| Popis: |
We discuss how hadronic total cross sections at high energy depend on the details of QCD, namely on the number of colours Nc and the quark masses. We find that while a “Froissart”-type behaviour σtot∼Blog2s is rather general, relying only on the presence of higher-spin stable particles in the spectrum, the value of B depends quite strongly on the quark masses. Moreover, we argue that B is of order O(Nc0) at large Nc, and we discuss a bound for B which does not become singular in the Nf=2 chiral limit, unlike the Froissart–Łukaszuk–Martin bound. Keywords: Total cross sections, QCD, Nonperturbative approach |
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