We investigate entanglement degradation in the vicinity of a quantum corrected black hole. We consider a biprtite system (Alice-Rob) with Alice freely falling (radially) into the event horizon of a quantum corrected black hole and Rob being in the vicinity of the event horizon of the black hole. We consider a maximally entangled state (in the Fock basis) and start with the basic assumption that Rob is an uniformly accelerated observer. We then give a pedagogical analysis of the relation involving the Minkowski vaccum state and Rindler number states. Following the analogy given in Martín-Martínez et al. [Phys. Rev. D 82, 064006 (2010)], we establish the relation between the Hartle-Hawking vacuum state and Boulware and anti-Bouware number states from the Minkowski-Rindler relation. We then write down the quantum corrected black hole metric by making use of the near horizon approximation in an appropriate form. Next, we obtain the analytical forms of logarithmic negativity and mutual information and plot as a function of Rob’s distance from the $r=0$ point. We observe that the entanglement degradation slows down because of the structural change in the lapse function of the metric via the incorporation of quantum gravity corrections in the Schwarzschild black hole. It is crucial to understand that any modified gravity theories that changes the metric structure results in a different rate of degradation of the entanglement. At the horizon radius, the entanglement degradation is always complete irrespective of the underlying theory. This observation may lead to the identification of the signature of modified gravity theories in a future generation of advanced observational scenarios. Such a modification can come from higher curvature corrections, higher dimensional gravity theories, quantum gravity corrections, etc. We can also interpret this effect as a noisy quantum channel with an operator sum representation of a completely positive and trace preserving map. We then finally obtain the entanglement fidelity using this operator sum representation.

In this study, we construct a $1+1$-dimensional, relativistic, free, complex scalar quantum field theory on the noncommutative spacetime known as lightlike $\kappa$-Minkowski. The associated $\kappa$-Poincaré quantum group of isometries is triangular, and its quantum R matrix enables the definition of a braided algebra of $N$ points that retains $\kappa$-Poincaré invariance. Leveraging our recent findings, we can now represent the generators of the deformed oscillator algebra as nonlinear redefinitions of undeformed oscillators, which are nonlocal in momentum space. The deformations manifest at the multiparticle level, as the one-particle states are identical to the undeformed ones. We successfully introduce a covariant and involutive deformed flip operator using the R matrix. The corresponding deformed (anti)symmetrization operators are covariant and idempotent, allowing for a well-posed definition of multiparticle states, a result long sought in quantum field theory on $\kappa$-Minkowski. We find that $P$ and $T$ are not symmetries of the theory, although $PT$ (and hence $CPT$) is. We conclude by noticing that identical particles appear distinguishable in the new theory, and discuss the fate of the Pauli exclusion principle in this setting.

The asymptotic symmetry algebra of $\mathcal{N}=1$ supergravity was recently constructed using the well-known two-dimensional celestial conformal field (CFT) theory technique [A. Fotopoulos et al., J. High Energy Phys. 09 (2020) 198]. In this paper, we extend the construction to the maximally supersymmetric four-dimensional $\mathcal{N}=8$ supergravity theory in asymptotically flat spacetime and construct the extended asymptotic symmetry algebra, which we call $\mathcal{N}=8{\mathfrak{s}\mathfrak{b}\mathfrak{m}\mathfrak{s}}_4$. We use the celestial CFT technique to find the appropriate currents for extensions of $\mathcal{N}=8$ super-Poincaré and $\mathrm{SU}(8{)}_R$ R-symmetry current algebra on the celestial sphere ${\mathcal{C}\mathcal{S}}^2$. We generalize the definition of shadow transformations and show that there is no infinite dimensional extension of the global $\mathrm{SU}(8{)}_R$ algebra in the theory.

Despite constituting a noteworthy $\sim 27\%$ share of the total energy budget of our Universe, dark matter (DM) has thus far eluded direct observations. Owing to its pervasive nature, there is a sincere expectation that astrophysical black holes (BHs) encompassed by DM should leave distinctive imprints on the gravitational waves arising from BH mergers. Theoretical models of DM present a diverse landscape of possibilities, with perfect fluid dark matter (PFDM) emerging as a recent and notably intriguing candidate model. In this work, utilizing the established quantum optical approach, we investigate the possibility of catching DM signatures via acceleration radiation emitted by a freely falling detector (e.g., an atom) within a PFDM-surrounded Schwarzschild BH. The setup involves a Casimir-type apparatus where the detector interacts with the field, and this situation induces excitations in the detector in a manner consistent with Unruh effect. We observe that our DM candidate, while making classical contributions to spacetime geometry, has the potential to leave quantum imprints in the radiation flux. Notably, it is observed that, in comparison to a pure Schwarzschild BH, PFDM can markedly reduce particle emission as long as its density remains below a critical threshold, and vice versa. Given the lessons we have learnt from realizing cosmological phenomena in simulated laboratory conditions, there is a remote possibility that such study may perhaps provide insights (to whatever degree) into the future table-top experiments in analog gravity paradigm.

In theories where physics depends on a global foliation of space-time, a black hole’s horizon is surrounded by an “eternity skin”: a pile-up of spacelike leaves that in the far-out region cover all times from the start of collapse to future eternity. Any future foliation-dependent change in the laws of physics would be enacted in this region and affect the last stages of collapse toward black hole formation. We show how in some cases the black hole never forms but, rather, bounces into an explosive event. There is also a nonlocal transfer of energy between the asymptotic Universe and the formed black hole precursor, so that the back hole (if formed) or the exploding star (otherwise) will have a different mass from what was initially thrown in. These last matters are generic to nonlocal theories and can be traced to the breakdown of the local Hamiltonian constraint.

In this work, I study the tidal deformation of black holes in binary mergers in the strong field regime. A different approach to the problem of tidal deformability of black holes is taken using the source multipole moments of their dynamical horizons and numerical relativity, instead of the field multipole moments of the gravitational field at infinity. I compute these source multipole moments in the inspiral phase of binary black hole mergers, uncover several interesting new features in the evolution of the deformations of the dynamical horizon geometry, and characterize how nonspinning black holes deform. Owing to the mutual tidal interactions, I describe how the dynamical horizons of the two black holes deform and steadily acquire various multipole moments that would otherwise vanish when the horizons are isolated. Out of these, the dominant deformation is shown to be quadrupolar. I further show that their evolution has a familiar chirplike behavior. I also find that these deformations encode detailed information about the dynamics of the binary black hole system. Particularly, the dominant quadrupolar deformation is shown to be strongly correlated with the gravitational field of the system at future null infinity. Therefore, the gravitational waves carried away from the system contain imprints of the geometrical structure of the dynamical horizons in the strong-field regime. Thus, although causally disconnected from observers, these correlations may present us with a novel way to probe the strong field structure of gravitational fields in astrophysical scenarios. The results here may be important in the strong field tests of black holes and general relativity, for the no-hair conjecture in the strong field, dynamical regimes, and in astrophysical contexts especially when the black holes are close to the merger.

Primordial magnetic fields (PMFs) are one of the plausible candidates for the origin of the observed large-scale magnetic fields. While many proposals have been made for the generation mechanism of PMFs by earlier studies, it remains a subject of debate. In this paper, to obtain new insights into PMFs, we focus on the intrinsic alignments (IAs) of galaxies induced by the vector and tensor modes of the anisotropic stress of PMFs. The long-wavelength vector and tensor modes locally induce the tidal gravitational fields, leading to the characteristic distortions of the intrinsic ellipticity of galaxies. We investigate the shear E- and B-mode power spectra induced by the magnetic vector and tensor modes in the three-dimensional space, assuming the combination of galaxy imaging and galaxy redshift surveys. We find that the magnetic tensor mode dominates both the E- and B-mode spectra. In particular, the B-mode spectrum induced by the magnetic tensor mode plays a crucial role in constraining the amplitude of PMFs, even in the presence of the nonmagnetic scalar contribution to the B-mode spectrum arising from the one-loop effect. In future galaxy redshift surveys, such as the Euclid and Square Kilometre Array, the minimum detectable value reaches $\sim 30\mathrm{nG}$, which can potentially get even smaller in proportion to the number of observed galaxies and reach $\sim \mathcal{O}(1\mathrm{nG})$. Measuring the IAs of galaxies would be a potential probe for PMFs in future galaxy surveys.

The Borde-Guth-Vilenkin theorem states that any spacetime with net positive expansion must be geodesically incomplete. We derive a new version of the theorem using the fluid flow formalism of general relativity. The theorem is purely kinematic, depending on the local expansion properties of geodesics, and makes no assumptions about energy conditions. We discuss the physical interpretation of this result in terms of coordinate patches on de Sitter space, and apply the theorem to Penrose’s model of conformal cyclic cosmology. We argue that the conformal cyclic extension of an asymptotically de Sitter universe is geodesically incomplete.

We investigate reentrant and dielectric loaded cavities for the purpose of extending the range of axion cavity haloscopes to lower masses, below the range where the Axion Dark Matter experiment (ADMX) has already searched. Reentrant and dielectric loaded cavities were simulated numerically to calculate and optimize their form factors and quality factors. A prototype reentrant cavity was built and its measured properties were compared with the simulations. We estimate the sensitivity of axion dark matter searches using reentrant and dielectric loaded cavities inserted in the existing ADMX magnet at the University of Washington and a large magnet being installed at Fermilab.

The LISA Pathfinder (LPF) mission successfully demonstrated the feasibility of the technology needed for the future space borne gravitational wave observatory LISA. A key subsystem under study was the laser interferometer, which measured the changes in relative distance in between two test masses (TMs). It achieved a sensitivity of ${32.0}_{-1.7}^{+2.4}\mathrm{fm}/\sqrt{\mathrm{Hz}}$, which was significantly better than the prelaunch tests. This improved performance allowed direct observation of the influence of laser frequency noise in the readout. The differences in optical path lengths between the measurement and reference beams in the individual interferometers of our setup determined the level of this undesired readout noise. Here, we discuss the dedicated experiments performed on LPF to measure these differences with high precision. We reached differences in path length difference between $(368\pm 5)\mathrm{\mu m}$ and $(329.6\pm 0.9)\mathrm{\mu m}$ which are significantly below the required level of 1 mm or $1000\mathrm{\mu m}$. These results are an important contribution to our understanding of the overall sensor performance. Moreover, we observed varying levels of laser frequency noise over the course of the mission. We provide evidence that these do not originate from the laser frequency stabilization scheme which worked as expected. Therefore, this frequency stabilization would be applicable to other missions with similar laser frequency stability requirements.

Long-lived particles (LLPs) arise in many theories beyond the Standard Model. These may be copiously produced from meson decays (or through their mixing with the LLPs) at neutrino facilities and leave a visible decay signal in nearby neutrino detectors. We compute the expected sensitivity of the DUNE liquid argon (LAr) and gaseous argon near detectors (NDs) to light LLP decays. In doing so, we determine the expected backgrounds for both detectors, which have been largely overlooked in the literature, taking into account their angular and energy resolution. We show that searches for LLP decays into muon pairs, or into three pions, would be extremely clean. Conversely, decays into two photons would be affected by large backgrounds from neutrino interactions for both near detectors; finally, the reduced signal efficiency for $e^{+}{e}^{-}$ pairs leads to a reduced sensitivity for ND-LAr. Our results are first presented in a model-independent way, as a function of the mass of the new state and its lifetime. We also provide detailed calculations for several phenomenological models with axionlike particles (coupled to gluons, electroweak bosons, or quark currents). Some of our results may also be of interest for other neutrino facilities using a similar detector technology (e.g., MicroBooNE, SBND, ICARUS, or the T2K near detector).

Numerical computations in strongly interacting quantum field theories are often performed using Monte Carlo sampling methods. A key task in these calculations is to estimate the value of a given physical quantity from the distribution of stochastic samples that are generated using the Monte Carlo method. Typically, the sample mean and sample variance are used to define the expectation values and uncertainties of computed quantities. However, the Monte Carlo sample distribution contains more information than these basic properties, and it is useful to investigate it more generally. In this work, the exact form of the probability distributions of two-point correlation functions at zero momentum in $O(N)$ lattice field theories in the disordered phase and in infinite volume are determined. These distributions allow for a robust investigation of the efficacy of the Monte Carlo sampling procedure and are shown also to allow for improved estimators of the target physical quantity to be constructed. The theoretical expectations are shown to agree with numerical calculations in the $O(2)$ model.

We simulate quantum electrodynamics (QED) in a strong constant homogeneous external magnetic field on a Euclidean space-time lattice using the rational hybrid Monte Carlo method, developed for simulating lattice quantum chromodynamics (QCD). Our primary goal is to measure the chiral condensate in the limit when the input electron mass $m$ is zero. We observe a nonzero value, indicating that the external magnetic field catalyzes chiral symmetry breaking as predicted by approximate truncated Schwinger-Dyson methods. Such behavior is associated with dominance by the lowest Landau level which causes the effective dimensional reduction from $3+1$ dimensions to $1+1$ dimensions for charged particles (electrons and positrons) where the attractive forces of QED can produce chiral symmetry breaking with a dynamical electron mass and associated chiral condensate. Since our lattice simulations use bare (lattice) parameters, while the Schwinger-Dyson analyses work with renormalized quantities, direct numerical comparison will require renormalization of our lattice results.

We investigate the chiral phase transition within a sphere under a uniform background magnetic field. The Nambu–Jona-Lasinio (NJL) model is employed and the MIT boundary condition is imposed for the spherical confinement. Using the wave expansion method, the diagonalizable Hamiltonian and energy spectrum are derived for the system. By solving the gap equation in the NJL model, the influence of magnetic field on quark matter in a sphere is studied. It is found that inverse magnetic catalysis occurs at small radii, while magnetic catalysis occurs at large radii. Additionally, both magnetic catalysis and inverse magnetic catalysis are observed at the intermediate radii ($R\approx 4\mathrm{fm}$).

Motivated by the recent lattice QCD study of the $D{D}^{*}$ interaction at unphysical quark masses, we perform a theoretical study of the $D{D}^{*}$ interaction in covariant chiral effective field theory. In particular, we calculate the relevant leading-order two-pion exchange contributions. The results compare favorably with the lattice QCD results, supporting the conclusion that the intermediate-range $D{D}^{*}$ interaction is dominated by two-pion exchanges and the one-pion exchange contribution is absent. At a quantitative level, the covariant chiral perturbation theory results agree better with the lattice QCD results than their nonrelativistic counterparts, showing the relevance of relativistic corrections in the charm sector.

We have analyzed $121.4{\mathrm{fb}}^{-1}$ of data collected at the $\mathrm{\Upsilon }(5S)$ resonance by the Belle experiment using the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider to search for the decay $B_s^0\to J/\psi {\pi }^0$. We observe no signal and report an upper limit on the branching fraction $\mathcal{B}(B_s^0\to J/\psi {\pi }^0)$ of $1.21\times {10}^{-5}$ at 90% confidence level. This result is the most stringent, improving the previous bound by 2 orders of magnitude.

Using a sample of 10 billion $J/\psi$ events collected with the BESIII detector, the decays ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$, ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$ and ${\eta }^{\prime }\to 4{\pi }^0$ are studied via the process $J/\psi \to \gamma {\eta }^{\prime }$. The branching fractions of ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ and ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\pi }^0$ ${\pi }^0$ are measured to be $(8.56\pm 0.25(\mathrm{stat})\pm 0.23(\mathrm{syst}))\times {10}^{-5}$ and $(2.12\pm 0.12(\mathrm{stat})\pm 0.10(\mathrm{syst}))\times {10}^{-4}$, respectively, which are consistent with previous measurements but with improved precision. No significant ${\eta }^{\prime }\to 4{\pi }^0$ signal is observed, and the upper limit on the branching fraction of this decay is determined to be less than $1.24\times {10}^{-5}$ at the 90% confidence level. In addition, an amplitude analysis of ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ is performed to extract the doubly virtual isovector form factor $\alpha$ for the first time. The measured value of $\alpha =1.22\pm 0.33(\mathrm{stat})\pm 0.04(\mathrm{syst})$, is in agreement with the prediction of the vector meson dominance model.

Belle II has reported the first evidence for $B^{+}\to K^{+}\nu \overline{\nu }$ with a branching ratio $2.7\sigma$ higher than the standard model expectation. We explain this and the MiniBooNE and muon anomalous magnetic moment anomalies in a model with a dark scalar that couples to a slightly heavier sterile Dirac neutrino and that communicates with the visible sector via a Higgs portal. We make predictions for rare kaon and other $B$ meson decays.

The free massless superparticle is reanalyzed, in particular by performing the Gupta-Bleuler quantization, using the first- and second-class constraints of the model, and obtaining as a result, the Weyl equation for the spinorial component of the chiral superfield. Then we construct a superconformal model of two interacting massless superparticles from the free case by the introduction of an invariant interaction. The interaction introduces an effective mass for each particle by modifying the structure of fermionic constraints, all becoming second class. The quantization of the model produces a bilocal chiral superfield. We also generalize the model by considering a system of superconformal interacting particles and its continuum limit.

A major challenge in causal set research is that theories need only to match general relativity and quantum field theory in the appropriate limits. This means that there should be many different ways to calculate a propagator in a causal set that match the known limits, but may give significantly different results on the small scale. In this work, we explore under what conditions a path sum will correspond to a propagator for a relativistic particle in such a way that it matches the known value in the continuum limit. A family of solutions for the path sum is found and is verified numerically in a few specific cases.