We search for an indirect signal of dark matter through very high-energy $\gamma$ rays from the Wolf-Lundmark-Melotte (WLM) dwarf irregular galaxy. The pair annihilation of dark matter particles would produce Standard Model particles in the final state such as $\gamma$ rays, which might be detected by ground-based Cherenkov telescopes. Dwarf irregular galaxies represent promising targets as they are dark matter dominated objects with well-measured kinematics and small uncertainties on their dark matter distribution profiles. In 2018, the five-telescopes of the high energy stereoscopic system observed the dwarf irregular galaxy WLM for 18 hours. We present the first analysis based on data obtained from an imaging atmospheric Cherenkov telescope for this subclass of dwarf galaxy. As we do not observe any significant excess in the direction of WLM, we interpret the result in terms of constraints on the velocity-weighted cross section for dark matter pair annihilation $⟨\sigma v⟩$ as a function of the dark matter particle mass for various continuum channels, as well as the prompt $\gamma \gamma$ emission. For the ${\tau }^{+}{\tau }^{-}$ channel, the limits reach a $⟨\sigma v⟩$ value of about $4\times {10}^{-22}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ for a dark matter particle mass of 1 TeV. For the prompt $\gamma \gamma$ channel, the upper limit reaches a $⟨\sigma v⟩$ value of about $5\times {10}^{-24}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$ for a mass of 370 GeV. These limits represent an improvement of up to a factor 200, with respect to previous results for the dwarf irregular galaxies for TeV dark matter search.

We propose new perspective in searching for axionlike particles (ALPs) from quark and lepton flavor physics: measurements of the time-dependent $CP$ asymmetry in $B^0\to K_S^0{\pi }^0\gamma$ and the branching ratio of $B_s\to e^{\pm }{\mu }^{\mp }$ decay possess, along with the anomalous magnetic moment of muon. In the mass range of sub-GeV, accessible by the flavorful ALPs search, the experimental sensitivity for these flavor observables reaches the maximum at around the pion mass scale (called the sweetest spots), where a couple of loopholes (unexplored regions) for the ALP parameter space have heretofore been present, because of an unavoidable contamination with pion background events. The proposed complementary probes can precisely determine the ALP coupling to photon at these sweetest spots/loopholes, and will significantly help cover whole parameter spaces in the ALP search including the present loopholes in the future.

We use the $SU(5)$ model to show the presence in grand unified theories of an electroweak monopole and a magnetic dumbbell (“meson”) made up of a monopole-antimonopole pair connected by a $Z$-magnetic flux tube. The monopole is associated with the spontaneous breaking of the weak $SU(2{)}_L$ gauge symmetry by the induced vacuum expectation value of a heavy scalar $SU(2{)}_L$ triplet with zero weak hypercharge contained in the adjoint Higgs 24-plet. This monopole carries a Coulomb magnetic charge of $(3/4)(2\pi /e)$ as well as $Z$-magnetic charge, where $2\pi /e$ denotes the unit Dirac magnetic charge. Its total magnetic charge is $\sqrt{3/8}(4\pi /e)$, which is in agreement with the Dirac quantization condition. The monopole weighs about 700 GeV, but because of the attached $Z$-magnetic tube it exists, together with the antimonopole, in a magnetic dumbbell configuration whose mass is expected to lie in the TeV range. The presence of these topological structures in $SU(5)$ and $SO(10)$ and in their supersymmetric extensions provides an exciting new avenue for testing these theories in high-energy colliders.

Cosmic rays (CRs) are a powerful tool for the investigation of the structure of the magnetic fields in the galactic halo and the properties of the interstellar medium. Two parameters of the CR propagation model—the galactic halo (half-)thickness $H$ and the diffusion coefficient $D$—are loosely constrained by current CR flux measurements; in particular, a large degeneracy exists being only $H/D$ well measured. The ${}^{10}\mathrm{Be}/{}^9\mathrm{Be}$ isotopic flux ratio (thanks to the 2 My lifetime of ${}^{10}\mathrm{Be}$) can be used as a radioactive clock, providing the measurement of CR residence time in the galaxy. This is an important tool for solving the $H/D$ degeneracy. Past measurements of the ${}^{10}\mathrm{Be}/{}^9\mathrm{Be}$ isotopic flux ratio in CRs are scarce, limited to low energy, and affected by large uncertainties. Here, a new technique to measure the ${}^{10}\mathrm{Be}/{}^9\mathrm{Be}$ isotopic flux ratio with a data-driven approach in magnetic spectrometers is presented. The analysis with the data driven approach of beryllium events collected by the PAMELA experiment is shown as an example. It is possible to measure the ${}^{10}\mathrm{Be}/{}^9\mathrm{Be}$ flux ratio avoiding the uncertainties related to the Monte Carlo simulation.

The decays ${\psi }_2(3823)\to \gamma {\chi }_{c0,1,2}$, ${\pi }^{+}{\pi }^{-}J/\psi$, ${\pi }^0{\pi }^{0}J/\psi$, $\eta J/\psi$, and ${\pi }^{0}J/\psi$ are searched for using the reaction $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_2(3823)$ in a $19{\mathrm{fb}}^{-1}$ data sample collected at center-of-mass energies between 4.1 and 4.7 GeV with the BESIII detector. The process ${\psi }_2(3823)\to \gamma {\chi }_{c1}$ is observed in a $9{\mathrm{fb}}^{-1}$ data sample in the center-of-mass energy range 4.3–4.7 GeV, which confirms a previous observation but with a higher significance of $11.8\sigma$, and evidence for ${\psi }_2(3823)\to \gamma {\chi }_{c2}$ is found with a significance of $3.2\sigma$ for the first time. The branching-fraction ratio $\frac{\mathcal{B}({\psi }_2(3823)\to \gamma {\chi }_{c2})}{\mathcal{B}({\psi }_2(3823)\to \gamma {\chi }_{c1})}$ is determined. No significant ${\psi }_2(3823)$ signals are observed for any of the other decay channels. Upper limits of branching-fraction ratios for ${\psi }_2(3823)\to {\pi }^{+}{\pi }^{-}J/\psi$, ${\pi }^0{\pi }^{0}J/\psi$, $\eta J/\psi$, ${\pi }^{0}J/\psi$, $\gamma {\chi }_{c0}$ relative to ${\psi }_2(3823)\to \gamma {\chi }_{c1}$ are reported. The process $e^{+}{e}^{-}\to {\pi }^0{\pi }^0{\psi }_2(3823)$ is also searched for, and we find evidence for the process with a significance of $4.3\sigma$. The average cross-section ratio $\frac{\sigma (e^{+}{e}^{-}\to {\pi }^0{\pi }^0{\psi }_2(3823))}{\sigma (e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_2(3823))}$ is also determined.

We report on a comparison of two possible ${\mathrm{\Lambda }}_c^{+}$ spin hypotheses, $J=\frac{1}{2}$ and $\frac{3}{2}$, via the process $e^{+}{e}^{-}\to {\mathrm{\Lambda }}_c^{+}{\overline{\mathrm{\Lambda }}}_c^{-}$, using the angular distributions of ${\mathrm{\Lambda }}_c^{+}$ decays into $p{K}_S^0$, $\mathrm{\Lambda }{\pi }^{+}$, ${\mathrm{\Sigma }}^0{\pi }^{+}$, and ${\mathrm{\Sigma }}^{+}{\pi }^0$. The data were recorded at $\sqrt{s}=4.6\mathrm{GeV}$ with the BESIII detector and correspond to an integrated luminosity of $587{\mathrm{pb}}^{-1}$. The ${\mathrm{\Lambda }}_c^{+}$ spin is determined to be $J=\frac{1}{2}$, with this value favored over the $\frac{3}{2}$ hypothesis with a significance corresponding to more than 6 Gaussian standard deviations.

Computational complexity is a quantum information concept that recently has found applications in the holographic understanding of the black hole interior. We consider quantum computational complexity for $n$ qubits using Nielsen’s geometrical approach. In the definition of complexity there is a big amount of arbitrariness due to the choice of the penalty factors, which parametrizes the cost of the elementary computational gates. In order to reproduce desired features in holography, such as ergodicity and exponential maximal complexity for large number of qubits $n$, negative curvatures are required. With the simplest choice of penalties, this is achieved at the price of singular sectional curvatures in the large $n$ limit. We investigate a choice of penalties in which we can obtain negative curvatures in a smooth way. We also analyze the relation between operator and state complexities, framing the discussion with the language of Riemannian submersions. This provides a direct relation between geodesics and curvatures in the unitaries and the states spaces, which we also exploit to give a closed-form expression for the metric on the states in terms of the one for the operators. Finally, we study conjugate points for a large number of qubits in the unitary space and we provide a strong indication that maximal complexity scales exponentially with the number of qubits in a certain regime of the penalties space.

We have run numerical simulations of Euclidean lattice quantum gravity for metrics which are time-independent and spherically symmetric. The radial variable is discretized as $r=h{L}_{\text{Planck}}$, with $h=0,1,\dots ,N$ and $N$ up to ${10}^5$. The Lagrangian is of the form $\sqrt{g}(R+\alpha R^2)$ (in units $c=\hslash =G=1$) and the action is positive-definite, allowing the use of a standard Metropolis algorithm with update probability $\exp (-\beta \mathrm{\Delta }S)$. By minimizing the $R+R^2$ action with respect to conformal modes, Bonanno and Reuter have recently found analytical evidence of a nontrivial “rippled” ground state resembling a kinetic condensate of QCD. Our simulations at low but finite temperature ($T={\beta }^{-1}$) also display strong localized oscillations of the metric, whose total action $S$ remains $\ll \hslash$ thanks to the indefinite sign of $R$. The average metric $⟨g_{rr}⟩$ is significantly different from flat space. The scaling properties of $S$ and $⟨g_{rr}⟩$ are investigated in dependence on $N$ and $\beta$.

In this paper we discuss a nonrelativistic system at large charge in a regime where Schrödinger symmetry is slightly broken by an explicit mass term for the dilaton field which nonlinearly realizes nonrelativistic scale invariance. To get there, we first develop the large-charge formalism from the linear sigma model perspective, including the harmonic trapping potential necessary for the nonrelativistic state-operator correspondence. As a signature of the explicit breaking, we identify a $\sqrt{\mathrm{Q}}\log \mathrm{Q}$ term, which depending on the space dimension is either of the same order as the effects coming from the breakdown of the EFT at the edge of the particle cloud, or can be distinguished from these effects over a large range of orders of magnitude.

The description of the electromagnetic interaction in two-dimensional Dirac materials, such as graphene and transition-metal dichalcogenides, in which electrons move in the plane and interact via virtual photons in 3D, leads naturally to the emergence of a projected theory, called pseudo-quantum electrodynamics (PQED), as an effective model suitable for describing electromagnetic interaction in these systems. In this work, we investigate the role of a complete set of four-fermion interactions in the renormalization group functions when we coupled it with the anisotropic version of massive PQED, where we take into account the fact that the Fermi velocity is not equal to the light velocity. We calculate the electron self-energy in the dominant order in the $1/N$ expansion in the regime where $m^2\ll p^2$. We show that the Fermi velocity renormalization is insensitive to the presence of quartic fermionic interactions, whereas the renormalized mass may have two different asymptotic behaviors at the high-density limit, which means a high-energy scale.

We classify all fundamental electrically charged thin shells in general relativity, i.e., static spherically symmetric perfect fluid thin shells with a Minkowski spacetime interior and a Reissner-Nordström spacetime exterior, characterized by the spacetime mass $M$, which we assume positive, and the electric charge $Q$, which without loss of generality in our analysis can always be assumed as being the modulus of the electric charge, be it positive or negative. The fundamental shell can exist in three states, namely, nonextremal when $\frac{Q}{M}<1$, which includes the Schwarzschild $\frac{Q}{M}=0$ state, extremal when $\frac{Q}{M}=1$, and overcharged when $\frac{Q}{M}>1$. The nonextremal state, $\frac{Q}{M}<1$, allows the shell to be located in such a way that the radius $R$ of the shell can be outside its own gravitational radius $r_{+}$, i.e., $R>r_{+}$, where $r_{+}$ is given in terms of $M$ and $Q$ by $r_{+}=M+\sqrt{M^2-Q^2}$, or can be inside its own Cauchy radius $r_{-}$, i.e., $R<r_{-}$, where $r_{-}$ is given in terms of $M$ and $Q$ by $r_{-}=M-\sqrt{M^2-Q^2}$. The extremal state, $\frac{Q}{M}=1$, allows the shell to be located in such a way that the radius $R$ of the shell can be outside its own gravitational radius $r_{+}$, i.e., $R>r_{+}$, where now $r_{+}=r_{-}$, or can be inside its own gravitational radius, i.e., $R<r_{+}$, or can be at its own gravitational radius $r_{+}$, i.e., $R=r_{+}$. The overcharged state, $\frac{Q}{M}>1$, allows the shell to be located anywhere $R\ge 0$. There is yet a further division; indeed, one has still to specify the orientation of the shell, i.e., whether the normal out of the shell points toward increasing radii or toward decreasing radii. For the shell’s orientation, the analysis in the nonextremal state is readily performed using Kruskal-Szekeres coordinates, whereas in the extremal and overcharged states the analysis can be performed in the usual spherical coordinates. There is still a subdivision in the extremal state $r_{+}=r_{-}$ when the shell is at $r_{+}$, $R=r_{+}$, in that the shell can approach $r_{+}$ from above or approach $r_{+}$ from below. The shell is assumed to be composed of an electrically charged perfect fluid characterized by the energy density, pressure, and electric charge density, for which an analysis of the energy conditions, null, weak, dominant, and strong, is performed. In addition, the shell spacetime has a corresponding Carter-Penrose diagram that can be built out of the diagrams for Minkowski and Reissner-Nordström spacetimes. Combining these two characterizations, specifically, the physical properties and the Carter-Penrose diagrams, one finds that there are fourteen cases that comprise a bewildering variety of shell spacetimes, namely, nonextremal star shells, nonextremal tension shell black holes, nonextremal tension shell regular and nonregular black holes, nonextremal compact shell naked singularities, Majumdar-Papapetrou star shells, extremal tension shell singularities, extremal tension shell regular and nonregular black holes, Majumdar-Papapetrou compact shell naked singularities, Majumdar-Papapetrou shell quasiblack holes, extremal null shell quasinonblack holes, extremal null shell singularities, Majumdar-Papapetrou null shell singularities, overcharged star shells, and overcharged compact shell naked singularities.

We use the frequency and time domain Teukolsky formalism to calculate gravitational-wave fluxes from a spinning body on a bound eccentric equatorial orbit around a Kerr black hole. The spinning body is represented as a point particle following the pole-dipole approximation of the Mathisson-Papapetrou-Dixon equations. Reformulating these equations we are not only able to find the trajectory of a spinning particle in terms of its constants of motion, but also to provide a method to calculate the azimuthal and the radial frequency of this trajectory. Using these orbital quantities, we introduce the machinery to calculate through the frequency domain Teukolsky formalism the energy and the angular momentum fluxes at infinity, and at the horizon, along with the gravitational strain at infinity. We crosscheck the results obtained from the frequency domain approach with the results obtained from a time domain Teukolsky equation solver called Teukode.

The geometry of black hole spacetimes can be probed with exquisite precision in the gravitational-wave window, and possibly also in the optical regime. We study the accretion of bright spots—objects which emit strongly in the optical or in gravitational waves—by nonspinning black holes. As the object approaches the event horizon, the emitted radiation to far-away distances is dominated by photons or gravitons orbiting the light ring, causing the total luminosity to decrease exponentially as ${\mathcal{L}}_o\sim e^{-t/(3\sqrt{3}M)}$. Late-time radiation is blueshifted, due to its having been emitted during the infall, trapped at the light ring and subsequently reemitted. These universal properties are a clear signature of the existence of light rings in the spacetime, and not particularly sensitive to near horizon details.

We clarify a number of issues that arise when extending the analysis of strong cosmic censorship (SCC) to perturbations of highly charged Reissner-Nordström de Sitter (RNdS) spacetimes. The linear stability of the Cauchy horizon can be determined from the spectral gap of quasinormal modes, thus giving a clear idea of the ranges of parameters that are likely to lead to SCC violations for infinitesimally small perturbations. However, the situation becomes much more subtle once the nonlinear backreaction is taken into account. These subtleties have created a considerable amount of confusion in the literature regarding the conclusions one is able to derive about SCC from the available numerical simulations. Here we present new numerical results concerning charged self-gravitating scalar fields in spherical symmetry, correct some previous claims concerning the neutral case, and argue that the existing numerical codes are insufficient to draw conclusions about the potential failure of SCC for near extremal RNdS black hole spacetimes.

We consider the construction of gauge theories of gravity that are invariant under local conformal transformations. We first clarify the geometric nature of global conformal transformations, in both their infinitesimal and finite forms, and the consequences of global conformal invariance for field theories, before reconsidering existing approaches for gauging the conformal group, namely auxiliary conformal gauge theory and biconformal gauge theory, neither of which is generally accepted as a complete solution. We then demonstrate that, provided any matter fields belong to an irreducible representation of the Lorentz group, the recently proposed extended Weyl gauge theory (eWGT) may be considered as an alternative method for gauging the conformal group, since eWGT is invariant under the full set of local conformal transformations, including inversions, as well as possessing conservation laws that provide a natural local generalization of those satisfied by field theories with global conformal invariance, and also having an “ungauged” limit that corresponds to global conformal transformations. By contrast, although standard Weyl gauge theory also enjoys the first of these properties, it does not share the other two, and so cannot be considered a valid gauge theory of the conformal group.

We derive a general quantum master equation for the dynamics of a scalar bosonic particle interacting with a weak, stochastic and classical external gravitational field. The dynamics predicts decoherence in position, momentum and energy. We show how our master equation reproduces the results present in the literature by taking appropriate limits, thus explaining the apparent contradiction in their dynamical description. Our result is relevant in light of the increasing interest in the low energy quantum-gravity regime.

We investigate the cosmological observational test of the extended quintessence model, i.e., a scalar-tensor gravity model with a scalar field potential serving as dark energy, by using the Planck 2018 cosmic microwave background (CMB) data, together with the baryon acoustic oscillations (BAO) and redshift-space distortion (RSD) data. As an example, we consider the model with a Brans-Dicke kinetic term $\frac{\omega (\varphi )}{\varphi }{\varphi }_{;\mu }{\varphi }^{;\mu }$ and a quadratic scalar potential $V(\varphi )=A+B(\varphi -{\varphi }_0)+\frac{C}{2}(\varphi -{\varphi }_0{)}^2$, which reduces to general relativity (GR) in the limit $\omega (\varphi )\to \infty$, and the cosmological constant in the limit $B=C=0$. In such a model, the scalar field typically rolls down the potential and oscillates around the minimum of $V(\varphi )$. We find that the model parameter estimate for the $\mathrm{CMB}+\mathrm{BAO}+\mathrm{RSD}$ data set is given by $\lg \alpha ={-3.6}_{-0.54}^{+0.66}(68\%)$ [$\alpha$ is defined in Eq. (3)], corresponding to $3.8\times {10}^5<{\omega }_0<9.5\times {10}^7$ (68%) and $\lg C=4.9\pm 1.4$ (68%). However, the GR $\mathrm{\Lambda }\mathrm{CDM}$ model can fit the data almost as good as this extended quintessence model and is favored by the Akaike information criterion. The variation of the gravitational constant since the epoch of Recombination is constrained to be $0.97<G_{\mathrm{rec}}/G_0<1.03(1\sigma )$. In light of a recent report that the CMB data favor a closed universe, we consider the case with nonflat geometry in our fit and find that the mean value of ${\mathrm{\Omega }}_k$ shifts a little bit from $-0.049$ to $-0.036$, and the parameters in our model are not degenerate with ${\mathrm{\Omega }}_k$.

Fast radio burst (FRB) discoveries are occurring rapidly, with thousands expected from upcoming surveys. The dispersion measures (DM) observed for FRB include important information on cosmological distances and the ionization state of the universe from the redshift of emission until today. Rather than considering the DM–redshift relation, we investigate the statistical ensemble of the distribution of dispersion measures. We explore the use of this abundance information, with and without redshift information, to probe helium reionization through simulated data to redshift $z=6$. Carrying out Monte Carlo simulations of FRB survey samples, we examine the effect of different source redshift distributions, host galaxy models, sudden vs gradual reionization, and covariance with cosmological parameters on determination of helium reionization properties. We find that a fluence limited survey with ${10}^4$ FRBs can discriminate different helium reionization histories at $\sim 6\sigma$ using the DM-distribution of bursts, without redshift information (and $\sim 10\sigma$ with redshifts).