Narrow Results

We consider the quark and antiquark transversity distributions inside a polarized proton and study how they are expected to be related to the corresponding helicity distributions, both in sign and magnitude. Our considerations lead to simple predictions in good agreement with their first determination for light quarks from experimental data. We also give our predictions for the light antiquarks transversity distributions, so far unknown.

Arnold showed that the Euler equations of an ideal fluid describe geodesics in the Lie algebra of incompressible vector fields. We will show that helicity induces a splitting of the Lie algebra into two isotropic subspaces, forming a Manin triple. Viewed another way, this shows that there is an infinitesimal quantum group (a.k.a. Lie bi-algebra) underlying classical fluid mechanics.

In this paper, we discuss fundamental aspects related to the helicity and dynamics of the spin-1/2 fermions encompassed within the very well-known Lounesto’s classification. More specifically, we investigate how the bi-spinorial structures behave under discrete symmetries, as well as analyze some consequences on the spinors dynamics. In addition, we find an interesting relation between the spinor helicity and the Lounesto spinor classification.