NT/RBRC Hybrid Seminar: DIS at NLO in the dipole factorization and mass renormalization on the light-front

by Guillaume Beuf (NCBJ, Warsaw)

Friday 30 Sept 2022, 11:00 → 13:00 US/Eastern

Large Seminar Room (https://bnl.zoomgov.com/j/1614715193?pwd=WkwxODVWdzZzb29zQnZRVGp3VTBDQT09)

In preparation for the start of the Electron Ion Collider, there is an intense activity to improve the precision of the theoretical predictions for DIS observables at low x, including gluon saturation effects. In that low x regime, DIS can be described in a dipole factorization form, which can be derived within light-front perturbation theory (LFPT) for example.  As well known from HERA data, heavy quark contributions to DIS observables (like the inclusive structure functions) are sizable. Motivated by this fact, I will present the recent derivation of NLO corrections to the dipole factorization formula for inclusive DIS structure functions, including full quark mass dependence, using LFPT. 

The main difficulty brought by the quark mass in this calculation is the need to perform mass renormalization. Indeed, mass renormalization in LFPT has been an open problem for over 30 years, since it naively leads to unphysical results, particularly in gauge theories. I will show how to resolve that issue. Indeed, mass renormalization can be performed in LFPT in a consistent way, but requires in particular a careful implementation of UV regularization (for example Dim Reg) in the instantaneous loop contributions arising in that context.