Why is LaMET an effective field theory for parton structure?

by Xiangdong Ji (University of Maryland)

Thursday 9 Jul 2020, 16:00 → 18:00 US/Eastern

Abstract:
Partons are effective degrees of freedom describing the structure of hadrons involved in high-energy collisions. The familiar theories for partons are QCD light-front quantization (LFQ) and soft-collinear effective theory (SCET), both of which are intrinsically Minkowskian and appear not suitable for classical Monte Carlo simulations. An alternative form of the parton theory can be formulated in term of the old-fashioned, Feynman's infinite momentum frame (IMF), in which the effective degrees of freedom are filtered through infinite-momentum hadrons states. In this form, the partonic structure of hadrons  is related to the IMF matrix elements of equal-time correlators. This observation allows approximating parton physics through a systematic $1/P^z$ expansion on the Euclidean matrix elements in a state with finite but large momentum $P^z$. The large-momentum effective theory (LaMET) program accomplishes this through simulations of the large-momentum matrix elements on Euclidean lattices, as well as standard EFT matching and running.

Zoom:

https://umd.zoom.us/j/4241669197