Strings with a confining core in a quark-gluon plasma

Abstract

We consider the intersection of N different interfaces interpolating between different Z N vacua of an SU(N) gauge theory using the Polyakov loop order parameter. Topological arguments show that at such a string-like junction, the order parameter should vanish, implying that the core of this string (i.e. the junction region of all the interfaces) is in the confining phase. Using the effective potential for the Polyakov loop proposed by Pisarski for QCD, we use numerical minimization technique and estimate the energy per unit length of the core of this string to be about 2.7 GeV/fm at a temperature about twice the critical temperature. For the parameters used, the interface tension is obtained to be about 7 GeV/fm 2 . Lattice simulation of pure gauge theories should be able to investigate properties of these strings. For QCD with quarks, it has been discussed in the literature that this Z N symmetry may still be meaningful, with quark contributions leading to explicit breaking of this Z N symmetry. With this interpretation, such QGP strings may play important role in the evolution of the quark-gluon plasma phase and in the dynamics of quark-hadron transition.PACS numbers: 12.38.Mh, 98.80.Cq

Z(3) metastable states in a Polyakov quark meson model

“…These interfaces have been well studied in SU(3) lattice pure gauge theory [21]. The interface solution for the Polyakov loop potential as a time independent solution is given in [12]. Here, we also use the same energy minimization technique as used in [12] to get the interface profile.…”

“…The interface solution for the Polyakov loop potential as a time independent solution is given in [12]. Here, we also use the same energy minimization technique as used in [12] to get the interface profile. To determine the interface profile one needs to consider the profile of Polyakov loop in one dimension ( say along z).…”

“…The configuration with the lowest value of energy is accepted (when the energy almost settles down to a definite value) as the correct profile of the interface. We refer to [12] for the details of the energy minimization technique. For the Polyakov loop potential with parameter set 1, the minimum energy configuration is such that the Polyakov order parameter goes very close to Φ = 0, since there is huge barrier between different Z(3) vacua.…”

“…(12) are chosen such that chiral symmetry is spontaneously broken in vacuum, where σ = f π = 93 MeV, and here f π is the pion decay constant. Since pions are pseudoscalar in character, the expectation values vanish π = 0.…”

“…The importance of Z(3) walls has also been discussed as non-trivial scattering of quarks from Z(3) walls. Its consequences for cosmology as well as for heavy ion collision have been explored [12][13][14][15], including the possibility of CP violating scattering of quarks from Z(3) walls leading to interesting observational implications [16].…”