Stiff self-interacting strings at high temperature QCD

Abstract

We investigate the implications of Nambu-Goto (NG), Lüscher Weisz (LW) and Polyakov-Kleinert (PK) effective string actions for the Casimir energy and the width of the quantum delocalization of the string in 4-dim pure SU(3) Yang-Mills lattice gauge theory. At a temperature closer to the critical point T/Tc=0.9, we found that the next to leading-order (NLO) contributions from the expansion of the NG string in addition to the boundary terms in LW action to decrease the deviations from the lattice data in the intermediate distance scales for both the quark-antiquark QQ̅ potential and broadening of the color tube compared to the free string approximation. We conjecture possible stiffness of the QCD string through studying the effects of extrinsic curvature term in PK action and find a good fitting behavior for the lattice Monte-Carlo data at both long and intermediate quark separations regions.

Revisiting the flux tube spectrum of 3d SU(2) lattice gauge theory

“…Candidate states with contributions from massive modes have been seen in 4d SUðNÞ gauge theories [29][30][31][32]. For closed strings, the results for such an anomalous state are in good agreement with the contribution of a massive pseudoscalar particle on the worldsheet, known as the worldsheet axion [33,34] (see also [35]). Similar anomalous states do not appear in 3d, which might be related to the absence of the topological coupling term and, consequently, less sensitivity of the energy levels to massive modes.…”

“…Since the nonuniversal coefficients appear in subleading terms, their extraction requires very accurate results for the energy levels up to large values of R. So far sufficient accuracy has only been achieved for the coefficient b 2 in three dimensions (3d) [15][16][17][18][19], where the simulations are at least an order of magnitude less expensive than in the 4d case. First hints for a nonvanishing b 2 in 4d SUð3Þ gauge theory, however, have recently been obtained from both the groundstate energy-the static potential-*Corresponding author, E-mail: brandt@physik.uni-bielefeld.de and the flux tube profile at nonzero temperature [20,21]. Despite a parametric suppression, the most precise computation of b 2 comes from the static potential, which can be obtained with much higher accuracy than the excitation spectrum.…”

Mesonic string of diquark-quark configuration at finite temperature

“…The QQ and (QQ)Q static potential is extracted from the logarithm [1] of Polyakov loop correlators P 2Q ( r 1 , r 2 ) and P 3Q ( r 1 , r 2 , r 3 ), respectively. The Diquark-quark (QQQ) is constructed as an isoscele triangle of two quark at the base (diquark) separated by two lattice spacing.…”

“…It would be interesting to reiterate these calculations [1,2,3] with the employment of finer lattices at lower or higher temperatures or by considering dynamical quarks. One would question also the persistence of meson-baryon symmetries in the presence of strong magnetic fields.…”

On boundary corrections of Lüscher-Weisz string

“…Nevertheless, the analysis of string's fine structure in the lattice numerical data for the broadening profile revealed substantial mismatch [2] from the free-string Nambu-Goto (NG) model in the intermediate distance region at high temperatures. The excited spectrum [3] and string tension [4] obtained from the partition function of the leading-order Gaussian formulation of NG string action show a similar disagreement with the numerical data [2,4,5] for source separation R less than 1.0 fm.…”