This work continues our program of lattice-QCD baryon physics using staggered fermions for both the sea and the valence quarks. We present a proof-of-concept study that demonstrates, for the first time, how to calculate baryon matrix elements using staggered quarks for the valence sector. We show how to relate the representations of the continuum staggered flavor-taste group $\mathrm{SU}(8{)}_{\mathrm{FT}}$ to those of the discrete lattice symmetry group. The resulting calculations yield the normalization factors relating staggered baryon matrix elements to their physical counterparts. We verify this methodology by calculating the isovector vector and axial-vector charges $g_V$ and $g_A$. We use a single ensemble from the MILC Collaboration with $2+1+1$ flavors of sea quark, lattice spacing $a\approx 0.12\mathrm{fm}$, and a pion mass $M_{\pi }\approx 305\mathrm{MeV}$. On this ensemble, we find results consistent with expectations from current conservation and neutron beta decay. Thus, this work demonstrates how highly improved staggered quarks can be used for precision calculations of baryon properties and, in particular, the isovector nucleon charges.

The existing theory of hard exclusive QCD processes is based on two assumptions: (i) factorization into a hard block convoluted with the light front distribution amplitudes; (ii) use of perturbative gluon exchanges within the hard block. However, unlike deep inelastic scattering and jet physics, the characteristic momentum transfer $Q$ involved in the factorized block is not large enough for this theory to be phenomenologically successful. In this work, we revisit the latter assumption (ii), by explicitly calculating the instanton-induced contributions to the hard block, and show that they contribute substantially to the vector, scalar, and gravitational form factors of the pseudoscalar, scalar, and vector mesons, over a wide range of momentum transfer.

We discuss the effects of rotation on confining properties of gauge theories focusing on compact electrodynamics in two spatial dimensions as an analytically tractable model. We show that at finite temperature, the rotation leads to a deconfining transition starting from a certain distance from the rotation axis. A uniformly rotating confining system possesses, in addition to the usual confinement and deconfinement phases, a mixed inhomogeneous phase which hosts spatially separated confinement and deconfinement regions. The phase diagram thus has two different deconfining temperatures. The first deconfining temperature can be made arbitrarily low by sufficiently rapid rotation while the second deconfining temperature is largely unaffected by the rotation. Implications of our results for the phase diagram of QCD are presented. We point out that uniformly rotating quark-gluon plasma should therefore experience an inverse hadronization effect when the hadronization starts from the core of the rotating plasma rather than from its boundary.

Ensemble averages of random field theories have recently become promising candidates of the holographic dual of classical gravity. Since quantum theories are discrete, we initiate the study of consistent averages over theories with discrete random variables—which admit a mathematically rigorous description as Poisson processes—and get results that mirror Liouville gravity. We show that this is equivalent to averaging over an ensemble of states in a single microscopic theory, which is an early top-down example trying to answer the crucial question of whether the gravitational path integral computes an ensemble average over true randomness or over pseudorandomness coming from a large number of microstates.

It has been suggested that the homogeneous black hole interior spacetime, when quantized following the techniques of loop quantum cosmology, has a resolved singularity replaced by a black-to-white hole transition. This result has however been derived so far only using effective classical evolution equations, and depends on details of the so-called polymerization scheme for the Hamiltonian constraint. Here we propose to use the unimodular formulation of general relativity to study the full quantum dynamics of this mini-superspace model. When applied to such cosmological models, unimodular gravity has the advantage of trivializing the problem of time by providing a true Hamiltonian which follows a Schrödinger evolution equation. By choosing variables adapted to this setup, we show how to write semiclassical states agreeing with that of the Wheeler–DeWitt theory at late times, and how in loop quantum cosmology they evolve through the would-be singularity while remaining sharply peaked. This provides a very simple setup for the study of the full quantum dynamics of these models, which can hopefully serve to tame regularization ambiguities.

In this paper, we consider the energy and momentum transport in ($1+1$)-dimension conformal field theories (CFTs) that are deformed by an irrelevant operator $T\overline{T}$, using the integrability based generalized hydrodynamics, and holography. The two complementary methods allow us to study the energy and momentum transport after the in-homogeneous quench, derive the exact nonequilibrium steady states, and calculate the Drude weights. Our analysis reveals that all of these quantities satisfy universal formulae regardless of the underlying CFT, thereby generalizing the universal formulas for these quantities in pure CFTs. We also compute the exact momentum diffusion constant using the integrability-based method and confirm that it agrees with the conformal perturbation. These fundamental physical insights have important consequences for our understanding of the $T\overline{T}$-deformed CFTs. First of all, they provide the first check of the $T\overline{T}$-deformed ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$ correspondence from the dynamical standpoint. And second, we are able to identify a remarkable connection between the $T\overline{T}$-deformed CFTs and reversible cellular automata.

An approach that has been given promising results concerning investigations on the physics of graphene is the so-called reduced quantum electrodynamics. In this work we consider the natural generalization of this formalism to curved spaces. We employ the local momentum space representation. We discuss the validity of the Ward identity and study one-loop diagrams in detail. We show that the one-loop beta function is zero. As an application, we calculate the one-loop optical conductivity of graphene by taking into account curvature effects which can be incorporated locally. In addition, we demonstrate how such effects may contribute to the conductivity. Furthermore, and quite unexpectedly, our calculations unveil the emergence of a curvature-induced effective chemical potential contribution in the optical conductivity.

We study axially symmetric multisoliton solutions of a complex scalar field theory with a sextic potential, minimally coupled to Einstein’s gravity. These solutions carry no angular momentum and can be classified by the number of nodes of the scalar field, $k_z$, along the symmetry axis; they are interpreted as chains with $k_z+1$ boson stars, bound by gravity, but kept apart by repulsive scalar interactions. Chains with an odd number of constituents show a spiraling behavior for their Arnowitt-Deser-Misner (ADM) mass (and Noether charge) in terms of their angular frequency, similarly to a single fundamental boson star, as long as the gravitational coupling is small; for larger coupling, however, the inner part of the spiral is replaced by a merging with the fundamental branch of radially excited spherical boson stars. Chains with an even number of constituents exhibit a truncated spiral pattern, with only two or three branches, ending at a limiting solution with finite values of ADM mass and Noether charge.

We study two dimensional soliton solutions in the $C{P}^2$ nonlinear sigma model with a Dzyaloshinskii-Moriya type interaction. First, we derive such a model as a continuous limit of the $SU(3)$ tilted ferromagnetic Heisenberg model on a square lattice. Then, introducing an additional potential term to the derived Hamiltonian, we obtain exact soliton solutions for particular sets of parameters of the model. The vacuum of the exact solution can be interpreted as a spin nematic state. For a wider range of coupling constants, we construct numerical solutions, which possess the same type of asymptotic decay as the exact analytical solution, both decaying into a spin nematic state.

An upper limit to distillable entanglement between two disconnected regions of massless noninteracting scalar field theory has an exponential decay defined by a geometric decay constant. When regulated at short distances with a spatial lattice, this entanglement abruptly vanishes beyond a dimensionless separation, defining a negativity sphere. In two spatial dimensions, we determine this geometric decay constant between a pair of disks and the growth of the negativity sphere toward the continuum through a series of lattice calculations. Making the connection to quantum field theories in three-spatial dimensions, assuming such quantum information scales appear also in quantum chromodynamics (QCD), a new relative scale may be present in effective field theories describing the low-energy dynamics of nucleons and nuclei. We highlight potential impacts of the distillable entanglement structure on effective field theories, lattice QCD calculations and future quantum simulations.

Assessing the probability that two or more gravitational wave (GW) events are lensed images of the same source requires an understanding of the properties of the lensed images. For short enough wavelengths where wave effects can be neglected, lensed images will generically have a fixed relative phase shift that needs to be taken into account in the lensing hypothesis. For nonprecessing, circular binaries dominated by quadrupole radiation, these lensing phase shifts are degenerate with either a shift in the coalescence phase or a detector and inclination-dependent shift in the orientation angle. This degeneracy is broken by the presence of higher harmonic modes with $|m|\ne 2$ in the former and $|m|\ne l$ in the latter. The presence of precession or eccentricity will also break this degeneracy. This implies that a lensed GW image will not necessarily be consistent with (unlensed) predictions from general relativity (GR). Therefore, unlike the conventional scenario of electromagnetic waves, strong lensing of GWs can lead to images with a modified phase evolution that can be observed. However, we find that for a wide range of parameters, the lensed (phase modified) waveform is similar enough to an unlensed (GR) waveform that GW detection pipelines will still find it. In particular, for present detectors, we find that templates with a shifted detector-dependent orientation angle have a signal-to-noise ratio differences of less than 1% for mass ratios up to 0.1, and less than 5% for precession parameters up to 0.5 and eccentricities up to 0.4 at 20 Hz. In these ranges, the mismatch is lower than 10% with the alternative detector-independent coalescence phase shift. Nonetheless, for a loud enough source, even with only one image it may be possible to directly identify it as a strongly lensed image from its non-GR, phase-shifted waveform. In more extreme cases, lensing may lead to considerable distortions, and the lensed images may even be undetected with current searches. Nevertheless, an exact template with a phase shift in Fourier space can always be constructed to fit any lensed image. We conclude that an optimal strong lensing search strategy would incorporate phase information in all stages of the identification of strong lensing, with an exact treatment in the final assessment of the probability of multiple lensed events. This work clarifies the role that strong lensing plays in the phase evolution of GWs: how it can lead to apparent deviations from GR, how it can affect the detectability of GW events, and how it can be exploited to help identify cases of strong gravitational lensing of gravitational wave sources.

In this paper we explore the five-dimensional $f(T,B)$ teleparallel modified gravity with $f_1(T,B)=T+k_1{B}^{n_1}$ and $f_2(T,B)=B+k_2{T}^{n_2}$ in the brane scenario. Asymptotically, the bulk geometry converges to an ${\mathrm{AdS}}_5$ spacetime whose cosmological constant is produced by parameters that control torsion and the boundary term. The analysis of the energy density condition reveals a splitting brane process satisfying the weak and strong energy conditions for some values of the parameters $n_{1,2}$ and $k_{1,2}$. In addition, we investigate the behavior of the gravitational perturbations in this scenario. In the bulk, the torsion keeps a gapless nonlocalizable and stable tower of massive modes. Inside the brane core, the torsion produces new barriers and potential wells leading to small amplitude massive modes and a massless mode localized for some values of the parameters $n_{1,2}$ and $k_{1,2}$.

We extend the previous analysis of (locally) asymptotically flat solutions of Kaluza-Klein (KK) theory by assuming that the dilaton charge is an independent parameter. This corresponds to a general nondegenerate matrix of charges within the geodesic sigma-model approach and comes into contact with singular solutions of the four-dimensional Einstein-scalar theory. New features of the degenerate class of solutions, which includes regular KK black holes, are also revealed. Solving the constraint equation, we find three distinct branches of the dilaton charge as a function of the other asymptotic charges, one of which contains the previously known solutions, and the other two, related by electric/magnetic duality, are new and singular. We also investigate whether a superextreme nonrotating solution in the presence of a Newman-Unti-Tamburino charge can become a wormhole, as is the case in Einstein-Maxwell theory. It is shown that the dilaton prevents this possibility, while nontraversable five-dimensional vacuum gravitational wormholes can exist. Finally, we analyze the geodesic structure within the chronosphere around the Misner string of nutty KK dyons, showing that there are no closed timelike geodesics.

In our previous paper A. Boîtier et al. [Phys. Rev. D 102, 064051 (2020)], we derived a generic expression for the pulse redshift, the main observable for the Pulsar Timing Array (PTA) experiment for detection of gravitational waves for all possible polarizations induced by modifications of general relativity. In this work, we provide a generic expression of the overlap reduction function for PTA without using the short wavelength approximation for tensorial polarization. We find that when the overlap reduction function does not have the exponential terms, which is the case when using short wavelength approximation, it leads to discontinuities and poles. In this work, we provide a series expansion to calculate the integral exactly and investigate the behavior of the series for short wavelength values via numerical evaluation of the analytical series. We find a disagreement for the limit of colocated pulsars with the Hellings and Downs curve. Otherwise, our formalism agrees with the Hellings and Downs curve for a broad range of pulsars.

In this paper we investigate the cosmological dynamics of geometric inflation by means of the tools of the dynamical systems theory. We focus on the study of two explicit models where it is possible to sum the infinite series of higher curvature corrections that arise in the formalism. These would be very interesting possibilities since, if we regard gravity as a quantum effective theory, a key feature is that higher powers of the curvature invariants are involved at higher loops. Hence, naively, consideration of the whole infinite tower of curvature invariants amounts to consideration of all of the higher-order loops. The global dynamics of these toy models in the phase space is discussed and the quantum origin of primordial inflation is exposed.

A theory of gravity is deduced from the axioms of the premetric program. The starting point is the conservation of energy and momenta, and the equivalence of gravitation and inertia. The latter is what leads to the framework of the so-called purified gravity. The local and linear constitutive relation has 14 components when it is assumed to be metrical, but the compatibility of the constitutive relation with an action principle fixes uniquely the theory of coincident general relativity. The premetric formalism of purified gravity has a direct analogy with massive electromagnetism, the Planck mass corresponding to the Proca mass of the gauge boson. The metric emerges as a Stueckelberg field, and the graviton as a Goldstone boson of the broken symmetry.

In the strong deflection gravitational lensing, given the fact that a black-bounce, traversable wormhole is indistinguishable from a Schwarzschild black hole and is loosely tested by the Event Horizon Telescope, we intensively study its signatures of weak deflection gravitational lensing in light of the tremendous progress made by the new generation of the near-infrared interferometer GRAVITY. After obtaining its observables, which are the positions, magnitudes of brightness, centroid, and differential time delay between the lensed images, we investigate three astrophysical scenarios: an orbiting star lensed by the Galactic Center Sgr A*, a microlensed star in the Galactic bulge, and microlensing by a nearby lens. We find that the measurements of the observables of Sgr A* provide a promising way to test the black-bounce, traversable wormhole spacetime. GRAVITY can resolve the angular separation, the angular difference, and the time delay between the two lensed images by Sgr A*, and it can marginally detect their deviations from those of the Schwarzschild black hole. The brightness difference between the images and its deviation might be measured by a dedicated space telescope. In the near future, we expect that such a spacetime would be more robustly tested with the weak deflection gravitational lensing by further improved and upgraded GRAVITY+.

The early Universe may have passed through an extended period of matter-dominated expansion following inflation and prior to the onset of radiation domination. Subhorizon density perturbations grow gravitationally during such an epoch, collapsing into bound structures if it lasts long enough. The strong analogy between this phase and structure formation in the present-day Universe allows the use of $N$-body simulations and approximate methods for halo formation to model the fragmentation of the inflaton condensate into inflaton halos. For a simple model we find that these halos have masses of up to 20 kg and radii of the order of ${10}^{-20}\mathrm{m}$, roughly ${10}^{-24}$ seconds after the big bang. We find that the $N$-body halo mass function matches predictions of the mass-peak patch method and the Press-Schechter formalism within the expected range of scales. A long matter-dominated phase would imply that reheating and thermalization occurs in a universe with large variations in density, potentially modifying the dynamics of this process. In addition, large overdensities can source gravitational waves and may lead to the formation of primordial black holes.

We perform for the first time a dedicated analysis of cosmological constraints on Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) QCD axion models. Such constructions are especially interesting in light of the recent xenon1texcess and of hints from stellar cooling. In DFSZ models, for $m_a\gtrsim 0.1\mathrm{eV}$, scatterings of pions and muons can produce a sizable cosmic background of thermal axions, that behave similarly to massive neutrinos. However, the pion coupling depends on the alignment between the vacuum expectation value (vevs) of two Higgs doublets, and can be significantly suppressed or enhanced with respect to the Kim-Shifman-Vainshtein-Zakharov scenario (KSVZ). Using the latest Planck and BAO data, we find $m_a\le 0.2\mathrm{eV}$ at 95% C.L., when the axion coupling to pions $c_{a\pi }$ is maximal. Constraints on $m_a$, instead, can be significantly relaxed when $c_{a\pi }$ is small. In particular, we point out that in the so-called DFSZ-II model, where the axion coupling to leptons does not vanish simultaneously with $c_{a\pi }$, production via muons gives $m_a\le 0.6\mathrm{eV}$ at 95% C.L., whereas in the DFSZ-I model bounds on $m_a$ can be fully lifted. We then combine cosmological data with recent hints of a DFSZ axion coupled to electrons from the xenon1t experiment, finding in this case that the axion mass is constrained to be in the window $0.07\mathrm{eV}\lesssim m_a\lesssim 1.8(0.3)\mathrm{eV}$ for the DFSZ-I (DFSZ-II) model. A similar analysis with stellar cooling hints gives $3\mathrm{meV}\lesssim m_a\lesssim 0.2\mathrm{eV}$ for DFSZ-II, while no constraint arises in the DFSZ-I case. Forthcoming cosmic microwave background stage 4 experiments will be able to further test such scenarios; for instance the xenon1t window should be fully probed at $2\sigma$ for a DFSZ-I axion.