[NT/RBRC Seminar] A unified description of DGLAP, CSS, and BFKL: TMD factorization bridging large and small x

by Dr Andrey Tarasov (North Carolina State University)

Friday 19 Apr 2024, 11:00 → 13:00 US/Eastern

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

The QCD factorization approach provides the theoretical framework for a systematic analysis of a wide class of observables in the high-energy scattering reactions. The various kinematic regimes of the high-energy scattering are described by different factorization schemes, each characterized by a unique structure of the partonic modes. At the same time, it’s important to understand, both from the theoretical and practical points of view, how different factorization schemes are related to each other and how the transition between them is realized. For example, this is essential for describing observables in the region of moderate Bjorken-x at the future Electron-Ion Collider. In this talk I will introduce a transverse-momentum dependent (TMD) factorization scheme designed to unify large and small Bjorken-x regimes. Within the proposed scheme, I will discuss the computation of the gluon TMD operator for an unpolarized hadron at the next-to-leading order (NLO).  This computation leads to a new TMD evolution, incorporating those in transverse momentum, rapidity, and Bjorken-x. When matched to the collinear factorization scheme, the novel factorization faithfully reproduces the well-established DGLAP and CSS evolutions. Conversely, matching with high-energy factorization not only yields the BFKL evolution but also reveals distinctive signatures of the CSS logarithms. The development of this novel TMD factorization scheme, capable of reconciling disparate Bjorken-x regimes and reproducing established QCD evolution equations, has the potential to significantly advance our understanding of high-energy scattering and three-dimensional structure of hadrons.