not all quasinormal modes of a massless scalar field in the Schwarzschild metric are encoded in the corresponding characteristic equation expressed by means of a continued fraction. We provide an analytical formula for these new hitherto missing quasinormal modes, and in doing that we also construct a generalization of the Gauss convergence criterion.

The Birkhoff theorem is a well-known result in general relativity, and it is used in many applications. However, its most general version, due to Bona, is almost unknown and presented in a form less accessible to the relativist and cosmologist community. Moreover, many wield it mistakenly as a simple transposition of Newton’s iron sphere theorem. In the present work, we propose a modern, dual null, presentation—useful in many explorations, including black holes—of the theorem that renders accessible most of the results of Bona’s version. In addition, we discuss the fluid contents admissible for the application of the theorem, beyond a vacuum, and we demonstrate how the formalism greatly simplifies solving the dynamical equations and allows one to express the solution as a power expansion in $r$. We present a family of solutions that share the properties predicted by the Birkhoff theorem and discuss the existence of trapped and antitrapped regions. The formalism manifestly shows how the type of region—trapped or untrapped—determines the character of the Killing vector.

We study the critical values of the quintessential and spin parameters, to distinguish a rotating Kiselev black hole from a naked singularity. For any value of the dimensionless quintessential parameter ${\omega }_q\in (-1,-1/3)$, when increasing the value of the quintessential parameter $\alpha$, the size of the event horizon increases, whereas the size of the outer horizon decreases. We then study the spin precession of a test gyroscope attached to a stationary observer in this spacetime. Using the spin precessions we differentiate black holes from naked singularities. If the precession frequency becomes larger as an observer approaches the central object in the quintessential field along any direction, then the spacetime is a black hole. A spacetime will contain a naked singularity if the precession frequency remains finite everywhere except at the singularity itself. Finally, we study the Lense-Thirring precession frequency for a rotating Kiselev black hole and the geodetic precession for a Kiselev black hole.

The main contribution to the pulsar power can be calculated by assuming a rotating magnetically dominated magnetosphere described by the force-free approximation. Although this simple model has been used thoroughly to study pulsar magnetospheres in the flat spacetime regime, only a few works have considered the relativistic corrections introduced by the curvature and frame-dragging effects induced by a rotating neutron star. Here, we revisit the problem and describe pulsar magnetospheres within full general relativity, quantifying the corrections as a function of the angular velocity, the compactness of the star, and the misalignment angle between the spin and the magnetic dipole. We provide analytical expressions for the pulsar luminosity by fitting our numerical results. Finally, we also analyze the effect of the relativistic corrections on the braking index, which indicates a slight increment in its value.

We revisit the problem of a spinning black hole immersed in a uniformly magnetized plasma within the context of force-free electrodynamics. Such configurations have been found to relax to stationary jetlike solutions that are powered by the rotational energy of the black hole. We write down an analytic description for the jet solutions in the low black hole spin limit and demonstrate that it provides a good approximation to the configurations found dynamically. For characterizing the magnetospheres of rapidly spinning black holes, we find that the current sheet which forms in the black hole ergosphere plays an essential role. We study the properties of the current sheet and its importance in determining the jet solution and the rate at which energy is extracted from the black hole.

The cosmological evolution can be described in terms of directly measurable cosmological scalar parameters (deceleration $q$, jerk $j$, snap $s$, etc...) constructed out of high order derivatives of the scale factor. Their behavior at the critical temperature of the quantum chromodynamics (QCD) phase transition in early universe could be a specific tool to study the transition, analogously to the fluctuations of conserved charges in QCD. We analyze the effect of the crossover transition from quarks and gluons to hadrons in early universe on the cosmological scalars and on the gravitational wave spectrum, by using the recent lattice QCD equation of state and including the electroweak degrees of freedom. Near the transition the cosmological parameters follow the behavior of QCD trace anomaly and of the speed of sound of the entire system. The effects of deconfinement turn out to be more relevant for the modification of the primordial spectrum of gravitational waves rather than for the evolution of the cosmological parameters. Our complete analysis, based on lattice QCD simulations and on the hadron resonance gas below the critical temperature, refines previous results.

The absolute accuracy of the estimated parameters of gravitational wave sources will be fundamentally limited by the calibration uncertainties of the detectors in upcoming observation runs with the increased number of source statistics. Photon calibrators have so far been the primary tools for the absolute calibration of a test-mass displacement, relying on the measurement of the photon pressure. The current technological limit of the absolute calibration uncertainty for gravitational-wave amplitudes is limited to a few percent, due to the uncertainty in the laser power standard maintained by the metrology institutes. To reduce this uncertainty, this article proposes a novel calibration method that combines a photon calibrator and a gravity field calibrator. The gravity field calibrator achieves modulation of the displacement of the test mass by generating a gravity gradient. In previous studies, uncertainty in the distance between the test mass and the gravity field calibrator has proven a serious source of systematic error. To suppress this uncertainty, we propose a novel method that uses a combination of quadrupole and hexapole mass distributions in the gravity field calibrator. We estimate the absolute uncertainty associated with the method to be as low as 0.17%, which is 10 times less than that of previous methods.

The flux of galactic cosmic rays (GCRs) is isotropic in the interstellar space. However, in the heliosphere, the ram pressure of outward-moving solar wind convects the GCRs away from the Sun, thereby producing a density gradient in the radial direction. The diffusion of GCRs due to this gradient and scattering with the irregularities in the interplanetary magnetic field (IMF) induce variations in their flux that can be observed near the Earth. A framework for the diffusion-convection mechanism of GCR propagation developed by Parker and collaborators [Phys. Rev. 110, 1445 (1958); Planet. Space Sci. 13, 9 (1965); Astrophys. J. 772, 46 (2013); Space Sci. Rev. 78, 401 (1996); Astrophys. J. 234, 746 (1979); Astrophys. J. 361, 162 (1990); Space Sci. Rev. 176, 299 (2013)] offers a good description of this phenomenon. One of the outcomes of this framework is an anticorrelation of the variation in solar wind velocity (${\mathrm{V}}_{\mathrm{SW}}$) and the GCR flux. A second outcome of this gradient in the presence of IMF is the movement of GCRs perpendicular to the ecliptic plane called “Swinson flow.” Therefore, (i) the correlated variations of ${\mathrm{V}}_{\mathrm{SW}}$ and GCR flux and (ii) the GCR radial density gradient obtained from Swinson flow can each be used to independently measure the radial diffusion coefficient of GCRs in the inner heliosphere. In an earlier work [Phys. Rev. D 91, 121303(R) (2015)], the GCR flux was shown to be anticorrelated with ${\mathrm{V}}_{\mathrm{SW}}$ at $(-1.33\pm 0.07)\times {10}^{-3}\%(\mathrm{km}{\mathrm{s}}^{-1}{)}^{-1}$. This anticorrelation yields a radial diffusion coefficient $\kappa =0.97\times {10}^{19}{\mathrm{m}}^2{\mathrm{s}}^{-1}$ at 1 AU. In another work [Astropart. Phys. 62, 21 (2015)], the measurement of Swinson flow was used to obtain a GCR radial density gradient of $0.65{\mathrm{A}\mathrm{U}}^{-1}$ at a median rigidity of 77 GV. Here, we report a measurement of radial diffusion coefficient $\kappa =1.04\times {10}^{19}{\mathrm{m}}^2{\mathrm{s}}^{-1}$ at 1 AU from the above-mentioned density gradient, for a mean ${\mathrm{V}}_{\mathrm{SW}}$ of $450\mathrm{km}{\mathrm{s}}^{-1}$. Thus, these two distinct approaches essentially yielded similar values of the radial diffusion coefficient $\kappa ={10}^{19}{\mathrm{m}}^2{\mathrm{s}}^{-1}$ at 1 AU, characterizing the diffusion of GCRs at 77 GV. From this value of $\kappa$, the mean free path length for parallel diffusion ${\lambda }_{\parallel }$ was estimated to be 1.2 AU at 77 GV, consistent with earlier reports [Rev. Geophys. Space Phys. 20, 335 (1982); Astrophys. J. 420, 294 (1994); Astrophys. J. 604, 861 (2004)].

We present, in an explicit form, the metric for all spherically symmetric Schwarzschild-Bach black holes in Einstein-Weyl theory. In addition to the black hole mass, this complete family of spacetimes involves a parameter that encodes the value of the Bach tensor on the horizon. When this additional “non-Schwarzschild parameter” is set to zero, the Bach tensor vanishes everywhere, and the “Schwa-Bach” solution reduces to the standard Schwarzschild metric of general relativity. Compared with previous studies, which were mainly based on numerical integration of a complicated form of field equations, the new form of the metric enables us to easily investigate geometrical and physical properties of these black holes, such as specific tidal effects on test particles, caused by the presence of the Bach tensor, as well as fundamental thermodynamical quantities.

Weak equivalence principle (WEP) is, for the first time, tested by astrometry on quasars in the sky measured in two wavelengths. Compared to previous WEP tests based on the Shapiro time delay of massless particles, this one has profound superiority that nearly 1 700 quasars with best measured positions commonly in the optical and radio bands are available. It ensures that, among the tests with photons, this one can give the most significantly robust bound on possible violation of WEP.

By assuming a dynamical source of $CP$ violation, the tension between sufficient $CP$ violation for successful electroweak baryogenesis and strong constraints from current electric dipole moment measurements could be alleviated. We study how to explore such scenarios through gravitational wave detection, collider experiments, and their possible synergies with a well-studied example.

Within the supersymmetric $SO(10)$ grand unified theory (GUT), a new mechanism giving the light Higgs doublet as a pseudo-Goldstone mode is suggested. Realizing this mechanism, we present an explicit model with fully realistic phenomenology. In particular, desirable symmetry breaking and natural all-order hierarchy are achieved. The constructed model allows one to have a realistic fermion pattern, nucleon stability, and successful gauge coupling unification. The suggested mechanism opens prospects in the field for a novel $SO(10)$ GUT model building and for further investigations.

Dark matter scenarios with spin-0 mediators in the $s$ channel have be tested in well-established processes with missing energy, such as top-pair- and mono-jet-associated production. We suggest electroweak single top production in association with a dark matter pair as an alternative channel. Based on a realistic analysis for the LHC at 13 TeV, we demonstrate how to efficiently discriminate between the signal and standard model background using event kinematics. With $300{\mathrm{fb}}^{-1}$ $(3{\mathrm{ab}}^{-1})$ of data, on-shell scalar mediators with a coupling strength $g_S^t=1$ to top quarks can be probed up to masses of 180(360) GeV. Single-top-associated dark matter production should thus be included as an independent search channel in the LHC dark matter program.

We propose a new window to detect axionlike particle dark matter from electrically charged fermions, such as electrons and quarks. We specifically consider a direct interaction between the axion and the electron and find that the nonrelativistic quantum dynamics induces a spin precession due to the axion and is enhanced by the application of an external electric field. This precession gives a change in magnetic flux which under certain circumstances can yield a detectable signal for superconducting quantum interference device.