Dispersion-relation-based nonperturbative approach
Dr. Hsiang-nan Li and his postdoc, Dr. Hiroyuki Umeeda, developed a novel analytical approach to studies of nonperturbative quantum chromodynamics (QCD) in a series of works recently. Given a quantity defined as a hadronic correlation function, they can solve the dispersion relation obeyed by the correlation function directly from its standard operator-product-expansion inputs at high energy, and obtain nonperturbative behaviors of the quantity at low energy. Compared to the well-known QCD-sum-rule method, which has been widely adopted for several decades, their approach is free of theoretical uncertainties from the resonance modeling and the assumption of the quark-hadron duality, has much higher predictive power, and can be improved systematically in precision. Applying their framework, they have reproduced rho meson (including excited states) properties, predicted glueball masses, and acquired the leading-twist pion distribution amplitude in the entire momentum-fraction space.
Journal links：
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.102.114014
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.114017
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.106.034015
