质子-质子碰撞中的粲-重子产生
Charm-Baryon Production in Proton-Proton Collisions
摘要：
最近在大型强子对撞机上对质子-质子碰撞中的粲-重子产生的测量发现，相对于$D$ -介子，粲-重子产生的产额惊人地大。我们建议，这一观察可以解释的统计强子化模型（SHM），通过采用一个大大增强的一组魅力重子状态超出了目前的粒子数据组的列表。我们利用相对论性夸克模型和格点量子色动力学的指导来估计额外的态。用粲夸克和奇夸克逸度因子来解释基元碰撞中重味的抑制，计算了$\sqrt{s}=5$ \，TeV质子-质子碰撞中$D$，$D_s$和$Λ_c$强子的产额和能谱.我们的主要发现是，从激发的魅力重子的增强馈下可以解释$Λ_c/D^0$比测量ALICE在中快度，与一些警告的前向快度LHCb的数据。此外，假设独立的粲夸克碎裂，但强子比率由SHM固定，测量的$D$ -介子和$Λ_c$的横动量（$p_T$）谱也可以描述;特别是，在所观察到的$Λ_c/D^0$比率的低$p_T$增强归因于“失踪”的粲重子状态的增强的反馈。我们评论的影响，这些研究结果的测量$D_s$和$Λ_c$在重离子碰撞。
英文摘要：
Recent measurements of charm-baryon production in proton-proton collisions at the LHC have found a surprisingly large yield relative to those of $D$-mesons. We propose that this observation can be explained by the statistical hadronization model (SHM), by employing a largely augmented set of charm-baryon states beyond the current listings of the particle data group. We estimate the additional states using guidance from the relativistic quark model and from lattice QCD. Using charm- and strange-quark fugacity factors to account for the well-known suppression of heavy flavor in elementary collisions, we compute the yields and spectra of $D$, $D_s$ and $Λ_c$ hadrons in proton-proton collisions at $\sqrt{s}=5$\,TeV. Our main finding is that the enhanced feeddown from excited charm baryons can account for the $Λ_c/D^0$ ratio measured by ALICE at midrapidity, with some caveat for the forward-rapidity LHCb data. Furthermore, assuming independent fragmentation of charm quarks but with the hadronic ratios fixed by the SHM, the measured transverse-momentum ($p_T$) spectra of $D$-mesons and $Λ_c$ can also be described; in particular, the low-$p_T$ enhancement in the observed $Λ_c/D^0$ ratio is attributed to the enhanced feeddown from "missing" charm-baryon states. We comment on the implications of these findings for measurements of $D_s$ and $Λ_c$ in heavy-ion collisions.
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