Measurement of Two-Particle Correlations of Hadrons in $e^{+}e^{−}$ Collisions at Belle

Physical review letters 128(14), 142005 (2022). doi:10.1103/PhysRevLett.128.142005
The measurement of two-particle angular correlation functions in high-multiplicity $e^+ e^-$ collisions at $\sqrt{s}$ = 10.52 GeV is reported. In this study, the 89.5 fb$^{-1}$ of hadronic $e^+ e^-$ annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle $(Δϕ)$ and three units of pseudorapidity $(Δη)$, defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.
Published by APS, College Park, Md.