Theory seminar - Anjie Gao

  • Theory seminar - Anjie Gao
    2022-03-07EST13:00:00 ~ 2022-03-07EST14:00:00
Not all computers/devices will add this event to your calendar automatically. A calendar event file named "jlab-calendar.ics" will be placed in your downloads location. Depending on how your device/computer is configured, you may have to locate this file and double click on it to add the event to your calendar. Event dates, times, and locations are subject to change. Event details will not be updated automatically once you add this event to your own calendar. It is recommended that you confirm details prior to the event by visiting The live JLab Event Calendar. If you need assistance contact

We kindly ask all attendees to provide their full name on Zoom for government upon entering the event. We also ask that attendees who ask questions during the event to introduce themselves by first and last name before asking their question.

Speaker: Anjie Gao (MIT)

Title: Factorization for TMDs in SIDIS at Subleading Power

Abstract: Since shortly after the discovery of partons people have thought about probing their transverse momentum inside hadrons. For example, in 1978 it was shown to give rise to an azimuthal cos(phi) asymmetry of the outgoing hadrons in the process of semi-inclusive DIS (SIDIS), known as the Cahn effect. Such asymmetry is difficult to study since in QCD it first appears at subleading order in the SIDIS power expansion. Besides the cos(phi) distribution, a number of other asymmetries also show up at this power, including some which probe the spin structure of hadrons. In the literature these observables have traditionally been studied at tree level using the parton model. In this talk I show that the use of effective field theory makes it possible to treat these observables systematically. Utilizing the soft-collinear effective theory formalism we completely determine all possible contributions to any order in perturbation theory. Interestingly, we find that dynamical soft gluon contribution remains simple at this power. We identified that the only new distribution functions are a set of the quark-gluon-quark correlators, which come along with only one new Wilson coefficient. Our final results yield factorization formulae for all subleading power azimuthal asymmetries, establishing these as useful observables within QCD, and enabling higher precision predictions.

Event Date
Scientific Program
Contact Name
Patrick Barry
(708) 612-0198