It is usually believed that MOND can describe the galactic rotational curves with only baryonic matter and without any dark matter very well, while the $\mathrm{\Lambda }\mathrm{CDM}$ model is expected to have difficulty in reproducing MOND-like behavior. Here, we use EAGLE’s data to learn whether the $\mathrm{\Lambda }\mathrm{CDM}$ model can reproduce MOND-like behavior. EAGLE’s simulation result clearly reproduces the MOND-like behavior for $a_b⪆{10}^{-12}{\mathrm{m}/\mathrm{s}}^2$ at $z=0$, although the acceleration constant, $a_0$, is a little larger than the observational data indicate. We find that $a_0$ increases with the redshift in a way different from what Milgrom proposed ($a_0\propto H$). Therefore, while galaxy rotation curves can be fitted by MOND’s empirical function in the $\mathrm{\Lambda }\mathrm{CDM}$ model, there is no clear connection between $a_0$ and the Hubble constant. We also find that $a_0$ at $z⪆1$ is well separated from $a_0$ at $z=0$. Once we have enough galaxies observed at high redshifts, we will be able to rule out the modified gravity model based on MOND-like empirical function with a $z$-independent $a_0$.

We investigate constraints on scalar dark matter (DM) by analyzing the Lyman-$\alpha$ forest, which probes structure formation at medium and small scales, and also by studying its cosmological consequences at high and low redshift. For scalar DM that constitutes more than 30% of the total DM density, we obtain a lower limit $m\gtrsim {10}^{-21}\mathrm{eV}$ for the mass of scalar DM. This implies an upper limit on the initial field displacement (or the decay constant for an axion-like field) of $\varphi \lesssim {10}^{16}\mathrm{GeV}$. We also derive limits on the energy scale of cosmic inflation and establish an upper bound on the tensor-to-scalar ratio of $r<{10}^{-3}$ in the presence of scalar DM. Furthermore, we show that there is very little room for ultralight scalar DM to solve the “small-scale crisis” of cold DM without spoiling the Lyman-$\alpha$ forest results. The constraints presented in this paper can be used for testing generic theories that contain light scalar fields.

We study preheating in models where a scalar inflaton is directly coupled to a non-Abelian $SU(2)$ gauge field. In particular, we examine $m^2{\varphi }^2$ inflation with a conformal, dilatonlike coupling to the non-Abelian sector. We describe a numerical scheme that combines lattice gauge theory with standard finite difference methods applied to the scalar field. We show that a significant tachyonic instability allows for efficient preheating, which is parametrically suppressed by increasing the non-Abelian self-coupling. Additionally, we comment on the technical implementation of the evolution scheme and setting initial conditions.

We study the effects of high magnetic fields on the structure and on the geometry of the crust in neutron stars. We find that the crust geometry is substantially modified by the magnetic field inside the star. We build stationary and axis-symmetric magnetized stellar models by using well-known equations of state to describe the neutron star crust, namely, the Skyrme model for the inner crust and the Baym-Pethick-Sutherland equation of state for the outer crust. We show that the magnetic field has a dual role, contributing to the crust deformation via the electromagnetic interaction (manifested in this case as the Lorentz force) and by contributing to curvature due to the energy stored in it. We also study a direct consequence of the crust deformation due to the magnetic field: the thermal relaxation time. This quantity, which is of great importance to the thermal evolution of neutron stars, is sensitive to the crust properties, and, as such, we show that it may be strongly affected by the magnetic field.

Cosmic rays have extremely high particle energies (up to $10^{20}\mathrm{eV}$) and can be used to search for violations of Lorentz invariance. We consider isotropic nonbirefringent Lorentz violation in the photon sector for the case of a photon velocity larger than the maximum attainable velocity of the standard fermions. Up to now, Earth-based bounds on this type of Lorentz violation have been determined from observations of TeV gamma rays. Here, we elaborate on a novel approach to test Lorentz invariance with greatly improved sensitivity. This approach is based on investigating extensive air showers which are induced by cosmic-ray particles in the Earth’s atmosphere. We study the impact of two Lorentz-violating decay processes on the longitudinal development of air showers, notably the atmospheric depth of the shower maximum $X_{\max }$. Specifically, the two Lorentz-violating decay processes considered are photon decay into an electron-positron pair and modified neutral-pion decay into two photons. We use Monte Carlo simulations performed with the conex code which was extended to include these two Lorentz-violating decay processes at a magnitude allowed by the best previous Earth-based bound. Compared to standard physics, these Lorentz-violating decay processes reduce the average $X_{\max }$ for showers with primary energies above $10^{18}\mathrm{eV}$ by an amount that is significantly larger than the average resolution of current air shower experiments. Comparing the simulations of the average $X_{\max }$ to observations, new Earth-based bounds on this type of Lorentz violation are obtained, which are better than the previous bounds by more than three orders of magnitude. Prospects of further studies are also discussed.

We study the behavior of strongly interacting matter under a uniform intense external magnetic field in the context of nonlocal extensions of the Polyakov–Nambu–Jona-Lasinio model. A detailed description of the formalism is presented, considering the cases of zero and finite temperature. In particular, we analyze the effect of the magnetic field on the chiral restoration and deconfinement transitions, which are found to occur at approximately the same critical temperatures. Our results show that these models offer a natural framework to account for the phenomenon of inverse magnetic catalysis found in lattice QCD calculations.

We study the long-distance properties of quantum chromodynamics in the Landau gauge in an expansion in powers of the three-gluon, four-gluon, and ghost-gluon couplings, but without expanding in the quark-gluon coupling. This is motivated by two observations. First, the gauge sector is well described by perturbation theory in the context of a phenomenological model with a massive gluon. Second, the quark-gluon coupling is significantly larger than those in the gauge sector at large distances. In order to resum the contributions of the remaining infinite set of QED-like diagrams, we further expand the theory in $1/N_c$, where $N_c$ is the number of colors. At leading order, this double expansion leads to the well-known rainbow approximation for the quark propagator. We take advantage of the systematic expansion to get a renormalization-group improvement of the rainbow resummation. A simple numerical solution of the resulting coupled set of equations reproduces the phenomenology of the spontaneous chiral symmetry breaking: for sufficiently large quark-gluon coupling constant, the constituent quark mass saturates when its valence mass approaches zero. We find very good agreement with lattice data for the scalar part of the propagator and explain why the vectorial part is poorly reproduced.

We calculate the contribution of the nonperturbative Pauli couplings in the quark-photon and quark-gluon vertices to the single-spin asymmetries (SSAs) in semi-inclusive deep inelastic scattering (SIDIS). We describe the nucleon using the spectator model with scalar and axial-vector diquarks. Both of the new couplings can cause the helicity flip of the struck quark. The helicity flip and the rescattering induced by the nonperturbative gluon exchange between the struck quark and diquark lead to the SSAs. Their azimuthal dependencies are the same as that usually ascribed to the Collins and Sivers effects. Our numerical results, based on the instanton model for the QCD vacuum, show that the nonperturbative quark-gluon and quark-photon interactions have a strong influence on these asymmetries.

Many excited charmed strange baryons such as ${\mathrm{\Xi }}_c(2790)$, ${\mathrm{\Xi }}_c(2815)$, ${\mathrm{\Xi }}_c(2930)$, ${\mathrm{\Xi }}_c(2980)$, ${\mathrm{\Xi }}_c(3055)$, ${\mathrm{\Xi }}_c(3080)$, and ${\mathrm{\Xi }}_c(3123)$ have been observed. In order to understand their internal structure and to determine their spin parities, the strong decay properties of these baryons as possible $P$-wave excited ${\mathrm{\Xi }}_c$ candidates have been systematically studied in a ${{}^{3}P}_0$ model. The configurations and $J^P$ assignments of ${\mathrm{\Xi }}_c(2790)$, ${\mathrm{\Xi }}_c(2815)$, ${\mathrm{\Xi }}_c(2930)$, ${\mathrm{\Xi }}_c(2980)$, ${\mathrm{\Xi }}_c(3055)$, ${\mathrm{\Xi }}_c(3080)$, and ${\mathrm{\Xi }}_c(3123)$ have been explored based on recent experimental data. In our analyses, ${\mathrm{\Xi }}_c(3055)$, ${\mathrm{\Xi }}_c(3080)$, and ${\mathrm{\Xi }}_c(3123)$ seem impossible to be the $P$-wave excited ${\mathrm{\Xi }}_c$. ${\mathrm{\Xi }}_c(2790)$, ${\mathrm{\Xi }}_c(2815)$, ${\mathrm{\Xi }}_c(2930)$, and ${\mathrm{\Xi }}_c(2980)$ may be the $P$-wave excited ${\mathrm{\Xi }}_c$. In particular, ${\mathrm{\Xi }}_c(2790)$ and ${\mathrm{\Xi }}_c(2815)$ are very possibly the $P$-wave excited ${\mathrm{\Xi }}_{c1}(1/2^{-})$ and ${\mathrm{\Xi }}_{c1}(3/2^{-})$, respectively. ${\mathrm{\Xi }}_c(2980)$ may be the $P$-wave excited ${\mathrm{\Xi }}_{c1}^{\prime }({\frac{1}{2}}^{-})$. ${\mathrm{\Xi }}_c(2930)$ may be the $P$-wave ${\mathrm{\Xi }}_{c0}^{\prime }({\frac{1}{2}}^{-})$, ${\tilde{\mathrm{\Xi }}}_{c0}({\frac{1}{2}}^{-})$, ${\mathrm{\Xi }}_{c2}^{\prime }({\frac{3}{2}}^{-})$, ${\mathrm{\Xi }}_{c2}^{\prime }({\frac{5}{2}}^{-})$, ${\tilde{\mathrm{\Xi }}}_{c2}({\frac{3}{2}}^{-})$, or ${\tilde{\mathrm{\Xi }}}_{c2}({\frac{5}{2}}^{-})$. Furthermore, some branching fraction ratios related to the internal structure and quark configuration of $P$-wave ${\mathrm{\Xi }}_c$ have also been computed. Measurements of these ratios in the future will be helpful to understand these excited ${\mathrm{\Xi }}_c$.

A measurement of the shape of the differential decay rate and the associated Isgur-Wise function for the decay ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{+}{\mu }^{-}{\overline{\nu }}_{\mu }$ is reported, using data corresponding to $3{\mathrm{fb}}^{-1}$ collected with the LHCb detector in proton-proton collisions. The ${\mathrm{\Lambda }}_c^{+}{\mu }^{-}{\overline{\nu }}_{\mu }(+\mathrm{anything})$ final states are reconstructed through the detection of a muon and a ${\mathrm{\Lambda }}_c^{+}$ baryon decaying into $p{K}^{-}{\pi }^{+}$, and the decays ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{+}{\pi }^{-}{\mu }^{-}{\overline{\nu }}_{\mu }$ are used to determine contributions from ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{*+}{\mu }^{-}{\overline{\nu }}_{\mu }$ decays. The measured dependence of the differential decay rate upon the squared four-momentum transfer between the heavy baryons, $q^2$, is compared with expectations from heavy-quark effective theory and from unquenched lattice QCD predictions.

Solvability of the ubiquitous quantum harmonic oscillator relies on a spectrum generating $\mathfrak{osp}(1|2)$ superconformal symmetry. We study the problem of constructing all quantum mechanical models with a hidden $\mathfrak{osp}(1|2)$ symmetry on a given space of states. This problem stems from interacting higher spin models coupled to gravity. In one dimension, we show that the solution to this problem is the Vasiliev–Plyushchay family of quantum mechanical models with hidden superconformal symmetry obtained by viewing the harmonic oscillator as a one dimensional Dirac system, so that Grassmann parity equals wave function parity. These models—both oscillator and particlelike—realize all possible unitary irreducible representations of $\mathfrak{osp}(1|2)$.

We construct the first analytic examples of topologically nontrivial solutions of the ($3+1$)-dimensional $U(1)$ gauged Skyrme model within a finite box in ($3+1$)-dimensional flat space-time. There are two types of gauged solitons. The first type corresponds to gauged Skyrmions living within a finite volume. The second corresponds to gauged time crystals (smooth solutions of the $U(1)$ gauged Skyrme model whose periodic time dependence is protected by a winding number). The notion of electromagnetic duality can be extended for these two types of configurations in the sense that the electric and one of the magnetic components can be interchanged. These analytic solutions show very explicitly the Callan-Witten mechanism (according to which magnetic monopoles may “swallow” part of the topological charge of the Skyrmion) since the electromagnetic field contributes directly to the conserved topological charge of the gauged Skyrmions. As it happens in superconductors, the magnetic field is suppressed in the core of the gauged Skyrmions. On the other hand, the electric field is strongly suppresed in the core of gauged time crystals.

We consider the first-order phase transition of a charged anti–de Sitter black hole and introduce a new dimensionless parameter, $\omega =(\mathrm{\Delta }S/\pi Q^2{)}^2$. The parametric solutions of the two reduced volumes are obtained. Each volume is described by a piecewise analytic function. The demarcation point is located at ${\omega }_d=12(2\sqrt{3}-3)$. The volume function is smoothly connected at the point. We show that all properties of the coexistence curve can be studied from the two volume functions. In other words, an arbitrary reduced thermodynamic variable of the two coexisting phases is only a function of $\omega$. Some phase diagrams are plotted by using parametric solutions. We find that, when the reduced pressure $\widehat{P}>{\widehat{P}}_A$ (of order $7.4\times {10}^{-4}$), the first-order phase transition of the black hole is similar to the van der Waals fluid. However, the similarity disappears when $\widehat{P}\le {\widehat{P}}_A$. At a van der Waals fluidlike stage, the values of the reduced Gibbs function and the reduced density average are equal. At a non–van der Waals fluid stage, the phase diagrams have extraordinarily rich structure. It is worth pointing out that the phase transition is very important for the low-pressure case since the pressure in essence is the cosmological constant, which is normally very small. Moreover, the thermodynamic behaviors as $\omega \to 0$ are discussed, from which one can easily obtain some critical exponents and amplitudes for small-large black hole phase transitions.

Trumpet geometries play an important role in numerical simulations of black hole spacetimes, which are usually performed under the assumption of asymptotic flatness. Our Universe is not asymptotically flat, however, which has motivated numerical studies of black holes in asymptotically de Sitter spacetimes. We derive analytical expressions for trumpet geometries in Schwarzschild-de Sitter spacetimes by first generalizing the static maximal trumpet slicing of the Schwarzschild spacetime to static constant mean curvature trumpet slicings of Schwarzschild–de Sitter spacetimes. We then switch to a comoving isotropic radial coordinate which results in a coordinate system analogous to McVittie coordinates. At large distances from the black hole the resulting metric asymptotes to a Friedmann-Lemaître-Robertson-Walker metric with an exponentially-expanding scale factor. While McVittie coordinates have another asymptotically de Sitter end as the radial coordinate goes to zero, so that they generalize the notion of a “wormhole” geometry, our new coordinates approach a horizon-penetrating trumpet geometry in the same limit. Our analytical expressions clarify the role of time-dependence, boundary conditions and coordinate conditions for trumpet slices in a cosmological context, and provide a useful test for black hole simulations in asymptotically de Sitter spacetimes.

We compute the exact Hamiltonian (and corresponding Dirac brackets) for a spinning particle with gravimagnetic moment $\kappa$ in an arbitrary gravitational background. The case $\kappa =0$ corresponds to the Mathisson-Papapetrou-Tulczyjew-Dixon (MPTD) equations. $\kappa =1$ leads to modified MPTD equations with improved behavior in the ultrarelativistic limit. So we study the modified equations in the leading post-Newtonian approximation. The rotating body with unit gravimagnetic moment has qualitatively different behavior as compared with the MPTD body: (A) If a number of gyroscopes with various rotation axes are freely traveling together, the angles between the axes change with time. (B) For specific binary systems, gravimagnetic moment gives a contribution to the frame-dragging effect with the magnitude that turns out to be comparable with that of Schiff frame dragging.

Scalar tensor theories can be expressed in different frames, such as the commonly used Einstein and Jordan frames, and it is generally accepted that cosmological observables are the same in these frames. We revisit this by making a detailed side-by-side comparison of the quantities and equations in two conformally related frames, from the actions and fully covariant field equations to the linearized equations in both real and Fourier spaces. This confirms that the field and conservation equations are equivalent in the two frames, in the sense that we can always re-express equations in one frame using relevant transformations of variables to derive the corresponding equations in the other. We show, with both analytical derivation and a numerical example, that the line-of-sight integration to calculate CMB temperature anisotropies can be done using either Einstein frame or Jordan frame quantities, and the results are identical, provided the correct redshift is used in the Einstein frame ($1+z\ne 1/a$).

We compute the running of the spectrum of cosmological perturbations in string gas cosmology, making use of a smooth parametrization of the transition between the early Hagedorn phase and the later radiation phase. We find that the running has the same sign as in simple models of single scalar field inflation. Its magnitude is proportional to $(1-n_s)$ ($n_s$ being the slope index of the spectrum), and it is thus parametrically larger than for inflationary cosmology, where it is proportional to $(1-n_s{)}^2$.

Delensing, the removal of the limiting lensing $B$-mode background, is crucial for the success of future cosmic microwave background (CMB) surveys in constraining inflationary gravitational waves (IGWs). In recent work, delensing with large-scale structure tracers has emerged as a promising method both for improving constraints on IGWs and for testing delensing methods for future use. However, the delensing fractions (i.e., the fraction of the lensing-$B$ mode power removed) achieved by recent efforts have been only 20%–30%. In this work, we provide a detailed characterization of a full-sky, dust-cleaned cosmic infrared background (CIB) map for delensing and construct a further-improved delensing template by adding additional tracers to increase delensing performance. In particular, we build a multitracer delensing template by combining the dust-cleaned Planck CIB map with a reconstructed CMB lensing map from Planck and a galaxy number density map from the Wide-field Infrared Survey Explorer (WISE) satellite. For this combination, we calculate the relevant weightings by fitting smooth templates to measurements of all the cross-spectra and autospectra of these maps. On a large fraction of the sky ($f_{\mathrm{sky}}=0.43$), we demonstrate that our maps are capable of providing a delensing factor of $43\pm 1\%$; using a more restrictive mask ($f_{\mathrm{sky}}=0.11$), the delensing factor reaches $48\pm 1\%$. For low-noise surveys, our delensing maps, which cover much of the sky, can thus improve constraints on the tensor-to-scalar ratio ($r$) by nearly a factor of 2. The delensing tracer maps are made publicly available, and we encourage their use in ongoing and upcoming $B$-mode surveys.

We present a Bayesian reconstruction algorithm that infers the three-dimensional large-scale matter distribution from the weak gravitational lensing effects measured in the image shapes of galaxies. The algorithm is designed to also work with non-Gaussian posterior distributions which arise, for example, from a non-Gaussian prior distribution. In this work, we use a lognormal prior and compare the reconstruction results to a Gaussian prior in a suite of increasingly realistic tests on mock data. We find that in cases of high noise levels (i.e. for low source galaxy densities and/or high shape measurement uncertainties), both normal and lognormal priors lead to reconstructions of comparable quality, but with the lognormal reconstruction being prone to mass-sheet degeneracy. In the low-noise regime and on small scales, the lognormal model produces better reconstructions than the normal model: The lognormal model (1) enforces non-negative densities, while negative densities are present when a normal prior is employed, (2) better traces the extremal values and the skewness of the true underlying distribution, and (3) yields a higher pixel-wise correlation between the reconstruction and the true density.