Several direct detection experiments, including recently CDMS-II, have reported signals consistent with 5 to 10 GeV dark matter (DM) that appear to be in tension with null results from XENON and LUX experiments; these indicate a careful review of the theoretical basis, including the galactic DM velocity distribution function (VDF). We establish a VDF parameter space from DM-only cosmological simulations and illustrate that seemingly contradictory experimental results can be made consistent within this parameter space. Future experimental limits should be reported after they are marginalized over a range of VDF parameters.

Anisotropic inflationary background geometries are analyzed in the context of an extended gauge action where the electric and magnetic susceptibilities are not bound to coincide and depend on the inflaton field. After deriving various classes of solutions with electric and magnetic hairs, we discuss the problem of the initial boundary conditions of the shear parameter and consider a globally neutral plasma as a possible relic of a preinflationary stage of expansion. While electric hairs are washed out by the finite value of the protoinflationary conductivity, magnetic hairs can persist and introduce a tiny amount of shear causing a different inflationary rate of expansion along orthogonal spatial directions. The plasma interactions are a necessary criterion to discriminate between physical and unphysical initial conditions but they are not strictly sufficient to warrant the stability of a given magnetic solution.

The observed hemispherical power asymmetry in cosmic microwave background radiation may have originated from the modulations of superhorizon long-wavelength modes. In this work, we unveil different aspects of asymmetries generated from the long-wavelength mode modulations. We show that the same mechanism that leads to the observed cosmic microwave background hemispherical power asymmetry via superhorizon long-mode perturbation also yields dipole asymmetry in (a) the tensor perturbations power spectrum and (b) the halo bias parameter. These are different phenomena relevant to different cosmological histories, but both share the same underlying mechanism in generating asymmetries in the sky. We obtain the set of consistency conditions relating the amplitude of dipole asymmetries generated on tensor perturbations and halo bias parameter to the amplitude of dipole asymmetry generated on cosmic microwave background power spectrum. In addition, we show that this mechanism does not produce dipole asymmetry in acceleration expansion in an $\mathrm{\Lambda }\mathrm{CDM}$ Universe because the superhorizon curvature perturbation is conserved in this background.

Some recent observations provide $>2\sigma$ evidence for phantom dark energy—a value of the dark energy equation of state less than the cosmological-constant value of $-1$. We focus on constraining the equation of state by combining current data from the most mature geometrical probes of dark energy: type Ia supernovae (SNe Ia) from the Supernova Legacy Survey (SNLS3), the Supernova Cosmology Project (Union2.1), and the Pan-STARRS1 survey (PS1); cosmic microwave background measurements from Planck and WMAP9; and a combination of measurements of baryon acoustic oscillations. The combined data are consistent with $w=-1$ for the Union2.1 sample, though they present moderate ($\sim 1.9\sigma$) evidence for a phantom value when either the SNLS3 or PS1 sample is used instead. We study the dependence of the constraints on the redshift, stretch, color, and host galaxy stellar mass of SNe, but we find no unusual trends. In contrast, the constraints strongly depend on any external $H_0$ prior: a higher adopted value for the direct measurement of the Hubble constant ($H_0\gtrsim 71\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$) leads to $\gtrsim 2\sigma$ evidence for phantom dark energy. Given Planck data, we can therefore make the following statement at $2\sigma$ confidence: either the SNLS3 and PS1 data have systematics that remain unaccounted for or the Hubble constant is below $71\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$; else the dark energy equation of state is indeed phantom.

The physical interpretation of cold dark matter perturbations is clarified by associating Bertschinger’s Poisson gauge with a Eulerian frame of reference. We obtain such an association by using a Lagrangian approach to relativistic cosmological structure formation. Explicitly, we begin with the second-order solution of the Einstein equations in a synchronous/comoving coordinate system, which defines the Lagrangian frame, and transform it to a Poissonian coordinate system. The generating vector of this coordinate/gauge transformation is found to be the relativistic displacement field. The metric perturbations in the Poissonian coordinate system contain known results from standard/Eulerian Newtonian perturbation theory but contain also purely relativistic corrections. On subhorizon scales, these relativistic corrections are dominated by the Newtonian bulk part. These corrections, however, set up nonlinear (initial) constraints for the density and for the velocity that become important on scales close to the horizon. Furthermore, we report the occurrence of a transverse component in the displacement field and find that it induces a nonlinear frame dragging as seen in the Eulerian frame, which is subdominant at late times and subhorizon scales. Finally, we find two other gauges that can be associated with a Eulerian frame. We argue that the Poisson gauge is to be preferred because it comes with the simplest physical interpretation.

We investigate the power spectrum of the distortion of the cosmic microwave background (CMB) due to the decay of the primordial magnetic fields. It is known that there are two types of the CMB distortions, so-called $\mu$ and $y$ types, and we find that the signal of the $y$-type distortion becomes larger than that of the $\mu$-type one. We also discuss cross power spectra between the CMB distortions and the CMB temperature anisotropy, which are naturally generated due to the existence of the primordial magnetic fields. We find that such cross power spectra have small amplitudes compared with the autopower spectra of the CMB distortions because of the Silk damping effect of the temperature anisotropy. We also investigate the possibility of detecting such a signal in the future CMB experiments, including not only absolutely calibrated experiments such as PIXIE but also relatively calibrated experiments such as LiteBIRD and CMBpol.

We consider the classical evolution of the inflaton field $\varphi (t)$ and the Hubble parameter $H(t)$ in homogeneous and isotropic single-field inflation models. Under an extremely broad assumption, we show that the Universe generically emerges from an initial singularity in a noninflating state where the kinetic energy of the inflaton dominates its potential energy, ${\stackrel{.}{\varphi }}^2\gg V(\varphi )$. In this kinetically dominated regime, the dynamical equations admit simple analytic solutions for $\varphi (t)$ and $H(t)$, which are independent of the form of $V(\varphi )$. In such models, these analytic solutions thus provide a simple way of setting the initial conditions from which to start the (usually numerical) integration of the coupled equations of motion for $\varphi (t)$ and $H(t)$. We illustrate this procedure by applying it to spatially flat models with polynomial and exponential potentials, and determine the background evolution in each case; generically $H(t)$ and $|\varphi (t)|$ as well as their time derivatives decrease during kinetic dominance until ${\stackrel{.}{\varphi }}^2\sim V(\varphi )$, marking the onset of a brief period of fast-roll inflation prior to a slow-roll phase. We also calculate the approximate spectrum of scalar perturbations produced in each model and show that it exhibits a generic damping of power on large scales. This may be relevant to the apparent low-$\ell$ falloff in the cosmic microwave background power spectrum.

Frequency domain studies have recently demonstrated that charged scalar fields exhibit fast growing superradiant instabilities when interacting with charged black holes in a cavity. Here, we present a time domain analysis of the long time evolution of test charged scalar field configurations on the Reissner-Nordström background, with or without a mirrorlike boundary condition. Initial data are taken to be either a Gaussian wave packet or a regularized (near the horizon) quasibound state. Then, Fourier transforming the data obtained in the evolution confirms the results obtained in the frequency domain analysis, in particular for the fast growing modes. We show that spherically symmetric ($\ell =0$) modes have even faster growth rates than the $\ell =1$ modes for a “small” field charge. Thus, our study confirms that this setup is particularly promising for considering the nonlinear development of the superradiant instability, since the fast growth makes the signal overcome the numerical error that dominates for small growth rates, and the analysis may be completely done in spherical symmetry.

We subject the steady solutions of a spherically symmetric accretion flow to a time-dependent radial perturbation. The equation of the perturbation includes nonlinearity up to any arbitrary order and bears a form that is very similar to the metric equation of an analogue acoustic black hole. Casting the perturbation as a standing wave on subsonic solutions, and maintaining nonlinearity in it up to the second order, we get the time dependence of the perturbation in the form of a Liénard system. A dynamical systems analysis of the Liénard system reveals a saddle point in real time, with the implication that instabilities will develop in the accreting system when the perturbation is extended into the nonlinear regime. The instability of initial subsonic states also adversely affects the temporal evolution of the flow toward a final and stable transonic state.

Neutron stars are thought to be excellent laboratories for determining the equation of state (EoS) of cold dense matter. Their strong gravity suggests that they can also be used to constrain gravity models. The two observables of neutron stars—mass and radius (M-R)—both depend on the choice of EoS and relativistic gravity, meaning that neutron stars cannot be simultaneously good laboratories for both of these questions. A measurement of mass and/or radius would constrain the less well known physics input. The most common assumption—namely, that M-R measurements can be used to constrain the EoS—presumes that general relativity (GR) is the ultimate model of gravity in the classical regime. We calculate the radial profile of compactness and curvature (square root of the full contraction of the Weyl tensor) within a neutron star and determine the domain not probed by the Solar System tests of GR. We find that, except for a tiny sphere of radius less than a millimeter at the center, the curvature is several orders of magnitude above the values present in Solar System tests. The compactness is beyond the solar surface value for $r>10\mathrm{m}$, and increases by 5 orders of magnitude towards the surface. With the density being only an order of magnitude higher than that probed by nuclear scattering experiments, our results suggest that the employment of GR as the theory of gravity describing the hydrostatic equilibrium of the neutron stars is a rather remarkable extrapolation from the regime of tested validity, as opposed to that of EoS models. Our ignorance of gravity within neutron stars suggests that a measurement of mass and/or radius constrains gravity rather than the EoS, and given that the EoS has yet to be determined by nucleon scattering experiments, M-R measurements cannot tightly constrain the gravity models either. Near the surface the curvature and compactness attain their largest values, while the EoS in this region is fairly well known. This renders the crust as the best site to look for deviations from GR.

We present results of a three-loop hard-thermal-loop perturbation theory calculation of the thermodynamical potential of a finite temperature and baryon chemical potential system of quarks and gluons. We compare the resulting pressure and diagonal quark susceptibilities with available lattice data. We find reasonable agreement between our analytic results and lattice data at both zero and finite chemical potential.

We study the quark spectrum at finite temperature near and above the pseudocritical temperature of the chiral phase transition incorporating the effects of the collective modes with the quantum number of the sigma (parasigma) and pion (parapion) in a chiral effective model with a nonzero current quark mass. Below the pion zero-binding temperature where the pionic modes are bound, the quark self-energy has van Hove singularity induced by the scattering of quarks with the composite bound pions with a nonhyperbolic dispersion curve. This singularity is found to cause a drastic change in the quark spectrum from that in the mean field picture near the pseudocritical temperature: The quark spectrum has an unexpected sharp peak at an energy considerably lower than the constituent quark mass, while the spectrum approaches the mean field one at high temperatures. We clarify that the emergence of this anomalous structure of the quark spectral function originates from the composite nature of the pionic modes with a non-Lorentz invariant dispersion relation in the medium at finite temperature.

We study phenomenological constraints in a simple $S\overline{E}\chi y$ extension of the Standard Model with a 125-GeV Higgs, a vectorlike heavy electron $(E)$, a complex scalar electron $(S)$ and a Standard Model singlet Dirac fermion $(\chi )$. The interactions among the dark matter candidate $\chi$ and the Standard Model particles occur via loop-induced processes involving the Yukawa interaction $S\overline{E}\chi y$. The model is an explicit perturbative realization of so-called magnetic dark matter. The field content allows for a cancellation of quadratic divergences in the scalar masses at one loop, a phenomenon which we refer to as perturbative naturality. The basic model is constrained dominantly by direct detection experiments and its parameter space can be nearly entirely covered by upcoming ton-scale direct detection experiments. We conclude this work by discussing different variations of the model.

The Bethe-Salpeter equation in unitarized chiral perturbation theory is usually solved with the so-called on-shell approximation. The underlying argument is that the off-shell effects can be absorbed by the corresponding coupling constants and physical masses, which has been corroborated by the success of unitarized chiral perturbation theory in describing a variety of physical phenomena. Such an approximation needs to be scrutinized when applied to study the light-quark mass evolution of physical observables, as routinely performed nowadays. In the present work, we propose to solve the Bethe-Salpeter equation with the full off-shell terms of the chiral potentials and apply this formalism to the description of the latest $n_f=2+1$ lattice QCD (LQCD) data on the scattering lengths of Nambu-Goldstone bosons off $D$ mesons. It is shown that the LQCD data can be better described in this formalism than in the widely used on-shell approximation. On the other hand, no qualitative difference between the on-shell and off-shell approaches is observed for the light-quark mass evolution of the scattering lengths, given the limited LQCD data and their relatively large uncertainties. We also show that the light-quark mass dependence of the $D_{s0}^{*}(2317)$ remains essentially the same in both approaches.

We investigated the possibility of determining the internal structure of exotic hadrons by using high-energy reaction processes, where quarks and gluons are appropriate degrees of freedom. In particular, it should be valuable to investigate the high-energy exclusive processes that include generalized parton distributions (GPDs) and generalized distribution amplitudes (GDAs). The GPDs and GDAs contain momentum distributions of partons and form factors. We found that the exotic nature appears in momentum distributions of quarks as suggested by the constituent-counting rule and in the form factors associated with exotic hadron sizes and the number of constituents. We also propose that these exotic signatures should be found in the exclusive production processes of exotic hadrons from ${\gamma }^{*}\gamma$ in electron-positron annihilation. For example, the GDAs contain information on a timelike form factor of the energy-momentum tensor of a hadron $h$. We show that the cross section of $e\gamma \to e+h\overline{h}$ is sensitive to the exotic signature by looking at the $h\overline{h}$ invariant-mass dependence by taking light hadrons, $h=f_0(980)$ and $a_0(980)$. From such GDA measurements, the tomography of exotic hadrons becomes possible, for example, with Belle and BABAR experiments and a future linear collider.

We study the two-body hadronic $D\to PV$ decays, where $P$ ($V$) denotes a pseudoscalar (vector) meson, in the factorization-assisted topological-amplitude approach proposed in our previous work. This approach is based on the factorization of short-distance and long-distance dynamics into Wilson coefficients and hadronic matrix elements of four-fermion operators, respectively, with the latter being parametrized in terms of several nonperturbative quantities. We further take into account the $\rho \text{−}\omega$ mixing effect, which improves the global fit to the branching ratios involving the ${\rho }^0$ and $\omega$ mesons. Combining short-distance dynamics associated with penguin operators and the hadronic parameters determined from the global fit to branching ratios, we predict direct $CP$ asymmetries. In particular, the direct $CP$ asymmetries in the $D^0\to K^0{\overline{K}}^{*0}$, ${\overline{K}}^0{K}^{*0}$, $D^{+}\to {\pi }^{+}{\rho }^0$, and $D_s^{+}\to K^{+}\omega$, $K^{+}\varphi$ decays are found to be of $\mathcal{O}({10}^{-3})$, which can be observed at the LHCb and future Belle II experiment. We also predict the $CP$ asymmetry observables of some neutral $D$ meson decays.

Using the most general form of the interpolating current for the octet baryons, the magnetic moments of the negative-parity baryons are calculated within the light-cone sum rules. The contributions coming from diagonal transitions of the positive-parity baryons and also from a nondiagonal transition between positive- and negative-parity baryons are eliminated by considering the combinations of different sum rules corresponding to the different Lorentz structures. A comparison of our results on magnetic moments of the negative-parity baryons with the other approaches existing in the literature is presented.

We use the open quantum systems framework to analyze the MINOS data and perform this analysis considering two different dissipative models. In the first model, the dissipative parameter describes the decoherence effect and in the second, the dissipative parameter describes other dissipative effects including decoherence. With the second model it is possible to study $CP$ violation since we consider Majorana neutrinos. The analysis from the muon neutrino and antineutrino beam assigns different values to all the parameters of the models, but is consistent between them. Assuming that neutrinos are equivalent to antineutrinos, the global analysis presents a nonvanishing Majorana $CP$ phase depending on the energetic parametrization of the dissipative parameter.

We search for the charmless $B^0$ decay with final state particles $p\overline{\mathrm{\Lambda }}{\pi }^{-}\gamma$ using the full data sample that contains $772\times 10^{6}B\overline{B}$ pairs collected at the $\mathrm{{\rm Y}}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. This decay is predicted to proceed predominantly via the $b\to s\gamma$ radiative penguin process with a high energy photon. No significant signal is found. We set an upper limit of $6.5\times 10^{-7}$ for the branching fraction of $B^0\to p\overline{\mathrm{\Lambda }}{\pi }^{-}\gamma$ at the 90% confidence level.