The optical characteristics of the Kazakov-Solodukhin black hole (BH) surrounded by a thin disk is investigated. By utilizing the ray-tracing method, we derive the direct and secondary images to illustrate the influence of observational inclination angle (${\theta }_0$) and quantum correction parameter ($a$) on the observable properties. Our calculation involves determining the effective potential, light deflection, and azimuthal angle of the BH as well as the radiation flux of the accretion disk. By assuming three function models, we determine that the exponential function is the most suitable for describing the relationship between the observed flux and the quantum deformation parameter. Our research reveals that the observable characteristics of a BH are affected not only by the shape of the accretion disk but also by its spatiotemporal properties and the observer’s inclination angle. We observe that a BH encircled by an optically thick accretion disk yields different results from those of an optically thin disk.

Spirals in multiphoton pair production are revisited by two counterrotating fields with time delay for different cycles in pulse. Novel findings include that for subcycle fields; the remarkable spiral structure in the momentum spectrum can be still caused by a large time delay compared to the previous study for the supercycle case where it is easier to be generated by a small time delay. Also there exist a range of critical polarization values for the spirals’ appearance corresponding to the different cycle numbers. The relative phase difference between two fields causes not only severe symmetry breaking of the momentum spectra pattern and spiral but also a significant change for the shape and the number of spiral arms. The number density is found to be more sensitive to the cycle number; in particular, it is enhanced by more than one order of magnitude for a small cycle pulse, while it is increased a few times when the time delay is small. These results provide an abundant theoretical testbed for the possible experimental observation of the multiphoton pair production in the future. Meanwhile, it is applicable to use the particles’ momentum signatures as a new way to probe the laser field information.

The branching fractions of the decays ${\tau }^{-}\to K^{-}{\pi }^{+}{\pi }^{-}{\nu }_{\tau }$, ${\tau }^{-}\to K^{-}{\pi }^0{\pi }^0{\nu }_{\tau }$, and ${\tau }^{-}\to {\overline{K}}^0{\pi }^{-}{\pi }^0{\nu }_{\tau }$ are calculated in the $U(3)\times U(3)$ Nambu–Jona-Lasinio-type chiral model. Four intermediate channels are considered: the contact channel and the channels with the intermediate axial-vector, vector, and pseudoscalar mesons. The additional resonance states $K^{*}\pi$ and $K\rho$ are taken into account in all channels. We show that the main contributions to the widths of these decays are given by the axial-vector channel. In the axial-vector channel, the intermediate resonances $K_1(1270)$ and $K_1(1400)$ are taken into account. The obtained results are in satisfactory agreement with the known experimental data.

We consider the process of diffusion or “prescrambling” of information in a quantum system. We define a measure for this spreading or “prescrambling” of the wave function in terms of a minimum probability threshold for the states in the system’s Hilbert space. We illustrate our findings on the example of a prototype model with enhanced memory capacity. We conjecture: (1) The fastest prescramblers require a time logarithmic in the number of degrees of freedom. (2) The investigated enhanced memory capacity model is a fast prescrambler. (3) (Fast) prescrambling occurs not later than (fast) scrambling. (4) Fast scramblers are fast prescramblers. (5) Black holes are fast prescramblers.

We perform a complete study of the electroweak precision observables and electroweak gauge boson pair production in terms of the Standard Model effective field theory up to $\mathcal{O}(1/{\mathrm{\Lambda }}^4)$ under the assumption of universal $C$ and $P$ conserving new physics. We show that the analysis of data from those two sectors allows us to obtain closed constraints in the relevant parameter space in this scenario. In particular, we find that the Large Hadron Collider data can independently constrain the Wilson coefficients of the dimension-six and -eight operators directly contributing to the triple gauge boson vertices. Our results show that the impact of dimension-eight operators in the study of triple gauge couplings is small.

It was recently shown that domain walls from the spontaneous breaking of $CP$ symmetry are exactly stable, and must be inflated away to recover a viable cosmology. We investigate the phenomenological implications of this result in Nelson-Barr solutions of the strong $CP$ problem. Combined with the upper bound on the scale of spontaneous $CP$ breaking necessary to suppress contributions from dangerous, nonrenormalizable operators to $\overline{\theta }$, this puts an upper bound on the scale of inflation and the reheating temperature after inflation. Minimal Nelson-Barr models are therefore in tension with thermal leptogenesis, models of large-field inflation, or potential future observations of signals from topological remnants of an unrelated, subsequent phase transition. We study how extending Nelson-Barr models with a new, continuous chiral gauge symmetry can ameliorate this tension by forbidding the dangerous dimension-five operators. In particular, we show that gauging a linear combination of baryon number and hypercharge allows for an economic, anomaly-free extension of the minimal Nelson-Barr model, and discuss the phenomenological implications.

We highlight general issues associated with quality and naturalness problems in theories of light QCD axions, axionlike particles, and relaxions. We show that the presence of Planck-suppressed operators generically lead to scalar coupling of axions with the Standard Model. We present a new class of ${\mathbb{Z}}_N$ QCD relaxion models that can address both the QCD relaxion $CP$ problem as well as its quality problem. This new class of models also leads to interesting experimental signatures, which can be searched for at the precision frontier.

We present a novel approach to the study of di-Higgs production via gluon-gluon fusion at the LHC. The relevant Feynman diagrams involving two Standard Model-like Higgs bosons $hh$ are computed within a simplified model approach that enables one to interpret possible signals of new physics in a model-independent way as well as to map these onto specific theories. This is possible thanks to a decomposition of such a signal process into all its squared amplitudes and their relative interferences, each of which has a well-defined coupling structure. We illustrate the power of this procedure for the case of both a minimal and next-to-minimal representation of supersymmetry, for which the new physics effects are due to top squarks entering the loops of $gg\to hh$. The squarks yield both a change of the integrated cross section and peculiar kinematic features in its differential distributions with respect to the Standard Model. These effects can in turn be traced back to the relevant diagrammatic and coupling structures and allow for a detailed analysis of the process. In order to do so, we perform systematic scans of the parameter spaces of such new physics scenarios and identify benchmark points which exhibit potentially observable features during the current and upcoming runs of the LHC.

The early kinetic decoupling (eKD) effect is an inevitable ingredient in calculating the relic density of dark matter (DM) for various well-motivated scenarios. It appears naturally in forbidden dark matter annihilation, the main focus of this work, which contains fermionic DM and a light singlet scalar that connects the DM and standard model (SM) leptons. The strong suppression of the scattering between DM and SM particles happens quite early in the DM depletion history, where the DM temperature drops away from the thermal equilibrium, $T_{\chi }<T_{\mathrm{SM}}$, leading to the decreased kinetic energy of DM. The forbidden annihilation thus becomes inefficient since small kinetic energy cannot help exceed the annihilation threshold, naturally leading to a larger abundance. To show the eKD discrepancy, we numerically solve the coupled Boltzmann equations that govern the evolution of DM number density and temperature. It is found that eKD significantly affects the DM abundance, resulting in almost an order of magnitude higher than that by the traditional calculation. We also discuss the constraints from experimental searches on the model parameters, where the viable parameter space shrinks when considering the eKD effect.

We introduce a new technique named latent CATHODE (LaCATHODE) for performing “enhanced bump hunts,” a type of resonant anomaly search that combines conventional one-dimensional bump hunts with a model-agnostic anomaly score in an auxiliary feature space where potential signals could also be localized. The main advantage of LaCATHODE over existing methods is that it provides an anomaly score that is well behaved when evaluating it beyond the signal region, which is essential to prevent the sculpting of background distributions in the bump hunt. LaCATHODE accomplishes this by constructing the anomaly score directly in the latent space learned by a conditional normalizing flow trained on sideband regions. We demonstrate the superior stability and comparable performance of LaCATHODE for enhanced bump hunting in an illustrative toy example as well as on the LHC Olympics R&D dataset.

Presented are the first measurements of the transverse single-spin asymmetries ($A_N$) for neutral pions and eta mesons in $p+\mathrm{Au}$ and $p+\mathrm{Al}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$ in the pseudorapidity range $|\eta |<0.35$ with the PHENIX detector at the Relativistic Heavy Ion Collider. The asymmetries are consistent with zero, similar to those for midrapidity neutral pions and eta mesons produced in $p+p$ collisions. These measurements show no evidence of additional effects that could potentially arise from the more complex partonic environment present in proton-nucleus collisions.

Although holographic duality has been regarded as a complementary tool in helping understand the nonequilibrium dynamics of strongly coupled many-body systems, it still remains a remarkable challenge how to confront its predictions quantitatively with real experimental scenarios. By matching the holographic vortex dynamics with the phenomenological dissipative Gross-Pitaevskii models, we find that the holographic dissipation mechanism can be well captured by the Landau form rather than the Keldysh one, although the latter is much more widely used in numerical simulations. Our finding is expected to open up novel avenues for facilitating the quantitative test of holographic predictions against upcoming experimental data. Our result also provides a prime example how holographic duality can help select proper phenomenological models to describe far-from-equilibrium nonlinear dynamics beyond the hydrodynamic regime.

A fluid model of self-gravitating strings is proposed. It is expected that black holes turn into strings around the end of black hole evaporation. The transition will occur near the Hagedorn temperature. After the transition, strings would form a bound state by the self-gravitation. Horowitz and Polchinski formulated a model of self-gravitating strings by using winding strings wrapping on the Euclidean time circle [Phys. Rev. D 57, 2557 (1998)]. In this paper, we first show that winding strings in the Horowitz-Polchinski model approximately behave as a perfect fluid. Then, we solve the Einstein equation for the fluid of winding strings. Our solution reproduces behaviors of the self-gravitating string solution in the Horowitz-Polchinski model near the Hagedorn temperature, while it approaches the Schwarzschild black hole at low temperatures. Thus, our fluid model of self-gravitating strings gives a description of the transition between black holes and strings.

We discuss loop corrections to the electric current produced by a strong and lengthy electric pulse. Namely we calculate the one-loop contribution to the electric current and distinguish terms which depend on the pulse duration. We show that the one-loop correction does not lead to a strong modification of the tree-level current, which linearly grows with the pulse duration. Meanwhile, the correction to the photon propagator contains additional secular growth with the pulse duration. Based on the latter observation we argue that higher-loop corrections will strongly modify the tree-level current, but that will demand a longer duration of the pulse than if the growth was at the first-loop level.

In special-relativistic physics, spacetime is imbued with a fixed, nondynamical metric tensor. A path to gravitational theory is to promote this tensor to a genuine dynamical field. An alternative description of special-relativistic physics involves no fixed spacetime geometry but instead the inclusion of scalar fields $X^I(x^{\mu })$ which dynamically may take the form of inertial coordinates in spacetime. This suggests an alternative approach to gravity where the invariance of actions under global Poincaré transformations of $X^I$ is promoted to either a local Poincaré, local translational, or local Lorentz symmetry via the introduction of gauge fields. Points of commonality and departure of the resulting gravitational theories as compared to general relativity are discussed. It is shown that the model based on local Lorentz symmetry is an extension of general relativity that can introduce a standard of time into the dynamics of the gravitational field and allows for spacetimes described by a Minkowski metric or flat Euclidean signature metric despite the gravitational gauge field possessing nonzero curvature.

We consider a generalization of the quintessence type scalar field cosmological models, by adding a multiplicative dissipative term in the scalar field Lagrangian, which generally is represented in an exponential form. The generalized dissipative Klein-Gordon equation is obtained in a general covariant form in Riemann geometry, from the variational principle with the help of the Euler-Lagrange equations. The energy-momentum tensor of the dissipative scalar field is also obtained from the dissipative Lagrangian, and its properties are discussed in detail. Several applications of the general formalism are presented for the case of the cosmological Friedmann-Lemaître-Robertson-Walker metric. The generalized Friedmann equations in the presence of the dissipative scalar field are obtained for a specific form of dissipation, with the dissipation exponent represented as the time integral of the product of the Hubble function, and of a function describing the dissipative properties of the scalar field. For this case the Friedmann equations reduce to a system of differential-integral equations, which, by means of some appropriate transformation, can be represented in the redshift space as a first order dynamical system. Several cosmological models, corresponding to different choices of the dissipation function, and of the scalar field potential, are considered in detail. For the different values of the model parameters the evolution of the cosmological parameters (scale factor, Hubble function, deceleration parameter, the effective density and pressure of the scalar field, and the parameter of the dark energy equation of state, respectively) is considered in detail by using both analytical and numerical techniques. A comparison with the observational data for the Hubble function and with the predictions of the standard $\mathrm{\Lambda }\mathrm{CDM}$ paradigm is presented for each dissipative scalar field model. In the large time limit the model describes an accelerating universe, with the effective negative pressure induced by the dissipative effects associated with the scalar field. Accelerated expansion in the absence of the scalar field potential is also possible, with the kinetic term dominating the expansionary evolution. The dissipative scalar field models describe well the data, with the model free parameters obtained by a trial and error method. The obtained results show the dissipative scalar field model offers an effective dynamical possibility for replacing the cosmological constant and for explaining the recent cosmological observational data.

The linear point (LP) standard ruler was identified as the basis of a purely geometric method for exploiting the baryon acoustic oscillations (BAO). The LP exploits the BAO feature imprinted in the galaxy two-point correlation function to measure cosmological distances independent of any specific cosmological model. We forecast the expected precision of future and ongoing spectroscopic galaxy surveys to measure distances leveraging the linear point. We investigate the cosmological implications of our forecasted results. We focus in particular on a relevant working example: the detection of the late-time cosmic acceleration independent of other cosmological probes. Our findings show that, even within the $\mathrm{\Lambda }\mathrm{CDM}$ standard cosmological paradigm, estimated distances need to be reliable over a very wide parameter range in order to realize their maximum utility. This is particularly relevant if we aim to properly characterize cosmological tensions. The LP is a promising candidate approach to achieve this reliability. In contrast, widely employed procedures in BAO analysis estimate distances keeping fixed cosmological parameters to fiducial values close to cosmic-microwave-background constraints in flat-$\mathrm{\Lambda }\mathrm{CDM}$. It is unclear whether they are purely geometric methods. Moreover, they rely on untested extrapolations to explore the parameter space away from those fiducial flat-$\mathrm{\Lambda }\mathrm{CDM}$ values. We recommend that all BAO methodologies be validated across the full range of models and parameters over which their results are quoted, first by means of linear predictions and then $N$-body simulations.

It is known that magnetic fields exist near black holes and photons can go around black holes due to strong gravity. Utilizing these facts, we can probe hypothetical pseudoscalar particles, so-called axions. In fact, photons can be converted into axions when they propagate in a magnetic field. The conversion of such photons into axions leads to a dimming of the photon ring around the black hole shadow. We show that photon ring dimming can occur efficiently for supermassive black holes. Remarkably, it turns out that the maximal dimming rate of the photon ring is 25%. In the case of $\mathrm{M}{87}^{*}$, dimming of 10% will be observed in the x-ray and gamma-ray bands if the angular resolution of ${10}^{-5}\mathrm{arcsec}$ is achieved. The frequency band and the magnitude of the dimming depend on the axion-photon coupling and axion mass. Hence, the distorted spectrum of the photon ring provides a novel tool for detecting axions.