Quasi-multi-Regge Processes with a Quark Exchange in the t-channel
L. N. Lipatov, M. I. Vyazovsky
TL;DR
The paper extends Regge theory to reggeized quarks by computing Born amplitudes for quasi-multi-Regge processes with quark exchange, providing essential input for next-to-leading corrections to the quark Regge trajectory and the t-channel Bethe-Salpeter kernel. It develops a factorized Born-amplitude framework for inelastic production in quasi-multi-Regge kinematics and introduces gauge-invariant induced vertices. A central contribution is the construction of a gauge-invariant, rapidity-local effective action for reggeized gluons and quarks, enabling systematic derivations of reggeon amplitudes and higher-order corrections. Together, these results establish a solid theoretical foundation for precise high-energy QCD predictions involving fermionic exchanges and reggeized degrees of freedom.
Abstract
The QCD amplitudes for particle's production in the quasi-multi-Regge kinematics with a quark exchange in crossing channels are calculated in the Born approximation. In particular they are needed to find next-to-leading corrections to the quark Regge trajectory and to the integral kernel of the Bethe-Salpeter equation for the t-channel partial wave with fermion quantum numbers and a negative signature. The gauge-invariant action for the interaction of the reggeized quarks and gluons with the usual particles is constructed.