论文标题

Quasi弹性$ a(e,e'\ vec p \,)$过程中诱导的极化的测量

Measurements of the induced polarization in the quasi-elastic $A(e,e'\vec p\,)$ process in non-coplanar kinematics

论文作者

Paul, Sebouh J., Kolar, Tim, Brecelj, Tilen, Achenbach, Patrick, Arenhövel, Hartmuth, Ashkenazi, Adi, Beričič, Jure, Böhm, Ralph, Bosnar, Damir, Cline, Ethan, Cohen, Erez O., Debenjak, Luka, Distler, Michael O., Esser, Anselm, Friščić, Ivica, Gilman, Ronald, Giusti, Carlotta, Heilig, Matthias, Hoek, Matthias, Izraeli, David, Kegel, Simon, Klag, Pascal, Kohl, Yvonne, Korover, Igor, Lichtenstadt, Jechiel, Mardor, Israel, Merkel, Harald, Middleton, Duncan G., Mihovilovič, Miha, Müller, Julian, Müller, Ulrich, Olivenboim, Mor, Piasetzky, Eliezer, Pochodzalla, Josef, Ron, Guy, Schlimme, Björn S., Schoth, Matthias, Schulz, Florian, Sfienti, Concettina, Širca, Simon, Spreckels, Rouven, Štajner, Samo, Strauch, Steffen, Thiel, Michaela, Tyukin, Alexey, Weber, Adrian, Yaron, Israel

论文摘要

我们报告了通过$ a(e,e'\ vec p \,)$反应的质子的质量$ \ vec p $的测量值。我们已经研究了$ \ vec p $对两个运动学变量的依赖性:缺失动量$ p _ {\ rm miss} $和散射和反应平面之间的“偏置”角$ ϕ_ {pq} $。对于整个360美元$ \度$,$ ϕ_ {pq} $的范围,既有普通($ p_y $),并且首次测量了诱导的极化的横向($ p_x $)组件,相对于与散射平面相关的坐标系统。 $ p_x $消失的共浮标运动学,但是在非链球运动学中,它与$ p_y $的规模相同。 我们发现,对$ ϕ_ {pq} $的依赖性对于$ p_x $和类似于$ p_y $的余弦。对于碳而言,当质子从$ p_ {3/2} $ shell击倒时,诱导的极化的大小特别大,以非常小的$ p _ {\ rm miss} $。对于deuteron,在小$ | p _ {\ rm siss} | $时,诱导的极化接近零,并且其幅度随$ | p _ {\ rm miss} | $而增加。对于这两个核,这种行为都是通过理论结果定性重现的,这主要由最终状态相互作用的自旋轨道部分驱动。但是,对于两个核,实验和理论之间都存在很大的差异。

We report measurements of the induced polarization $\vec P$ of protons knocked out from $^2$H and $^{12}$C via the $A(e,e'\vec p\,)$ reaction. We have studied the dependence of $\vec P$ on two kinematic variables: the missing momentum $p_{\rm miss}$ and the "off-coplanarity" angle $ϕ_{pq}$ between the scattering and reaction planes. For the full 360$\degree$ range in $ϕ_{pq}$, both the normal ($P_y$) and, for the first time, the transverse ($P_x$) components of the induced polarization were measured with respect to the coordinate system associated with the scattering plane. $P_x$ vanishes in coplanar kinematics, however in non-coplanar kinematics, it is on the same scale as $P_y$. We find that the dependence on $ϕ_{pq}$ is sine-like for $P_x$ and cosine-like for $P_y$. For carbon, the magnitude of the induced polarization is especially large when protons are knocked out from the $p_{3/2}$ shell at very small $p_{\rm miss}$. For the deuteron, the induced polarization is near zero at small $|p_{\rm miss}|$, and its magnitude increases with $|p_{\rm miss}|$. For both nuclei such behavior is reproduced qualitatively by theoretical results, driven largely by the spin-orbit part of the final-state interactions. However, for both nuclei, sizeable discrepancies exist between experiment and theory.

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