Unitarity bounds on elastic absorptive parts in terms of the diffration peak width

McDowell and Martin (1964) derived a lower bound on the forward logarithmic slope b of the absorptive contribution to the elastic differential cross-section d sigma /sup A//dt of two spinless particles, in terms of the total cross-section sigma /sub tot/ and the absorptive contribution to the elastic cross-section sigma /sub el //sup A/. The authors show that, by using the experimental information that the band is close to saturation, one may obtain both a nontrivial lower bound on (d sigma /sup A//dt)(s, t) as well as information on the existence and location of zeros of A(s, t). (10 refs)