论文标题
通过横梁横向单个自旋不对称在电子 - 普罗希望的弹性散射在宽的能量范围内的电子 - 普罗希望的弹性散射中的两光子交换
Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range
论文作者
论文摘要
我们报告了电子透射弹性散射中光束横向单个旋转不对称的新测量，$ a^{ep} _ {\ perp} $，在五个光束能量中，从315.1 MeV到1508.4 MeV，至1508.4 MEV，散射角度为$ 30^{\ circ} {\ circ} <usive} <x <40^<40^<40^{\ cirs} $。覆盖的$ q^2 $值为0.032、0.057、0.082、0.218、0.613（GEV/c）$^2 $。该测量清楚地表明，在低$ q^2 $运动区域中对两光量 - 交换（TPE）幅度的显着无弹性贡献。没有理论计算能够重现我们的结果。与基于单位性的计算进行比较，该计算仅考虑了弹性和$ \ mathrm {πn} $非弹性中间状态，这表明还有其他不弹性中间状态，例如$ \ mathrm {ππn} $，$ \ mathrm {kλ} $ and $ \ mathrm} $ {我们的新高精度数据涵盖了广泛的能源范围，为研究这些中间状态提供了基准。
We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, $A^{ep}_{\perp}$, at five beam energies from 315.1 MeV to 1508.4 MeV and at a scattering angle of $30^{\circ} < θ< 40^{\circ}$. The covered $Q^2$ values are 0.032, 0.057, 0.082, 0.218, 0.613 (GeV/c)$^2$. The measurement clearly indicates significant inelastic contributions to the two-photon-exchange (TPE) amplitude in the low-$Q^2$ kinematic region. No theoretical calculation is able to reproduce our result. Comparison with a calculation based on unitarity, which only takes into account elastic and $\mathrm{πN}$ inelastic intermediate states, suggests that there are other inelastic intermediate states such as $\mathrm{ππN}$, $\mathrm{K Λ}$ and $\mathrm{ηN}$. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states.
