  We present a phenomenological extraction of transversity distribution
functions and Collins fragmentation functions by simultaneously fitting to
semi-inclusive deep inelastic scattering and electron-positron annihilation
data. The analysis is performed within the transverse momentum dependent
factorization formalism, and sea quark transversity distributions are taken
into account for the first time. We find the $\bar u$ quark favors a negative
transversity distribution while that of the $\bar d$ quark is consistent with
zero according to the current accuracy. In addition, based on a combined
analysis of world data and simulated data, we quantitatively demonstrate the
impact of the proposed Electron-ion Collider in China on precise determinations
of the transversity distributions, especially for sea quarks, and the Collins
fragmentation functions.
