Robust extraction of the proton charge radius from electron-proton scattering data
Xuefei Yan Duke University, Durham, North Carolina 27708, USA Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA Douglas W. Higinbotham Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, Virginia 23606, USA Dipangkar Dutta Mississippi State University, Mississippi State 39762, USA Haiyan Gao Duke University, Durham, North Carolina 27708, USA Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA Duke Kunshan University, Jiangsu 215316, China Ashot Gasparian North Carolina A、T State University, Greensboro, North Carolina 27411, USA Mahbub A. Khandaker Idaho State University, Idaho 83209, USA Nilanga Liyanage University of Virginia, Charlottesville, VA 22904, USA Eugene Pasyuk Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, Virginia 23606, USA Chao Peng Duke University, Durham, North Carolina 27708, USA Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA Weizhi Xiong Duke University, Durham, North Carolina 27708, USA Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
Abstract
Extracting the proton charge radius from electron scattering data, requires determining the slope of the charge form factor at $Q^{2}$ of zero. As experimental data cannot reach that limit, numerous methods for making the extraction have been proposed.
中文速览
质子电荷半径的精确测量长期存在争议，不同实验给出的数值相差悬殊，核心难题在于电子散射实验无法直接测到动量转移为零的极限，必须通过拟合形状因子的斜率来外推。研究者构建了一套系统性框架，用十余种不同的形状因子参数化形式生成模拟伪数据，再用多种拟合函数反复提取质子半径，通过比较已知输入半径与拟合结果，客观评估各类拟合函数的"稳健性"。针对即将开展的PRad实验的动量转移范围和统计精度，研究发现两参数有理函数、两参数连分数以及二阶z展开多项式这三种拟合形式，无论输入的形状因子模型如何变化都能准确还原真实半径。这一工作为如何从低动量转移散射数据中可靠提取质子电荷半径提供了有据可查的方法论依据，有助于化解持续多年的"质子半径之谜"。
原文 arXiv:1803.01629;中英对照 + 大白话阅读 https://aha.fim.ai/paper/1803.01629v2