
Book Nr. 11 Path Integrals in Quantum Mechanics, Statistics, Polymer Physics, and Financial Markets
on the theory and applications of path integrals. It is the first book to explicitly solve path integrals of a wide variety of nontrivial quantummechanical systems, in particular of the hydrogen atom. The solutions have been made possible by two major advances.
In contrast to ordinary perturbation expansions, divergencies are absent. Instead, there is a uniform convergence from weak to strong couplings, opening a way to precise approximate evaluations of analytically unsolvable path integrals. Tunneling processes are treated in detail. The results are used to determine the lifetime of supercurrents, the stability of metastable thermodynamic phases, and the largeorder behavior of perturbation expansions. A new variational treatment extends the range of validity of previous tunneling theories from large to small barriers. A corresponding extension of largeorder perturbation theory now also applies to small orders. Special attention is devoted to path integrals with topological restrictions. These are relevant to the understanding of the statistical properties of elementary particles and the entanglement phenomena in polymer physics and biophysics. The ChernSimons theory of particles with fractional statistics (anyons) is introduced and applied to explain the fractional quantum Hall effect. The relevance of path integral to financial markets is discussed, and improvements of the famous BlackScholes formula for option prices are developed which account for the fact that large market fluctuation occur much more frequently than in Gaussian distributions. 

© by Hagen Kleinert 2018 