We study the error threshold properties of holographic quantum error-correcting codes. We demonstrate that holographic conformal field theories admit an algebraic threshold, which is related to the confinement-deconfinement phase transition. We then apply geometric intuition from holography and the Hawking-Page phase transition to motivate the conformal field theory result, and comment on potential extensions to other confining theories.

We provide a quantum picture for the emergence of a bouncing cosmology, according to the idea that a semiclassical behavior of the universe towards the singularity is not available in many relevant minisuperspace models. In particular, we study the Bianchi I model in vacuum adopting the isotropic Misner variable as an internal clock for the quantum evolution. The isomorphism between the Wheeler-DeWitt equation in this minisuperspace representation and the Klein-Gordon one for a relativistic scalar field allows to identify the positive and negative frequency solutions as associated to the collapsing and expanding universe respectively. We clarify how any Bianchi I localized wave packet unavoidably spreads when the singularity is approached and therefore the semiclassical description of the model evolution in the Planckian region loses its predictability. Then, we calculate the transition amplitude that a collapsing universe is turned into an expanding one, according to the standard techniques of relativistic quantum mechanics, thanks to the introduction of an ekpyroticlike matter component which mimics a “quantum” time-dependent potential term and breaks the frequency separation. In particular, the transition probability of this “quantum big bounce” acquires a maximum value when the mean values of the momenta conjugate to the anisotropies in the collapsing universe are close enough to the corresponding mean values in the expanding one, depending on the variances of the ingoing and outgoing universe wave packets. This symmetry between the prebounce and postbounce mean values reflects what happens in the semiclassical bouncing cosmology, with the difference that here the connection of the two branches takes place on a pure probabilistic level.

We study the Hamiltonian formulation of the Ashtekar-Olmedo-Singh model for the description of the interior geometry of nonrotating, uncharged black holes. This model incorporates loop quantum effects through the introduction of two regularization parameters. We consider an extended phase space formalism proposed by the creators of the model that includes such parameters as configuration variables, constrained to be functions of the black hole mass. We generalize this restriction, allowing for an off shell phase space dependence. We then introduce a gauge fixing procedure and reduce the system, proving that the reduced symplectic structure cannot reproduce the standard relativistic one in terms of the densitized triad and the Ashtekar-Barbero connection. Actually, the reduced structure precisely compensates the modifications that arise in the Hamilton equations when the regularization parameters are treated as phase space functions, rather than as numbers, attaining a consistent Hamiltonian derivation of the dynamics. We then choose the extended phase space formalism as starting point to address the loop quantization of the model. Taking the definition of certain geometric operators as the only basic ingredient and adopting prescriptions that have proven successful in loop quantum cosmology, we construct a polymer representation of all the constraints and deduce the formal expression of the physical states, assuming reasonable spectral properties for the constraint operators. The physical states turn out to be characterized by a wave function of the black hole mass with support on a very specific set. We finally discuss conditions that guarantee the existence of physical states in the region of large black hole masses. This is a first step in the development of a new loop quantum theory of black holes.

We apply a Bayesian approach to construct a large number of minimally constrained equations of state (EOSs) and study their correlations with a few selected properties of a neutron star (NS). Our set of minimal constraints includes a few basic properties of saturated nuclear matter and low-density pure neutron matter EOS which is obtained from a precise next-to-next-to-next-to-leading-order (${\mathrm{N}}^3\mathrm{LO}$) calculation in chiral effective field theory. The tidal deformability and radius of a NS with mass $1–2M_{\odot }$ are found to be strongly correlated with the pressure of $\beta$-equilibrated matter at densities higher than the saturation density (${\rho }_0=0.16{\mathrm{fm}}^{-3}$) in a nearly model-independent manner. These correlations are employed to parametrize the pressure for $\beta$-equilibrated matter, around $2{\rho }_0$, as a function of neutron star mass and the corresponding tidal deformability. The maximum mass of the neutron star is also found to be strongly correlated with the pressure of $\beta$-equilibrated matter at densities $\sim 4.5{\rho }_0$.

We present simulations of the development of high-energy cosmic-ray air showers penetrating high-altitude ice layers that can be found at the polar regions. We use a combination of the corsika Monte Carlo code and the geant4 simulation toolkit, and focus on the particle cascade that develops in the ice to describe its most prominent features. We discuss the impact of the ice layer on the total number of particles in function of depth of the air shower, and we give a general parametrization of the charge distribution in the cascade front in function of $X_{\max }$ of the cosmic ray air shower, which can be used for analytical and semianalytical calculations of the expected Askaryan radio emission of the in-ice particle cascade. We show that the core of the cosmic ray air shower dominates during the propagation in ice, therefore creating an in-ice particle cascade strongly resembling a neutrino-induced particle cascade. Finally, we present the results of simulations of the Askaryan radio emission of the in-ice particle cascade, showing that the emission is dominated by the shower core, and discuss the feasibility of detecting the plasma created by the particle cascade in the ice using RADAR echo techniques.

Collective neutrino oscillations play a crucial role in transporting lepton flavor in astrophysical settings like supernovae and neutron star binary merger remnants, which are characterized by large neutrino densities. In these settings, simulations in the mean-field approximation show that neutrino-neutrino interactions can overtake vacuum oscillations and give rise to fast collective flavor evolution on timescales $t\propto {\mu }^{-1}$, with $\mu$ proportional to the local neutrino density. In this work, we study the full out-of-equilibrium flavor dynamics in simple multiangle geometries displaying fast oscillations in the mean field linear stability analysis. Focusing on simple initial conditions, we analyze the production of pair correlations and entanglement in the complete many-body-dynamics as a function of the number $N$ of neutrinos in the system, for up to thousands of neutrinos. Similarly to simpler geometries with only two neutrino beams, we identify three regimes: stable configurations with vanishing flavor oscillations, marginally unstable configurations with evolution occurring on long timescales $\tau \approx {\mu }^{-1}\sqrt{N}$, and unstable configurations showing flavor evolution on short timescales $\tau \approx {\mu }^{-1}\log (N)$. We present evidence that these fast collective modes are generated by the same dynamical phase transition which leads to the slow bipolar oscillations, establishing a connection between these two phenomena and explaining the difference in their timescales. We conclude by discussing a semiclassical approximation which reproduces the entanglement entropy at short to medium timescales and can be potentially useful in situations with more complicated geometries where classical simulation methods starts to become inefficient.

Ultralight bosons can affect the dynamics of spinning black holes (BHs) via superradiant instability, which can lead to a time evolution of the supermassive BH shadow. We study prospects for witnessing the superradiance-induced BH shadow evolution, considering ultralight vector and tensor fields. We introduce two observables sensitive to the shadow time-evolution: the shadow drift, and the variation in the azimuthal angle lapse associated to the photon ring autocorrelation. The two observables are shown to be highly complementary, depending on the observer’s inclination angle. Focusing on the supermassive object Sgr ${\mathrm{A}}^{\star }$ we show that both observables can vary appreciably over human timescales of a few years in the presence of superradiant instability, leading to signatures which are well within the reach of the Event Horizon Telescope for realistic observation times (but benefiting significantly from extended observation periods) and paving the way towards probing ultralight bosons in the $\sim {10}^{-17}\mathrm{eV}$ mass range.

We apply the multiparticle fields model to calculate the differential cross section $d\sigma /dt$ of elastic proton-proton scattering. This problem includes the calculation of multidimensional integrals arising from the loop Feynman diagrams. We demonstrated how these integrals can be reduced with Laplace’s method to one- and two-dimensional integrals which can be calculated numerically. The obtained result qualitatively describes the minimum in differential cross section dependency $d\sigma /dt(t)$.

The fundamental nature of dark matter is entirely unknown. A compelling candidate is twin Higgs mirror matter, invisible hidden-sector cousins of the Standard Model particles and forces. This predicts mirror neutron stars made entirely of mirror nuclear matter. We find their structure using realistic equations of state, robustly modified based on first-principle quantum chromodynamic calculations, for the first time. This allows us to predict their gravitational wave signals, demonstrating an impressive discovery potential and ability to probe dark sectors connected to the hierarchy problem.

The kinetic mixing (KM) portal is a popular mechanism that allows light dark matter (DM) in the mass range below $\sim 1\mathrm{GeV}$ to achieve the observed relic density by thermal means and can be effectively described by only a few parameters, e.g., $\epsilon$, the strength of this KM. In the simplest setup, the Standard Model (SM) $U(1{)}_Y$ hypercharge gauge boson and a $U(1{)}_D$ dark photon (DP), which only couples to fields in the dark sector, experience KM via loops of portal matter (PM) fields which have both SM and dark charges, thus generating a small coupling between us and dark matter (DM). However, if one wishes to understand the underlying physics behind this idea in a deeper fashion we need to take a step upward to a more UV-complete picture. Meanwhile, CDFII has measured a value for the $W$-boson mass which lies significantly above SM expectations. In this paper, we speculate that this shift in the $W$’s mass may be related to the $\sim 1\mathrm{GeV}$ mass of the DP within a framework of scalar PM that leads to phenomenologically interesting values of $\epsilon$ via non-Abelian KM due to the existence of an $SU(2{)}_L$, $Y=0$, complex Higgs triplet which carries a nonzero value of the $U(1{)}_D$ dark charge. Possible gauge boson plus missing energy signatures of this scenario that can appear at the LHC and elsewhere are examined. Indeed, with modest assumptions, all of the new scalar PM states are predicted to have masses below roughly $\simeq 630\mathrm{GeV}$ and so should be at least kinematically accessible. The HL-LHC will very likely to be able to explore all of this model’s allowed parameter space.

Proton beam-dump experiments are a high-intensity source of secondary muons and provide an opportunity to probe muon-specific dark sectors. We adopt a simplified-models framework for an exotic light scalar particle coupling predominantly or exclusively to muons. Equipped with state-of-the-art muon simulations, we compute the sensitivity reach in the parameter space $(m_S,g_{\mu })$ of the dark mediator, examining in detail the examples of the experiment NA62 in beam-dump mode and the proposed experiment SHiP. We find a significant yield of such exotics in the sub-GeV mass range. Our projections are competitive with those of primary muon-beam experiments and complementary to current constraints, spanning uncharted parameter space and accessing new physics potentially responsible for the $(g-2{)}_{\mu }$ anomaly.

We consider quantum chromodynamics with external vector, axial-vector, scalar, and pseudoscalar currents and compute three-loop corrections to the corresponding vertex function taking into account massive quarks. We consider all nonsinglet contributions as well as those singlet contributions where the external current couples to a massive quark loop. We apply a seminumerical method which is based on expansions around singular and regular kinematical points. They are matched at intermediate values of the squared partonic center-of-mass energy $s$ which allows one to cover the whole kinematic range for negative and positive values of $s$. Our method permits a systematic increase of the precision by varying the expansion depth and the choice of the intermediate matching points. In our current setup we have at least seven significant digits for the finite contribution of all form factors. We present our results as a combination of series expansions and interpolation functions which allows for a straightforward use in practical applications.

We study multipole expansion of the momentum currents in hadrons with three series $S^{(J)}$, ${\tilde{T}}^{(J)}$, and $T^{(J)}$ in connection with the gravitational fields generated nearby. The momentum currents are related to their energy-momentum form factors, which in principle can be probed through processes like the deeply virtual Compton scattering currently studied at the Jefferson Lab 12 GeV facility and future Electron-Ion Collider. We define the leading momentum-current multipoles [the “tensor monopole” $\tau$ ($T0$) and “scalar quadrupole” ${\widehat{\sigma }}^{ij}$ ($S2$) moments], relating the former to the so-called $D$ term in the literature. We calculate the momentum-current distribution in the hydrogen atom and its monopole moment in the basic unit of ${\tau }_0={\hslash }^2/4m_e$, showing that the sign of the $D$ term has little to do with mechanical stability. The momentum-current distribution also strongly modifies the static gravitational field inside hadrons.

We present the first simultaneous global QCD analysis of spin-dependent parton distribution functions alongside their spin-averaged counterparts and pion, kaon, and unidentified hadron fragmentation functions. This analysis includes all data relevant for constraining the polarized light quark sea asymmetry $\mathrm{\Delta }\overline{u}-\mathrm{\Delta }\overline{d}$, in particular the latest polarized $W$-lepton production data from the STAR Collaboration at RHIC and semi-inclusive deep inelastic scattering data from COMPASS, allowing the most robust extraction available with minimal theoretical assumptions. We also extract a self-consistent set of antiquark polarization ratios $\mathrm{\Delta }\overline{u}/\overline{u}$ and $\mathrm{\Delta }\overline{d}/\overline{d}$ and determine the signs of the truncated contributions to the proton spin from the light antiquarks.

We explore the quantum nature of black holes by introducing an effective framework that takes into account deviations from the classical results. The approach is based on introducing quantum corrections to the classical Schwarzschild geometry in a way that is consistent with the physical scales of the black hole and its classical symmetries. This is achieved by organizing the quantum corrections in inverse powers of a physical distance. By solving the system in a self-consistent way we show that the derived physical quantities, such as event horizons, temperature and entropy can be expressed in a well-defined expansion in the inverse powers of the black hole mass. The approach captures the general form of the quantum corrections to black hole physics without requiring us to commit to a specific model of quantum gravity.

Relativistic gravitational anomalies lead to anomalous transport coefficients that can be activated at finite temperature in hydrodynamic and condensed matter systems with gapless, linearly dispersing fermions. One is the chiral vortical effect (CVE), an anomalous chiral current along the system’s rotation axis, expressed in terms of a gravimagnetic metric field in a rotating frame with mixed gravitational anomaly. Another one arises in the presence of hydrodynamically independent frame fields (and spin connection) and leads to the thermal chiral torsional effect (CTE). We discuss the relation of CVE, CTE, and gravitational anomalies for relativistic fermions from the perspective of nonzero torsion and the Nieh-Yan anomaly when the currents depend on the frame fields and connection instead of the metric. The transport coefficients induced by the two gravitational anomalies at zero frequency and momentum are found to be closely related and equal. At level of linear response, their difference is demarcated whether or not torsion is nonzero and the existence of nonmetric degrees of freedom in the hydrodynamic constitutive relations with sources. In particular, the relativistic anomaly from torsion is well defined, since instead of an UV divergent term the chemical potential or temperature scales enter. This is closely related to the derivation of CVE from the fourth order in gradients gravitational anomaly and its appearance already in the linear response. However, the torsional anomaly is second order in gradients and directly contributes in linear response for CTE, implying also the same for CVE. For an example where the two anomalies are sourced independently, we consider chiral $p+ip$ Weyl superfluids and superconductors rotating at finite temperature. At low energies in the linear approximation, the system is effectively relativistic along a special anisotropy axis. The hydrodynamics is governed by two velocities, the normal velocity ${\mathit{v}}_n$ and superfluid velocity ${\mathit{v}}_s$. The existence of the two thermal anomalies in the condensate follows from the normal component rotation and the dependence of the momentum density on the superfluid velocity (order parameter). In the CVE, the chiral current is produced by the solid body rotation of the normal component with (angular) velocity ${\mathit{v}}_n=\mathbf{\Omega }\times \mathit{r}$. In the CTE, a chiral current is produced by the vorticity of the superfluid velocity $\nabla \times {\mathit{v}}_s$, which in the low-energy quasirelativistic effective theory plays the role of gravitational torsion. In thermal equilibrium, $⟪\nabla \times {\mathit{v}}_s⟫=2\mathbf{\Omega }$ spatially averaged and the two gravitational anomaly currents cancel each other. This is a version of the Bloch theorem for axial currents, prohibiting finite current in equilibrium, realized as the cancellation of two gravitational anomalies with independent sources: gravimagnetic rotation field $\mathbf{\Omega }$ and torsion from ${\mathit{v}}_s$. Although the latter physically represents the superfluid vorticity similar to the CVE, in the low-energy quasirelativistic theory, it arises from torsion coupling to the normal component chiral fermions.

We study quasinormal modes (QNMs) of massive Klein-Gordon fields in static Bañados-Teitelboim-Zanelli (BTZ) black holes in terms of ladder operators constructed from spacetime conformal symmetries. Because the BTZ spacetime is locally isometric to the three-dimensional anti-de Sitter spacetime, ladder operators, which map a solution of the massive Klein-Gordon equation into that with different mass squared, can be constructed from spacetime conformal symmetries. In this paper, we apply the ladder operators to the QNMs of the Klein-Gordon equations in the BTZ spacetime. We demonstrate that the ladder operators can change indices of QNM overtones, and all overtone modes can be generated from a fundamental mode when we impose the Dirichlet or Neumann boundary condition at infinity. We also discuss the case with the Robin boundary condition.

We consider conceptual issues of deep learning (DL) for metric detectors using test particle geodesics in curved spacetimes. Advantages of DL metric detectors are emphasized from a viewpoint of general coordinate transformations. Two given metrics (two spacetimes) are defined to be connected by a DL isometry if their geodesic image data cannot be discriminated by any DL metric detector at any time. The fundamental question of when the DL isometry appears is extensively explored. If the two spacetimes connected by the DL isometry are in superposition of quantum gravity theory, the postmeasurement state may be still in the same superposition even after DL metric detectors observe the superposed state. We also demonstrate metric-detection DL methods in $2+1$-dimensional anti–de Sitter (AdS) spacetimes to estimate the cosmological constants and Brown-Henneaux charges. In the $\mathrm{AdS}/\mathrm{CFT}$ correspondence dictionary, it may be expected that such metric detectors in the AdS bulk region correspond to quantum measurement devices in the conformal field theory at the AdS boundary.