The nonperturbative structure of the photon and gluon propagators plays an important role in governing the dynamics of quantum electrodynamics (QED) and quantum chromodynamics (QCD), respectively. Although it is often assumed that these interacting field propagators can be decomposed into longitudinal and transverse components, as for the free case, it turns out that in general this is not possible. Moreover, the non-Abelian gauge symmetry of QCD permits the momentum space gluon propagator to contain additional singular terms involving derivatives of $\delta (p)$, the appearance of which is related to confinement. Despite the possibility of the failure of the transverse-longitudinal decomposition for the photon and gluon propagators, and the appearance of singular terms in the gluon propagator, the Slavnov-Taylor identity nevertheless remains preserved.

A family of exact vacuum solutions, representing generalized plane waves propagating on the (anti-)de Sitter background, is constructed in the framework of Poincaré gauge theory. The wave dynamics is defined by the general Lagrangian that includes all parity even and parity odd invariants up to the second order in the gauge field strength. The structure of the solution shows that the wave metric significantly depends on the spacetime torsion.

In previous work, we developed tools for quantifying the tidal distortion of a black hole’s event horizon due to an orbiting companion. These tools use techniques which require large mass ratios (companion mass $\mu$ much smaller than black hole mass $M$), but can be used for arbitrary bound orbits and for any black hole spin. We also showed how to visualize these distorted black holes by embedding their horizons in a global Euclidean three-space, ${\mathbb{E}}^3$. Such visualizations illustrate interesting and important information about horizon dynamics. Unfortunately, we could not visualize black holes with spin parameter $a_{*}>\sqrt{3}/2\approx 0.866$: such holes cannot be globally embedded into ${\mathbb{E}}^3$. In this paper, we overcome this difficulty by showing how to embed the horizons of tidally distorted Kerr black holes in a hyperbolic three-space, ${\mathbb{H}}^3$. We use black hole perturbation theory to compute the Gaussian curvatures of tidally distorted event horizons, from which we build a two-dimensional metric of their distorted horizons. We develop a numerical method for embedding the tidally distorted horizons in ${\mathbb{H}}^3$. As an application, we give a sequence of embeddings into ${\mathbb{H}}^3$ of a tidally interacting black hole with spin $a_{*}=0.9999$. A small-amplitude, high-frequency oscillation seen in previous work shows up particularly clearly in these embeddings.

Noncommutative (NC) gravity is constructed on the canonical noncommutative (Moyal-Weyl) spacetime as a noncommutative $SO(2,3{)}_{\star }$ gauge theory. The NC gravity action consists of three different terms: the first term is of Mac-Dowell Mansouri type, while the other two are generalizations of the Einstein-Hilbert action and the cosmological constant term. The expanded NC gravity action is then calculated using the Seiberg-Witten (SW) map and the expansion is done up second order in the deformation parameter. We analyze in details the low energy sector of the full model. We calculate the equations of motion, discuss their general properties and present one solution: the NC correction to Minkowski spacetime. Using this solution, we explain breaking of the diffeomorphism symmetry as a consequence of working in a particular coordinate system given by the Fermi normal coordinates.

We study the dynamics of the Affleck-Dine field after inflation in more detail. After inflation, the Affleck-Dine field inevitably oscillates around the potential minimum. This oscillation is hard to decay and can cause accidental suppression of the consequential baryon asymmetry. This suppression is most effective for the model with nonrenormalizable superpotential $W_{\mathrm{AD}}\sim {\mathrm{\Phi }}^4$ ($\mathrm{\Phi }$: Affleck-Dine field). It is found that the Affleck-Dine leptogenesis in high-scale inflation, which suffers from serious gravitino overproduction, becomes workable, owing to this effect.

In this paper we present conjoined constraints on several cosmological models from the expansion history $H(z)$ and cosmic growth $f{\sigma }_8$. The models we study include the CPL $w_0{w}_a$ parametrization, the holographic dark energy (HDE) model, the time-varying vacuum (${\mathrm{\Lambda }}_t\mathrm{CDM}$) model, the Dvali, Gabadadze and Porrati (DGP) and Finsler-Randers (FRDE) models, a power-law $f(T)$ model, and finally the Hu-Sawicki $f(R)$ model. In all cases we perform a simultaneous fit to the SnIa, CMB, BAO, $H(z)$ and growth data, while also following the conjoined visualization of $H(z)$ and $f{\sigma }_8$ as in Linder (2017). Furthermore, we introduce the figure of merit (FoM) in the $H(z)\text{−}f{\sigma }_8$ parameter space as a way to constrain models that jointly fit both probes well. We use both the latest $H(z)$ and $f{\sigma }_8$ data, but also LSST-like mocks with 1% measurements, and we find that the conjoined method of constraining the expansion history and cosmic growth simultaneously is able not only to place stringent constraints on these parameters, but also to provide an easy visual way to discriminate cosmological models. Finally, we confirm the existence of a tension between the growth-rate and Planck CMB data, and we find that the FoM in the conjoined parameter space of $H(z)\text{−}f{\sigma }_8(z)$ can be used to discriminate between the $\mathrm{\Lambda }\mathrm{CDM}$ model and certain classes of modified gravity models, namely the DGP and $f(T)$.

We show that observations of solar $\gamma$ rays offer a novel probe of dark matter in scenarios where interactions with the visible sector proceed via a long-lived mediator. As a proof of principle, we demonstrate that there exists a class of models which yield solar $\gamma$-ray fluxes observable with the next generation of $\gamma$-ray telescopes, while being allowed by a variety of current experimental constraints. The parameter space allowed by big bang nucleosynthesis and beam dump experiments naturally leads to mediator lifetimes sufficient to produce observable solar $\gamma$-ray signals. The model allows for solar $\gamma$-ray fluxes up to orders of magnitude larger compared to dwarf spheroidal galaxies, without reaching equilibrium between dark matter annihilation and capture rate. Our results suggest that solar $\gamma$-ray observations are complementary, and in some cases superior, to existing and future dark matter detection efforts.

The properties of magnetized color superconducting cold dense quark matter under compact star conditions are investigated using an $SU(2{)}_f$ Nambu Jona-Lasinio (NJL)-type model in which the divergences are treated using a magnetic field independent regularization scheme in order to avoid unphysical oscillations. We study the phase diagram for several model parametrizations. The features of each phase are analyzed through the behavior of the chiral and superconducting condensates together with the different particle densities for increasing chemical potential or magnetic field. While confirming previous results derived for the zero magnetic field or isospin symmetric matter case, we show how the phases are modified in the presence of $\beta$-equilibrium as well as color and electric charge neutrality conditions.

We use Lagrangian effective field theory techniques to construct the equations of motion for an ideal relativistic fluid of which the constituent degrees of freedom have microscopic polarization. We discuss the meaning of such a system and argue that it is the first term in the Effective Field Theory (EFT) appropriate for describing polarization observables in heavy ion collisions, such as final-state particle polarization and chiral magnetic and vortaic effects. We show that this system will generally require nondissipative dynamics at higher order in the gradient than second order, leading to potential stability issues known with such systems. We comment on the significance of this in the light of conjectured lower limits on viscosity.

Following previous work [A. Bzdak and D. Teaney, Longitudinal fluctuations of the fireball density in heavy-ion collisions, Phys. Rev. C 87, 024906 (2013)], we propose to analyze the rapidity dependence of transverse momentum and transverse-momentum multiplicity correlations. We demonstrate that the orthogonal polynomial expansion of the latter has the potential to discriminate between models of particle production.

We study the possibility of an ultraviolet (UV) zero in the six-loop beta function of an $\mathrm{O}(N)$ $\lambda |\overrightarrow{\varphi }{|}^4$ field theory in $d=4$ spacetime dimensions. For general $N$, in the range of values of $\lambda$ where a perturbative calculation is reliable, we find evidence against such a UV zero in this six-loop beta function.

New laboratory constraints are obtained on exotic interactions between electrons through pseudoscalar or pseudovector coupling by analyzing a recent measurement of the magnetic dipole-dipole interaction between two iron atoms at the nanometer scale. The analysis imposes the strongest bounds on the pseudovector coupling constant $(g_A^e{)}^2/4\pi \hslash c$ between electrons for exchange bosons heavier than 1 eV. Even with the counterpart of electron-positron interaction considered by assuming $CPT$ invariance, the constraints are still the most stringent for bosons in the mass range from 1 eV to 20 eV. The constraints on the pseudoscalar coupling constant $(g_p^e{)}^2/4\pi \hslash c$ are only stronger than the limits derived from the trapped-strontium-ion experiment for exchange bosons heavier than 0.14 eV. Furthermore, a new experiment for more stringent constraints is proposed by measuring the interaction between one iron atom and multiple Holmium atoms.

The idea that dark matter may be a composite state of a hidden non-Abelian gauge sector has received great attention in recent years. Frameworks such as asymmetric dark matter motivate the idea that dark matter may have similar mass to the proton, while mirror matter and $G\times G$ grand unified theories provide rationales for additional gauge sectors which may have minimal interactions with standard model particles. In this work we explore the hadronic spectra that these dark QCD models can allow. The effects of the number of light colored particles and the value of the confinement scale on the lightest stable state, the dark matter candidate, are examined in the hyperspherical constituent quark model for baryonic and mesonic states.

We present ${\psi }^{\prime }$MSSM, a model based on a $U(1{)}_{{\psi }^{\prime }}$ extension of the minimal supersymmetric standard model. The gauge symmetry $U(1{)}_{{\psi }^{\prime }}$, also known as $U(1{)}_N$, is a linear combination of the $U(1{)}_{\chi }$ and $U(1{)}_{\psi }$ subgroups of $E_6$. The model predicts the existence of three sterile neutrinos with masses $\lesssim 0.1\mathrm{eV}$, if the $U(1{)}_{{\psi }^{\prime }}$ breaking scale is of order 10 TeV. Their contribution to the effective number of neutrinos at nucleosynthesis is $\mathrm{\Delta }{N}_{\nu }\simeq 0.29$. The model can provide a variety of possible cold dark matter candidates including the lightest sterile sneutrino. If the $U(1{)}_{{\psi }^{\prime }}$ breaking scale is increased to $10^3\mathrm{TeV}$, the sterile neutrinos, which are stable on account of a $Z_2$ symmetry, become viable warm dark matter candidates. The observed value of the standard model Higgs boson mass can be obtained with relatively light stop quarks thanks to the D-term contribution from $U(1{)}_{{\psi }^{\prime }}$. The model predicts diquark and diphoton resonances which may be found at an updated LHC. The well-known $\mu$ problem is resolved and the observed baryon asymmetry of the universe can be generated via leptogenesis. The breaking of $U(1{)}_{{\psi }^{\prime }}$ produces superconducting strings that may be present in our galaxy. A $U(1)$ R symmetry plays a key role in keeping the proton stable and providing the light sterile neutrinos.

The dark matter issue is among the most perplexing in contemporary physics. The problem is more enigmatic due to the wide range of possible solutions, ranging from the ultralight to the supermassive. String theory gives rise to plausible dark matter candidates due to the breaking of the non-Abelian grand unified theory (GUT) symmetries by Wilson lines. The physical spectrum then contains states that do not satisfy the quantization conditions of the unbroken GUT symmetry. Given that the Standard Model states are identified with broken GUT representations, and provided that any ensuing symmetry breakings are induced by components of GUT states, a remnant discrete symmetry remains that forbids the decay of the Wilsonian states. A class of such states are obtained in a heterotic-string-derived $Z^{\prime }$ model. The model exploits the spinor-vector duality symmetry, observed in the fermionic $Z_2\times Z_2$ heterotic-string orbifolds, to generate a $Z^{\prime }\in E_6$ symmetry that may remain unbroken down to low energies. The $E_6$ symmetry is broken at the string level with discrete Wilson lines. The Wilsonian dark matter candidates in the string-derived model are $SO(10)$, and hence Standard Model, singlets and possess non-$E_6$ $U(1{)}_{Z^{\prime }}$ charges. Depending on the $U(1{)}_{Z^{\prime }}$ breaking scale and the reheating temperature they give rise to different scenarios for the relic abundance, and are in accordance with the cosmological constraints.

Suppressing naturalness concerns, we discuss the compatibility requirements of high-scale supersymmetry breaking with the Higgs boson mass constraint and gauge coupling unification. We find that to accommodate superpartner masses significantly greater than the electroweak scale, one must introduce large nondegeneracy factors. These factors are enumerated for the Minimal Supersymmetric Standard Model, and implications for the allowed forms of supersymmetry breaking are discussed. We find that superpartner masses of arbitrarily high values are allowed for suitable values of $\tan \beta$ and the nondegeneracy factors. We also compute the large, but viable, threshold corrections that would be necessary at the unification scale for exact gauge coupling unification. Whether or not high-scale supersymmetry can be realized in this context is highly sensitive to the precise value of the top quark Yukawa coupling, highlighting the importance of future improvements in the top quark mass measurement.

We suggest that the forward-backward asymmetry $(A_{FB})$ of the charged leptons in the $gg\to H\to \gamma Z\to \gamma {\ell }^{-}{\ell }^{+}$ process could be used to probe the $CP$-violating $H\gamma Z$ coupling when the interference from the $gg\to \gamma Z\to \gamma {\ell }^{-}{\ell }^{+}$ process is included. With $CP$ violation in $H\gamma Z$ coupling, the interference effect leads to a nonvanishing $A_{FB}$, which is also sensitive to the strong phase differences. The resonant and nonresonant strong phases together make $A_{FB}(\widehat{s})$ change sign around Higgs mass $M_H$. For the phenomenology study, we suggest the integral over the one-side mass region below $M_H$ to magnify the $A_{FB}$ strength.

We prove the existence of the lattice fermion zero mode associated with the self-dual lattice gravity solution.

In the present work, the hidden-charm decays of $Y(4390)$ are investigated in a $D^{*}{\overline{D}}_1+\mathrm{H}.\mathrm{c}.$ molecular scenario. We find in this frame the observation of the $Y(4390)$ in the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$ process and the absence of this state in the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}J/\psi$ process are very natural. The partial width of $Y(4390)\to {\pi }^{+}{\pi }^{-}{h}_c$ could reach up to 1.26 MeV, which is large enough to be observed. The result also indicates that the partial widths of $Y(4390)\to \eta J/\psi$ and $Y(4390)\to \eta h_c$ are of the same order of magnitude as the one of $Y(4390)\to {\pi }^{+}{\pi }^{-}{h}_c$, which could be tested by the precise measurements at BES III and Belle II.