We search for a unified instrumental explanation of the spectral features seen near $E_{\gamma }=130$ GeV in photons collected by Fermi-LAT from the galactic center and from the Earth’s limb. We report for the first time a similar feature in photons originating from the vicinity of the Sun, and examine the instrumental characteristics of this Solar feature. To test an instrumental hypothesis, we identify the range of photon incident angles where most of the peak photons are observed in these three spectral features. An examination of the spectrum of photons from the rest of the sky in this angular region reveals a hint of a spectral feature near $E_{\gamma }=130\mathrm{GeV}$. These results cast further doubt on the dark-matter-annihilation interpretation of the galactic center peak.

Analyses of TeV–PeV cosmic ray (CR) diffusion around their sources usually assume either isotropic diffusion or anisotropic diffusion due to the regular Galactic magnetic field. We show that none of them are adequate on distances smaller than the maximal scale $l_{\max }\sim 100\mathrm{pc}$ of fluctuations in the turbulent interstellar magnetic field. As a result, we predict anisotropic gamma-ray emissions around CR proton and electron sources, even for uniform densities of target gas. The centers of extended emission regions may have non-negligible offsets from their sources, leading to risks of misidentification. Gamma rays from CR filaments have steeper energy spectra than those from surrounding regions. We point out that gamma-ray telescopes can be used in the future as a new way to probe and deduce the parameters of the interstellar magnetic field.

The size of the smallest dark matter collapsed structures, or protohalos, is set by the temperature at which dark matter particles fall out of kinetic equilibrium. The process of kinetic decoupling involves elastic scattering of dark matter off of Standard Model particles in the early universe, and the relevant cross section is thus closely related to the cross section for dark matter scattering off of nuclei (direct detection) but also, via crossing symmetries, for dark matter pair production at colliders and for pair annihilation. In this study, we employ an effective-field-theoretic approach to calculate constraints on the kinetic decoupling temperature, and thus on the size of the smallest protohalos, from a variety of direct, indirect and collider probes of particle dark matter.

We extract the next-to-leading-order low-energy constants ${\overline{\ell }}_3$ and ${\overline{\ell }}_4$ of SU(2) chiral perturbation theory, based on precise lattice data for the pion mass and decay constant on ensembles generated by the Wuppertal-Budapest Collaboration for QCD thermodynamics. These ensembles feature $2+1$ flavors of two-fold stout-smeared dynamical staggered fermions combined with Symanzik glue, with pion masses varying from 135 to 435 MeV, lattice scales between 0.7 and 2.0 GeV, while $m_s$ is kept fixed at its physical value. Moderate taste splittings and the scale being set through the pion decay constant allow us to restrict ourselves to the taste pseudoscalar state and to use formulas from continuum chiral perturbation theory. Finally, by dropping the data points near 135 MeV from the fits, we can explore the range of pion masses that is needed in SU(2) chiral perturbation theory to reliably extrapolate to the physical point.

We calculate the transition form factor of the neutral pion where one photon is virtual and another photon is real in the model where the light constituent quark mass and the quark-pion vertex are taken to be momentum independent. Radiative corrections to the lowest order triangle quark Feynman amplitude are calculated. The resummation of the lowest radiative corrections to the virtual photon vertex is done by applying the Sudakov exponential hypothesis. By using fitting parameters, the quark mass and the strong coupling constant, the results on the pion transition form factor are compared with existing data published by CELLO, CLEO, BABAR, and Belle collaborations.

In the collinear twist-three approach, we calculate for the first time the gluon contribution to double- (longitudinal-transverse) spin asymmetry $A_{LT}$ for open charm production in proton-proton collisions measurable at RHIC. Utilizing the Ward-Takahashi identity for the nonpole part of the hard scattering amplitude, we derive a factorized, gauge invariant formula for the asymmetry. The result may be combined with the previous studies of single-spin asymmetry in the same channel and allows for a systematic analysis of three-gluon correlations inside a transversely polarized nucleon.

We derive asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave function at large space separations for systems with more than two particles in quantum field theories. To deal with $n$ particles in the center-of-mass frame coherently, we introduce the Jacobi coordinates of $n$ particles and then combine their $3(n-1)$ coordinates into the one spherical coordinate in $D=3(n-1)$ dimensions. We parametrize the on-shell $T$ matrix for $n$ scalar particles at low energy using the unitarity constraint of the $S$ matrix. We then express asymptotic behaviors of the NBS wave function for $n$ particles at low energy in terms of parameters of the $T$ matrix and show that the NBS wave function carries information of the $T$ matrix such as phase shifts and mixing angles of the $n$-particle system in its own asymptotic behavior, so that the NBS wave function can be considered as the scattering wave of $n$ particles in quantum mechanics. This property is one of the essential ingredients of the HAL QCD scheme to define “potential” from the NBS wave function in quantum field theories such as QCD. Our results, together with an extension to systems with spin $1/2$ particles, justify the HAL QCD’s definition of potentials for three or more nucleons (or baryons) in terms of the NBS wave functions.

We study the constraints that can be placed on anomalous $\tau$-lepton couplings at the LHC. We use an effective Lagrangian description for physics beyond the standard model which contains the $\tau$-lepton anomalous magnetic moment, electric dipole moment, and weak dipole moments in two operators of dimension 6. We include in our study two additional operators of dimension 8 that directly couple the $\tau$ leptons to gluons and are therefore enhanced at the LHC. We consider the two main effects from these couplings: modifications to the Drell-Yan cross section and to the $\tau$-lepton pair production in association with a Higgs boson. We find that a measurement of the former at the 14% level can produce constraints comparable to existing ones for the anomalous dipole couplings and that a bound on the latter at a sensitivity level of 500 ${\sigma }_{\mathrm{SM}}$ or better would produce the best constraint on the $\tau$-gluonic couplings.

The effects of phase space deformations on standard scalar field cosmology are studied. The deformation is introduced by modifying the symplectic structure of the minisuperspace variables to have a deformed Poisson algebra among the coordinates and the canonical momenta. It is found that in the deformed minisuperspace model, an accelerating scale factor arises in the absence of a cosmological constant, and this acceleration is a consequence of the phase space deformation parameter $\beta$.

We compute the leading finite-size effects on the normalized structure constants in semiclassical three-point correlation functions of two finite-size giant magnon string states and three different types of “light” states: primary scalar operators, the dilaton operator with nonzero momentum, and singlet scalar operators on higher string levels. This is done for the case of the $TsT$-transformed, or $\gamma$-deformed, ${\mathrm{AdS}}_5\times S^5$ string theory background, dual to $\mathcal{N}=1$ super Yang-Mills theory in four dimensions, arising as an exactly marginal deformation of $\mathcal{N}=4$ super Yang-Mills theory.

We consider the interatomic van der Waals interaction energy between two neutral ground-state atoms moving in vacuum space with the same uniform acceleration. We assume the acceleration orthogonal to their separation so that their mutual distance remains constant. Using a model for the van der Waals dispersion interaction based on the interaction between the instantaneous atomic dipole moments, which are induced and correlated by the zero-point field fluctuations, we evaluate the interaction energy between the two accelerating atoms in terms of quantities expressed in the laboratory reference frame. We find that the dependence of the van der Waals interaction between the atoms from the distance is different with respect to the case of atoms at rest, and the relation of our results with the Unruh effect is discussed. We show that in the near zone a new term proportional to $R^{-5}$ adds to the usual $R^{-6}$ behavior, and in the far zone a term proportional to $R^{-6}$ adds to the usual $R^{-7}$ behavior, making the interaction of a longer range. We also find that the interaction energy is time dependent, and the physical meaning of this result is discussed. In particular, we find acceleration-dependent corrections to the $R^{-7}$ (far zone) and $R^{-6}$ (near zone) proportional to $a^2{t}^2/c^2$; this suggests that significant changes to the van der Waals interaction between the atoms could be obtained if sufficiently long times are taken, without necessity of the extremely high accelerations required by other known manifestations of the Unruh effect.

We study the transport properties of topological insulators, encoding them in a generating functional of gauge and gravitational sources. Much of our focus is on the simple example of a free massive Dirac fermion, the so-called Chern insulator, especially in $2+1$ dimensions. In such cases, when parity and time-reversal symmetry are broken, it is necessary to consider the gravitational sources to include a frame and an independent spin connection with torsion. In $2+1$ dimensions, the simplest parity-odd response is the Hall viscosity. We compute the Hall viscosity of the Chern insulator using a careful regularization scheme, and find that although the Hall viscosity is generally divergent, the difference in Hall viscosities of distinct topological phases is well defined and determined by the mass gap. Furthermore, on a $1+1$-dimensional edge between topological phases, the jump in the Hall viscosity across the interface is encoded, through familiar anomaly inflow mechanisms, in the structure of anomalies. In particular, we find new torsional contributions to the covariant diffeomorphism anomaly in $1+1$ dimensions. Including parity-even contributions, we find that the renormalized generating functionals of the two topological phases differ by a chiral gravity action with a negative cosmological constant. This (nondynamical) chiral gravity action and the corresponding physics of the interface theory is reminiscent of well-known properties of dynamical holographic gravitational systems. Finally, we consider some properties of spectral flow of the edge theory driven by torsional dislocations.

In an attempt to understand a recently discovered torque anomaly in quantum field theory with boundaries, we calculate the Casimir energy and torque of a scalar field subject to Dirichlet boundary conditions on an annular sector defined by two coaxial cylinders intercut by two planes through the axis. In this model the particularly troublesome divergence at the cylinder axis does not appear, but new divergences associated with the curved boundaries are introduced. All the divergences associated with the volume, the surface area, the corners, and the curvature are regulated by point separation either in the direction of the axis of the cylinder or in the (Euclidean) time; the full divergence structure is isolated, and the remaining finite energy and torque are extracted. Formally, only the regulator based on axis splitting yields the expected balance between energy and torque. Because of the logarithmic curvature divergences, there is an ambiguity in the linear dependence of the energy on the wedge angle; if the terms constant and linear in this angle are removed by a process of renormalization, the expected torque-energy balance is preserved.

In a spacetime with no global timelike Killing vector, we do not have a natural choice for the vacuum state of matter fields, which leads to an ambiguity in defining the Feynman propagators. In this paper, taking the vacuum state to be the instantaneous ground state of the Hamiltonian at each moment, we develop a method for calculating wave functions associated with the vacuum and the corresponding in-in and in-out propagators. We apply this method to free scalar field theory in de Sitter space and obtain de Sitter invariant propagators in various coordinate patches. We show that the in-out propagator in the Poincaré patch has a finite massless limit in a de Sitter invariant form. We argue and numerically check that our in-out propagators agree with those obtained by a path integral with the standard $\mathrm{i}\epsilon$ prescription, and we identify the condition on a foliation of spacetime under which such coincidence can happen for the foliation. We also show that the in-out propagators satisfy Polyakov’s composition law. Several applications of our framework are also discussed.

Previous analytic and numerical calculations suggest that, at each instant, the emission from a precessing black-hole binary closely resembles the emission from a nonprecessing analog. In this paper we quantitatively explore the validity and limitations of that correspondence, extracting the radiation from a large collection of 224 generic black-hole binary merger simulations both in the simulation frame and in a corotating frame that tracks precession. To a first approximation, the corotating-frame waveforms resemble nonprecessing analogs, based on similarity over a band-limited frequency interval defined using a fiducial detector (here, advanced LIGO) and the source’s total mass $M$. By restricting attention to masses $M\in 100$, $1000M_{\odot }$, we ensure that our comparisons are sensitive only to our simulated late-time inspiral, merger, and ringdown signals. In this mass region, every one of our precessing simulations can be fit by some physically similar member of the IMRPhenomB phenomenological waveform family to better than 95%; most fit significantly better. The best-fit parameters at low and high mass correspond to natural physical limits: the pre-merger orbit and post-merger perturbed black hole. Our results suggest that physically motivated synthetic signals can be derived by viewing radiation from suitable nonprecessing binaries in a suitable nonintertial reference frame. While a good first approximation, precessing systems have degrees of freedom (i.e., the transverse spins) which a nonprecessing simulation cannot reproduce. We quantify the extent to which these missing degrees of freedom limit the utility of synthetic precessing signals for detection and parameter estimation.

We revisit the classical stability of the Schwarzschild black hole in fourth-order theories of gravity. Contrary to the stability of this black hole, it turns out that the linearized perturbations exhibit unstable modes featuring the Gregory-Laflamme instability of the five-dimensional black string. This shows clearly an instability of the black hole in fourth-order gravity with $\alpha =-\beta /3$.

Extreme mass ratio inspirals (EMRIs), the inspirals of compact objects into supermassive black holes, are important gravitational wave sources for the Laser Interferometer Space Antenna (LISA). We study the performance of various post-Newtonian (PN) template families relative to the waveforms that are high-precision numerical solutions of the Teukolsky equation in the context of EMRI parameter estimation with LISA. Expressions for the time-domain waveforms TaylorT1, TaylorT2, TaylorT3, TaylorT4 and TaylorEt are derived up to 22 PN order, i.e. $\mathcal{O}(v^{44})$ ($v$ is the characteristic velocity of the binary) beyond the Newtonian term, for a test particle in a circular orbit around a Schwarzschild black hole. The phase difference between the above 22 PN waveform families and numerical waveforms are evaluated during two-year inspirals for two prototypical EMRI systems with mass ratios ${10}^{-4}$ and ${10}^{-5}$. We find that the dephases (in radians) for TaylorT1 and TaylorT2, respectively, are about ${10}^{-9}$ (${10}^{-2}$) and ${10}^{-9}$ (${10}^{-3}$) for mass ratio ${10}^{-4}$ (${10}^{-5}$). This suggests that using 22 PN TaylorT1 or TaylorT2 waveforms for parameter estimation of EMRIs will result in accuracies comparable to numerical waveform accuracy for most of the LISA parameter space. On the other hand, from the dephase results, we find that TaylorT3, TaylorT4 and TaylorEt fare relatively poorly as one approaches the last stable orbit. This implies that, as for comparable mass binaries using the 3.5 PN phase of waveforms, the 22 PN TaylorT3 and TaylorEt approximants do not perform well enough for the EMRIs. The reason underlying the poor performance of TaylorT3, TaylorT4 and TaylorEt relative to TaylorT1 and TaylorT2 is finally examined.

Conformal geometry is considered within a general relativistic framework. An invariant distant for proper time is defined and a parallel displacement is applied in the distorted space-time, modifying Einstein’s equation appropriately. A particular solution is introduced for the covariant acceleration potential that matches the observed velocity distribution at large distances from the Galactic Center, i.e. modified Newtonian dynamics. This explicit solution of a general framework that allows both curvature and explicit local expansion of space-time, thus reproduces the observed flattening of galaxys’ rotation curves without the need to assume the existence of dark matter. The large distance expansion rate is found to match the speed of a spherical shock wave.

We place observational constraints on slow-variation single-field inflationary models by carrying out the cosmological Monte Carlo simulation with the recent data of Planck combined with the WMAP large-angle polarization, baryon acoustic oscillations, and Atacama Cosmology Telescope/South Pole Telescope temperature data. Our analysis covers a wide variety of models with second-order equations of motion, including potential-driven slow-roll inflation, nonminimally coupled models, running kinetic couplings, Brans-Dicke theories, potential-driven Galileon inflation, field-derivative couplings to the Einstein tensor, and k-inflation. In the presence of running kinetic exponential couplings, covariant Galileon terms, and field-derivative couplings, the tensor-to-scalar ratio of the self-coupling potential $V(\varphi )=\lambda {\varphi }^4/4$ gets smaller relative to that in standard slow-roll inflation, but the models lie outside the $1\sigma$ observational contour. We also show that k-inflation models can be tightly constrained by adding the bounds from the scalar non-Gaussianities. The small-field inflationary models with asymptotic flat Einstein-frame potentials in the regime $\varphi \gg M_{\mathrm{pl}}$ generally fit the data very well. These include the models such as Kähler-moduli inflation, nonminimally coupled Higgs inflation, and inflation in Brans-Dicke theories in the presence of the potential $V(\varphi )=3M^2(\varphi -M_{\mathrm{pl}}{)}^2/4$ with the Brans-Dicke parameter ${\omega }_{\mathrm{BD}}\lesssim \mathcal{O}(1)$ (which covers the Starobinsky’s model $f(R)=R+R^2/(6M^2)$ as a special case).

Galileons are higher-derivative theories of a real scalar which nevertheless admit second-order equations of motion. They have interesting applications as dark energy models and in early universe cosmology, and have been conjectured to arise as descriptions of brane dynamics in string theory. In the present paper, we study the bosonic sector of globally $N=1$ supersymmetric extensions of the cubic Galileon Lagrangian in detail. Supersymmetry requires that the Galileon scalar now becomes paired with a second real scalar field. We prove that the presence of this second scalar causes the equations of motion to become higher than second order, thus leading to the appearance of ghosts. We also analyze the energy scales up to which, in an effective field theory description, the ghosts can be tamed.