Medium Modifications of Heavy-Flavor Jet Angularities in High-Energy Nuclear Collisions

Abstract We present the first theoretical study on heavy-flavor jet angularities ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>λ</mml:mi> <mml:mi>α</mml:mi> <mml:mi>κ</mml:mi> </mml:msubsup> </mml:mrow> </mml:math> ) in Pb+Pb collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msqrt> <mml:mrow> <mml:msub> <mml:mi>s</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">NN</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>5.02</mml:mn> </mml:mrow> </mml:math> TeV. The initial production of heavy-flavor jets was carried out using the POWHEG+PYTHIA8 prescription. In contrast, the SHELL transport model describes jet evolution in the quark-gluon plasma (QGP). In p+p collisions, we observed narrower angularity distributions for D 0 -tagged jets than for inclusive jets, consistent with the ALICE preliminary results. We then demonstrate that jet quenching in the QGP slightly widens the angularity distribution of D 0 -tagged jets in Pb+Pb collisions relative to that in p+p collisions for a jet transverse momentum of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>10</mml:mn> <mml:mo>&lt;</mml:mo> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">T</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="normal">jet</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">ch</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>&lt;</mml:mo> <mml:mn>20</mml:mn> </mml:mrow> </mml:math> GeV/c. In contrast, the angularity distributions of the inclusive and D 0 -tagged jets become narrower in Pb+Pb collisions relative to p+p at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">T</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="normal">jet</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">ch</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>&gt;</mml:mo> <mml:mn>20</mml:mn> </mml:mrow> </mml:math> GeV/c because of the strong influence of selection bias. Additionally, by comparing the average angularities <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">〈</mml:mo> <mml:msubsup> <mml:mi>λ</mml:mi> <mml:mi>α</mml:mi> <mml:mi>κ</mml:mi> </mml:msubsup> <mml:mo stretchy="false">〉</mml:mo> </mml:mrow> </mml:math> of the inclusive, D 0 -tagged, and B 0 -tagged jets with varying α and κ , we show that the larger the quark mass, the lower the jet’s <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">〈</mml:mo> <mml:msubsup> <mml:mi>λ</mml:mi> <mml:mi>α</mml:mi> <mml:mi>κ</mml:mi> </mml:msubsup> <mml:mo stretchy="false">〉</mml:mo> </mml:mrow> </mml:math> values are. As a result of the slenderer initial distribution, we predict that compared with inclusive jets, heavy-flavor jets, especially B 0 -tagged ones, will suffer stronger modifications of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">〈</mml:mo> <mml:msubsup> <mml:mi>λ</mml:mi> <mml:mi>α</mml:mi> <mml:mi>κ</mml:mi> </mml:msubsup> <mml:mo stretchy="false">〉</mml:mo> </mml:mrow> </mml:math> in Pb+Pb relative to p+p at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>10</mml:mn> <mml:mo>&lt;</mml:mo> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">T</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="normal">jet</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">ch</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>&lt;</mml:mo> <mml:mn>20</mml:mn> </mml:mrow> </mml:math> GeV/c. For a larger jet radius, a more significant broadening of the jet angularities was predicted because of the enhanced contribution of the wide-angle particles.