Flavor dependence of charged pion fragmentation functions

Abstract

We have measured the flavor dependence of multiplicities for ${\pi }^{+}$ and ${\pi }^{-}$ production in semi-inclusive deep-inelastic scattering (SIDIS) on proton and deuteron to explore a possible charge symmetry violation in fragmentation functions. The experiment used an electron beam with energies of 10.2 and 10.6 GeV at Jefferson Lab and the Hall-C spectrometers. The electron kinematics spanned the range $0.3<x<0.6$, $2<Q^2<5.5$ GeV², and $2.2<W<3.2$ GeV. The pion fractional momentum range was $0.3<z<0.7$, and the transverse momentum range was $0<p_T<0.25$ GeV/c. Assuming factorization and allowing for isospin breaking, the results can be described by two “favored” and two “unfavored” effective low $p_T$ fragmentation functions that are flavor-dependent. We find each pair converges to a common flavor-independent fragmentation function at the highest W, where factorization is most applicable.