General-mass treatment for deep inelastic scattering at two-loop accuracy

Understand

We present a next-to-next-to-leading order (NNLO) realization of a general quark mass scheme (S-ACOT-$\chi$) in deep inelastic scattering and explore the impact of NNLO terms on heavy-quark structure functions $F_{2,L}^{c}(x,Q)$.

• An amended QCD factorization theorem for DIS is discussed that validates the S-ACOT-$\chi$ scheme to all orders in the QCD coupling strength.
• As a new feature, kinematical constraints on collinear production of heavy quarks that are crucial near the heavy-quark threshold are included in the amended factorization theorem.
• An algorithmic procedure is outlined for implementing this scheme at NNLO by using mass-dependent and massless results from literature.