A general approach to jet cross sections in QCD
S. Frixione
TL;DR
This work presents a general subtraction-method framework (FKS) for computing next-to-leading order jet cross sections in QCD with any number of final-state partons, across photon-hadron and hadron-hadron collisions. It defines infrared-safe observables via measurement functions and restructures the calculation into finite N-parton and (N-1)-parton contributions, enabling straightforward numerical evaluation. A key contribution is the construction of parton generators that output event-by-event parton kinematics and support multiple jet definitions in a single run, while maintaining independence from specific jet algorithms through the P functions. The paper demonstrates this approach with numerical results for two-jet and one-jet observables in ep and hadronic collisions, including tests against established calculations and discussions of numerical stability parameters, highlighting the method’s applicability to HERA physics.
Abstract
I illustrate a general formalism based upon the subtraction method for the calculation of next-to-leading order QCD cross sections for any number of jets in any type of hard collisions. I discuss the implementation of this formalism in a numerical program which generates partonic kinematical configurations with an appropriate weight, thus allowing the definition of arbitrary jet algorithms and cuts matching the experimental setup at the last step of the computation. I present results obtained with computer codes which calculate one-jet and two-jet inclusive quantities in photon-hadron and hadron-hadron collisions.