Signatures of jet drift in quark-gluon plasma hard-probe observables

Hard-probe tomography of the quark-gluon plasma (QGP) in heavy ion collisions has long been a preeminent goal of the high-energy nuclear physics program. In service of this goal, the isotropic modification of jets and high-energy hadrons has been studied in great detail at the leading-power (eikonal) level, with effects originating from sub-eikonal <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mi mathvariant="script">O</a:mi> <a:mo>(</a:mo> <a:mi>μ</a:mi> <a:mo>/</a:mo> <a:mi>E</a:mi> <a:mo>)</a:mo> </a:mrow> </a:math> anisotropic interactions presumed to be small. We present the first investigation of sub-eikonal, collective-flow-induced asymmetric jet broadening (jet drift) in event-by-event <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:msqrt> <c:mi>s</c:mi> </c:msqrt> <c:mo>=</c:mo> <c:mn>5.02</c:mn> </c:mrow> </c:math> TeV PbPb collisions at the Large Hadron Collider using the Anisotropic Parton Evolution computational framework. We show that jet drift imparts a significant enhancement of elliptic flow ( <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:msub> <d:mi>v</d:mi> <d:mn>2</d:mn> </d:msub> </d:math> ) larger than the experimental resolution and increases the mean acoplanarity for low- and intermediate-energy particles ( <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:msub> <e:mi>p</e:mi> <e:mi>T</e:mi> </e:msub> <e:mo>&lt;</e:mo> <e:mn>10</e:mn> </e:mrow> </e:math> GeV). Importantly, these modifications to hard-probe observables are shown to survive averaging over events and collision geometry. They couple to the collective flow of the medium seen by the jet and encode information about the QGP dynamics inaccessible to studies considering only isotropic, eikonal-level effects.