Production of leptons from decay of heavy-flavor hadrons in high-energy nuclear collisions

This paper presents a theoretical study on the production of leptons from decay of heavy-flavor hadrons (denoted as HFLs) in high-energy nuclear collisions at the CERN Large Hadron Collider. The <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi mathvariant="italic">pp</a:mi></a:math> baseline is calculated by the fonll program, which matches the next-to-leading order perturbative QCD (pQCD) calculation with the next-to-leading-logarithm large-<c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>p</c:mi><c:mi>T</c:mi></c:msub></c:math> resummation. The in-medium propagation of heavy quarks is driven by the modified Langevin equations, which consider both the elastic and inelastic partonic interactions. We propose a method to separate the respective influence of the six factors, i.e., <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mi mathvariant="italic">pp</d:mi></d:math> spectra, cold nuclear matter (CNM) effects, in-medium energy loss (E-loss), fragmentation functions (FFs), coalescence (Coal), and decay channels, which may contribute to the larger <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:msub><f:mi>R</f:mi><f:mrow><f:mi>A</f:mi><f:mi>A</f:mi></f:mrow></f:msub></f:math> of HFL <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:mrow><g:mo>←</g:mo><g:mi>b</g:mi></g:mrow></g:math> compared to that of HFL <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mrow><h:mo>←</h:mo><h:mi>c</h:mi></h:mrow></h:math> in nucleus-nucleus collisions. Based on quantitative analysis, we demonstrate that both coalescence hadronization decay channels and the mass-dependent E-loss play an essential role at <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:mrow><i:msub><i:mi>p</i:mi><i:mi>T</i:mi></i:msub><i:mo>&lt;</i:mo><i:mn>5</i:mn><i:mspace width="0.16em"/><i:mi>GeV</i:mi></i:mrow></i:math>, while the latter dominates the higher <k:math xmlns:k="http://www.w3.org/1998/Math/MathML"><k:msub><k:mi>p</k:mi><k:mi>T</k:mi></k:msub></k:math> region. It is also found that the influences of the CNM effects and FFs are insignificant. At the same time, different initial <l:math xmlns:l="http://www.w3.org/1998/Math/MathML"><l:mi mathvariant="italic">pp</l:mi></l:math> spectra of charm and bottom quarks have a considerable impact at <n:math xmlns:n="http://www.w3.org/1998/Math/MathML"><n:mrow><n:msub><n:mi>p</n:mi><n:mi>T</n:mi></n:msub><n:mo>&gt;</n:mo><n:mn>5</n:mn><n:mspace width="0.16em"/><n:mi>GeV</n:mi></n:mrow></n:math>. Furthermore, we explore the path-length dependence of jet quenching by comparing the HFL <p:math xmlns:p="http://www.w3.org/1998/Math/MathML"><p:msub><p:mi>R</p:mi><p:mrow><p:mi>A</p:mi><p:mi>A</p:mi></p:mrow></p:msub></p:math> in two different collision systems. Our investigations show smaller HFL <q:math xmlns:q="http://www.w3.org/1998/Math/MathML"><q:msub><q:mi>R</q:mi><q:mrow><q:mi>A</q:mi><q:mi>A</q:mi></q:mrow></q:msub></q:math> in <r:math xmlns:r="http://www.w3.org/1998/Math/MathML"><r:mrow><r:mi>Pb</r:mi><r:mo>+</r:mo><r:mi>Pb</r:mi></r:mrow></r:math> than in <s:math xmlns:s="http://www.w3.org/1998/Math/MathML"><s:mrow><s:mi>Xe</s:mi><s:mo>+</s:mo><s:mi>Xe</s:mi></s:mrow></s:math> within the same centrality bin, consistent with the ALICE data. The longer propagation time and more effective energy loss of heavy quarks in <t:math xmlns:t="http://www.w3.org/1998/Math/MathML"><t:mrow><t:mi>Pb</t:mi><t:mo>+</t:mo><t:mi>Pb</t:mi></t:mrow></t:math> collisions play critical roles in the stronger yield suppression of the HFLs compared to that in <u:math xmlns:u="http://www.w3.org/1998/Math/MathML"><u:mrow><u:mi>Xe</u:mi><u:mo>+</u:mo><u:mi>Xe</u:mi></u:mrow></u:math>. In addition, we observe a scaling behavior of the HFL <v:math xmlns:v="http://www.w3.org/1998/Math/MathML"><v:msub><v:mi>R</v:mi><v:mrow><v:mi>A</v:mi><v:mi>A</v:mi></v:mrow></v:msub></v:math> in <w:math xmlns:w="http://www.w3.org/1998/Math/MathML"><w:mrow><w:mi>Xe</w:mi><w:mo>+</w:mo><w:mi>Xe</w:mi></w:mrow></w:math> and <x:math xmlns:x="http://www.w3.org/1998/Math/MathML"><x:mrow><x:mi>Pb</x:mi><x:mo>+</x:mo><x:mi>Pb</x:mi></x:mrow></x:math> collisions.