Speaker
Description
We investigate the quark transversity parton distribution functions (PDFs) in the nucleon within the framework of a covariant and confining Nambu-Jona-Lasinio (NJL) model. The nucleon bound state is obtained by solving the Faddeev equation in the quark–diquark approximation. The parameters of the model are fitted to the well-known experimentally measurable quantities such as the proton mass, pion mass, and pion decay constant. After that, the PDFs can be obtained by straightforwardly evaluating Feynman diagrams. In contrast to the earlier work, we include not only the scalar and axial vector diquark channels but now also the pseudoscalar and vector diquarks. The inclusion of these new diquark channels is crucial in maintaining chiral symmetry. We present the transversity quark PDFs in our new model and compare them to the available empirical fits. In our new model, we treat the Dirac matrix $\gamma_5$ with extreme caution due to the well-known issue of $\gamma_5$ once a regularization scheme is applied. Our model, along with the application of our self-consistent regularization prescription (SCRP) and the treatment of $\gamma_5$ in the Larin scheme, preserves the Ward identity, satisfies the axial anomaly, and gives consistent result for the two formally equivalent transversity operators.
