Variable Energy Cyclotron Centre, Homi Bhabha National Institute.
Nuclear Physics Institute of the Czech Academy of Sciences.
Phys Rev Lett. 2019 Sep 13;123(11):112002. doi: 10.1103/PhysRevLett.123.112002.
This Letter presents the first experimental observation of the attractive strong interaction between a proton and a multistrange baryon (hyperon) Ξ^{-}. The result is extracted from two-particle correlations of combined p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+} pairs measured in p-Pb collisions at sqrt[s_{NN}]=5.02 TeV at the LHC with ALICE. The measured correlation function is compared with the prediction obtained assuming only an attractive Coulomb interaction and a standard deviation in the range [3.6, 5.3] is found. Since the measured p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+} correlation is significantly enhanced with respect to the Coulomb prediction, the presence of an additional, strong, attractive interaction is evident. The data are compatible with recent lattice calculations by the HAL-QCD Collaboration, with a standard deviation in the range [1.8, 3.7]. The lattice potential predicts a shallow repulsive Ξ^{-} interaction within pure neutron matter and this implies stiffer equations of state for neutron-rich matter including hyperons. Implications of the strong interaction for the modeling of neutron stars are discussed.
这封信件呈现了质子与多奇异重子（超子）Ξ^{-}之间的强相互吸引作用的首次实验观测结果。该结果是从在 LHC 的 ALICE 探测器中，在质心系能量为 sqrt[s_{NN}]=5.02 TeV 的 p-Pb 碰撞中测量到的 p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+}对的双粒子关联中提取的。测量的关联函数与仅假设存在吸引力库仑相互作用的预测进行了比较，发现标准偏差在 [3.6, 5.3] 的范围内。由于与库仑预测相比，测量到的 p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+}关联明显增强，因此明显存在额外的强吸引相互作用。数据与 HAL-QCD 合作最近的晶格计算结果兼容，标准偏差在 [1.8, 3.7] 的范围内。晶格势预测了在纯中子物质中 Ξ^{-}的弱相互作用，这意味着包括超子在内的富含中子的物质的状态方程更硬。还讨论了强相互作用对中子星建模的影响。
