String fragmentation with a time-dependent tension

Abstract

Motivated by recent theoretical arguments that expanding strings can be regarded as having a temperature that is inversely proportional to the proper time, tau , we investigate the consequences of adding a term propto 1/tau to the string tension in the Lund string-hadronization model. The lattice value for the tension, kappa _0 sim 0.18,{mathrm {GeV}}^2sim 0.9,{mathrm {GeV}}/{mathrm {fm}}, is then interpreted as the late-time/equilibrium limit. A generic prediction of this type of model is that early string breaks should be associated with higher strangeness (and baryon) fractions and higher fragmentation langle p_perp rangle values. It should be possible to use archival ee data sets to provide model-independent constraints on this type of scenario, and we propose a few simple key measurements to do so.