Speaker
Description
Within jets originating from initial stages of hadron collisions, angular scales have been shown correlated with temporal and energy scales, giving insights into jet evolution from perturbative to non-perturbative quantum chromodynamic (p/npQCD) regimes. Contributions from pQCD interactions to jet substructure are isolated by grooming techniques, which minimizes npQCD effects by removing soft, wide-angle radiation from the jets. In presence of quark-gluon plasma (QGP), comparing angular distributions of both groomed and ungroomed jet constituents to a (p+p) baseline reveal signatures of jet quenching in QGP, like broadening.
Generalized jet angularities, defined as $\Lambda^\kappa_\beta = \sum_{i\in\mathrm{jet}}\left(\frac{p_{\mathrm{T}, i}}{p_{\rm T, jet}}\right)^\kappa \left(\frac{\Delta R}{R_0}\right)^\beta$ [1], are jet substructure observables characterized by exponents $\kappa$ and $\beta$ which tune dependence on transverse momentum fraction $\left(\frac{p_{\mathrm{T}, i}}{p_{\rm T, jet}}\right)$ and rapidity/azimuth angle $\Delta R$, scaled by jet-resolution parameter $R_0$ from the jet-axis respectively, varying sensitivity of the observable to collinear and soft radiation. Measurements at RHIC energy scales complement previous LHC results [2] by studying the impact of grooming on jet substructure in regions of the phase-space unexplored by LHC. As theoretical calculations need to capture the full spectrum of pQCD and npQCD processes to explain jet evolution in vacuum and medium, these results will provide useful constraints.
In this study, we present measurements of various angularities using jets from (p + p) collisions at $\sqrt{s}$ = 200 GeV, collected by the STAR experiment. The measurements are fully corrected for detector effects using MultiFold [3], featuring various improvements to the unbinned unfolding method. Measurements from inclusive jets are compared with those from their SoftDrop-groomed counterparts. Finally, the data are compared with model calculations and the physics implications are discussed.
[1] Larkoski, A., Thaler, J. & Waalewijn, W. Gaining (mutual) information about quark/gluon discrimination. Journal Of High Energy Physics 2014 (2014,11), http://dx.doi.org/10.1007/JHEP11(2014)129
[2] Acharya, S. & Others, Measurements of the groomed and ungroomed jet angularities in pp collisions at $\sqrt{s}$ = 5.02 TeV. JHEP 05 pp.061 (2022)
[3] Andreassen, A., Komiske, P., Metodiev, E., Nachman, B. & Thaler, J. OmniFold: A Method to Simultaneously Unfold All Observables. Physical Review Letters. 124 (2020,5), http://dx.doi.org/10.1103/PhysRevLett.124.182001
| Is this an experimental talk? | Yes |
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| Is this on behalf of a collaboration? | Yes |
| Which collaboration? | STAR Collaboration |
| Are you willing to present as a poster if it is not selected for oral presentation? | Yes |