Photoelectron Diffraction and Synchrotron Radiation

Abstract

The basic concepts of photoelectron diffraction are briefly introduced. The increasing number of synchrotron beam lines devoted to this type of experiments is explained by the variety of surface phenomena that can be studied. New devełopments, such as the measurement of full hemispherical angular distributions, photoelectron holography, energy-scanned photoelectron diffraction, chemical-state resolved photoelectron diffraction, and spin-polarized photoelectron diffraction all benefit from the special attributes of synchrotron radiation.

Quantum Algorithms for Quantum Field Theories

“…There are then no known feasible classical methods for calculating scattering amplitudes, although lattice field theory can be used to obtain static quantities, such as mass ratios. Even at weak coupling, the perturbation series is not convergent, although it is asymptotic (23)(24)(25). Including higher-order contributions beyond a certain point makes the approximation worse.…”

Is spacetime really doomed?

“…One cannot construct a propagator for Euclidean spinor fields that transforms under Spin(4) as expected without using both chiralities of spinor. Even doing this, the conventional definition of Euclidean spinor fields involves an additional doubling of the number of degrees of freedom (see [10]).…”