Speaker
Description
The sPHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) is designed to study the properties of the Quark-Gluon Plasma (QGP) using high-energy jets as calibrated hard probes. With high-resolution calorimetry and tracking, sPHENIX enables precision measurements of jet substructure observables that are sensitive to medium-induced modifications of parton showers. Jet substructure observables such as the subjet opening angle $\theta_{sj}$ and momentum sharing fraction $z_{sj}$ probe the angular and momentum scales at which the QGP resolves partonic radiation, providing sensitivity to color coherence effects and the medium coherence length, $\lambda_{\perp}$. Systematic measurements across multiple jet radii allow differential access to collinear and wide-angle radiation within jets.
In this work, we present feasibility studies of calorimeter-based measurements of $R_{g}$ in $\sqrt{s}$ = 200 GeV p+p collisions. Jets are reconstructed using the anti-$k_T$ algorithm by clustering calorimeter towers into anti-$k_{T}$ R=0.2 ``constituent'' jets before reclustering them into anti-$k_{T}$ R=0.4 jets for substructure study via the SoftDrop algorithm. Detector-level distributions are corrected for jet energy scale and resolution effects and unfolded to particle level using multidimensional response matrices constructed from Monte Carlo simulation. Comparisons between unfolded reconstructed MC and generator-level predictions are presented.
