论文标题
专用媒介膜产量的高能核几何形状
Nuclear geometry at high energy from exclusive vector meson production
论文作者
论文摘要
我们表明，当包括饱和效应时，人们可以在超级外围铅铅碰撞中对独家$ \ mathrm {j}/ψ$生产光谱进行很好的描述，如LHC的Alice Collaboration最近测量的。由于独家光谱对小bjorken-$ x $在核物质的空间分布敏感，因此这意味着Gluon饱和效应会改变目标的影响参数曲线，因为我们朝着小$ x $迈进。除饱和效应外，我们还发现对较大的核强相互作用半径的偏好与典型的电荷半径相比。我们证明了有限的光子横向动量的作用以及光子发射极和靶的作用在核之间切换的病例之间的干扰。我们表明，这些效果可与$ p_t $ - 差异横截面的实验精度相提并论，并且在与LHC数据相比时需要包括在内。最后，显示出来自LHC的综合$ \ MATHRM {J}/ψ$生产横截面和RHIC的初步横向动量光谱偏爱具有波动的核子子结构的计算，尽管这些数据集将需要比我们框架预测的更强的饱和效应。
We show that when saturation effects are included one obtains a good description of the exclusive $\mathrm{J}/ψ$ production spectra in ultra peripheral lead-lead collisions as recently measured by the ALICE Collaboration at the LHC. As exclusive spectra are sensitive to the spatial distribution of nuclear matter at small Bjorken-$x$, this implies that gluon saturation effects modify the impact parameter profile of the target as we move towards small $x$. In addition to saturation effects, we find a preference for larger nuclear strong-interaction radii compared to the typical charge radius. We demonstrate the role of finite photon transverse momentum and the interference between the cases for which the role of photon emitter and target are switched between the nuclei. We show that these effects are comparable to the experimental precision for $p_T$-differential cross sections and as such need to be included when comparing to LHC data. Finally, the integrated $\mathrm{J}/ψ$ production cross sections from the LHC and preliminary transverse momentum spectra from RHIC are shown to prefer calculations with fluctuating nucleon substructure, although these datasets would require even stronger saturation effects than predicted from our framework.
