Measurement of splittings along a jet shower in $\sqrt{s} = 200$ GeV pp collisions at STAR

TL;DR

This paper presents the first measurements of jet substructure at multiple splits in proton-proton collisions at 200 GeV, providing insights into parton shower evolution and constraints on theoretical models.

Contribution

It introduces a novel analysis of jet substructure at multiple splits using SoftDrop, with fully corrected data compared to Monte Carlo models.

Findings

Measured groomed shared momentum fraction ( extsubscript{z}) and jet radius ( extsubscript{r}) at multiple splits.

Compared data to Monte Carlo models, constraining parton shower and hadronization parameters.

Tested self-similarity of jet substructure evolution with DGLAP splitting functions.

Abstract

Jets are algorithmic proxies of hard scattered partons, i.e. quarks and gluons, in high energy particle collisions. The STAR collaboration presents the first measurements of substructure observables at the first, second and third splits in the jet clustering tree via the iterative SoftDrop procedure. For each of these splits, we measure the fully corrected groomed shared momentum fraction (\zg) and groomed jet radius (\rg). We discuss the evolution of jet substructure in both the angular and momentum scales which allows for a self-similarity test of the DGLAP splitting function. We compare the fully corrected data to Monte Carlo models, providing stringent constraints on model parameters related to the parton shower and non-perturbative effects such as hadronization.