Excerpt from Bounds on Scattering Phase Shifts Variational techniques have proved invaluable in scattering theory, in the evaluation of phase shifts, for example. They nevertheless suffer from the serious disadvantage, compared to the corresponding variational calculations of binding energies, for instance, that they do not provide a bound on the phase shift. This disadvantage is most pronounced in problems of such difficulty that one cannot guess at a reasonable form for the trial function, though it is precisely for those problems that variational techniques are potentially most valuable. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.