Hanbury Brown--Twiss interferometry (HBT) provides crucial insights into both the space-time structure and the momentum-space evolution of ultrarelativistic nuclear collisions at freeze-out. In particular, the dependence of the HBT radii on the transverse pair momentum $K_T$ and the system charged multiplicity $dN_{\mathrm{ch}}/d\eta$ may reflect the mechanisms driving collective behavior in small systems. This paper argues that certain features observed in the multiplicity dependence of the HBT radii can be naturally understood if small systems evolve hydrodynamically at high-multiplicity. This study thus establishes a baseline for the multiplicity dependence of HBT in hydrodynamics which may prove useful in discriminating between competing models of collectivity in nuclear collisions.

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Hanbury-Brown-Twiss 干涉测量和 p+p、p+Pb 和 Pb+Pb 碰撞中的集合

Hanbury Brown--Twiss 干涉测量法 (HBT) 提供了对冻结时超相对论核碰撞的时空结构和动量空间演化的重要见解。特别是，HBT 半径对横向对动量 $K_T$ 和系统带电多重性 $dN_{\mathrm{ch}}/d\eta$ 的依赖性可能反映了驱动小系统中集体行为的机制。本文认为，如果小系统以高多重性进行流体动力学演化，则可以自然地理解在 HBT 半径的多重性依赖性中观察到的某些特征。因此，这项研究为 HBT 在流体动力学中的多重性依赖性建立了基线，这可能有助于区分核碰撞中的集体竞争模型。