Perturbative width of open rigid strings

TL;DR

This paper calculates the width of open rigid strings perturbatively up to two loops, comparing theoretical predictions with lattice QCD data to understand flux tube broadening near deconfinement.

Contribution

It provides a perturbative calculation of the string width including rigidity effects, extending the Nambu-Goto model with the Polyakov-Kleinert action.

Findings

Good agreement with lattice data at intermediate and large separations.

Perturbative expansion captures rigidity effects on string broadening.

Derived mean-square width for open strings with Dirichlet boundary conditions.

Abstract

We present perturbative calculation of the width of the energy profile of rigid strings up to two loops in D dimensions. The perturbative expansion of the extrinsic curvature term signifying the rigidity/smoothness of the string in Polyakov-Kleinert action is taken around the free Nambu-Goto string. The mean-square width of the string field is derived for open strings with Dirichlet boundary condition. We compare the broadening of the smooth Polyakov-Kleinert string to the lattice Mont-Carlo data of the QCD flux tube just before the deconfinement point and find a good match at the intermediate and large color source separation.