Using the Virasoro conditions to revise the model of a quark-gluon string fragmentation

Abstract

Quark-gluon string fragmentation is usually seen as a universal process with its physics remaining unchanged for different colliding systems and center-of-mass energy. However, there is a way to go beyond this assumption by considering the angular momentum of the fragmenting system. An accurate calculation of the spin of the string requires a specific definition of the initial state of the string. In this paper, I present a new method for defining the initial data for the Nambu-Goto relativistic string and derive the basics of its fragmentation process using the so-called Virasoro conditions. It is shown that very non-trivial consequences arise for non-zero mass strings, including the discrete spectrum of string spin, the discreteness of the possible string breaking points, the close-to-Regge behavior of the spin-mass relation for the light string fragments, and the natural stopping mechanism for fragmentation.