Kao, Chung-Wen Chung Yuan Christian University Kaon and Pion Fragmentation functions and SIDIS off deuteron Kao, Chung-Wen Chung Yuan Christian University In collaboration of D.-J. Yang, F.-J.Jiang (NTNU, Taiwan) W.-C.Chang (AS), S-.i. Nam (Pukyong National University, Korea)
How to extract Fragmentation functions?
SIDIS using deuteron target p: proton, n: neutron
SIDIS using deuteron target Charge Conjugation
SIDIS using deuteron target Assume PDFs are charge symmetric:
SIDIS using deuteron target
Constrains on A and B Since S(x)>0, Q(x)>0, then S(x)/Q(x) is positive! Note that the values of A and B are independent of x!
HERMES Data of Pion multiplicity
HKNS (LO) HKNS (NLO) DSS (LO) DSS (NLO) 5.NJL-Jet Model 6.Nonlocal Chiral Quark Model 7.AKK08 8.SMKA 9.DSEHS
Analysis of A and B
Kaon Multiplicity
HERMES Kaon Data A. Airapetian et al. (HERMES Collaboration), Phys. Rev. D 448 89, 097101 (2014).
HKNS (LO) HKNS (NLO) DSS (LO) DSS (NLO) 5.NJL-Jet Model 6.Nonlocal Chiral Quark Model 7.AKK08
M.Stolarski (COMPASS Collaboration), in SPIN2014, 21st International Symposium on Spin Physics, Beijing, October 19–24, 2014
HKNS (LO) HKNS (NLO) DSS (LO) DSS (NLO) 5.NJL-Jet Model 6.Nonlocal Chiral Quark Model 7.AKK08 8.SMKA
Analysis
HERMES Pion Data:
HERMES Kaon Data:
COMPASS Kaon Data:
Best fit values of A and B Aπ<Bπ! Bk<0!
Conclusion To be consistent with HERMES data, the u quark is more likely to fragment to pion rather than kaon. Only Nonlocal chiral quark model can be compatible with both HERMES data of pion and kaon. But the S(x)/Q(x) derived from pion and kaon multiplicity of SIDIS are not consistent with the one from PDFs.
Outlook: NLO analysis
Outlook: NLO analysis Analysis will become formidable!