Matrix Product States (MPS) are used for the simulation of the real-time dynamics induced by an electric quench on the vacuum state of the massive Schwinger model. For small quenches it is found that the obtained oscillatory behavior of local observables can be explained from the single-particle excitations of the quenched Hamiltonian. For large quenches damped oscillations are found and comparison of the late time behavior with the appropriate Gibbs states seems to give some evidence for the onset of thermalization. Finally, the MPS real-time simulations are compared with results from real-time lattice gauge theory which are expected to agree in the limit of large quenches.

We study the color entanglement like effect for T-odd cases in collinear twist-3 factorization. For an example, we compute the transverse single spin asymmetry for direct photon production in pp collisions in a pure collinear twist-3 approach. By analyzing the gauge link structure of the collinear gluon distribution on the unpolarized target side, we demonstrate how the color entanglement–like effect arises in the presence of the additional gluon attachment from a polarized projectile. The result is consistent with that obtained from a hybrid approach calculation.

In this paper we use the effective blackfold description of branes to extend the study of the thermal BIon, a D-brane, and parallel anti-D-brane connected by a wormhole with F-string charge in hot flat space, by introducing a radial boost along the brane. The boosted system behaves qualitatively differently from both the extremal and the thermal BIon considered previously. Interestingly, we are able to formulate a first law of thermodynamics for the system as a whole, despite the fact that it is not a stationary blackfold. In particular, the global temperature is given by the rest frame temperature times the gamma factor of special relativity which is the inverse transformation compared to the case of stationary blackfolds. In addition we define two new kinds of thermodynamic conjugate variables, the energy flux $W$ and the integrated velocity on the brane. We find that a phase transition occurs by varying the energy flux $W$. Below a critical value of $W$ the brane separation $\mathrm{\Delta }$ changes only slightly with $W$. Instead above the critical value $\mathrm{\Delta }$ grows exponentially.

In Lorentz violating theories of gravitation with a preferred foliation a notion of black hole is still possible, despite the presence of infinitely fast propagating modes. Such event horizons are known as universal horizons. Their discovery poses the question of whether they satisfy mechanical laws, analogous to the ones of Killing horizons in Lorentz symmetric theories, and whether they admit a thermodynamical interpretation. In this paper we study the viability of the first law for several exact universal horizon solutions previously derived in the literature. Our results show that a simple mechanical and thermodynamical interpretation is problematic in these cases, and call for a more systematic study of rotating universal horizons.

In this work, we shall incorporate a stiff era in the Universe’s evolution in the context of $F(R)$ gravity. After deriving the vacuum $F(R)$ gravity, which may realize a stiff evolution, we combine the stiff $F(R)$ gravity with an $R^2$ model, and we construct a qualitative model for the inflationary and stiff era, with the latter commencing after the end of the inflationary era. We assume that the baryogenesis occurs during the stiff era, and we calculate the baryon to entropy ratio, which effectively constraints the functional form of the stiff $F(R)$ gravity. Further constraints on the stiff $F(R)$ gravity may come from the primordial gravitational waves, and particularly their scalar mode, which is characteristic of the $F(R)$ gravity theory. The stiff era presence does not contradict the standard cosmology era, namely, inflation, and the radiation-matter domination eras. Furthermore, we investigate which $F(R)$ gravity may realize a dust and stiff matter dominated Einstein-Hilbert evolution.

Solitonic boson stars are stable objects made of a complex scalar field with a compactness that can reach values comparable to that of neutron stars. A recent study of the collision of identical boson stars produced only nonrotating boson stars or black holes, suggesting that rotating boson stars may not form from binary mergers. Here we extend this study to include an analysis of the gravitational waves radiated during the coalescence of such a binary, which is crucial to distinguish these events from other binaries with LIGO and Virgo observations. Our studies reveal that the remnant’s gravitational wave signature is mainly governed by its fundamental frequency as it settles down to a nonrotating boson star, emitting significant gravitational radiation during this post-merger state. We calculate how the waveforms and their post-merger frequencies depend on the compactness of the initial boson stars and estimate analytically the amount of energy radiated after the merger.

A method is described for the detection and estimation of transient chirp signals that are characterized by smoothly evolving, but otherwise unmodeled, amplitude envelopes and instantaneous frequencies. Such signals are particularly relevant for gravitational wave searches, where they may arise in a wide range of astrophysical scenarios. The method uses splines with continuously adjustable breakpoints to represent the amplitude envelope and instantaneous frequency of a signal, and estimates them from noisy data using penalized least squares and model selection. Simulations based on waveforms spanning a wide morphological range show that the method performs well in a signal-to-noise ratio regime where the time-frequency signature of a signal is highly degraded, thereby extending the coverage of current unmodeled gravitational wave searches to a wider class of signals.

We construct generalized diffeomorphisms for ${\mathrm{E}}_9$ exceptional field theory. The transformations, which like in the ${\mathrm{E}}_8$ case contain constrained local transformations, close when acting on fields. This is the first example of a generalized diffeomorphism algebra based on an infinite-dimensional Lie algebra and an infinite-dimensional coordinate module. As a byproduct, we give a simple generic expression for the invariant tensors used in any extended geometry. We perform a generalized Scherk–Schwarz reduction and verify that our transformations reproduce the structure of gauged supergravity in two dimensions. The results are valid also for other affine algebras.

The polymer representations, which are partially motivated by loop quantum gravity, have been suggested as alternative schemes to quantize the matter fields. Here we apply a version of the polymer representations to the free electromagnetic field, in a reduced phase space setting, and derive the corresponding effective (i.e., semiclassical) Hamiltonian. We study the propagation of an electromagnetic pulse, and we confront our theoretical results with gamma ray burst observations. This comparison reveals that the dimensionless polymer scale must be smaller than $4\times {10}^{-35}$, casting doubts on the possibility that the matter fields are quantized with the polymer representation we employed.

In the presence of a gravitational field, decay rates may significantly differ from the flat space equivalent. By studying mutually interacting quantum fields, the decay rates can be calculated on a given spacetime. This paper presents the calculation of the transition probability for the decay of a massive scalar particle in a stiff-matter–dominated universe. We find that, due to the presence of a gravitational field, a finite correction to the transition probability is added which depends inversely on the mass. Moreover, the decay rate is smaller, and lifetime of the particles is longer compared to flat space. The mass dependence is such that the lifetime of lighter particles is prolonged more compared to heavier particles. This result may be of significance when studying cosmological situations involving stiff matter.

It is reported that Kerr-Newman and Kerr-Sen black holes are unstable to perturbations of charged massive scalar field. In this paper, we study analytically the complex frequencies which characterize charged massive scalar fields in a near-extremal Kerr-Sen black hole. For near-extremal Kerr-Sen black holes and for charged massive scalar fields in the eikonal large-mass $\mathcal{M}\gg \mu$ regime, where $\mathcal{M}$ is the mass of the black hole, and $\mu$ is the mass of the charged scalar field, we have obtained a simple expression for the dimensionless ratio ${\omega }_I/({\omega }_R-{\omega }_c)$, where ${\omega }_I$ and ${\omega }_R$ are, respectively, the imaginary and real parts of the frequency of the modes, and ${\omega }_c$ is the critical frequency for the onset of super-radiance. We have also found our expression is consistent with the result of Hod [Phys. Rev. D 94, 044036 (2016)] for the case of a near-extremal Kerr-Newman black hole and the result of Zouros and Eardly [Ann. Phys. (N.Y.) 118, 139 (1979)] for the case of neutral scalar fields in the background of a near-extremal Kerr black hole.

We use the $SU(2)$ ’t Hooft-Polyakov monopole configuration, and its Bogomolny-Prasad-Sommerfield (BPS) version, to test the integral equations of the Yang-Mills theory. Those integral equations involve two (complex) parameters which do not appear in the differential Yang-Mills equations, and if they are considered to be arbitrary, it then implies that non-Abelian gauge theories (but not Abelian ones) possess an infinity of integral equations. For static monopole configurations, only one of those parameters is relevant. We expand the integral Yang-Mills equation in a power series of that parameter and show that the ’t Hooft-Polyakov monopole and its BPS version satisfy the integral equations obtained in first and second order of that expansion. Our results point to the importance of exploring the physical consequences of such an infinity of integral equations on the global properties of the Yang-Mills theory.

We study a five-dimensional Horava-Lifshitz–like scalar QED with dynamical exponent $z=2$. Consistency of the renormalization procedure requires the presence of four quartic and one sixfold scalar couplings besides the terms bilinear in the scalar fields. We compute one-loop radiative corrections to the parameters in the original Lagrangian, employing dimensional regularization in the spatial part of the Feynman integrals and prove the relevant Ward identities. By using renormalization group methods, we determine the behavior of the coupling constants with changes in the energy and discuss the emergence of Lorentz symmetry at low energies.

In order to be traversable, the static Lorentzian wormhole must be made out of some exotic matter that violates the weak energy condition. The quantized fields are the natural candidates as their stress-energy tensor, in many cases, possesses desired properties. In this paper we construct and examine the stress-energy tensor of the quantized massive scalar, spinor and vector fields in six static wormhole spacetimes. We find that in all considered cases the quantum fields violate the Morris-Thorne conditions and do not have the form necessary to support the wormhole throat. This is in concord with the previous results and indicates that the massive quantum fields make the wormholes less operable.

Rotating and twisting locally rotationally symmetric imperfect fluids in general relativity admit a much larger set of solutions than the self-similar ones recently suggested in the literature. Explicit forms of the metrics are given and the self-similar subcases are discussed.

For asymptotically flat spacetimes the Penrose inequality gives an initial data test for the weak cosmic censorship hypothesis. We give a formulation of this inequality for asymptotically anti–de Sitter (AAdS) spacetimes, and show that the inequality holds for time asymmetric data in spherical symmetry. Our analysis is motivated by the constant-negative-spatial-curvature form of the AdS black hole metric.

The pseudospectral code bamps is used to evolve axisymmetric gravitational waves. We consider a one-parameter family of Brill wave initial data, taking the seed function and strength parameter of Holz et al. A careful comparison is made to earlier work. Our results are mostly in agreement with the literature, but we do find that some amplitudes reported elsewhere as subcritical evolve to form apparent horizons. Related to this point we find that by altering the slicing condition, the position of the peak of the Kretschmann scalar in these supercritical data can be controlled so that it appears away from the symmetry axis before the method fails, demonstrating that such behavior is at least partially a coordinate effect. We are able to tune the strength parameter to an interval of range $1-A_{\star }/A\simeq {10}^{-6}$ around the onset of apparent horizon formation. In this regime we find that large spikes appear in the Kretschmann scalar on the symmetry axis but away from the origin. From the supercritical side disjoint apparent horizons form around these spikes. On the subcritical side, down to this range, evidence of power-law scaling of the Kretschmann scalar is not conclusive, but the data can be fitted as a power-law with periodic wiggle.

The tunnelling of virtual matter-antimatter pairs from the quantum vacuum in multidimensions is studied. We consider electric backgrounds as a linear combination of a spatial Sauter field and, interchangeably, certain weaker time dependent fields without poles in the complex plane such as the sinusoidal and Gaussian cases. Based on recent geometric considerations within the worldline formalism, we employ the relevant critical points in order to analytically estimate a characteristic threshold for the temporal inhomogeneity. We set appropriate initial conditions and apply additional symmetry constraints in order to determine the classical periodic paths in spacetime. Using these worldline instantons, we compute the corresponding leading order exponential factors showing large dynamical enhancement in general. We work out the main differences caused by the analytic structure of such composite backgrounds and also discuss the case with a strong temporal variation of Sauter type.