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Corresponding author.

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Recently, transport coefficients, viz., shear viscosity, electrical conductivity, etc., of strongly interacting matter produced in heavy-ion collisions have drawn considerable interest. We study the normalized electrical conductivity (

Ultrarelativistic heavy-ion collision programs at the Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) produce a strongly interacting matter known as quark-gluon plasma (QGP)

Electrical conductivity (

With the prior knowledge of color charges and the associated electric charges of the quarks, one might presume the QCD matter to be highly conductive. In contrast, this assumption fails due to the high interaction rates of the produced QCD matter, which again suggests a low shear viscosity–to–entropy density ratio (

The experimental measurement of electrical conductivity (

The color string percolation model (CSPM) is a QCD-inspired model

In this work, for the first time, we give the formulation of

In this section, we develop the formulation for evaluating the electrical conductivity of strongly interacting matter using the color string percolation approach. We start with few basic equations of the CSPM. The percolation density parameter,

Here,

To calculate the electrical conductivity of strongly interacting matter, which is one of the most important transport properties of QCD matter, we proceed as follows. The mean free path, which describes the relaxation of the system far from equilibrium can be written in terms of the number density and cross section as

Here,

In general,

Now, using Eqs.

Now, we derive the formula for electrical conductivity. For this, we use the Anderson-Witting model, in which the Boltzmann transport equation is given as

Putting Eq.

Here, the prefactor

In the framework of a relativistic kinetic theory, the shear viscosity–to–entropy density ratio,

In the context of the CSPM, the above equation can be reduced using Eq.

In this section, we discuss the results obtained in the CSPM along with those obtained in various approaches. In Fig.

Although the percolation of the string approach is not directly obtained from QCD, it is QCD inspired, like how the BAMPS model is governed by perturbative QCD. The basic ingredients in the percolation approach are strings, which are stretched between the partons of the projectile and target and forms color electric and magnetic fields in the longitudinal direction. The color strings fragment into

A nonconformal holographic model (NCH)

Figure

The ratio

The ratio

Recently, the ratio

In summary, we have developed a method to calculate the electric conductivity of strongly interacting matter using the color string percolation approach. We use basically the well-known Drude formula for the estimation of electrical conductivity, which can be obtained after solving the Boltzmann transport equation in relaxation time approximation assuming very small electric fields and no cross-effects between heat and electrical conductivity. We see that the CSPM results for the conductivity stays almost constant with increasing temperature in a fashion similar to that shown by BAMPS data and matches the results obtained in BAMPS with the fixed strong coupling constant considering the elastic cross section only. The CSPM results lie well above the lQCD results for all the temperatures. We have shown

The authors acknowledge the financial support from ALICE Project No. SR/MF/PS-01/2014-IITI(G) of Department of Science and Technology, Government of India.