sPHENIX Study of High-Energy Isolated Electromagnetic Clusters in p + p Collisions at √s = 200 GeV*

sPHENIX,  a state-of-the-art jet detector at the Relativistic Heavy Ion Collider (RHIC), is designed to study the properties of quark-gluon plasma (QGP), with one of the flagship measurements to understand how high-energy partons interact with the QGP. In hard scatterings, photons and associated partons are produced nearly back-to-back, with photons providing a calibration of the initial momentum vector of the partner parton, as the photons do not strongly interact with the medium. The sPHENIX electromagnetic calorimeter (EMCal) can reconstruct these high transverse momentum photons; however, neutral pion decays present a significant background. By using isolation energy (event activity in the immediate vicinity of the photon), one can study the influence of and reduce such background effects. 

In this talk, we present the progress towards the identification of direct photons through isolated high-energy EM clusters using the 2024 p+p dataset. The p+p measurements are of interest in comparison with pQCD calculations and in serving as a baseline for future sPHENIX Au+Au measurements.