Gauge theory high-energy behavior from j-plane unitarity Original Research Article

In a non-abelian gauge theory the t-channel multiparticle unitarity equations continued in the complex j-plane can be systematically expanded around j = 1 and t = 0. The combination of Ward identity constraints with unitarity is sufficient to produce directly many of the results obtained by Regge limit leading-log and next-to-leading log momentum-space calculations. The O(g2) BFKL kernel is completely determined. O(g4) infrared contributions to this kernel are also obtained, including the leading contribution of a new partial-wave amplitude—previously identified as a separate forward component with a holomorphically factorizable spectrum. For this amplitude the only scale ambiguity is the overall normalization and it is anticipated to be a new conformally invariant kernel. While scale-dependent non-leading reggeon interactions can not be derived by the techniques developed, it is conjectured that all conformally invariant interactions may be determined by t-channel unitarity.