We describe the properties of evanescent gravitational waves (EGWs)—wave solutions of Einstein equations which decay exponentially in some direction while propagating in another. Evanescent waves are well known in acoustics and optics and have recently received much attention due to their extraordinary properties such as their transverse spin and spin-momentum locking. We show that EGWs possess similarly remarkable properties, carrying transverse spin angular momenta and driving freely falling test masses along in elliptical trajectories. Hence, test masses on a plane transverse to the direction of propagation exhibit correlated vector and scalarlike deformation—correlations which can be used to distinguish it from modified gravity. We demonstrate that EGWs are present and dominant in the vicinity of subwavelength sources such as orbiting binaries.

We combine different techniques to extract information about the logarithmic contributions to the two-body conservative dynamics within the post-Newtonian (PN) approximation of general relativity. The logarithms come from the conservative part of nonlinear gravitational-wave tails and their iterations. Explicit, original expressions are found for conservative dynamics logarithmic tail terms up to 6PN order by adopting both traditional PN calculations and effective field theory methods. We also determine all logarithmic terms at 7PN order, fixing a subleading logarithm from a tail-of-tail-of-tail process by comparison with self-force results. Moreover, we use renormalization group techniques to obtain the leading logarithmic terms to generic power $n$, appearing at $(3n+1)\mathrm{PN}$ order, and we resum the infinite series in a closed form. Half-integer PN orders enter the conservative dynamics starting at 5.5PN, but they do not generate logarithmic contributions up to next-to-next-to-leading order included. We nevertheless present their contribution at leading order in the small mass ratio limit.

We study metric transformations including not just the field strength tensor of a $U(1)$ gauge field but also its dual tensor. We first consider an arbitrary symmetric matrix built up with these two tensors in the metric transformation. It turns out the form of transformation reduces to a quite simple form on imposing the parity evenness of the transformed metric and by utilizing the Cayley-Hamilton theorem as well as other useful identities. Interestingly, the same form for the transformation was recently argued in the process of seeking for a generic metric transformation but without the inclusion of the dual tensor.

In this paper we revisit the canonical analysis of $BF$ gravity with the Immirzi parameter and a cosmological constant. By examining the constraint on the $B$ field, we realize that the analysis can be performed in a Lorentz-covariant fashion while utterly avoiding the introduction of second-class constraints during the whole process. Finally, we make contact with the description of the phase space of first-order general relativity in terms of canonical variables with manifest Lorentz covariance subject to first-class constraints only recently introduced.

We provide an exhaustive and illustrated classification of timelike and null geodesics in the near-horizon region of near-extremal Kerr black holes. The classification of polar motion extends to Kerr black holes of arbitrary spin. The classification of radial motion leads to a simple parametrization of the separatrix between bound and unbound motion. Furthermore, we prove that each timelike or null geodesic is related via conformal transformations and discrete symmetries to spherical orbits, and we provide the explicit mappings. We detail the high-spin behavior of both the innermost stable and the innermost bound spherical orbits.

We perform a study both statistical and theoretical for cosmological models of matter creation and their ability to describe effective phantom models of dark energy. Such models are beyond the $\mathrm{\Lambda }\mathrm{CDM}$ model since the resulting cosmic expansion is not adiabatic. In fact, we show that this approach exhibits transient phantom/quintessence scenarios at present time and tends to the standard cosmological model at some stage of the cosmic evolution. We discuss some generalities of the thermodynamics properties for this type of cosmological model; we emphasize on the behavior of the temperature associated to dark matter, which keeps positive along cosmic evolution together with the entropy. The enrichment of this type of model by means of the incorporation of cosmological constant and dissipative effects in the fluid description to explore their cosmological consequences in the expansion of the Universe is considered. Finally, a generalization for the matter production rate as an inhomogeneous expression of the Hubble parameter and its derivatives is discussed; as in all the cases examined, such election leads to an effective phantom/quintessence behavior.

Equilibrium configurations of a circling electrically charged fluid surrounding a central static black hole endowed with a test electric charge and embedded in a large-scale asymptotically uniform magnetic field are presented. Various configurations of the fluid are influenced by the balance between the gravitational and electromagnetic actions; previous studies of the circling charged fluid configurations around a rotating black hole showed a strong dependence on the spin of the black hole. In this work, we focus on configurations centered in the equatorial plane taking shapes of single or double toroidal structures. Our interest is the existence of these structures, and how various actions, such as electromagnetic, gravitational and centrifugal, influence their shapes and physics.

The detection of gravitational waves (GWs) from binary black holes (BBHs) has allowed the theory of general relativity to be tested in a previously unstudied regime: that of strong curvature and high GW luminosities. One distinctive and measurable effect associated with this aspect of the theory is the nonlinear GW memory effect. The GW memory effect is characterized by its effect on freely falling observers: the proper distance between their locations differs before and after a burst of GWs passes by their locations. Gravitational-wave interferometers, like the LIGO and Virgo detectors, can measure features of this effect from a single BBH merger, but previous work has shown that it will require an event that is significantly more massive and closer than any previously detected GW event. Finding evidence for the GW memory effect within the entire population of BBH mergers detected by LIGO and Virgo is more likely to occur sooner. A prior study has shown that the GW memory effect could be detected in a population of BBHs consisting of binaries like the first GW150914 event after roughly one-hundred events. In this paper, we compute forecasts of the time it will take the Advanced LIGO and Virgo detectors (when the detectors are operating at their design sensitivities) to find evidence for the GW memory effect in a population of BBHs that is consistent with the measured population of events in the first two observing runs of the LIGO detectors. We find that after five years of data collected by the Advanced LIGO and Virgo detectors the signal-to-noise ratio for the nonlinear GW memory effect in the population will be about three (near a previously used threshold for detection). We point out that the different approximation methods used to compute the GW memory effect can lead to notably different signal-to-noise ratios.

In this work, direct measurements of the muon density at 1000 m from the shower axis obtained by the Akeno Giant Air Shower Array (AGASA) are analyzed. The selected events have zenith angles $\theta \le 36°$ and reconstructed energies in the range $18.83\le {\log }_{10}(E_R/\mathrm{eV})\le 19.46$. These are compared to the predictions corresponding to proton, iron, and mixed composition scenarios obtained by using the high-energy hadronic interaction models EPOS-LHC, QGSJetII-04, and Sibyll2.3c. The mass fractions of the mixed composition scenarios are taken from the fits to the depth of the shower maximum distributions performed by the Pierre Auger Collaboration. The cross-calibrated energy scale from the Spectrum Working Group [D. Ivanov, for the Pierre Auger Collaboration and the Telescope Array Collaboration, PoS(ICRC2017) 498 (2017)] is used to combine results from different experiments. The analysis shows that the AGASA data are compatible with a heavier composition with respect to the one predicted by the mixed composition scenarios. Interpreting this as a muon deficit in air shower simulations, the incompatibility is quantified. The muon density obtained from AGASA data is greater than that of the mixed composition scenarios by a factor of $1.49\pm 0.11(\mathrm{stat})\pm 0.18(\mathrm{syst})$, $1.54\pm 0.12(\mathrm{stat})\pm 0.18(\mathrm{syst})$, and $1.66\pm 0.13(\mathrm{stat})\pm 0.20(\mathrm{syst})$ for EPOS-LHC, Sibyll2.3c, and QGSJetII-04, respectively.

Gravitational wave signals from compact astrophysical sources such as those observed by LIGO and Virgo require a high-accuracy, theory-based waveform model for the analysis of the recorded signal. Current inspiral-merger-ringdown models are calibrated only up to moderate mass ratios, thereby limiting their applicability to signals from high-mass-ratio binary systems. We present EMRISur1dq1e4, a reduced-order surrogate model for gravitational waveforms of $13500M$ in duration and including several harmonic modes for nonspinning black hole binary systems with mass ratios varying from 3 to 10000, thus vastly expanding the parameter range beyond the current models. This surrogate model is trained on waveform data generated by point-particle black hole perturbation theory (ppBHPT) both for large-mass-ratio and comparable mass-ratio binaries. We observe that the gravitational waveforms generated through a simple application of ppBHPT to the comparable mass-ratio cases agree surprisingly well with those from full numerical relativity after a rescaling of the ppBHPT’s total mass parameter. This observation and the EMRISur1dq1e4 surrogate model will enable data analysis studies in the high-mass-ratio regime, including potential intermediate-mass-ratio signals from LIGO/Virgo and extreme-mass-ratio events of interest to the future space-based observatory LISA.

In this paper we show how to recast the results of the semiclassical method of Baier, Katkov and Strakhovenko for pair production, including the possibility of specifying all the spin states and photon polarization, in a form that is suitable for numerical implementation. In this case, a new type of integral appears in addition to the ones required for the radiation emission process. We compare the resulting formulas with those obtained for a short pulse plane wave external field by using the Volkov state. We investigate the applicability of the local constant field approximation for the proposed upcoming experiments at FACET II at SLAC and LUXE at DESY. Finally, we provide results on the dependence of the pair production rate on the relative polarization between a linearly polarized laser pulse and a linearly polarized incoming high energy photon. We observe that even in the somewhat intermediate multiphoton regime of these experiments, there is roughly a factor of 2 difference between the pair production rates corresponding to the two relative photon polarizations, as predicted by Ritus in the monochromatic highly multiphoton weak field limit. This finding is of interest in light of the vacuum birefringence of QED.

The presence of a Higgsino-like neutralino next-to-lightest sparticle (NLSP) and a keV scale gravitino ($\tilde{G}$) LSP opens up new decay modes of the NLSP, mainly to a $\mathrm{Higgs}/Z$ boson and the LSP. Besides, a keV-scale gravitino as a warm dark matter candidate salvages a relatively light Higgsino-like NLSP from dark matter constraints. We focus on the prospects of observing at least one b jet and two opposite sign leptons with a large missing transverse momenta ($\ge 1b+{\ell }^{+}{\ell }^{-}+{\cancel{E}}_T$) signal at the LHC. A distinguishing feature of this scenario is the production of longitudinal $Z$ bosons in neutralino decays, unlike in the case of gauginolike neutralinos, where the $Z$ is mostly transverse. The polarization information of the parent $Z$ boson gets reflected in the angular distributions of the decay leptons and in some other variables derived therefrom.

We discuss a general formula which allows to automatically reproduce experimental data for Majorana neutrino mass models, while keeping the complete set of the remaining model parameters free for general scans, as necessary in order to provide reliable predictions for observables outside the neutrino sector. We provide a proof of this master parametrization and show how to apply it for several well-known neutrino mass models from the literature. We also discuss a list of special cases, in which the Yukawa couplings have to fulfill some particular additional conditions.

The approximated partial-wave decomposition method for discrete data on a cubic lattice, developed by Misner, is applied to the calculation of $S$-wave hadron-hadron scatterings by the HAL QCD method in lattice QCD. We consider the Nambu-Bethe-Salpeter (NBS) wave function for the spin-singlet ${\mathrm{\Lambda }}_{c}N$ system calculated in ($2+1$)-flavor QCD on a $(32a\mathrm{fm}{)}^3$ lattice with lattice spacing $a\simeq 0.0907\mathrm{fm}$ and $m_{\pi }\simeq 700\mathrm{MeV}$. We find that by Misner’s method the $l=0$ component can be successfully extracted from the NBS wave function projected to the $A_1^{+}$ representation of the cubic group, which contains small $l\ge 4$ components. Furthermore, while the higher partial-wave components are enhanced so as to produce significant comb-like structures in the conventional HAL QCD potential if the Laplacian approximated by the usual second-order difference is applied to the NBS wave function, such structures are found to be absent in the potential extracted by Misner’s method, where the Laplacian can be evaluated analytically for each partial-wave component. Despite the difference in the potentials, the two methods give almost identical results on the central values and magnitude of statistical errors for the fits of the potentials, and consequently on the scattering phase shifts. This indicates not only that Misner’s method works well in lattice QCD with the HAL QCD method, but also that the contaminations from higher partial waves in the study of $S$-wave scatterings are well under control even in the conventional HAL QCD method. It will be of interest to study interactions in higher partial-wave channels in the HAL QCD method with Misner’s decomposition, where the utility of this new technique may become clearer.

We present a lattice QCD determination of the $B_s\to D_s\ell \nu$ scalar and vector form factors over the full physical range of momentum transfer. The result is derived from correlation functions computed using the highly improved staggered quark (HISQ) formalism, on the second generation MILC gluon ensembles accounting for up, down, strange and charm contributions from the sea. We calculate correlation functions for three lattice spacing values and an array of unphysically light $b$-quark masses, and extrapolate to the physical value. Using the HISQ formalism for all quarks means that the lattice current coupling to the $W$ can be renormalized nonperturbatively, giving a result free from perturbative matching errors for the first time. Our results are in agreement with, and more accurate than, previous determinations of these form factors. From the form factors we also determine the ratio of branching fractions that is sensitive to violation of lepton universality: $R(D_s)=\mathcal{B}(B_s\to D_s\tau {\nu }_{\tau })/\mathcal{B}(B_s\to D_s\ell {\nu }_l)$, where $\ell$ is an electron or a muon. We find $R(D_s)=0.2993(46)$, which is also more accurate than previous lattice QCD results. Combined with a future measurement of $R(D_s)$, this could supply a new test of the Standard Model. We also compare the dependence on heavy quark mass of our form factors to expectations from heavy quark effective theory.

We demonstrate that the elastic diffractive scattering of nucleons at collision energies higher than 540 GeV and transferred momenta lower than 2 GeV, including the Coulomb-nuclear interference region, can be described in the framework of a very simple Regge-eikonal model where the eikonal is just a sum of two supercritical Regge pole terms. The predictive value of the proposed approximation is verified.

We present that, if unitarizing the $B^{(*)}{B}^{(*)}$ scattering amplitudes in the constituent interchange model, one can find two bound-state poles for $(I_{\mathrm{tot}},S_{\mathrm{tot}})=(0,1)$ $B{B}^{*}$ and $B^{*}{B}^{*}$ system, which correspond to two $I(J^P)=0(1^{+})$ doubly bottomed molecular states. Furthermore, it is noticed that the virtual states in (1,0) $BB$, (1,1) $B{B}^{*}$, (1,0) $B^{*}{B}^{*}$, and (1,2) $B^{*}{B}^{*}$ systems could produce enhancements of the squared moduli of the scattering $T$ matrix just above the related thresholds, which might correspond to $I(J^P)=1(0^{+})$, $1(1^{+})$, and $1(2^{+})$ doubly bottomed molecular states, respectively. The calculation may be helpful for searching for the doubly bottomed molecular state in future experiments.

Recent work on 6D superconformal field theories has established an intricate correspondence between certain Higgs branch deformations and nilpotent orbits of flavor symmetry algebras associated with $T$-branes. In this paper, we return to the stringy origin of these theories and show that many aspects of these deformations can be understood in terms of simple combinatorial data associated with multipronged strings stretched between stacks of intersecting 7-branes in F theory. These data let us determine the full structure of the nilpotent cone for each semisimple flavor symmetry algebra, and they further allow us to characterize symmetry-breaking patterns in quiverlike theories with classical gauge groups. An especially helpful feature of this analysis is that it extends to “short quivers” in which the breaking patterns from different flavor symmetry factors are correlated.

We study confining strings in massive adjoint two-dimensional chromodynamics. Off shell, as a consequence of zigzag formation, the resulting world sheet theory provides a nontrivial dynamical realization of infinite quon statistics. Taking the high energy limit we identify a remarkably simple and novel integrable relativistic $N$-body system. Its symmetry algebra contains an additional “shadow” Poincaré subalgebra. This model describes the $N$-particle subsector of a $T\overline{T}$-deformed massless fermion.

We investigate the scattering of a quark on a heavy nucleus at high energies using the time-dependent basis light-front quantization (tBLFQ) formalism, which is the first application of the tBLFQ formalism in QCD. We present the real-time evolution of the quark wave function in a strong classical color field of the relativistic nucleus, described as the color glass condensate. The quark and the nucleus color field are simulated in the QCD SU(3) color space. We calculate the total and the differential cross sections, and the quark distribution in coordinate and color spaces using the tBLFQ approach. We recover the eikonal cross sections in the eikonal limit. We find that the differential cross section from the tBLFQ simulation is in agreement with a perturbative calculation at large $p_{\perp }$, and it deviates from the perturbative calculation at small $p_{\perp }$ due to higher-order contributions. In particular, we relax the eikonal limit by letting the quark carry realistic finite longitudinal momenta. We study the sub-eikonal effect on the quark through the transverse coordinate distribution of the quark with different longitudinal momentum, and we find the sub-eikonal effect to be sizable. Our results can significantly reduce the theoretical uncertainties in small $p_{\perp }$ region which has important implications to the phenomenology of the hadron-nucleus and deep inelastic scattering at high energies.