BOUND ON RELIABLE ONE-INSTANTON CROSS-SECTIONS
GABRIELE VENEZIANO · Modern Physics Letters A · 1992
Unitarity considerations imply an upper bound on the value of the one-instanton-induced B and L violating cross-section at which multi-instanton contributions become of comparable order. The bound is inversely proportional to a sum of positive-definite terms and, most likely, keeps any reliable one-instanton cross-section exponentially suppressed.