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Seminars 李政道研究所-粒子核物理研究所联合演讲

Four-loop non-singlet splitting functions in QCD

by Prof. Tongzhi Yang(杨通智) (South China Normal University)

Asia/Shanghai
5#/6th-603 - Meeting Room 603 (Science Building)

5#/6th-603 - Meeting Room 603

Science Building

20
Description

Abstract:

In this talk, we report the first complete computation of the four-loop non-singlet splitting functions in QCD. Splitting functions govern the scale evolution of parton distribution functions, which enter the theoretical predictions for all physical processes at high-energy hadron colliders. According to their flavor group structure, splitting functions are classified into non-singlet and singlet components. In the non-singlet case, a direct multiplicative renormalization formula applies, leaving the integration-by-parts (IBP) reduction and the solution of master integrals as the primary bottleneck. After five years of effort, we obtained recently the complete four-loop non-singlet splitting functions for the first time, in fully analytic form. We also report on progress in the singlet case, where twist-two operators mix with unphysical operators. We present a systematic procedure to derive the counterterm Feynman rules for these unphysical operators, which provides a path toward the complete four-loop singlet splitting functions.

Biography:

Current Position
Researcher, Institute of Quantum Matter, South China Normal University, Guangzhou, China (July 2025 – present).
Previous Position
Postdoctoral Researcher, Physik-Institut, Universit¨at Z¨urich, Switzerland, supervised by Prof. Dr. Thomas Gehrmann (October 2020 – May 2025).
Education
Ph.D. in Theoretical Physics, Zhejiang University, China, 2020. Thesis: Quark transverse beam function at N3LO and energy correlation at NLO. Supervisors: Prof. Ming-xing Luo and Prof. Hua Xing Zhu. B.Sc. in Physics, Zhejiang University, China, 2015.
Research Interests
Perturbative higher-order calculations in QCD and QED; four-loop splitting functions; multi-loop Feynman integral reduction; TMDPDFs/TMDFFs at N3LO; energy correlators; precision LHC phenomenology.

Host: Prof. Jun Gao

Alternative online link:https://meeting.tencent.com/dm/b9pYiNga9xT9

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