We calculate the renormalization group flows of all perturbatively renormalizable interactions in the three-dimensional Ginzburg-Landau potential for the chiral phase transition of three-flavor quantum chromodynamics. On the contrary to the common belief we find a fixed point in the system that is able to describe a second-order phase transition in the infrared. This shows that long-standing assumptions on the transition order might be false. If the transition is indeed of second order, our results may hint that the axial $U(1)$ symmetry restores at the transition temperature.

In this note we study two-dimensional conformal field theories at large global charge. Since the large-charge sector decouples from the dynamics, it does not control the dynamics and an effective field theory construction that works in higher-dimensional theories fails. It is however possible to use large charge in a double-scaling limit when another controlling parameter is present. We find some general features of the spectrum of models that admit a nonlinear sigma model description in a Wentzel-Kramers-Brillouin approximation and use the large-charge sector of the solvable $SU(2{)}_k$ Wess-Zumino-Witten model to argue the regimes of applicability of both the large-$Q$ expansion and the double-scaling limit.

The $w_{1+\infty }$ symmetry algebra appears in the Einstein–Yang–Mills theory, proposed recently by Strominger. In this paper, we derive the supersymmetric $w_{1+\infty }$ symmetry by using the known results on the operator product expansions (OPEs) between the graviton, gravitino, gluon, and gluino in the supersymmetric version of the above theory. We calculate the four additional commutator relations between the soft currents explicitly. In addition, we analyze the works of Odake et al. and Pope et al. and introduce the additional symmetry current that corresponds to the celestial gluino operator. Through this procedure, all seven commutator relations can be connected to the ones associated with the supersymmetric $w_{1+\infty }$ algebra with $SU(N)$ symmetry under the restrictions of wedge modes.

We treat the effects of quantum field fluctuations on the decay of a metastable state of a self-coupled scalar field. We consider two varieties of field fluctuations and their potential effects in a semiclassical description. The first are the fluctuations of the time derivative of a free massive scalar field operator, which has been averaged over finite regions of space and time. These fluctuations obey a Gaussian probability distribution. A sufficiently large fluctuation is assumed to produce an effect analogous to a classical initial field velocity, which can cause a finite region to fly over the barrier separating the metastable state from the stable vacuum state. Here we find a contribution to the decay rate which can be comparable to the decay rate by quantum tunneling, as computed in an instanton approximation. This result is consistent with those of other authors. We next consider the effects of the fluctuations of operators which are quadratic in the time derivative of the free scalar field. The quadratic operator is also averaged over finite regions of space and of time. Now the probability distribution for the averaged operator falls more slowly than an exponential function, allowing for the possibility of very large fluctuations. We find a contribution to the decay rate which, under certain conditions, may be larger than those coming from either quantum tunneling or linear field fluctuations.

In this paper, we study the finite-temperature quantum fluctuation of a classical liquid induced by the topology of an effective conical spacetime, as well as by a quasiperiodic boundary condition. The conical spacetime could be either a disclination or a cosmic string. In this context, we consider a phonon field representing quantum excitations of the liquid density, which obeys an effective Klein-Gordon equation with the sound velocity replaced by the light velocity. We obtain closed analytic expressions for the thermal Hadamard function, and consequently, the renormalized mean square density fluctuation of the liquid along with thermodynamics quantities such as internal energy, free energy, total energy, and entropy densities. We also discuss the limiting cases, including low- and high-temperature regimes, and the situations in which there is only either the conical spacetime or quasiperiodicity.

We discuss several aspects of the stress-energy tensor for a quantum scalar field in an inhomogeneous background, the latter being modeled by a variable mass. Using a perturbative approach, dimensional regularization, and adiabatic subtraction, we present all-order formal expressions for the stress-energy tensor. Importantly, we provide an explicit proof of the principle of virtual work for Casimir forces, taking advantage of the conservation law for the renormalized stress-energy tensor. We discuss also discontinuity-induced divergences. For the particular case of planar inhomogeneities, we corroborate the perturbative results with a WKB-inspired expansion.

We report observations made on a run of transcritical flows over an obstacle in a narrow channel. Downstream from the obstacle, the flows decelerate from supercritical to subcritical, typically with an undulation on the subcritical side (known in hydrodynamics as an undular hydraulic jump). In the Analogue Gravity context, this transition corresponds to a white-hole horizon. Free-surface deformations are analyzed, mainly via the two-point correlation function which shows the presence of a checkerboard pattern in the vicinity of the undulation. In nongated flows where the white-hole horizon occurs far downstream from the obstacle, this checkerboard pattern is shown to be due to low-frequency fluctuations associated with slow longitudinal movement of the undulation. It can thus be considered as an artifact due to a time-varying background. In gated flows, however, the undulation is typically “attached” to the obstacle, and the fluctuations associated with its movement are strongly suppressed. In this case, the observed correlation pattern is likely due to a stochastic ensemble of surface waves, scattering on a background that is essentially stationary.

We study evolution of the braneworld Kerr-Newman (K-N) naked singularities, namely their mass $M$, spin $a$, and tidal charge $b$ characterizing the role of the bulk space, due to matter in-falling from Keplerian accretion disk. We construct the evolution in two limiting cases applied to the tidal charge. In the first case we assume $b=\text{const}$ during the evolution, in the second one we assume that the dimensionless tidal charge $\beta \equiv b/M^2=\mathrm{const}$. For positive values of the tidal charge the evolution is equivalent to the case of the standard K-N naked singularity under accretion of electrically neutral matter. We demonstrate that counterrotating accretion always converts a K-N naked singularity into an extreme K-N black hole and that the corotating accretion leads to a variety of outcomes. The conversion to an extreme K-N black hole is possible for naked singularity with dimensionless tidal charge $\beta <0.25$, and $\beta \in (0.25,1)$ with sufficiently low spin. In other cases the accretion ends in a transcendental state. For $0.25<\beta <1$ this is a mining unstable K-N naked singularity enabling formally unlimited energy extraction from the naked singularity. In the case of $\beta >1$, the corotating accretion creates unlimited torodial structure of mater orbiting the naked singularity. Both nonstandard outcomes of the corotating accretion imply a transcendence of such naked singularity due to nonlinear gravitational effects.

A new polymer black hole solution in loop quantum gravity was recently proposed. The difference between the polymer black hole and Schwarzschild black hole is captured by a quantum parameter $A$. In order to get the constraints on the parameter $A$, we consider the observational constraints imposed on $A$ by using the Solar System experiments and calculate the deflection of light, Shapiro time delay, and perihelion precession, and obtain the effects associated with the parameter $A$. We also perform a parametrized post-Newtonian analysis of this loop quantum gravity black hole. It turns out that the tightest constraint on $A$ can be improved to $0<A<4.0\times {10}^{-6}$.

We study a Born-Infeld inspired model of gravity and electromagnetism in which both types of fields are treated on an equal footing via a determinantal approach in a metric-affine formulation. Though this formulation is a priori in conflict with the postulates of metric theories of gravity, we find that the resulting equations can also be obtained from an action combining the Einstein-Hilbert action with a minimally coupled nonlinear electrodynamics. As an example, the dynamics is solved for the charged static black hole.

It has been argued that a particular type of quantum-vacuum variable $q$ can provide a solution to the main cosmological constant problem and possibly also give a cold-dark-matter component. We now show that the same $q$ field may suggest a new interpretation of the big bang, namely as a quantum phase transition between topologically inequivalent vacua. These two vacua are characterized by the equilibrium values $q=\pm q_0$, and there is a kink-type solution $q(t)$ interpolating between $q=-q_0$ for $t\to -\infty$ and $q=+q_0$ for $t\to \infty$, with conformal symmetry for $q=0$ at $t=0$.

Dark matter or violations of the Einstein equivalence principle influence the motion of atoms, their internal states as well as electromagnetic fields, thus causing a signature in the signal of atomic detectors. To model such new physics, we introduce dilaton fields and study the modified propagation of light used to manipulate atoms in light-pulse atom interferometers. Their interference signal is dominated by the matter’s coupling to gravity and the dilaton. Even though the electromagnetic field contributes to the phase, no additional dilaton-dependent effect can be observed. However, the light’s propagation in gravity enters via a modified momentum transfer and its finite speed. For illustration, we discuss effects from light propagation and the dilaton on different atom-interferometric setups, including gradiometers, equivalence principle tests, and dark matter detection.

Several interesting physical systems, such as the Lovelock extension of general relativity in higher dimensions, classical time crystals, $k$-essence fields, Horndeski theories, compressible fluids, and nonlinear electrodynamics, have apparent ill-defined sympletic structures, due to the fact that their Hamiltonians are multivalued functions of the momenta. In this paper, the dynamical evolution generated by such Hamiltonians is described as a degenerate dynamical system, whose sympletic form does not have a constant rank, allowing novel features and interpretations not present in previous investigations. In particular, it is shown how the multivaluedness is associated with a dynamical mechanism of dimensional reduction, as some degrees of freedom turn into gauge symmetries when the system degenerates.

In this work we explore and test new formulations of cosmological scenarios in $f(Q)$ theories. In these settings, the nonmetricity scalar ($Q$) is the main source of gravity and Friedmann equations are modified to account for the associated degrees of freedom. This work focuses first on the derivation, and then theoretical and observational analysis of two such (new) exact cosmological models; they both display a nonstandard behavior in which an additional parameter encoding nonmetricity effects acts in the fashion of a screened cosmological constant. One of the new settings has the same background evolution as the well know DGP cosmological model, while the other resembles the former considerably, although its origin is purely phenomenological. We use the Markov Chain Montecarlo method combined with standard statistical techniques to perform observational astrophysical tests relying upon background data, specifically these are type Ia supernovae luminosities and direct Hubble data (from cosmic clocks), along with cosmic microwave background shift and baryon acoustic oscillations data. In addition, we compute some of the cosmographic parameters and other discriminators with the purpose of refining our knowledge about these models in the light of their theoretical and observational signatures, and this allows for a better comparison with the (concordance) $\mathrm{\Lambda }\mathrm{CDM}$ setup. We conclude that these scenarios do not show signatures indicating a departure from the $\mathrm{\Lambda }\mathrm{CDM}$ behavior.

Dark matter particles can be gravitationally trapped by celestial bodies, motivating searches for localized annihilation or decay. If neutrinos are among the decay products, then IceCube and other neutrino observatories could detect them. We investigate this scenario for dark matter particles above $m_{\chi }\gtrsim \mathrm{PeV}$ producing tau neutrino signals, using updated modeling of dark matter capture and thermalization. At these energies, tau neutrino regeneration is an important effect during propagation through Earth, allowing detection at distances far longer than one interaction length. We show how large energy loss of tau leptons above $\sim \mathrm{PeV}$ drives a wide range of initial energies to the same final energy spectrum of “secondary” tau neutrinos at the detector, and we provide an analytic approximation to the numerical results. This effect enables an experiment to constrain decays that occur at very high energies, and we examine the reach of the IceCube high-energy starting event sample in the parameter space of trapped dark matter annihilations and decays above PeV. We find that the parameter space probed by IceCube searches would require dark matter cross sections in tension with existing direct-detection bounds.

The outflows from neutrino-cooled black hole accretion disks formed in neutron-star mergers or cores of collapsing stars are expected to be neutron-rich enough to explain a large fraction of elements created by the rapid neutron-capture process, but their precise chemical composition remains elusive. Here, we investigate the role of fast neutrino flavor conversion, motivated by the findings of our post-processing analysis that shows evidence of electron-neutrino lepton-number crossings deep inside the disk, hence suggesting possibly nontrivial effects due to neutrino flavor mixing. We implement a parametric, dynamically self-consistent treatment of fast conversion in time-dependent simulations and examine the impact on the disk and its outflows. By activating the otherwise inefficient, emission of heavy-lepton neutrinos, fast conversions enhance the disk cooling rates and reduce the absorption rates of electron-type neutrinos, causing a reduction of the electron fraction in the disk by 0.03–0.06 and in the ejected material by 0.01–0.03. The rapid neutron-capture process yields are enhanced by typically no more than a factor of two, rendering the overall impact of fast conversions modest. The kilonova is prolonged as a net result of increased lanthanide opacities and enhanced radioactive heating rates. We observe only mild sensitivity to the disk mass, the condition for the onset of flavor conversion, and to the considered cases of flavor mixing. Remarkably, parametric models of flavor mixing that conserve the lepton numbers per family result in an overall smaller impact than models invoking three-flavor equipartition, often assumed in previous works.

Neutrinos with energies ranging from GeV to sub-TeV are expected to be produced in gamma-ray bursts (GRBs) as a result of the dissipation of the jet kinetic energy through nuclear collisions occurring around or below the photosphere, where the jet is still optically thick to high-energy radiation. So far, the neutrino emission from the “inelastic collisional model” in GRBs has been poorly investigated from the experimental point of view. In the present work, we discuss prospects for identifying neutrinos produced in such collisionally heated GRBs with the large volume neutrino telescopes KM3NeT and IceCube, including their low-energy extensions, $\mathrm{KM}3\mathrm{NeT}/\mathrm{ORCA}$ and DeepCore, respectively. To this aim, we evaluate the detection sensitivity for neutrinos from both individual and stacked GRBs, exploring bulk Lorentz factor values ranging from 100 to 600. As a result of our analysis, individual searches appear feasible only for extreme sources, characterized by gamma-ray fluence values at the level of $F_{\gamma }\ge {10}^{-2}\mathrm{erg}{\mathrm{cm}}^{-2}$. In turn, it is possible to detect a significant flux of neutrinos from a stacking sample of $\sim 900$ long GRBs (that could be detected by current gamma-ray satellites in about five years) already with DeepCore and $\mathrm{KM}3\mathrm{NeT}/\mathrm{ORCA}$. The detection sensitivity increases with the inclusion of data from the high-energy telescopes, IceCube and $\mathrm{KM}3\mathrm{NeT}/\mathrm{ARCA}$, respectively.

Based on the one-state assumption of $\eta (1405)$ and $\eta (1475)$, $\eta (1295)$ and $\eta (1405/1475)$ thus being organized as the first radial excitations of $\eta$ and ${\eta }^{\prime }$, respectively, we investigate the productions and radiative decays of these two states in $J/\psi \to \gamma {\eta }_X\to \gamma \gamma V$, where ${\eta }_X$ stands for $\eta (1295)$ and $\eta (1405/1475)$ and $V$ stands for vector mesons ${\rho }^0$, $\omega$, $\varphi$. As we have learned from previous studies that the hadronic decays of these two states receive important contributions from the intermediate $\overline{K}{K}^{*}+\mathrm{c}.\mathrm{c}.$ meson loops due to the triangle singularity mechanism, we show that some measurable effects can also arise from the $\overline{K}{K}^{*}+\mathrm{c}.\mathrm{c}.$ meson loops in their radiative decays. Our calculation shows that the impact of the $\overline{K}{K}^{*}+\mathrm{c}.\mathrm{c}.$ meson loops on the $\eta (1405/1475)$ radiative decays is relatively smaller than on $\eta (1295)$ since the latter has a much larger coupling to $\overline{K}{K}^{*}+\mathrm{c}.\mathrm{c}$. However, the production of $\eta (1295)$ in the $J/\psi$ radiative decays will be strongly suppressed due to its being the radial excitation state of the $\eta$ meson. As a consequence of the $\overline{K}{K}^{*}+\mathrm{c}.\mathrm{c}.$ meson loop contributions, we find that the mixing angle extracted in the radiative decays of $\eta (1295)$ and $\eta (1405/1475)$ will be different from each other, and both are different from the one determined in other processes.

In this paper we study the high-energy exclusive photoproduction of heavy quarkonia pairs in the leading order of the strong coupling constant ${\alpha }_s$. In the suggested mechanism, the quarkonia pairs are produced with opposite charge parities, and predominantly have oppositely directed transverse momenta. Using the Color Glass Condensate approach, we numerically estimate the production cross sections in the kinematics of the forthcoming electron-proton colliders, as well as proton-ion colliders in ultraperipheral collisions. We find that the cross sections are within the reach of planned experiments and can be measured with reasonable precision. The suggested mechanism has a significantly larger cross section than that of the same $C$-parity quarkonia pair production.

The effect of the temporal pulse shape of intense pulses on the momentum distribution of $e^{+}{e}^{-}$ pairs is studied using the quantum kinetic equation. Two closely resembling temporal envelopes, namely, Gaussian and Sauter, keeping all the other pulse parameters the same, are considered to this end. Contrary to the common perception which can be gauged from the interchangeable use of these temporal profiles, the longitudinal momentum spectrum of the pairs created by the two pulses is found to differ significantly in all the temporal regimes. For the pulses having a few cycles of oscillations, the temporal profile of the pulse is revealed in the oscillatory interference pattern riding over the otherwise smooth longitudinal momentum spectrum at asymptotic times. The onset of the oscillation due to the quantum interference of reflection amplitudes from the scattering potential due to the pulses having a temporal structure of multiple barriers takes place for fewer-cycle oscillations for the Gaussian pulse compared to that for the Sauter pulse. Furthermore, the oscillation amplitude for the same number of oscillations within the pulse duration is larger for the Gaussian pulse. The presence of the carrier-envelope phase and the frequency chirping is found to magnify these differences. In the absence of any appreciable interference effect for the pulses having less than five oscillations, the longitudinal momentum spectrum has a higher peak value for the Sauter pulse at asymptotic times. On the other hand, before the transient stage of evolution, the peak of the spectrum shows the opposite trend.