论文标题
弹性电子散射中中间状态共振的两光子交换
Two-photon exchange from intermediate state resonances in elastic electron-proton scattering
论文作者
论文摘要
我们使用最近开发的分散方法来计算弹性电子普罗顿散射的两光子交换（TPE）校正，包括来自HADRONIC $ J^p = 1/2^\ pm $的贡献，$ 3/2^\ pm $ resonant resonant中间状态低于〜1.8〜GEV。对于从质子基态到谐振激发状态的过渡幅度，我们采用了来自CLAS的新独家梅森电源数据，$ q^2 \ Lessim 5 $ 〜GEV $^2 $，我们探索固定宽度和动态宽度的效果。在共振状态中，$ n（1520）〜\！3/2^ - $以$ q^2 \ gtrsim 2 $ 〜GTRSIM 2 $ 〜GEV $^2 $占主导地位，标志与尺寸相对大小的$δ（1232）〜\！3/2^+$相反，贡献了$ nuct $ $ qurte $ q of tpe $ q of tpe $ q的总体增加。结果与最近的$ e^+ p $至$ e^ - p $横截面比率和极化转移测量值保持良好的总体一致，并为解决电力与磁性外形比率差异提供了令人信服的证据。
We use a recently developed dispersive approach to compute the two-photon exchange (TPE) correction to elastic electron-proton scattering, including contributions from hadronic $J^P=1/2^\pm$ and $3/2^\pm$ resonant intermediate states below~1.8~GeV. For the transition amplitudes from the proton ground state to the resonant excited states we employ new exclusive meson electroproduction data from CLAS at $Q^2 \lesssim 5$~GeV$^2$, and we explore the effects of both fixed and dynamic widths for the resonances. Among the resonant states, the $N(1520)~\!3/2^-$ becomes dominant for $Q^2 \gtrsim 2$~GeV$^2$, with a sign opposite to the comparably sized $Δ(1232)~\!3/2^+$ contribution, leading to an overall increase in the size of the TPE correction to the cross section relative to the nucleon only contribution at higher $Q^2$ values. The results are in good overall agreement with recent $e^+ p$ to $e^- p$ cross section ratio and polarization transfer measurements, and provide compelling evidence for a resolution of the electric to magnetic form factor ratio discrepancy.
