Recently we have derived a set of mapping relations that enables the reconstruction of the family of Horndeski scalar-tensor theories which reproduce the background dynamics and linear perturbations of a given set of effective field theory of dark energy coefficients. In this paper we present a number of applications of this reconstruction. We examine the form of the underlying theories behind different phenomenological parametrizations of modified gravity and dark energy used in the literature, as well as examine theories that exhibit weak gravity, linear shielding, and minimal self-acceleration. Finally, we propose a new inherently stable parametrization basis for modified gravity and dark energy models.

We investigate the sensitivity of the reheating history to the abundance of primordial black holes (PBHs). Contrary to the monochromatic case of the mass fraction of PBHs, the reheating era with different $e$-foldings and equations of state can have a substantial impact on the abundance of PBHs with an extended mass fraction. We demonstrate explicitly this reheating sensitivity in an illustrative model of single-field inflation with a quasi-inflection point, and find that both the peak position and amplitude of the extended mass fraction as well as the abundance of PBHs in DM can vary by many orders of magnitude, which adds another layer of uncertainty to the PBH scenarios as dark matter.

The role of equatorial boundary condition in the structure of a force-free black hole magnetosphere was rarely discussed, since previous studies have been focused on the field lines entering the horizon. However, recent high-accuracy force-free electrodynamics (FFE) simulations [W. E. East and H. Yang, Phys. Rev. D 98, 023008 (2018).] show that there are both field lines entering the horizon and field lines ending up on the equatorial current sheet within the ergosphere for asymptotic uniform field configuration. For the latter field lines, the equatorial boundary condition is well approximated being marginally force-free, i.e., $B^2-E^2\approx 0$, where $B$ and $E$ are the magnetic and electric field strength, respectively. In this paper, we revisit the uniform field solution to the Kerr BH magnetosphere structure and investigate the role of the marginally force-free equatorial boundary condition. We find this boundary condition plays an important role in shaping the BH magnetosphere in various aspects, including the shape of the light surface, the near-horizon field line configuration and the source of the Poynting flux. We also propose an algorithm for numerically solving the Grad-Shafranov equation and self-consistently imposing the marginally force-free equatorial condition. As a result, we find a good agreement between our numerical solutions and the high-accuracy FFE simulations. We also discuss the applicability of the marginally force-free boundary condition and the numerical algorithm proposed in this paper for general magnetic field configurations.

Identification of the cosmic-ray (CR) “PeVatrons,” which are sources capable of accelerating particles to $\sim {10}^{15}\mathrm{eV}$ energies and higher, may lead to resolving the long-standing question of the origin of the spectral feature in the all-particle CR spectrum known as the “knee.” Because CRs with these energies are deflected by interstellar magnetic fields identification of individual sources and determination of their spectral characteristics is more likely via very high energy $\gamma$-ray emissions, which provide the necessary directional information. However, pair production on the interstellar radiation field (ISRF) and cosmic microwave background (CMB) leads to steepening of the high energy tails of $\gamma$-ray spectra, and should be corrected for to enable true properties of the spectrum at the source to be recovered. Employing recently developed three-dimensional ISRF models this paper quantifies the pair-absorption effect on spectra for sources in the Galactic center (GC) direction at 8.5 and 23.5 kpc distances, with the latter corresponding to the far side of the Galactic stellar disc where it is expected that discrimination of spectral features $>10\mathrm{TeV}$ is possible by the forthcoming Cherenkov Telescope Array (CTA). The estimates made suggest spectral cutoffs could be underestimated by factors of a few in the energy range so far sampled by TeV $\gamma$-ray telescopes. As an example to illustrate this, the recent HESS measurements of diffuse $\gamma$-ray emissions possibly associated with injection of CRs nearby Sgr A* are ISRF corrected, and estimates of the spectral cutoff are reevaluated. It is found that it could be higher by up to a factor of $\sim 2$, indicating that these emissions may be consistent with a CR accelerator with a spectral cutoff of at least 1 PeV at the 95% confidence level.

In recent work, Hill and Paz apply the operator product expansion to forward doubly virtual Compton scattering. The resulting large-$Q^2$ form of the amplitude $W_1(0,Q^2)$ is compatible with the one we obtain by extrapolation of low-$Q^2$ results from a chiral effective field theory, providing support for our approach. That paper also presents a result for the two-photon contribution to the Lamb shift in muonic hydrogen that has a much larger uncertainty than in previous work. We show that this is an overestimate arising from the inclusion of the proton pole term in the subtracted dispersion relation for $W_1$.

We study the invisible decay of neutral hadrons in a representative model of the dark sector. The mesons $K_L$ and $B^0$ decay into the dark sector with branching rates that can be at the current experimental limits. The neutron decays with a rate that could either explain the neutron lifetime puzzle (although only for an extreme choice of the parameters and a fine-tuned value of the masses) or be just above the current limit of its invisible decay (${\tau }_N^{\mathrm{inv}}\gtrsim {10}^{29}\mathrm{years}$) if kinematically allowed. These invisible decays of ordinary matter provide a novel and promising window into new physics that should be vigorously pursued.

The exchange of an axionlike particle between atomic electrons and the nucleus may induce electric dipole moments (EDMs) of atoms and molecules. This interaction is described by a parity- and time-reversal-invariance-violating potential which depends on the product of a scalar $g^s$ and a pseudoscalar $g^p$ coupling constant. We consider the interaction with the specific combination of these constants, $g_e^s{g}_N^p$, which gives significant contributions to the EDMs of diamagnetic atoms. In this paper, we calculate these contributions to the EDMs of ${}^{199}\mathrm{Hg}$, ${}^{129}\mathrm{Xe}$, ${}^{211}\mathrm{Rn}$, and ${}^{225}\mathrm{Ra}$ for a wide range of axion masses. Comparing these results with recent experimental EDM measurements, we place new constraints on $g_e^s{g}_N^p$. The most stringent atomic EDM limits come from ${}^{199}\mathrm{Hg}$ and improve on existing laboratory limits from other experiments for axion masses exceeding ${10}^{-2}\mathrm{eV}$.

We show how the scales responsible for the Peccei-Quinn (PQ), seesaw, and Froggatt-Nielsen (FN) mechanisms can be fixed by constructing a compact model to resolve rather recent, but increasingly important issues in astroparticle physics, including quark and leptonic mixings and $CP$ violations, high-energy neutrinos, the QCD axion, and axion cooling of stars. The model is motivated by the flavored-PQ symmetry to unify flavor physics and string theory. The QCD axion decay constant congruent to the seesaw scale—through its connection to the astroparticle constraints of both the stellar evolution induced by the flavored-axion bremsstrahlung off electrons $e+Ze\to Ze+e+A_i$ and the rare flavor-changing decay process induced by the flavored-axion $K^{+}\to {\pi }^{+}+A_i$—is shown to be fixed at $F_A=3.56_{-0.84}^{+0.84}\times {10}^{10}\mathrm{GeV}$. Consequently, the QCD axion mass $m_a=1.54_{-0.29}^{+0.48}\times {10}^{-4}\mathrm{eV}$, the Compton wavelength of its oscillation ${\lambda }_a=8.04_{-1.90}^{+1.90}\mathrm{mm}$, and the axion-to-neutron coupling $g_{\mathrm{Ann}}=2.14_{-0.41}^{+0.66}\times {10}^{-12}$. Subsequently, the scale associated with the FN mechanism is dynamically fixed, $\mathrm{\Lambda }=2.04_{-0.48}^{+0.48}\times {10}^{11}\mathrm{GeV}$, through its connection to the standard model fermion masses and mixings, and such a fundamental scale might give a hint of where some string moduli are stabilized in type IIB string vacua. In the near future, the NA62 experiment—which is expected to reach a sensitivity of $\text{Br}(K^{+}\to {\pi }^{+}+A_i)<1.0\times {10}^{-12}$—will probe the flavored axions or exclude the model if the astrophysical constraint of star cooling is really responsible for the flavored axion.

We study the interface effects in strangelets adopting mean-field approximation (MFA). Based on an equivparticle model, the linear confinement and leading-order perturbative interactions are included with density-dependent quark masses. By increasing the confinement strength, the surface tension and curvature term of strange quark matter (SQM) become larger, while the perturbative interaction does the opposite. For those parameters constrained according to the $2M_{\odot }$ strange star, the surface tension is $\sim 2.4\mathrm{MeV}/{\mathrm{fm}}^2$, while unstable SQM indicates a slightly larger surface tension. The obtained results are then compared with those predicted by the multiple reflection expansion (MRE) method. In contrast to the bag model case, it is found that MRE method overestimates the surface tension and underestimates the curvature term. To reproduce our results, the density of states in the MRE approach should be modified by proper damping factors.

We study the nonequilibrium condensation process of a holographic $p$-wave superconductor model, which is described by Einstein-Maxwell theory coupled with the charged complex vector field in asymptotic anti-de Sitter (AdS) spacetime. By solving the gravitational dynamics in the asymptotic AdS spacetime numerically, we obtain the full time dependent solution of the system, and observe a dynamical process from the perturbed Reissner-Nordström-AdS black hole to the anisotropic black hole with vector hair when the initial black hole temperature is smaller than the critical temperature $T_c$. By holography, this nonlinear dynamical process is then dual to the phase transition process from a normal state to a $p$-wave superconducting state on the boundary theory. We also investigate the time evolution of the superconducting condensate operator and horizon area.

We conjecture fuzzy configurations of D0-branes in the Banks-Fischler-Shenker-Susskind (BFSS) matrix model as microstates of the black hole. Fuzzy configurations of D0-branes consist of localized fuzzy objects in three spatial directions which are smeared into six internal directions. Since the solutions are time dependent, these are non-Bogomol’nyi-Prasad-Sommerfield (non-BPS) configurations and have internal energy compared with static case. Especially, we examine the smeared fuzzy sphere in the BFSS matrix model, which will correspond to the microstate of the charged black hole in four dimensions, and compare the effective potential in that background with the result obtained by the near horizon geometry of the black 0-brane. The qualitative features of two descriptions agree with each other; thus, we expect that the smeared fuzzy sphere corresponds to one of the microstates of the charged black hole. We also examine the smeared fuzzy cylinder which will correspond to the flat space time.

Through likelihood analyses of both current and future data that constrain both the expansion history of the Universe and the clustering of matter fluctuations, we provide falsifiable predictions for three broad classes of models that explain the accelerated expansions of the Universe: $\mathrm{\Lambda }\mathrm{CDM}$, the quintessence scenario, and a more general class of smooth dark energy models that can cross the phantom barrier $w(z)=-1$. Our predictions are model independent in the sense that we do not rely on a specific parametrization, but we instead use a principal component (PC) basis function constructed a priori from a noise model of supernovae and cosmic microwave background observations. For the supernovae measurements, we consider two type of surveys: the current JLA and the upcoming WFIRST surveys. We show that WFIRST will be able to improve growth predictions in curved models significantly. The remaining degeneracy between spatial curvature and $w(z)$ could be overcome with improved measurements of ${\sigma }_8{\mathrm{\Omega }}_m^{1/2}$, a combination that controls the amplitude of the growth of structure. We also point out that a PC-based figure of merit reveals that the usual two-parameter description of $w(z)$ does not exhaust the information that can be extracted from current data (JLA) or future data (WFIRST).

Thermodynamic properties of strange quark matter (SQM) in a nonuniform magnetic field are studied within the phenomenological MIT bag model under the charge neutrality and beta equilibrium conditions, relevant to the interior of strange quark stars. The spatial dependence of the magnetic field strength is modeled by the dependence on the baryon chemical potential in the exponential and power forms. The total energy density, longitudinal and transverse pressures in magnetized SQM are found as functions of the baryon chemical potential. It is clarified that the central magnetic field strength in a strange quark star is bound from above by the critical value at which the derivative of the longitudinal pressure with respect to the baryon chemical potential vanishes first somewhere in the interior of a star under varying the central field. Above this upper bound, the instability along the magnetic field is developed in magnetized SQM. The change in the form of the dependence of the magnetic field strength on the baryon chemical potential between the exponential and power ones has a nonnegligible effect on the critical magnetic field strength while the variation of the bag pressure within the absolute stability window for magnetized SQM has a little effect on the critical field.

We study the helicity distributions of light flavor quark-antiquark ($q\overline{q}$) pairs in the nucleon sea. The valence quarks are handled by adopting the light-cone SU(6) quark-spectator-diquark model and the sea $q\overline{q}$ pairs are treated from statistical consideration by introducing the helicity suppression factors $l_q(x)$ and ${\overline{l}}_q(x)$ to parametrize the helicity distributions of q-flavor sea quark and antiquark respectively, while $\mathrm{\Delta }{l}_q(x)=l_q(x)-{\overline{l}}_q(x)$ represents a combined effect of helicity contribution due to sea $q\overline{q}$ pairs. From fitting the nucleon polarization asymmetries $A_1^N$ in inclusive deep inelastic scattering processes and the single-spin asymmetries $A_L^{W^{\pm }}$ in Drell-Yan type processes, we find a significant asymmetry between the quark and antiquark helicity distributions of the nucleon sea. Therefore the quark-antiquark asymmetry of helicity distributions of nucleon sea $q\overline{q}$ pairs, i.e., $\mathrm{\Delta }{q}_s(x)\ne \mathrm{\Delta }{\overline{q}}_s(x)$, plays an important role for a comprehensive understanding of the nucleon spin content.

In extensions of the Standard Model with two Higgs doublets, flavor-changing Yukawa couplings of the neutral scalars may be present at tree level. In this work, we consider the most general scenario in which those flavor-changing couplings are absent. We revise the conditions that the Yukawa coupling matrices must obey for such general flavour conservation (gFC) and study the one-loop renormalization group evolution of such conditions in both the quark and lepton sectors. We show that gFC in the leptonic sector is one-loop stable under the renormalization group evolution, and in the quark sector, we present some new Cabibbo-like solution also one-loop stable under renormalization group evolution. At a phenomenological level, we obtain the regions for the different gFC parameters that are allowed by the existing experimental constraints related to the 125 GeV Higgs.

We generalize the scalar triplet neutrino mass model, the type II seesaw. Our model displays compelling theoretical and experimental features. First, lepton number violation is dynamically generated, without introducing a naturalness problem, nor relying on arbitrarily small parameters. Second, we identify a smoking gun signature at the LHC that both probes the triplet structure of our seesaw mechanism and allows to disentangle it from the usual type II scenario. Additionally, we discuss other interesting phenomenological aspects of the model such as the presence of a massless Goldstone boson and deviations of standard model Higgs couplings.

We consider a supersymmetric ${\mathrm{SU}(4)}_c\times {\mathrm{SU}(2)}_L\times \mathrm{SU}(2{)}_R$ model with a minimal number of Higgs multiplets and Dirac and Majorana $CP$-violating phases in the neutrino flavor mixing matrix. The model incorporates the charged fermion masses and quark mixings, and uses type I seesaw to explain the solar and atmospheric neutrino oscillations. With the neutrino oscillation data of two mass squared differences and three flavor mixing angles, we employ thermal leptogenesis and the observed baryon asymmetry to find the allowed regions for the Dirac and Majorana phases. For a normal neutrino mass hierarchy, we find that the observed baryon asymmetry can be reproduced by a Dirac phase of around ${\delta }_{CP}=3\pi /2$, which is strongly indicated by the recent T2K and $\mathrm{NO}\nu \mathrm{A}$ data. For the case of inverted neutrino mass hierarchy, the predicted baryon asymmetry is not compatible with the observed value.

One strategy for reducing the sign problem in finite-density field theories is to deform the path integral contour from real to complex fields. If the deformed manifold is the appropriate combination of Lefschetz thimbles—or somewhat close to them—the sign problem is alleviated. Gauge theories require generalizing the definition of thimble decompositions, and therefore it is unclear how to carry out a generalized thimble method. In this paper we discuss some of the conceptual issues involved by applying this method to ${\mathrm{QED}}_{1+1}$ at finite density, showing that the generalized thimble method yields correct results with less computational effort than standard methods.

The chromoelectric polarizability of $J/\psi$ is extracted from lattice QCD data on the nucleon-$J/\psi$ potential in the heavy quark limit. The value of $\alpha (1S)=(1.6\pm 0.8){\mathrm{GeV}}^{-3}$ is obtained. This value may have a systematic uncertainty due to lattice artifacts which cannot be estimated at present, but will become controllable in future studies. We also comment on the possibility of hadrocharmonia.