论文标题
Pion极化性2022状态报告
Pion Polarizability 2022 Status Report
论文作者
论文摘要
电力$α_π$和磁性$β_π$带电的Pion Compton极化在量子染色体动力学（QCD）的低能领域具有基本兴趣。它们表征了$γπ$ compton散射期间呈触发的偶极矩。 PION极化会影响$γπ$ compton散射的形状。组合$（α_π-β_π）$由以下方式测量：（1）Cern Compass通过$πZ \rightarrowπzγ$rightarrowπzγ$ radiative pradiative Pion primakoff Primakoff Primakoff Primakoff Primakoff Primakoff在核Coulomb Field中的Slac slac slac slac pep pep mark-ii pivia pivavia pivavia p p p prodpia p p p productia p p p produs p。 \ rightArrowπ^+π^ - $，（3）Mainz Microtron Mami通过质子的辐射式Pion光生生产，$γp \rightarrowγπ^+ n $。还描述了正在进行的和计划中的Pion极化实验（Cern Compass，北京的Besiii，Newport News的JLAB）。基于$（α_π-β_π）=（4.4 \ pm 3.2）\ times 10^{ - 4} { - 4} {-4} {fm} {fm} {fm} {fm} {3}^{3} $，标记 - ii p palliansion 95％置信区间约为$ 0-11 \ times 10^{ - 4} {-4} {-4} {-4} {3} $。 MAINZ值$（α_π-β_π）= 11.6 \ times 10^{ - 4} {fm}^{3} $根据分散关系计算，该计算将mainz值作为输入作为输入，并给出了太大的$ umectal of $γγ\rightArrowπ^vis partions crots crots crots crots crots crots crots crots crots crots crots crots crots crots crots cront crots sct and scty scty sc crots s s n} 0} 0} n}。迄今为止，只有指南针极化测量值可接受的不确定性。它的值$（α_π-β_π）=（4.0 \ pm 1.8）\ times 10^{ - 4} {fm}^{3} $与两环chpt预测$（α_π-β_π）=（5.7 \ pm 1.0 \ pm 1.0 \ pm 1.0）用QCD的Goldstone Boson茶。
The electric $α_π$ and magnetic $β_π$ charged pion Compton polarizabilities are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD). They characterize the induced dipole moments of the pion during $γπ$ Compton scattering. Pion polarizabilities affect the shape of the $γπ$ Compton scattering angular distribution.The combination $(α_π - β_π)$ was measured by: (1) CERN COMPASS via $π Z \rightarrow π Z γ$ radiative pion Primakoff scattering in the nuclear Coulomb field, (2) SLAC PEP Mark-II via two-photon production of pion pairs, $γ γ \rightarrow π^+ π^-$, and (3) Mainz Microtron MAMI via radiative pion photoproduction from the proton, $γ p \rightarrow γ π^+ n$. Ongoing and planned pion polarizability experiments (CERN COMPASS, BESIII at Beijing, JLab at Newport News) are also described. The Mark-II pion polarizability 95% confidence interval is approximately $0-11 \times 10^{-4} {fm}^{3}$, based on $(α_π - β_π) = (4.4 \pm 3.2) \times 10^{-4} {fm}^{3}$. The Mainz value $(α_π - β_π) = 11.6 \times 10^{-4} {fm}^{3}$ is excluded on the basis of a dispersion relations calculation which uses the Mainz value as input, and gives significantly too large $γ γ \rightarrow π^{0} π^{0}$ cross sections compared to DESY Crystal Ball data. To date, only the COMPASS polarizability measurement has acceptably small uncertainties. Its value $(α_π - β_π) = (4.0 \pm 1.8) \times 10^{-4} {fm}^{3}$ agrees well with the two-loop ChPT prediction $(α_π - β_π) = (5.7 \pm 1.0) \times 10^{-4} {fm}^{3}$, thereby strengthening the identification of the pion with the Goldstone boson of QCD.
