Edward T. Dressler
Published: 2017-11-19
Total Pages: 48
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Excerpt from Threshold Photo and Electroproduction of Pions From Nuclei To find the amplitude from a single nucleon, one usually starts by considering which relativistic Feynman diagrams are important in the particular energy region under consideration. For the case of a purely electromagnetic interaction as in electron scattering, photo or electro disintegration, or Compton scattering, one can use perturbation theory and quantum field theory to give the appropriate Feynman diagrams to a particular order in the coupling constant. However, in photo or electro production of pions, we now have electromagnetic and strong interactions, and since the coupling constant in strong interactions is large, the perturbation expansion in powers of the coupling constant will not con verge. In spite of this fact, the lowest order term in the expansion using pseudovector pion-nuclear coupling, gives results which under cer tain conditions agree very well with experiment and with the low energy theorem derived from the theory of the pcac (partially conserved axial current) Therefore, we will use the lowest order perturbation term as our model for the threshold photo pion production amplitude off of a nucleon. 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.
