论文标题
横截面比的测量$σ_{ψ（2s）}/σ_{J/ψ（1s）} $在HERA的独家光生效中
Measurement of the cross-section ratio $σ_{ψ(2S )}/σ_{J/ψ(1S )}$ in exclusive photoproduction at HERA
论文作者
论文摘要
独家光增生反应$γp\ to J/ψ（1s）P $和$γp\ toψ（2s）P $以$ EP $ $ $的质量能量为318 GEV的Zeus detector，使用373 Pb $^{-1} $的Zeus detector，Hera的Zeus detector在HERA上测量。测量是在运动范围内进行的$ 30 <w <180 $ gev，$ q^2 <1 $ gev $^2 $和$ | t | <1 $ gev $^2 $，其中$ w $是光子 - 普罗顿质量中心，$ q^2 $是光子虚拟性，而$ t $是Proton Vertex的四平方四摩托姆转移。所使用的衰减通道为$ j/ψ（1s）\toμ^+μ^ - $，$ψ（2s）\toμ^+μ^ - $和$ψ（2S）\ to J/ψ（1s）π^+π^ - $，随后的衰减$ j/ψ（1ss）\ toμ^+μ The ratio of the production cross sections, $R = σ_{ψ(2S)} / σ_{J/ψ(1S)}$, has been measured as a function of $W$ and $|t|$ and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production, which are in reasonable agreement with the data.
The exclusive photoproduction reactions $γp \to J/ψ(1S) p$ and $γp \to ψ(2S) p$ have been measured at an $ep$ centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb$^{-1}$. The measurement was made in the kinematic range $30 < W < 180$ GeV, $Q^2 < 1$ GeV$^2$ and $|t| < 1$ GeV$^2$, where $W$ is the photon--proton centre-of-mass energy, $Q^2$ is the photon virtuality and $t$ is the squared four-momentum transfer at the proton vertex. The decay channels used were $J/ψ(1S) \to μ^+ μ^-$, $ψ(2S) \to μ^+ μ^-$ and $ψ(2S) \to J/ψ(1S) π^+ π^-$ with subsequent decay $J/ψ(1S) \to μ^+ μ^-$. The ratio of the production cross sections, $R = σ_{ψ(2S)} / σ_{J/ψ(1S)}$, has been measured as a function of $W$ and $|t|$ and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production, which are in reasonable agreement with the data.
