标题： 数据分析技术，微分截面和反应的自旋密度矩阵元素$γp \rightarrow φp$ 显示英文标题

标题： Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction $γp \rightarrow φp$

摘要： 高统计量的微分截面和自旋密度矩阵元素测量对于反应$\gamma p \to \phi p$已经使用杰弗逊实验室的 CLAS 探测器进行。 我们覆盖质心系能量 ($\sqrt{s}$) 从 1.97 到 2.84 GeV，且在$\phi$产生角度上有广泛的覆盖。 数据样本的高统计量使得必须仔细考虑$\phi$自然线形与探测器分辨率效应之间的相互作用，这些效应的大小被发现是相当的。 We study both the charged- ($\phi \to K^+ K^-$) and neutral- ($\phi \to K^0_S K^0_L$) $K\overline{K}$ decay modes of the $\phi$. Further, for the charged mode, we differentiate between the cases where the final $K^-$ track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed $\phi$ mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide $\sqrt{s}$ bins for the charged- and the neutral-mode, respectively. 可能的来自$K^+ \Lambda^\ast$通道与$p K\overline{K}$最终态的效应被讨论。 这些目前的结果是迄今为止最精确和最广泛的$\phi$光生测量结果，并且结合 CLAS 最近发表的$\omega$光生结果，将大大增进我们对低能矢量介子光生过程的理解。 显示英文摘要

摘要： High-statistics measurements of differential cross sections and spin density matrix elements for the reaction $\gamma p \to \phi p$ have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies ($\sqrt{s}$) from 1.97 to 2.84 GeV, with an extensive coverage in the $\phi$ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the $\phi$ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- ($\phi \to K^+ K^-$) and neutral- ($\phi \to K^0_S K^0_L$) $K\overline{K}$ decay modes of the $\phi$. Further, for the charged mode, we differentiate between the cases where the final $K^-$ track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed $\phi$ mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide $\sqrt{s}$ bins for the charged- and the neutral-mode, respectively. Possible effects from $K^+ \Lambda^\ast$ channels with $p K\overline{K}$ final-states are discussed. These present results constitute the most precise and extensive $\phi$ photoproduction measurements to date and in conjunction with the $\omega$ photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.