Generalized angularities measurements from STAR at $\sqrt{s_{\rm NN}} = $ 200 GeV

Abstract

Jets are produced in early stages of heavy-ion collisions and undergo modified showering in the quark-gluon plasma (QGP) medium relative to a vacuum case. These modifications can be measured using observables like jet momentum profile and generalized angularities to study the details of jet-medium interactions. Jet momentum profile ($\rho(r)$) encodes radially differential information about jet broadening and has shown migration of charged energy towards the jet periphery in Pb+Pb collisions at the LHC. Measurements of generalized angularities (girth $g$ and momentum dispersion $p_T^D$) and LeSub (difference between leading and subleading constituents) from Pb+Pb collisions at the LHC show harder, or more quark-like jet fragmentation, in the presence of the medium. Measuring these distributions in heavy-ion collisions at RHIC will help us further characterize the jet-medium interactions in a phase-space region complimentary to that of the LHC. In this contribution, we present the first measurements of fully corrected $g$, $p_T^D$ and LeSub observables using hard-core jets in Au+Au collisions at $\sqrt{s_{\rm NN}}=200$ GeV, collected by the STAR experiment at RHIC.