Speaker
Description
The singlet axial-vector and topological current operators play central roles in determining the quark and gluon spin contributions to the proton spin. As a consequence of the Adler–Bell–Jackiw anomaly, the axial-vector current $J_A^\mu$ acquires a non-trivial renormalization starting at two loops in perturbation theory, which is closely related to the renormalization of the topological current. The determination of the renormalization constant for $J_A^\mu$ at high orders is complicated by the notorious difficulty of treating $\gamma_5$ in dimensional regularization. Employing an newly proposed efficient variant of Larin's renormalization condition for $J_A^\mu$ in dimensionally regularized QCD, we compute the finite matching coefficients from (S)MOM to $\overline{\mathrm{MS}}$ schemes up to unprecedented (3)4 loops. These results provide essential theoretical input for accurately converting (S)MOM-renormalized currents computed in lattice QCD to their $\overline{\mathrm{MS}}$-renormalized counterparts.
