SMuK 2021 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 14: Hadron Structure and Spectroscopy III

HK 14.7: Talk

Tuesday, August 31, 2021, 18:15–18:30, H3

Inclusive production of two hadrons in electron-positron annihilation at Belle — •Gunar Schnell — University of the Basque Country UPV/EHU & IKERBASQUE, Bilbao, Spain

Fragmentation functions (FFs), describing the formation of hadrons from partons, are an indispensable tool in the interpretation of hadron-production data, e.g., in the investigation of nucleon structure via semi-inclusive deep-inelastic scattering. The cleanest process to access FFs is hadron production in electron-positron annihilation. However, little information can be derived on charge-separated FFs from single-inclusive hadron production. A better handle on the flavor contributions can be gotten by flavor correlations or tagging: the hadron type in one hemisphere puts constraints on the parton flavor in the other hemisphere and thus on the flavor decomposition of the hadronization process. This can be exploited in inclusive hadron-pair production in electron-positron annihilation. While two hadrons in the same hemispheres, e.g., originating from the same parton, open an avenue to an unusual class class of FFs, dihadron-FFs, two hadrons in opposite hemispheres can be used for flavor and polarization tagging of single-hadron FFs. These scenarios have recently been subject to renewed studies at the Belle experiment. The dependences of the production cross section of pairs of identified light mesons (charged pions and kaons) as well as of (anti)protons on the individual z of the hadrons or on the combined z will be presented in this talk. In addition, azimuthal modulations of such cross sections for pions and the eta meson, related to the spin-dependent Collins effect, will be discussed.