Search

We demonstrate an efficient numerical method for obtaining unique solutions to the Eilenberger equation for a mesoscopic or nanoscale superconductor. In particular, we calculate the local density of states of a circular d- wave island containing a single vortex. The “vortex shadow” effect is found to depend strongly on the quasiparticle energy in such small systems. We show how to construct by geometry quasiparticle trajectories confined in a finite-size system with specular reflections at the boundary, and we discuss the stability of the numerical solutions even in the case of vanishing order parameter as for nodal quasiparticles in a rf-wave superconductor or for quasiparticles passing through the vortex center with zero energy. [ABSTRACT FROM AUTHOR]

We study the vortex lattice in a two-dimensional s-wave topological superconductor with Rashba spin-orbit coupling and Zeeman field by solving the Bogoliubov-de Gennes equations self-consistently for the superconducting order parameter. We find that when spin-orbit coupling is relatively weak, one of the two underlying chiralities in the topological superconducting state can be strongly manifest in the vortex core structure and govern the response of the system to vorticity and a nonmagnetic impurity where the vortex is pinned. The Majorana zero mode in the vortex core is found to be robust against the nonmagnetic impurity in that it remains effectively a zero-energy bound state regardless of the impurity potential strength and the major chirality. The spin polarization of the Majorana bound state depends on the major chirality for weak spin-orbit coupling, while it is determined simply by the vorticity when spin-orbit coupling is relatively strong. [ABSTRACT FROM AUTHOR]

Abstract: The ground state hyperfine splitting of positronium is sensitive to high order corrections of quantum electrodynamics (QED) in bound state. The theoretical prediction and the averaged experimental value for have a discrepancy of 15 ppm, which is equivalent to 3.9 standard deviations (s.d.). A new precision measurement which reduces the systematic uncertainty from the positronium thermalization effect was performed, in which the non-thermalization effect was measured to be as large as in a timing window we used. When this effect is taken into account, our new result becomes , which favors the QED prediction within 1.2 s.d. and disfavors the previous experimental average by 2.6 s.d. [Copyright &y& Elsevier]

The unbound excited states of the neutron drip-line isotope 240 have been investigated via the 240(p, p')230 + n reaction in inverse kinematics at a beam energy of 62 MeV/nucleon. The decay energy spectrum of 240* was reconstructed from the momenta of 230 and the neutron. The spin parity of the first excited state, observed at Ex = 4.65 ± 0.14 MeV, was determined to be Jπ = 2+ from the angular distribution of the cross section. Higher-lying states were also observed. The quadrupole transition parameter ß2 of the 2+1 state was deduced, for the first time, to be 0.15 ± 0.04. The relatively high excitation energy and small ß2 value are indicative of the N = 16 shell closure in 240. [ABSTRACT FROM AUTHOR]