Shear and bulk viscosity of the quark-gluon plasma with Gribov gluons and quasiparticle quarks

In this study, we analyze the transport properties of the quark-gluon plasma (QGP), focusing on bulk (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>ζ</a:mi></a:math>) and shear (<c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>η</c:mi></c:math>) viscosities at vanishing chemical potential. To describe the QGP, we employ a quasiparticle model for quarks along with Gribov’s prescription for gluons, which effectively captures nonperturbative dynamics. The Gribov parameter <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>γ</e:mi><e:mi>G</e:mi></e:msub></e:math> and the dynamical mass <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi>m</g:mi><g:mi>g</g:mi></g:msub></g:math> are obtained by solving the one-loop gap equation in the <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mover accent="true"><i:mi>MS</i:mi><i:mo stretchy="true">¯</i:mo></i:mover></i:math> renormalization scheme and further using lattice QCD data for the equation of state (EOS) of pure gluonic matter. The interaction between quarks and gluons is reflected in the quark quasimass <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:msub><m:mi>m</m:mi><m:mi>q</m:mi></m:msub></m:math>, again obtained using lattice EOS data for (<o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mrow><o:mn>2</o:mn><o:mo>+</o:mo><o:mn>1</o:mn></o:mrow></o:math>)-flavor QCD. Our primary goal is to investigate the influence of quasiquarks on the transport coefficients of QGP. Interestingly, we find a substantial decrease in the scaled transport coefficients with rising temperatures within the range (<q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mn>1</q:mn><q:mo>≤</q:mo><q:mi>T</q:mi><q:mo>/</q:mo><q:msub><q:mi>T</q:mi><q:mi>c</q:mi></q:msub><q:mo>≤</q:mo><q:mn>3.5</q:mn></q:math>). Published by the American Physical Society 2024