Particle Physics Seminar: Nambu-Goto Strings With Spinning Particles

Abstract: 

We consider the localization of massive spinors at the ends of a Nambu-Goto string and study the corresponding spin effects of the system. We begin by describing a classical spinning particle in external vector and scalar fields, and compute the corresponding spin-orbit energy of a spinning particle moving in a circular motion, under the influence of electromagnetic fields. We construct a consistent action for spinning particles localized at the ends of a Nambu-Goto string. We verify that the spin possesses Thomas precession and compute the corresponding classical spin-orbit energy. In the relativistic limit, the computed classical spin-orbit energy is of similar form has the one obtained by quantum mechanical calculations. We compute the energy E and the total angular momentum J of the system and write down an analytic expression for its Regge trajectory in the relativistic limit. Using experimental data, we extract from the various meson and baryon trajectories, universal values for the string tension, endpoint masses and the intercept. We obtain an improvement in fittings over the spinless massive model. Finally, we present a model for massive charged spinors localized at the end of a Nambu-Goto string. We recompute E and J taking into account the electromagnetic fields generated by the charges. In the relativistic limit, we present an analytic expression for the Regge trajectory.

Seminar Organizer: Prof. Nissan Itzhaki