Novel subjet observables for jet quenching in heavy-ion collisions

Abstract

Using a novel observable that relies on the momentum difference of the two most energetic subjets within a jet ΔS 12 we study the internal structure of highenergy jets simulated by several Monte Carlo event generators that implement the partonic energy-loss in a dense partonic medium. Based on inclusive jet and dijet production we demonstrate that ΔS 12 is an effective tool to discriminate between different models of jet modifications over a broad kinematic range. The new quantity, while preserving the collinear and infrared safety of modern jet algorithms, it is experimentally attractive because of its inherent resilience against backgrounds of heavy-ion collisions.

Time reclustering for jet quenching studies

“…Elastic energy loss is not important since the parton is very energetic, and inelastic scattering is extremely rare due to the very short formation time of the first vacuum-like splitting. On top of energy loss, QGP inter- actions also induce jet collimation, an effect that has already been observed in other observables [13,34,35]. The surviving jets in PbPb collisions are biased towards having a hard (vacuum-like) fragmentation pattern, which is correlated to larger formation times.…”

Jet sub-structure and parton shower evolution in p+p and Au+Au collisions at STAR

“…Jet sub-structure at STAR Raghav Kunnawalkam Elayavalli for the STAR Collaboration In our studies, we found the groomed jet radii (R g ) to be highly sensitive to the fluctuating underlying event in Au+Au collisions and therefore we devised a new observable involving subjets of a smaller radius reconstructed within the original jet (see here [13]…”

Measurements of the jet internal sub-structure and its relevance to parton evolution in p+p and Au+Au collisions at STAR

“…The Au+Au data used in these proceedings were collected during the 2007 run with its corre- In our studies, we found the groomed jet radii (R g ) to be highly sensitive to the fluctuating underlying event found in Au+Au collisions and therefore we devised a new observable involving sub-jets of a smaller radius reconstructed within the original jet (see here [11] for a recent theoreti- We also observe a remarkable difference in the shape of z SJ when compared to that of the SoftDrop z g , which is caused by selecting the core of the jet. The θ SJ for jets within the considered p T range peaks at small values and includes a natural lower cutoff at the sub-jet radius and we now select jets based on this distribution.…”