论文标题
$π^-Δ^{++} $ photoduction propodon的束不对称的测量$e_γ$ = 8.5
Measurement of beam asymmetry for $π^-Δ^{++}$ photoproduction on the proton at $E_γ$=8.5 GeV
论文作者
论文摘要
我们报告了使用光子束能量范围8.2----8.8 GEV中的gluex实验中的数据,报告了反应$ \vecγp\rightarrowπ^ - δ^ - δ^{++} $的$π^ - $光增生光束不对称的测量值。不对称$σ$的测量是四摩托姆传输$ t $对$δ^{++} $的函数,并与现象学模型进行了比较。我们发现$σ$随着$ t $的函数而变化:在较小的值下为$ t | $ | t | $的较小值。可以通过$ t $通道的粒子交换在理论上描述该反应,需要伪尺度,矢量和张量中间体。特别是,该反应需要电荷交换,使我们能够探测较高的交换以及高阶校正在低动量传递下对一杆式交换的重要性。常规介子的限制生产机制可能有助于寻找和研究非常规媒介。这是该能量下过程的第一个测量。
We report a measurement of the $π^-$ photoproduction beam asymmetry for the reaction $\vecγ p \rightarrow π^- Δ^{++}$ using data from the GlueX experiment in the photon beam energy range 8.2--8.8 GeV. The asymmetry $Σ$ is measured as a function of four-momentum transfer $t$ to the $Δ^{++}$ and compared to phenomenological models. We find that $Σ$ varies as a function of $t$: negative at smaller values and positive at higher values of $|t|$. The reaction can be described theoretically by $t$-channel particle exchange requiring pseudoscalar, vector, and tensor intermediaries. In particular, this reaction requires charge exchange, allowing us to probe pion exchange and the significance of higher-order corrections to one-pion exchange at low momentum transfer. Constraining production mechanisms of conventional mesons may aid in the search for and study of unconventional mesons. This is the first measurement of the process at this energy.