论文标题
$ A_2（1320）^0 $ MESON质子上的直接光生源的首次测量
First measurement of direct photoproduction of the $a_2(1320)^0$ meson on the proton
论文作者
论文摘要
我们介绍了独家反应$γp\ rightarrow a_2（1320）^0 \，p $在光子能量范围内的$ 3.5 $ 3.5 $ -5.5 $ - $ 5.5 $ - $ 5.5 $ gev和四摩托车传输平方$ 0.2 <-t <2.0 $ gev $^2 $。用托马斯·杰斐逊国家加速器设施的CEBAF大型接受光谱仪收集数据。通过测量反应$γp\rightarrowπ^0ηp$并重建$π^0η$不变质量来检测到中性$ a_2 $共振。差分横截面$dσ/dt $是在每个$ t $ bin中以不同的梁能量提取的。差分横截面最突出的功能是$ -T \ simeq 0.55 $ gev $^2 $的倾角。这可以在Regge现象学的框架中得到很好的描述，其中交换退化假设预测了四摩梅转移的该值的反应幅度为零。
We present the first measurement of the exclusive reaction $γp \rightarrow a_2(1320)^0 \, p$ in the photon energy range $3.5$-$5.5$ GeV and four-momentum transfer squared $0.2<-t<2.0$ GeV$^2$. Data were collected with the CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Accelerator Facility. The neutral $a_2$ resonance was detected by measuring the reaction $γp \rightarrow π^0 ηp$ and reconstructing the $π^0 η$ invariant mass. The differential cross section $dσ/dt$ was extracted at different beam energies in each $-t$ bin. The most prominent feature of the differential cross section is a dip at $-t\simeq 0.55$ GeV$^2$. This can be well described in the framework of Regge phenomenology, where the exchange degeneracy hypothesis predicts a zero in the reaction amplitude for this value of the four-momentum transfer.
