QCD deconfinement transition line up to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>μ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>400</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>MeV</mml:mi> </mml:mrow> </mml:math> from finite volume lattice simulations

Abstract

The QCD crossover line in the temperature ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>T</a:mi> </a:math> )-baryochemical potential ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msub> <c:mi>μ</c:mi> <c:mi>B</c:mi> </c:msub> </c:math> ) plane has been computed by several lattice groups by calculating the chiral order parameter and its susceptibility at finite values of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msub> <e:mi>μ</e:mi> <e:mi>B</e:mi> </e:msub> </e:math> . In this work we focus on the deconfinement aspect of the transition between hadronic and quark gluon plasma phases. We define the deconfinement temperature as the peak position of the static quark entropy [ <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msub> <g:mi>S</g:mi> <g:mi>Q</g:mi> </g:msub> <g:mo stretchy="false">(</g:mo> <g:mi>T</g:mi> <g:mo>,</g:mo> <g:msub> <g:mi>μ</g:mi> <g:mi>B</g:mi> </g:msub> <g:mo stretchy="false">)</g:mo> </g:math> ] in <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"> <k:mi>T</k:mi> </k:math> , which is based on the renormalized Polyakov loop. We extrapolate <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:msub> <m:mi>S</m:mi> <m:mi>Q</m:mi> </m:msub> <m:mo stretchy="false">(</m:mo> <m:mi>T</m:mi> <m:mo>,</m:mo> <m:msub> <m:mi>μ</m:mi> <m:mi>B</m:mi> </m:msub> <m:mo stretchy="false">)</m:mo> </m:math> based on high statistics finite temperature ensembles on a <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:msup> <q:mn>16</q:mn> <q:mn>3</q:mn> </q:msup> <q:mo>×</q:mo> <q:mn>8</q:mn> </q:math> lattice to finite density by means of a Taylor expansion to eighth order in <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"> <s:msub> <s:mi>μ</s:mi> <s:mi>B</s:mi> </s:msub> </s:math> (NNNLO) along the strangeness neutral line. For the simulations the 4HEX staggered action was used with <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"> <u:mrow> <u:mn>2</u:mn> <u:mo>+</u:mo> <u:mn>1</u:mn> </u:mrow> </u:math> flavors at physical quark masses. In this setup the phase diagram can be drawn up to unprecedentedly high chemical potentials. Our results for the deconfinement temperature are in rough agreement with phenomenological estimates of the freeze-out curve in relativistic heavy ion collisions. In addition, we study the width of the deconfinement crossover. We show that up to <w:math xmlns:w="http://www.w3.org/1998/Math/MathML" display="inline"> <w:msub> <w:mi>μ</w:mi> <w:mi>B</w:mi> </w:msub> <w:mo>≈</w:mo> <w:mn>400</w:mn> <w:mtext> </w:mtext> <w:mtext> </w:mtext> <w:mi>MeV</w:mi> </w:math> , the deconfinement transition gets broader at higher densities, disfavoring the existence of a deconfinement critical endpoint in this range. Finally, we examine the transition line without the strangeness neutrality condition and observe a hint for the narrowing of the crossover towards large <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"> <y:msub> <y:mi>μ</y:mi> <y:mi>B</y:mi> </y:msub> </y:math> . Published by the American Physical Society 2024

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