In this contribution, we extend the scope of the JETSCAPE framework to cover the jet radius ($R$) dependence of the jet nuclear modification factor, ${R_{AA}}$, for broader area jet cones, going all the way up to $R$ = 1.0. The primary focus of this work has been the in-depth analysis of the high-${p_{T}}$ inclusive jets and the quenching effects observed in the quark-gluon plasma formed in...
Jets are excellent probes for studying the deconfined matter formed in heavy ion collisions. However, competing energy-loss effects, such as the dependence on the opening angle of the shower, radiative emissions to large angles, and the medium response to the jet, can obscure interpretation. This talk presents two new observables aimed at disentangling these effects. First, we introduce a new...
Energy-energy correlators (EEC) have been proposed to study the structure of energy flow within jets. These functions are defined as the energy-weighted cross-section of particle pairs inside jets. The correlation as a function of pair distance and jet transverse momentum offers a clear separation between the perturbative and non-perturbative regimes, where one can probe the dynamics of quarks...
Heavy-ion collisions produce a quark-gluon plasma that undergoes rapid expansion and cooling, which presents a challenge for calculating jet quenching observables. Current approaches rely on analytical results for static cases, introducing theoretical uncertainties and biases in our understanding of the pre-equilibrated medium. To address this issue, we employ analytical re-summation schemes...
We investigate the characteristics of gluonic cascades in static and expanding media by numerically solving the complete BDIM (Blaizot-Dominguez-Iancu-Mehtar-Tani) evolution equations in longitudinal and transverse momentum using the Monte Carlo event generator MINCAS. In this analysis, we compare angular distributions of in-cone radiation across various medium profiles with effective scaling...
Measurements of jet substructure in ultra-relativistic heavy ion collisions suggest that the jet showering process is modified by the interaction with quark gluon plasma. Modifications of the hard substructure of jets can be explored with modern data-driven techniques. In this study, we use a machine learning approach to identify jet quenching amounts. Jet showering processes, with and without...
Previous applications of machine learning to jet background subtraction have shown improvements over the traditional background subtraction methods, especially at low jet momentum. While machine learning applications generally lead to improvements, care must be taken to ensure they are not at the cost of interpretability and bias from models used for training. We present a novel application of...
Jet quenching measurements in heavy-ion collisions, such as the suppression of the jet yield compared to pp collisions, aim to elucidate the various mechanisms of parton energy loss. Differential measurements of the dependence of the inclusive jet nuclear modification factor ($R_{\rm AA}$) on the jet resolution parameter ($R$) may help disentangle energy loss mechanisms and discriminate...
The sPHENIX detector at the Relativistic Heavy Ion Collider (RHIC) is designed to study the small scale structure of the quark-gluon plasma (QGP) created in collisions of heavy ions. Jets, produced in hard scatterings early in the collisions, provide an ideal probe for the full evolution of the QGP. sPHENIX is the first detector at RHIC with full coverage electromagnetic and hadronic...
The new sPHENIX detector at Brookhaven’s National Laboratory’s Relativistic Heavy Ion Collider (RHIC) was designed to significantly further the study of the nature of hot nuclear matter. The use of jets as a probe in p+A and A+A collisions allows access to the interaction of the hard-scattered partons with the nuclear environment and is sensitive to a wide range of scales. sPHENIX will use...
Jets are collimated sprays of hadrons fragmented by highly virtual partons produced in the early stage of heavy-ion collisions via hard scatterings. Different observables of the jet-medium interaction probe the properties of the Quark-Gluon Plasma and its dynamics. The bulk medium produced in non-central heavy-ion collisions is expected to be tilted with respect to the beam axis, while the...
Particle production in ultra-relativistic pp collisions can be factorized into the parton density function (PDF), the partonic cross-section and the fragmentation function (FF). FFs need to be constrained by experimental data for each particle species. Measurements of the momentum fraction $z$ of a particle species contained in a high energetic jet give direct access to the FF of the...
Measurement of the jet substructure and the distribution of final state hadrons within a jet provide a detailed look into both the partonic shower and hadronisation process. These processes can be studied using the transverse momentum ($j_\mathrm{T}$) and longitudinal momentum fraction ($z$) of constituent particles. ALICE has recently measured the transverse momentum distributions of the jet...
Energetic partons lose energy in the quark-gluon plasma (QGP) and then fragment and hadronize into showers of particles called jets. Measurements of the internal structure of these jets can constrain how energetic partons interact with the QGP. Though species-independent jet substructure measurements have made much progress recently, a complete understanding of the identified particle...
Hard partonic scatterings, occurring at the early stages of heavy-ion collisions, produce jets, which experience the full evolution of the quark-gluon plasma (QGP). As they traverse through the QGP, jets lose energy through collisional and radiative processes, collectively known as the jet quenching. In semi-central heavy-ion events, the QGP takes an approximately elliptical shape in the...
Hard-scattered partons ejected from high-energy collisions undergo fragmentation and hadronization, resulting in collimated sprays of particles that are clustered into jets. The Energy-Energy correlator (EEC) is a jet substructure observable used to study the time evolution of the parton shower. This observable re-contextualizes jet substructure study by using the distribution of angular...
When a jet injects energy and momentum into a droplet of QGP, it generates a wake that, after the QGP hadronizes, results in the creation of soft and semi-hard particles correlated with the jet direction. This medium response phenomenon plays a crucial role in describing various jet observables, as demonstrated by many jet quenching studies. However, the computational complexity of current...
With the newly upgraded sPHENIX detector capable of performing high precision jet substructure measurements, we present a comprehensive and systematic jet substructure study at the Relativistic Heavy Ion Collider. The study includes a variety of key jet substructure variables such as jet angularities with and without soft-drop or collinear-drop grooming, as well as recoil-free di-jet and...
The sequential clustering of particles into jets offers an algorithmic connection of hadrons to the partons of the radiation shower. Jet substructure allows us to access the radiation history of a jet thereby providing a useful avenue to probe QCD through different energy scales. The N-point Energy Correlator (ENC) is a recently proposed observable that highlights this feature of jets as a...
Studies of gluon fragmentation at LEP have shown hints that gluon-initiated jets produce more baryons than quark-initiated jets. Our current knowledge of fragmentation functions is almost exclusively based on fits to data from $e^+ e^-$ collisions and semi-inclusive deep inelastic scattering processes, both of which are mainly sensitive to quark fragmentation, leaving gluon fragmentation...
We present a new model for jet quenching via coherent gluon radiation and elastic scatterings off medium partons. The jet energy loss is simulated as a perturbative final-state vacuum parton shower followed by a medium-induced shower originating from elastic and radiative collisions with the medium constituents. Coherency is achieved by starting with trial gluons that act as field dressing of...
The study of the suppression of the leading two hadrons within jets, by virtue of being robust against the underlying event background, provides an insight into the onset of quenching in the history of the evolution of relativistic heavy-ion collisions, which can help discriminate between different partonic energy loss mechanisms. The modification of their flavor correlations, on the other...
In studies of QGP, it has been observed that at high-energy heavy-ion (A$+$A) collisions, high-momentum particles with light and heavy flavors receive significant suppression. This indicates that particles lose their energies in QGP. One of the most important topics is to quantify the energy loss and to investigate the energy loss mechanism.
PHENIX measured the fractional momentum loss,...
We employ the AdS/CFT correspondence to study the jet quenching effect in Quark-gluon plasma in heavy-ion collisions.The nuclear modification factor $R_{AA}$ and elliptic flow parameter $v_{2}$ are studied in different-centrality collisions at RHIC and LHC.Our numerical results agree with data.Magnetic field and chemical potential of the medium are also considered for the observable...
Experimental data on a wide range of jet observables measured in heavy ion collisions provide a rich picture of the modification of jets as perturbative probes and of the properties of the quark-gluon plasma. However, their interpretation is often limited by the assumptions of specific quenching models, and it remains a challenge to establish model-independent statements about the universality...
Rare probes such as jets and heavy flavor hadrons provide unique opportunities to study the short-distance scale properties of the QGP created in heavy ion collisions. For example, recent measurements at the LHC and RHIC indicate that jet energy loss is correlated with the distance traveled through the QGP medium, and as a result, the initial geometry of the QGP. While estimates of...
