In this paper we discuss the construction and the dynamics of vortex-like topological spin excitations in the Schwinger-boson description of Heisenberg antiferromagnets in two dimensions. The topological spin excitations are Dirac fermions (with gap) when spin value S is a half-integer. Experimental and theoretical implications of these excitations are being investigated. 71.10.Fd,75.10.Jm,75.4...

The measured signal in conventional single-voxel proton MR spectroscopy (MRS) is generated by three orthogonal slice-selective excitation pulses. This localization method limits the region of interest to cuboidal shapes. 2D-selective RF (2DRF) excitations [1] can be used to excite arbitrarily shaped regions of interest matching the shape of the target region in order to maximize SNR and minimiz...

We use cold neutron spectroscopy to study the low-energy spin excitations of superconducting (SC) FeSe0.4Te0.6 and essentially nonsuperconducting (NSC) FeSe0.45Te0.55. In contrast with BaFe2-x(Co,Ni)xAs2, where the low-energy spin excitations are commensurate both in the SC and normal state, the normal-state spin excitations in SC FeSe0.4Te0.6 are incommensurate and show an hourglass dispersion...

We observe quasi-static incommensurate magnetic peaks in neutron scattering experiments on layered cobalt oxides La2-xSrxCoO4 with high Co oxidation states that have been reported to be paramagnetic. This enables us to measure the magnetic excitations in this highly hole-doped incommensurate regime and compare our results with those found in the low-doped incommensurate regime that exhibit hour...

In this paper, properties of a homogeneous Bose gas with Feshbach resonance are studied in the dilute region at zero temperature. In the stationary state, there are condensations of atoms and molecules. The ratio of the molecule density to the atom density is proportional to na. There are two types of excitations, molecular excitations and atomic excitations. Atomic excitations are gapless, con...

Time evolution of the probability density is investigated for initially quiescent dynamical systems exposed suddenly to random excitations. A variety of dynamical systems is considered, including the usual linear oscillator, and nonlinear oscillators of hardening spring, of softening spring, and of the van del Pol type. The random excitations are assumed to be stationary stochastic processes, s...

The low-temperature dynamics of quantum systems are dominated by the low-energy eigenstates. For two-dimensional systems in particular, exotic phenomena such as topological order and anyon excitations can emerge. While a complete low-energy description of strongly correlated systems is hard to obtain, essential information about the elementary excitations is encoded in the eigenvalue structure ...

The electric excitation and the parameter excitation from mesh stiffness fluctuation are analyzed. The forced response equations of the drive system to the coupled excitations are presented. For the exciting frequencies far from and near natural frequencies, the forced responses of the drive system to the coupled excitations are investigated. Results show that the nonlinear forced responses of ...

We generalize the Jackiw-Rebbi-Hasenfratz-’t Hooft construction of fermions from bosons to demonstrate the fermionic nature of certain bound states involving SU(N) instantons in even spatial dimensions and SO(N) instantons in 8k + 1 spatial dimensions. We use this result to identify several fermionic excitations in various perturbatively bosonic string theories. In some examples we are able to ...