Role of sea quarks in the nucleon transverse spin

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 u over bar quark favors a negative transversity distribution, while that of the d over bar 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.