2026/09/23(Wed) 11:00 -12:30 五樓第一會議室 5F, 1st Meeting Room
Title
Pure Proton Data Questions Light-Flavor Sea Antiquark Asymmetry
Speaker
「董武基」講座教授（粒子物理學） 袁簡鵬教授 (密西根州立大學) Wu-Ki Tung Professor in Particle Physics, Prof. Chien Peng Yuan (Michigan State University)Abstract
For decades, deuteron-based experiments established a canonical SU(2) flavor asymmetry in the proton’s light sea, with more $\bar{d}$ than $\bar{u}$ antiquarks, interpreted as a non-perturbative signature. However, these results rely on nuclear assumptions and isospin symmetry. Here, we analyze pure proton collision data from the Fermilab Tevatron and CERN LHC using measurements of Drell–Yan forward–backward asymmetries, free of nuclear corrections. We find that the proton’s $\bar{d}/\bar{u}$ ratio is consistent with unity at $x\sim 0.1$, contradicting the long-standing asymmetry mentioned above. This suggests a symmetric, perturbative origin for light sea antiquarks, implying the deuteron anomaly arises from high-energy nuclear effects rather than intrinsic proton asymmetry. Implications for proton structure and global PDF analyses are also discussed.
Language
演講語言 (Language): in English