arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2406.09381hep-phhep-ex
收藏

来自正负电子对撞机双光子碰撞的新型方位角观测量

Novel azimuthal observables from two-photon collision at $e^+e^-$ colliders

Yu Jia, Jian Zhou, Ya-jin Zhou

AI总结:

本文提出在正负电子对撞机双光子融合中利用 $γγ\to ππ$ 过程的 $\cos2ϕ$ 方位角不对称性,在TMD因子化框架下预言其调制幅度可达40%,为提取螺旋度振幅相对相位及确定强子逐光贡献提供新途径。

摘要:

在这项工作中,我们提出一组与正负电子对撞机上双光子融合产生的遍举强子产生过程相关的新型方位角观测量,并以 $γγ\to ππ$ 作为基准过程。作为电子束和正电子束辐射出的线偏振准实光子的直接结果,双π介子产生中的 $\cos 2ϕ$ 方位角不对称性在横动量依赖(TMD)因子化框架内被预言。在数值分析中,我们采用由色散关系中的分波解确定的 $γγ\to ππ$ 螺旋度振幅作为输入,并发现在 {\tt Belle 2} 和 {\tt BESIII} 实验的典型运动学设置下,所预言的 $\cos2ϕ$ 方位角调制幅度可达 40%。未来对这一方位角不对称性的精确测量可能有助于直接提取光子螺旋度构型为 $++$ 和 $+-$ 的两个螺旋度振幅之间的相对相位。这一认识为强子逐光(Hlbl)贡献的色散确定提供了有价值的输入。

英文摘要:

In this work we advocate a set of novel azimuthal-angle-related observables associated with exclusive hadron production from two-photon fusion at $e^+ e^-$ colliders, taking the $γγ\to ππ$ as a benchmark process. As a direct consequence of the linearly polarized quasi-real photons emitted off the electron and positron beams, the $\cos 2ϕ$ azimuthal asymmetry in dipion production is predicted within the transverse-momentum-dependent (TMD) factorization framework. In numerical analysis, we take the helicity amplitudes of $γγ\to ππ$ determined from the partial wave solutions in dispersion relation as input, and find that the predicted $\cos2ϕ$ azimuthal modulation may reach 40\% for the typical kinematical setup of {\tt Belle 2} and {\tt BESIII} experiments. Future accurate measurement of this azimuthal asymmetry may facilitate the direct extraction of the relative phase between two helicity amplitudes with photon helicity configurations $++$ and $+-$. This knowledge provides a valuable input for the dispersive determination of the hadronic light-by-light (Hlbl) contributions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑