We study the pole skipping phenomenon of the scalar retarded Green’s function in the rotating BTZ black hole background. In the static case, the pole skipping points are typically located at negative imaginary Matsubara frequencies $\omega =-(2\pi T)ni$ with appropriate values of complex wave number $q$. But, in a ($1+1$)-dimensional CFT, one can introduce temperatures for left-moving and right-moving sectors independently. As a result, the pole skipping points $\omega$ depend both on left and right temperatures in the rotating background. In the extreme limit, the pole skipping does not occur in general. But in a special case, the pole skipping does occur even in the extreme limit, and the pole skipping points are given by right Matsubara frequencies.

We define and study kinematical observables involving fermion spin, such as the total spin of a collection of particles, in loop quantum gravity. Due to the requirement of gauge invariance, the relevant quantum states contain strong entanglement between gravity and fermionic degrees of freedom. Interestingly we find that properties and spectra of the observables are nevertheless similar to their counterparts from quantum mechanics. However, there are also new effects. Due to the entanglement between gravity and fermionic degrees of freedom, alignment of quantum spins has consequences for quantized geometry. We sketch a particular effect of this kind that may in principle be observable.

Flavor transitions of neutrinos with a nonstandard interaction are studied. A scalar field is conformally coupled to matter and neutrinos. This interaction alters the neutrino effective mass and its wave function leading to a damping factor, causing deficits in the probability densities and affecting the oscillation phase. As the matter density determines the scalar field’s behavior, we also have an indirect matter density effect on the flavor conversion. We explain our results in the context of screening models and study the deficit in the total flux of electron-neutrinos produced in the Sun through the decay process, and we confront our results with observational data.

Theories involving localized collapse allow the possibility that classical information could be obtained about quantum states by mechanisms other than the standard quantum dynamical maps defined by positive operator valued measurements, but nonetheless without allowing superluminal signaling. We can model this by extending quantum theory to include hypothetical devices that read out information about the local quantum state at a given point, which is defined by considering unitary evolution modified only by the effects of collapses in its past light cone. Like Popescu-Rohrlich boxes, these hypothetical devices would have practical and scientific implications if realizable. These include signaling through opaque media, probing the physics of distant or opaque systems without needing a reflected signal and giving detailed information about collapse dynamics without requiring direct observation of the collapsing system. These potential applications add to the motivation for systematic searches for possible signatures of these nonstandard extensions of quantum theory, and in particular for relevant gravitational effects, such as the validity of semiclassical gravity on small scales.

The spacetime of a boosted Bondi-Sachs rotating black hole is considered as a proper background to examine electromagnetic configurations connected to analytic solutions of Maxwell equations. In our analysis, we first use the Bondi-Sachs transformations in order to bring the boosted rotating black hole metric into the Kerr-Schild form, from which zero angular momentum observers (ZAMOs) are constructed via the ADM formalism. In Kerr-Schild coordinates, we obtain the Killing fields as sources of Maxwell electrodynamics, and we fix a ZAMO in order to evaluate the components of the electric and magnetic fields, from which we obtain nonsingular patterns of an eventual momentum-energy emission of a boosted Kerr-Schild black hole. Distinct patterns are examined and discussed in the case of variations of the boost parameter $\gamma$. We extend our analysis by considering the nonsingular electromagnetic emission in the framework of a boosted Bondi-Sachs rotating black hole, as it moves at relativistic speeds. We also discuss possible mechanisms that may resemble magnetospheres of rotating boosted black holes and give rise to hydromagnetic flows from accretion discs and to the production of jets.

We use International Geodynamics and Earth Tide Service absolute gravitational acceleration measurement data to study the gravitational acceleration variance. The relative variance of $\delta g/g$ in 22 years is less than $4\times {10}^{-8}$. Since $\delta G/G⪅\delta g/g$, this implies the relative variance of Newtonian constant is less than $3\times {10}^{-9}$ based on a sinelike oscillation hypothesis. This limit is at least 4 orders of magnitude better than the existing $G$ measurements. The scattered values of reported $G$ measurements coming from different experiments are most probably coming from systematic errors associated with these experiments and not due to intrinsic time variation of $G$. We also find that $\dot{G}/G<5.61\times {10}^{-10}{\mathrm{yr}}^{-1}$ based on a linear hypothesis. This is the best terrestrial result so far.

We construct a toy model for isothermal spheres in Hořava gravity, which includes Einstein’s gravity if a parameter is appropriately chosen. The equations for the isothermal spheres are derived from the partition function of the gravitating particle system. We confirm that the Newtonian limit of the system coincides with the model of the well-known isothermal sphere. The stability of the isothermal sphere is found to be sensitive to the energy density at the center of the sphere.

A model of spontaneous Lorentz violation in four dimension is given, which seems to provide a Lorentz invariant effective theory. An SU(2) Yang-Mills gauge field and an auxiliary U(1) vector field generate gravity and other interactions when they have vacuum expectation values. The emergent gravity is equivalent to conventional general relativity up to the third order terms in the Lagrangian. The coupling to matter, including spin-$1/2$ fermions, is also given correctly to this level. It remains to be seen whether this formalism reproduces the properties of black holes and other consequences obtained from Einstein’s theory.

The possibility for Lorentz and $CPT$ breaking, which is motivated by unification theories, can be systematically tested within the Standard Model extension (SME) framework. In the pure gravity sector, the mass dimension 5 operators produce new Lorentz- and $CPT$-breaking terms in the two-body equations of motion that depend on the relative velocity of the bodies, and, hence, they can be constrained with gravity experiments. In this paper, we report new constraints on 15 independent SME coefficients for Lorentz and $CPT$ violations with mass dimension 5 using lunar laser ranging. We perform a global analysis of lunar ranging data within the SME framework using more than 26 000 normal points between 1969 and 2018. We also perform a jackknife analysis in order to provide realistic estimates of the systematic uncertainties. No deviation from Lorentz and $CPT$ symmetries is reported. In addition, when fitting simultaneously for the 15 canonical SME coefficients for Lorentz and $CPT$ violations, we improve up to 3 orders of magnitude previous postfit constraints from radio pulsars.

In Einstein-Gauss-Bonnet gravity, for a group of warped product spacetimes, we get a generalized master equation for the perturbation of tensor type. We show that the “effective metric” or “acoustic metric” for the tensor perturbation equation can be defined even without a static condition. Since this master equation does not depend on the mode expansion, the hyperbolicity and causality of the tensor perturbation equation can be investigated for every mode of the perturbation. Based on the master equation, we study the hyperbolicity and causality for all relevant vacuum solutions of this theory. For each solution, we give the exact hyperbolic condition of the tensor perturbation equations. Our approach can also applied to dynamical spacetimes, and Vaidya spacetime have been investigated as an example.

Searches for continuous gravitational waves from unknown sources attempt to detect long-lasting gravitational radiation by identifying Doppler-modulated signatures in the data. Semicoherent methods allow for wide parameter space surveys, identifying interesting regions to be followed up using more sensitive (and computationally expensive) tools. Thus, it is required to properly understand the parameter space structure under study, as failing to do so could significantly affect the effectiveness of said strategies. We introduce a new measure for distances in parameter space suited for semicoherent continuous wave searches. This novel approach, based on comparing time-frequency tracks, can be applied to any kind of quasimonochromatic continuous wave signals and adapts itself to the underlying structure of the parameter space under study. In a first application to the post-processing stage of an all-sky search for continuous waves from neutron stars in binary systems, we demonstrate a search sensitivity improvement by solely replacing previous ad hoc distance measures in the candidate clustering procedure by the new proposal.

Exotic compact objects can be difficult to distinguish from black holes in the inspiral phase of the binaries observed by gravitational-wave detectors, but significant differences may be present in the merger and post-merger signal. We introduce a toy model capturing the salient features of binaries of exotic compact objects with compactness below 0.2, which do not collapse promptly following the merger. We use it to assess their detectability with current and future detectors, and whether they can be distinguished from black hole binaries. We find that the Einstein Telescope (LISA) could observe exotic binaries with total mass $\mathcal{O}({10}^2)M_{\odot }$ (${10}^4–{10}^6{M}_{\odot }$), and potentially distinguish them from black hole binaries, throughout the observable Universe, as compared to $z\lesssim 1$ for Advanced LIGO. Moreover, we show that using standard black hole templates for detection could lead to a loss of up to 60% in the signal-to-noise ratio, greatly reducing our chances of observing these signals. Finally, we estimate that if the loudest events in the $\mathrm{O}1/\mathrm{O}2$ catalog released by the LIGO/Virgo collaboration were ECO binaries as the ones considered in this paper, they would have left a post-merger signal detectable with model-agnostic searches, making this hypothesis unlikely.

Cosmic-ray (CR) propagation in the interstellar medium (ISM) of the Galaxy might be a superdiffusion process, rather than the commonly adopted normal diffusion. The spatial distribution of CRs around a pointlike source can be adopted to test the real picture that describes the CR propagation. The TeV $\gamma$-ray halo around the Geminga pulsar is an ideal target, where the spatial distribution of the escaped electrons and positrons can be derived from the morphology of the halo. In this work, we test the superdiffusion model in the ISM around the Geminga pulsar by fitting it to the surface brightness profile of the Geminga halo measured by HAWC. Our results show that the chi-square statistic monotonously increases as $\alpha$ decreases from 2 to 1, where $\alpha$ is the characteristic index of superdiffusion describing the degree of fractality of the ISM and $\alpha =2$ corresponds to the normal diffusion model. We find that a model with $\alpha <1.32$ (using the data within 4° around the pulsar) or $\alpha <1.4$ (using the data within 6° around the pulsar) is disfavored at 95% confidence level. A superdiffusion model with $\alpha$ close to 2 can well explain the morphology of the Geminga halo, while it predicts much higher positron flux at Earth than the normal diffusion model. This has important implication for the interpretation of the CR positron excess.

We study the nonequilibrium dissipative dynamics of the center of mass of a particle coupled to a field via its internal degrees of freedom. We model the internal and external degrees of freedom of the particle as quantum harmonic oscillators in $1+1\mathrm{D}$, with the internal oscillator coupled to a scalar quantum field at the center of mass position. Such a coupling results in a nonlinear interaction between the three pertinent degrees of freedom—the center of mass, internal degree of freedom, and the field. It is typically assumed that the internal dynamics is decoupled from that of the center of mass owing to their disparate characteristic timescales. Here we use an influence functional approach that allows one to account for the self-consistent backaction of the different degrees of freedom on each other, including the coupled nonequilibrium dynamics of the internal degree of freedom and the field, and their influence on the dissipation and noise of the center of mass. Considering a weak nonlinear interaction term, we employ a perturbative generating functional approach to derive a second order effective action and a corresponding quantum Langevin equation describing the non-equilibrium dynamics of the center of mass. We analyze the resulting dissipation and noise arising from the field and the internal degree of freedom as a composite environment. Furthermore, we establish a generalized fluctuation-dissipation relation for the late-time dissipation and noise kernels. Our results are pertinent to open quantum systems that possess intermediary degrees of freedom between system and environment, such as in the case of optomechanical interactions.

We give detailed results of $\mathcal{O}(\alpha )$ QED corrections (both real emission and virtual corrections) to $B\to K{\ell }^{+}{\ell }^{-}$ modes. Requiring the real emission to be gauge invariant, the structure of the contact term(s) is fixed. The calculation is done with a fictitious photon mass as the IR regulator and results are shown to be independent of it, establishing the cancellation of the soft divergences. Results are presented for a choice of photon energy, $k_{\max }$, and photon angle ${\theta }_{\mathrm{cut}}$. The QED effects are negative, thereby reducing the rate compared to that without QED effects. Electron channels are shown to receive large corrections ($\mathcal{O}(20\%)$). Impacts on lepton flavor universality ratio $R_K^{\mu e}$ are also discussed.

We report on a subpercent scale determination using the omega baryon mass and gradient-flow methods. The calculations are performed on 22 ensembles of $N_f=2+1+1$ highly improved, rooted staggered sea-quark configurations generated by the MILC and CalLat Collaborations. The valence quark action used is Möbius domain wall fermions solved on these configurations after a gradient-flow smearing is applied with a flowtime of $t_{\mathrm{gf}}=1$ in lattice units. The ensembles span four lattice spacings in the range $0.06\lesssim a\lesssim 0.15\mathrm{fm}$, six pion masses in the range $130\lesssim m_{\pi }\lesssim 400\mathrm{MeV}$ and multiple lattice volumes. On each ensemble, the gradient-flow scales $t_0/a^2$ and $w_0/a$ and the omega baryon mass $a{m}_{\mathrm{\Omega }}$ are computed. The dimensionless product of these quantities is then extrapolated to the continuum and infinite volume limits and interpolated to the physical light, strange and charm quark mass point in the isospin limit, resulting in the determination of $\sqrt{t_0}=0.1422(14)\mathrm{fm}$ and $w_0=0.1709(11)\mathrm{fm}$ with all sources of statistical and systematic uncertainty accounted for. The dominant uncertainty in both results is the stochastic uncertainty, though for $\sqrt{t_0}$ there are comparable continuum extrapolation uncertainties. For $w_0$, there is a clear path for a few-per-mille uncertainty just through improved stochastic precision, as recently obtained by the Budapest-Marseille-Wuppertal Collaboration.

The angular-averaged differential cross section (dcs) of the elastic electron-proton (ep) scattering, covering $Q^2<1.0{\mathrm{GeV}}^2$, was fitted via a combined modified $eq$-scatterings where $q$ is a point particle. The modifications represent the cloud-covering effects to $q$. An energy-decaying ratio (edr) was derived by inspecting the generated $dc{s}_{ep}$ from the form factor data gathered at Mainz Microtron (A1-Collaboration) and Continuous Electron Beam Accelerator Facility (Jefferson Laboratory) when compared to the $dc{s}_{eq}$ with modified relativistic recoil factor. The diminishing cloud layer, edr, has a decay rate of $-2.8$ for the datasets under investigation. The formulated spin bare mass (SBM) and spin effective mass (SEM) fitting models use the bare and effective $u$ and $d$-quark masses, respectively, while spin with other criteria bare mass (SCBM) and spin with other criteria effective mass (SCEM) integrate other considerations. Three comparison methods were used and all of them favor the models with other additional considerations. SCEM was the most favored model in general.

In the scattering of a small onium off a large nucleus at high center-of-mass energies, when the parameters are set in such a way that the cross section at a fixed impact parameter is small, events are triggered by rare partonic fluctuations of the onium, which are very deformed with respect to typical configurations. Using the color dipole picture of high-energy interactions in quantum chromodynamics, in which the quantum states of the onium are represented by sets of dipoles generated by a branching process, we describe the typical scattering configurations as seen from different reference frames, from the rest frame of the nucleus to frames in which the rapidity is shared between the projectile onium and the nucleus. We show that taking advantage of the freedom to select a frame in the latter class makes it possible to derive complete asymptotic expressions for some boost-invariant quantities, beyond the total cross section, from a procedure which leverages the limited available knowledge on the properties of the solutions to the Balitsky-Kovchegov equation that governs the rapidity dependence of total cross sections. We obtain, in this way, an analytic expression for the rapidity distribution of the first branching of the slowest parent dipole of the set of those which scatter. This distribution provides an estimator of the correlations of the interacting dipoles and is also known to be related to the rapidity-gap distribution in diffractive dissociation, an observable measurable at a future electron-ion collider. Furthermore, our result may be formulated as a more general conjecture that we expect to hold true for any one-dimensional branching random walk model, on the branching time of the most recent common ancestor of all the particles that end up to the right of a given position.

We study the energy loss and the energy gain of heavy quarks in a hot thermal medium, aiming to mimic the initial stage of the high energy nuclear collisions. The processes we are interested in include the energy change due to the polarization and to the interaction with the thermal fluctuations of the medium. The dynamics of the heavy quarks with the medium is described by the Wong equations, that allow for the inclusion of both the backreaction on the heavy quarks due to the polarization of the medium, and of the interaction with the thermal fluctuations of the gluon field. Both the momentum as well as the temperature dependence of the energy loss and gain of charm and beauty are studied. We find that heavy quark energy gain dominate the energy loss at high-temperature domain achievable at the early stage of the high energy collisions. This finding supports the recently observed heavy quarks results in glasma and will have a significant impact on heavy quark observables at RHIC and LHC energies.

$CP$ violation (CPV) in $D^0-{\overline{D}}^0$ mixing is described in terms of the dispersive and absorptive “weak phases” ${\varphi }_f^M$ and ${\varphi }_f^{\mathrm{\Gamma }}$. They parametrize CPV originating from the interference of $D^0$ decays with and without dispersive mixing, and with and without absorptive mixing, respectively, for $CP$ conjugate hadronic final states $f$, $\overline{f}$. These are distinct and separately measurable effects. For $CP$ eigenstate final states, indirect CPV only depends on ${\varphi }_f^M$ (dispersive CPV), whereas ${\varphi }_f^{\mathrm{\Gamma }}$ (absorptive CPV) can only be probed with non-$CP$ eigenstate final states. Measurements of the final state dependent phases ${\varphi }_f^M$, ${\varphi }_f^{\mathrm{\Gamma }}$ determine the intrinsic dispersive and absorptive mixing phases ${\varphi }_2^M$ and ${\varphi }_2^{\mathrm{\Gamma }}$. The latter are the arguments of the dispersive and absorptive mixing amplitudes $M_{12}$ and ${\mathrm{\Gamma }}_{12}$, relative to their dominant ($\mathrm{\Delta }U=2$) $U$-spin components. The intrinsic phases are experimentally accessible due to approximate universality: in the SM, and in extensions with negligible new CPV phases in Cabibbo favored/doubly Cabibbo suppressed (CF/DCS) decays, the deviation of ${\varphi }_f^{M,\mathrm{\Gamma }}$ from ${\varphi }_2^{M,\mathrm{\Gamma }}$ is negligible in CF/DCS decays $D^0\to K^{\pm }X$, and below 10% in CF/DCS decays $D^0\to K_{S,L}X$ (up to precisely known $O({\epsilon }_K)$ corrections). In singly Cabibbo suppressed (SCS) decays, QCD pollution enters at $O(\epsilon )$ in $U$-spin breaking and can be significant, but is $O({\epsilon }^2)$ in the average over $f=K^{+}{K}^{-}$, ${\pi }^{+}{\pi }^{-}$. SM estimates yield ${\varphi }_2^M,{\varphi }_2^{\mathrm{\Gamma }}=O(0.2\%)$. A fit to current data allows $O(10)$ larger phases at $2\sigma$, from new physics. A fit based on naively extrapolated experimental precision suggests that sensitivity to ${\varphi }_2^M$ and ${\varphi }_2^{\mathrm{\Gamma }}$ in the SM may be achieved at the LHCb Phase II upgrade.