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arXiv 1606.09526hep-ph
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双粲介子产生的新单部分子和双部分子散射机制

New single- and double-parton scattering mechanisms for double charmed meson production

Antoni Szczurek, Rafal Maciula, Vladimir A. Saleev, Alexandra V. Shipilova

摘要:

讨论了LHCb协作组最近在$\sqrt{s}$ = 7 TeV质子-质子散射中观测到的粲介子-介子对的产生.我们研究了双$c \bar c$产生和随后的$cc \to D^{0}D^{0}$强子化以及双$g$和混合$g c\bar c $产生与$gg \to D^{0}D^{0}$和$gc \to D^{0}D^{0}$强子化的双部分子散射(DPS)机制与尺度相关的KKKS 08碎裂函数的帮助下计算。一个新的单部分子散射(SPS)机制的$gg$生产也被考虑在内。计算的微分分布作为一个$D^{0}$介子的横动量$p_{T}$的函数,对不变质量$M_{D^{0}D^{0}}$和方位角$φ_{D^{0}D^{0}}$分布面临的测量。在尺度依赖性片段化方案内具有$g \to D^{0}$片段化的新SPS机制的表现改变了适合于仅存在DPS $cc \to D^{0}D^{0}$机制的标准尺度无关性片段化的整体画面。一些后果的新机制进行了讨论

英文摘要:

We discuss charm meson-meson pair production recently observed by the LHCb Collaboration at $\sqrt{s}$ = 7 TeV in proton-proton scattering. We examine double-parton scattering (DPS) mechanisms of double $c \bar c$ production and following $cc \to D^{0}D^{0}$ hadronization as well as double $g$ and mixed $g c\bar c $ production with $gg \to D^{0}D^{0}$ and $gc \to D^{0}D^{0}$ hadronization calculated with the help of the scale-dependent KKKS08 fragmentation functions. A new single-parton scattering (SPS) mechanism of $gg$ production is also taken into consideration. Calculated differential distributions as a function of transverse momentum $p_{T}$ of one of the $D^{0}$ mesons, pair invariant mass $M_{D^{0}D^{0}}$ and azimuthal angle $φ_{D^{0}D^{0}}$ distributions are confronted with the measured ones. The manifestation of the new SPS mechanisms with $g \to D^{0}$ fragmentation within the scale-dependent fragmentation scheme change the overall picture suitable for standard scale-independent fragmentation where only DPS $cc \to D^{0}D^{0}$ mechanism is present. Some consequences of the new mechanisms are discussed

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