We study the dynamics of inhomogeneous scalar and pseudoscalar chiral order parameters within the framework of the time-dependent Ginzburg-Landau equations. We utilize a nonlocal chiral quark model to obtain the phase diagram of the model as a function of temperature and baryon chemical potential and study the formation of metastable spatial domains of matter where the order parameters acquire a spatial modulation in the course of their dynamical evolution. We found that, before reaching the expected equilibrium homogeneous state, both scalar and pseudoscalar chiral condensates go through long-lived metastable inhomogeneous structures. For different initial configurations of the order parameters, the lifetimes of the inhomogeneous structures are compared to timescales in a relativistic heavy-ion collision.

Systems of integration-by-parts identities play an important role in simplifying the higher-loop Feynman integrals that arise in quantum field theory. Solving these systems is equivalent to reducing integrals containing numerator products of irreducible invariants to a small set of master integrals. We present a new approach to solving these systems that finds direct reduction equations for numerator terms of a given Feynman integral. As a particular example of its power, we show how to obtain reduction equations for arbitrary powers of irreducible invariants, along with their solutions.

The EDGES experiment recently announced evidence for a broad absorption feature in the sky-averaged radio spectrum around 78 MHz, as may result from absorption in the 21 cm line by neutral hydrogen at $z\sim 15–20$. If confirmed, one implication is that the spin temperature of the 21 cm line is coupled to the gas temperature by $z=20$. The known mechanism for accomplishing this is the Wouthuysen-Field effect, whereby Lyman-alpha photons scatter in the intergalactic medium (IGM) and impact the hyperfine level populations. This suggests that early star formation had already produced a copious Lyman-alpha background by $z=20$, and strongly constrains models in which the linear matter power spectrum is suppressed on small-scales, since halo and star formation are delayed in such scenarios. Here we consider the case that the dark matter consists of ultra-light axions with macroscopic de Broglie wavelengths (fuzzy dark matter, FDM). We assume that star formation tracks halo formation and adopt two simple models from the current literature for the halo mass function in FDM. We further suppose that the fraction of halo baryons which form stars is less than a conservative upper limit of $f_{\star }\le 0.05$, and that $\sim {10}^4$ Lyman-alpha to Lyman-limit photons are produced per stellar baryon. We find that the requirement that the 21 cm spin temperature is coupled to the gas temperature by $z=20$ places a lower-limit on the FDM particle mass of $m_a\ge 5\times {10}^{-21}\mathrm{eV}$. The constraint is insensitive to the precise minimum mass of halos where stars form. As the global 21 cm measurements are refined, the coupling redshift could change and we quantify how the FDM constraint would be modified. A rough translation of the FDM mass bound to a thermal relic warm dark matter (WDM) mass bound is also provided.

Thunderstorm ground enhancements (TGEs) comprise large particle fluxes coming from the clouds that usually coincide with thunderstorms. Most of TGEs observed at the Aragats research station in Armenia during the last ten years originated from “beams of the electron accelerator” operating in the thunderclouds above the research station. Observed TGEs contain high-energy electrons and gamma rays (as well as neutrons) and usually last a few minutes. Starting from 2014, we use particle detectors tuned for the registration of lower energies particles coming from thunderclouds (starting from 0.3 MeV). In 2016, we already noticed that TGEs measured by particle detectors with a low energy threshold demonstrated a drastically larger duration. The flux of the high-energy particles (with energies up to 40 MeV) lasts 1–10 min; the lowest ones (less than 3 MeV)—more than two hours. All intense TGEs contain a high-energy peak and a prolonged low-energy extension lasting 2–3 h. In the presented paper, we describe examples of long-lasting TGEs and discuss correlations of enhanced particle fluxes with disturbances of the electric field and with precipitation.

In this paper, the production of the charged Higgs pair associated with the $Z^0$ boson is analyzed in the minimal extension of the standard model, the so-called two-Higgs-doublet model. The process $e^{+}{e}^{-}\to H^{+}{H}^{-}{Z}^0$ is calculated at the tree level including all the possible diagrams in the two-Higgs-doublet model. The numerical analysis is performed in consideration of the current experimental constraints and various scenarios for the free parameters of the model. The results are presented as a function of the center-of-mass energy, the charged Higgs mass ($m_{H^{\pm }}$), and the ratio of the vacuum expectation values ($t_{\beta }$). The unpolarized cross section, taking into account the results in the flavor physics, gets up to 0.278 fb for $m_{H^{\pm }}=175\mathrm{GeV}$, and it declines with decreasing $m_{H^{\pm }}$ in type I. However, it gets down to 0.073 fb for $m_{H^{\pm }}=500\mathrm{GeV}$ in type II. Further, the calculation is also carried out in the nonalignment scenario and low-$m_{h^0}$ scenario. The effect of the polarized incoming $e^{+}$ and $e^{-}$ beams shows that the cross section is enhanced by a factor up to 2.5 at $\mathrm{P}(+0.60,-0.80)$ polarization configuration. Decay channels of the charged Higgs, possible final states of the process, and some differential distributions belonging to the charged Higgs and $Z^0$ boson are examined for each scenario. The analysis shows that some channels have a higher branching ratio such as $H^{+}\to t\overline{b}$, $H^{+}\to W^{+}{h}^0$, and $H^{+}\to W^{+}{H}^0$. These decay channels are essential in the charged Higgs searches at the lepton colliders for the scenarios interested. The detection of the charged Higgs is a powerful sign for the extended scalar sectors, and the results show the potential of a future lepton collider.

We present numerical results showing how our recently proposed relativistic three-particle quantization condition can be used in practice. Using the isotropic (generalized s-wave) approximation, and keeping only the leading terms in the effective range expansion, we show how the quantization condition can be solved numerically in a straightforward manner. In addition, we show how the integral equations that relate the intermediate three-particle infinite-volume scattering quantity, ${\mathcal{K}}_{\mathrm{df},3}$, to the physical scattering amplitude can be solved at and below threshold. We test our methods by reproducing known analytic results for the $1/L$ expansion of the threshold state, the volume dependence of three-particle bound-state energies, and the Bethe-Salpeter wave functions for these bound states. We also find that certain values of ${\mathcal{K}}_{\mathrm{df},3}$ lead to unphysical finite-volume energies, and give a preliminary analysis of these artifacts.

We explore the existence of $D\mathrm{\Xi }$ and $D^{*}\mathrm{\Xi }$ molecular states within the one boson exchange model. We regularize the potential derived in this model with a form factor and a cutoff of the order of 1 GeV. To determine the cutoff, we use the condition that the $X(3872)$ is reproduced as a pole in the $J^{PC}=1^{++}$ $D^{*}\overline{D}$ amplitude. From this, we find that the $J^P={\frac{1}{2}}^{-}$ $D^{*}\mathrm{\Xi }$ system is on the verge of binding and has an unnaturally large scattering length. For the $J^P={\frac{1}{2}}^{-}D\mathrm{\Xi }$ and the $J^P={\frac{3}{2}}^{-}$ $D^{*}\mathrm{\Xi }$ systems, the attraction is not enough to form a bound state. From heavy quark symmetry and the quark model, we can extend the previous model to the $P{\mathrm{\Xi }}_{QQ}$ and $P^{*}{\mathrm{\Xi }}_{QQ}$ systems, with $P=B$, $D$ and ${\mathrm{\Xi }}_{QQ}={\mathrm{\Xi }}_{cc},{\mathrm{\Xi }}_{bb}$. In this case, we predict a series of triply heavy pentaquarklike molecules.

The models with the gauge group $SU(3{)}_c\times SU(3{)}_L\times U(1{)}_X$ (331 models) have been advocated to explain why there are three fermion generations in nature. As such, they can provide partial understanding of the flavor sector. The hierarchy of Yukawa couplings in the Standard Model is another puzzle that remains without a compelling explanation. We propose to use the Froggatt-Nielsen mechanism in a 331 model to explain both fundamental problems. It turns out that no additional representations in the scalar sector are needed to take care of this. The traditional 331 models predict unsuppressed scalar flavor-changing neutral currents at tree level. We show that they are strongly suppressed in our model.

Sachdev-Ye-Kitaev (SYK) or embedded random ensembles are models of $N$ fermions with random k-body interactions. They play an important role in understanding black hole dynamics, quantum chaos, and thermalization. We study out-of-equilibrium scenarios in these systems and show how they display perfect decoherence at all times. This peculiar feature makes them very attractive in the context of the quantum-to-classical transition and the emergence of classical general relativity. Based on this feature and unitarity, we propose a rate/continuity equation for the dynamics of the $\mathcal{O}(e^N)$ microstates probabilities. The effective permutation symmetry of the models drastically reduces the number of variables, allowing for compact expressions of n-point correlation functions and entropy of the microscopic distribution. Further assuming a generalized Fermi golden rule allows finding analytic formulas for the kernel spectrum at finite $N$, providing a series of short- and long-time scales controlling the out-of-equilibrium dynamics of this model.

We use the isomorphism between the ${\mathrm{BMS}}_3$ and the $W(2,2)$ algebras to reconsider some generic aspects of conformal field theories (CFTs) with the ${\mathrm{BMS}}_3$ algebra defined as a chiral symmetry. For unitarity theories, it is known that the extended symmetry generator acts trivially, and the resulting theory is equivalent to a CFT with a Virasoro symmetry only. For nonunitary CFTs, we define an operator depending on a nilpotent variable, and we organize the Verma module through the action of this new operator. Finally, we find the conditions imposed by the modified Ward identity.

Gravitational waves perturb the paths of photons, impacting both the time of flight and the arrival direction of light from stars. Pulsar timing arrays can detect gravitational waves by measuring the variations in the time of flight of radio pulses, while astrometry missions such as Gaia can detect gravitational waves from the time-varying changes in the apparent position of a field of stars. Just as gravitational waves impart a characteristic correlation pattern in the arrival times of pulses from pulsars at different sky locations, the deflection of starlight is similarly correlated across the sky. Here, we compute the astrometric correlation patterns for the full range of polarization states found in alternative theories of gravity and decompose the sky-averaged correlation patterns into vector spherical harmonics. We find that the tensor and vector polarization states produce equal power in the electric- and magnetic-type vector spherical harmonics, while the scalar modes produce only electric-type correlations. Any difference in the measured electric and magnetic-type correlations would represent a clear violation of Einstein gravity. The angular correlation functions for the vector and scalar longitudinal modes show the same enhanced response at small angular separations that is familiar from pulsar timing.

We study the nature of phase transitions between dilute and dense axion stars interpreted as self-gravitating Bose-Einstein condensates. We develop a Newtonian model based on the Gross-Pitaevskii-Poisson equations for a complex scalar field with a self-interaction potential $V(|\psi {|}^2)$ involving an attractive $|\psi {|}^4$ term and a repulsive $|\psi {|}^6$ term. Using a Gaussian Ansatz for the wave function, we analytically obtain the mass-radius relation of dilute and dense axion stars for arbitrary values of the self-interaction parameter $\lambda \le 0$. We show the existence of a critical point $|\lambda {|}_c\sim (m/M_P{)}^2$, where $m$ is the axion mass and $M_P$ is the Planck mass, above which a first-order phase transition takes place. We qualitatively estimate general relativistic corrections on the mass-radius relation of axion stars. For weak self-interactions $|\lambda |<|\lambda {|}_c$, a system of self-gravitating axions forms a stable dilute axion star below a general relativistic maximum mass $M_{\max ,\mathrm{GR}}^{\text{dilute}}\sim M_P^2/m$ and collapses into a black hole above that mass. For strong self-interactions $|\lambda |>|\lambda {|}_c$, a system of self-gravitating axions forms a stable dilute axion star below a Newtonian maximum mass $M_{\max ,\mathrm{N}}^{\text{dilute}}=5.073M_P/\sqrt{|\lambda |}$ [Phys. Rev. D 84, 043531 (2011)], collapses into a dense axion star above that mass, and collapses into a black hole above a general relativistic maximum mass $M_{\max ,\mathrm{GR}}^{\text{dense}}\sim \sqrt{|\lambda |}{M}_P^3/m^2$. Dense axion stars explode below a Newtonian minimum mass $M_{\min ,\mathrm{N}}^{\text{dense}}=98.9m/\sqrt{|\lambda |}$ and form dilute axion stars of large size or disperse away. We determine the phase diagram of self-gravitating axions and show the existence of a triple point $(|\lambda {|}_{*},M_{*}/(M_P^2/m))$ separating dilute axion stars, dense axion stars, and black holes. We make numerical applications for QCD axions and ultralight axions. Our approximate analytical results are in good agreement with the exact numerical results of Braaten et al. [Phys. Rev. Lett. 117, 121801 (2016)] for Newtonian dense axion stars. They are also qualitatively similar to those obtained by Helfer et al. [J. Cosmol. Astropart. Phys. 03 (2017) 055] for general relativistic axion stars, but they differ quantitatively for weak self-interactions presumably due to the use of a different self-interaction potential $V(|\psi {|}^2)$. We point out analogies between the evolution of self-gravitating axions (bosons) at zero temperature evolving from dilute axion stars to dense axion stars and black holes and the evolution of compact degenerate (fermion) stars at zero temperature evolving from white dwarfs to neutron stars and black holes. We also discuss some analogies between the phase transitions of Newtonian axion stars at zero temperature and the phase transitions of Newtonian self-gravitating fermions at nonzero temperature. Finally, we suggest that a dense axionic nucleus may form at the center of dark matter halos through the collapse of a dilute axionic core (soliton) passing above the maximum mass $M_{\max ,\mathrm{N}}^{\text{dilute}}$. It would have a mass $1.11\times {10}^9(f/m)M_{\odot }$, a radius $0.949/(m{f}^{1/3})\mathrm{pc}$, a density $2.10\times {10}^{-8}(m^2{f}^2)\mathrm{g}/{\mathrm{m}}^3$, a pulsation period $8.24/(m{f}^{1/3})\mathrm{yr}$, and an energy $-5.59\times {10}^{62}(f/m)\mathrm{erg}$, where the axion mass $m$ is measured in units of ${10}^{-22}\mathrm{eV}/{\mathrm{c}}^2$ and the axion decay constant $f$ is measured in units of $10^{15}\mathrm{GeV}$. This dense axionic nucleus could be the remnant of a bosenova associated with the emission of a characteristic radiation [Phys. Rev. Lett. 118, 011301 (2017)].

The Large Area Telescope onboard the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events. Possible features in their energy spectrum could be a signature of the presence of nearby astrophysical sources or of more exotic sources, such as annihilation or decay of dark matter (DM) particles in the Galaxy. In this paper, for the first time we search for a deltalike line feature in the cosmic-ray electron and positron spectrum. We also search for a possible feature originating from DM particles annihilating into electron-positron pairs. Both searches yield negative results, but we are able to set constraints on the line intensity and on the velocity-averaged DM annihilation cross section. Our limits extend up to DM masses of $1.7\mathrm{TeV}/c^2$ and exclude the thermal value of the annihilation cross section for DM lighter than $150\mathrm{GeV}/c^2$.

An analytical result for Euler-Heisenberg effective action, valid for electron spin $g-$factor $|g|<2$, was extended to the domain $|g|>2$ via discovered periodicity of the effective action. This allows for a simplified computation of vacuum instability modified by the electron’s measured $g=2.002319$. We find a strong suppression of vacuum decay into electron positron pairs when magnetic fields are dominant. The result is reminiscent of mass catalysis by magnetic fields.

We present an overview of a program to understand the low-energy physics of quantum Yang-Mills theory from a quantum-information perspective. Our setting is that of the Hamiltonian formulation of pure Yang-Mills theory in the temporal gauge on the lattice. Firstly, inspired by recent constructions for $\mathbb{Z}/2\mathbb{Z}$ lattice gauge theory, in particular, Kitaev’s toric code, we describe the gauge-invariant sector of Hilbert space by introducing a primitive quantum gate: the quantum parallel transporter. We then develop a non-Abelian generalization of Laplace interpolation to present an ansatz for the ground state of pure Yang-Mills theory which interpolates between the weak- and strong-coupling renormalization group fixed points. The resulting state acquires the structure of a tensor network, namely, a multiscale entanglement renormalization ansatz, and allows for the efficient computation of local observables and Wilson loops. Various refinements of the tensor network are discussed leading to several generalizations. Finally, the continuum limit of our ansatz as the lattice regulator is removed is then described. This paper is intended as an abstract for an ongoing program: there are still many open problems.

We smear quenched lattice QCD ensembles with lattice volume $32^3\times 8$ by using Wilson flow. Six ensembles at temperature near the critical temperature $T_c$ corresponding to the critical inverse coupling ${\beta }_c=6.06173(49)$ are used to investigate the localization of topological charge density. If the effective smearing radius of Wilson flow is large enough, the density, size and peak of Harrington-Shepard (HS) caloron-like topological lumps of ensembles are stable when $\beta \le 6.050$, but start to change significantly when $\beta \ge 6.055$. The inverse participation ratio (IPR) of topological charge density shows similar results, it begins to increase when $\beta \ge 6.055$ and is stable when $\beta \le 6.050$. The pseudoscalar glueball mass is extracted from the topological charge density correlator (TCDC) of ensembles at $T=1.19T_c$, and $1.36T_c$, the masses are 1.915(98) and 1.829(123) GeV respectively, they are consistent with results from conventional methods.

The spectral dimension has proven to be a very informative observable to understand the properties of quantum geometries in approaches to quantum gravity. In loop quantum gravity and its spin-foam description, it has not been possible so far to calculate the spectral dimension of spacetime. As a first step towards this goal, here we determine the spacetime spectral dimension in the simplified spin-foam model restricted to hypercuboids. Using Monte Carlo methods we compute the spectral dimension for state sums over periodic spin-foam configurations on infinite lattices. For given periodicity, i.e. number of degrees of freedom, we find a range of scale where an intermediate spectral dimension between 0 and 4 can be found, continuously depending on the parameter of the model. Under an assumption on the statistical behavior of the Laplacian we can explain these results analytically. This allows us to take the thermodynamic limit of large periodicity and find a phase transition from a regime of effectively zero-dimensional to four-dimensional spacetime. At the point of phase transition, dynamics of the model are scale invariant which can be seen as restoration of diffeomorphism invariance of flat space. Considering the spectral dimension as an order parameter for renormalization we find a renormalization group flow to this point as well. Being the first instance of an emergence of four-dimensional spacetime in a spin-foam model, the properties responsible for this result seem to be rather generic. We thus expect similar results for more general, less restricted spin-foam models.

Signature change has been identified as a generic consequence of holonomy modifications in spherically symmetric models of loop quantum gravity with real connections, which includes modified Schwarzschild solutions. An extension of this result to two-dimensional dilaton models, including in particular the Callan-Giddings-Harvey-Strominger (CGHS) solution, further elucidates properties of black holes in this setting. In addition, new obstructions are found to coupling matter and to including operator-ordering effects in an anomaly-free manner.

We present new relations for scattering amplitudes of color ordered gluons, massive quarks and scalars minimally coupled to gravity. Tree-level amplitudes of arbitrary matter and gluon multiplicities involving one graviton are reduced to partial amplitudes in QCD or scalar QCD. The obtained relations are a direct generalization of the recently found Einstein-Yang-Mills relations. The proof of the new relation employs a simple diagrammatic argument trading the graviton-matter couplings to an “upgrade” of a gluon coupling with a color-kinematic replacement rule enforced. The use of the Melia-Johansson-Ochirov color basis is a key element of the reduction. We comment on the generalization to multiple gravitons in the single color trace case.