Froissart Bounds for Amplitudes and Cross Sections at High Energies

Abstract

High-energy behavior of total cross sections is discussed in experiment and theory. Origin and meaning of the Froissart bounds are described and explained. Violation of the familiar log-squared bound appears to not violate unitarity (contrary to the common opinion), but correspond to rapid high-energy increase of the amplitude in nonphysical regions.

Comments: 7 pages, 2 figures; based on the lecture presented at the XLV Winter School of PNPI (March 2011) and on the seminar talk at the Ruhr University Bochum (October 2011). The Russian version is published in "Nuclear and particle physics, Theoretical physics (Proceedings of the XLV Winter School of PNPI, Feb. 28 - March 5, 2011)", ed. V.T.Kim, PNPI, St.Petersburg, 2011, pp.20-26