Large momentum effective field theory for non-perturbative parton structure

by Xiangdong Ji

Wednesday 16 Dec 2020, 16:00 → 17:00 Europe/Zurich

Partons are effective degrees of freedom describing the structure of hadrons involved in high-energy collisions. Familiar theories of partons are QCD light-front quantization and soft-collinear effective theory, both of which are intrinsically Minkowskian and appear unsuitable for classical Monte Carlo simulations. A ``new'' form of the parton theory has been formulated in terms of the old-fashioned, Feynman's infinite momentum frame, in which the parton degrees of freedom are filtered through infinite-momentum external states. The partonic structure of hadrons is then related to the matrix elements of static (equal-time) correlators in the state |P_z=∞⟩. This representation lays the foundation of large-momentum effective theory (LaMET) which approximates parton physics through a systematic M/P_z expansion  at a finite but large momentum P_z.

All_EFT.pdf