Measurement of Collins asymmetry at BESIII

In this talk, I present the recent measurement of the Collins fragmentation function based on a set of 62 pb-1 e+e- annihilation data at √s = 3.65 GeV collected with the BESIII detector at the BEPCII storage rings. In this work, the azimuthal asymmetries of two charged pions in the inclusive process...

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Bibliographic Details
Published inJournal of physics. Conference series Vol. 678; no. 1; pp. 12057 - 12062
Main Author Lyu, Xiao-Rui
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 05.02.2016
Subjects
Asymmetry
Fragmentation
Hadrons
Momentum transfer
Physics
Pions
Quarks
Storage rings (particle accelerators)
Transverse momentum
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Summary:In this talk, I present the recent measurement of the Collins fragmentation function based on a set of 62 pb-1 e+e- annihilation data at √s = 3.65 GeV collected with the BESIII detector at the BEPCII storage rings. In this work, the azimuthal asymmetries of two charged pions in the inclusive process e+e- → ππX are explored. These asymmetries can be attributed to the Collins fragmentation function, which describes the behavior of a hadron produced from a transversely polarized quark. The corresponding four-momentum transfer of the virtual photon, Q2, is close to the energy scale of the existing semi-inclusive DIS experimental data. We observe a nonzero asymmetry, which increases with increasing pion momentum and also indicates a larger spin-dependent Collins effect than at higher energy scale. The dependence of the asymmetry on the transverse momentum of hadrons to the reference axis is also investigated. The measured asymmetries are important inputs for the global analysis of extracting the quark transversity distribution inside the nucleon, and are valuable to explore the energy evolution of the spin-dependent fragmentation function.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/678/1/012057