出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The derivative of the topological susceptibility at zero momentum is responsible for the validity
of the Witten-Veneziano formula for the η0 mass, and also for the resolution of the EMC proton
spin problem. We investigate the momentum dependence of the topological susceptibility
and its derivative at zero momentum using lattice QCD simulations with overlap fermions within
quenched approximation. We expose the role of the low-lying Dirac eigenmodes for the topological
charge density, and find the negative value for the derivative. While the sign of the derivative
is consistent with the QCD sum rule in pure Yang-Mills theory, the absolute value becomes larger
if only the contribution from the zero modes and the low-lying eigenmodes is taken into account.
