Aspects of the chiral crossover transition in ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> )-flavor QCD with Möbius domain-wall fermions
Rajiv V. Gavai, Mischa E. Jaensch, Olaf Kaczmarek, F. Karsch, Mugdha Sarkar, Ravi Shanker, Sayantan Sharma, Sipaz Sharma, Tristan Ueding
Abstract
The nonsinglet part of the chiral symmetry in quantum chromodynamics (QCD) with two light flavors is known to be restored through a crossover transition at a pseudocritical temperature. However, the temperature dependence of the singlet part of the chiral symmetry and whether it is effectively restored at the same temperature is not well understood. Using ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mn>2</a:mn> <a:mo>+</a:mo> <a:mn>1</a:mn> </a:mrow> </a:math> )-flavor QCD configurations generated using the Möbius domain-wall discretization on an <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msub> <c:mi>N</c:mi> <c:mi>τ</c:mi> </c:msub> <c:mo>=</c:mo> <c:mn>8</c:mn> </c:math> lattice, we construct suitable observables where the singlet and nonsinglet chiral symmetries are disentangled in order to study their temperature dependence across the crossover transition. From the peak of the disconnected part of the chiral susceptibility, we obtain a pseudocritical temperature <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mrow> <e:msub> <e:mrow> <e:mi>T</e:mi> </e:mrow> <e:mrow> <e:mi>p</e:mi> <e:mi>c</e:mi> </e:mrow> </e:msub> <e:mo>=</e:mo> <e:msubsup> <e:mrow> <e:mn>158.7</e:mn> </e:mrow> <e:mrow> <e:mo>−</e:mo> <e:mn>2.3</e:mn> </e:mrow> <e:mrow> <e:mo>+</e:mo> <e:mn>2.6</e:mn> </e:mrow> </e:msubsup> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:mi>MeV</e:mi> </e:mrow> </e:math> where the nonsinglet part of the chiral symmetry is effectively restored. From a calculation of the topological susceptibility and its temperature dependence we find that the singlet <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msub> <g:mi mathvariant="normal">U</g:mi> <g:mi>A</g:mi> </g:msub> <g:mo stretchy="false">(</g:mo> <g:mn>1</g:mn> <g:mo stretchy="false">)</g:mo> </g:math> part of the chiral symmetry is not effectively restored at <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"> <l:mi>T</l:mi> <l:mo>≲</l:mo> <l:mn>186</l:mn> <l:mtext> </l:mtext> <l:mtext> </l:mtext> <l:mi>MeV</l:mi> </l:math> .