arXiv subjects

Rafet Kavak

Publications and source records attributed to Rafet Kavak.

3 recordsLinked to original sources

arXiv2026

Jet Radius Dependence of Energy Loss in Pb+Pb Collisions: A Comparative Analysis of the Ratio of Nuclear Modification Factors and Fractional Energy Loss

The quark-gluon plasma (QGP) is a deconfined state of strongly interacting matter formed at extreme temperature and energy density in ultra-relativistic nucleus-nucleus collisions at RHIC and the LHC. High transverse momentum jets, produced in initial hard scatterings, traverse the QGP and lose energy via elastic and radiative processes, an effect known as jet quenching. The nuclear modification factor, $R_{\mathrm{AA}}$, defined as the ratio of the Pb+Pb jet yield to the $pp$ cross section scaled by the nuclear thickness function, is widely used to quantify jet quenching. However, its value depends strongly on both the $pp$ jet spectral shape and the strength of the quenching, complicating comparisons across jet selections. The fractional energy loss, $S_{\text{loss}}$, quantifying the average medium-induced momentum shift of jets, is designed to mitigate this dependence. In central Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02~\mathrm{TeV}$, we compile and compare published ATLAS and ALICE measurements of jet suppression for inclusive single-jet and dijet selections across multiple jet radii, considering (i) the ratio of the nuclear modification factor at a given radius to that at a reference radius of 0.2, and (ii) the fractional energy loss. The radius dependence of this ratio differs between single-jet and dijet measurements, and between ATLAS calorimeter jets and ALICE charged-particle jets, reflecting differences in kinematic event selections and jet constituents. Expressing the results in terms of $S_{\text{loss}}$ allows direct, radius-differential comparisons across experiments with reduced sensitivity to the $pp$ spectral slope. Combining these approaches enables constraints on the radius dependence of jet modification that account for selection biases, and facilitates cross-experiment benchmarking of jet quenching models.

nucl-ex↗

arXiv2025

Machine Learning Power Week 2023: Clustering in Hadronic Calorimeters

In both high-energy physics and industry applications, a crowd-sourced approach to difficult problems is becoming increasingly common. These innovative approaches are ideal for the development of future facilities where the simulations can be publicly distributed, such as the Electron-Ion Collider (EIC). In this paper, we discuss a so-called ``Power Week" where graduate students were able to learn about machine learning while also contributing to an unsolved problem at a future facility. Here, the problem of interest was the clustering of the forward hadronic calorimeter in the foreseen electron-proton/ion collider experiment (ePIC) detector at the EIC. The different possible approaches, developed over the course of a single week, and their performance are detailed and summarised. Feedback on the format of the week and recommendations for future similar programs are provided in the hopes to inspire future learning opportunities for students that also serve as a crowd-sourced approaches to unsolved problems.

nucl-ex↗

arXiv2024

Quantification of the low-$p_{\rm T}$ pion excess in heavy-ion collisions at the LHC and top RHIC energy

While the abundances of the final state hadrons in relativistic heavy-ion collisions are rather well described by the thermal particle production, the shape of the transverse momentum, $p_{\rm T}$, distribution below $p_{\rm T}\approx500$ MeV$/c$, is still poorly understood. We propose a procedure to quantify the model-to-data differences using Bayesian inference techniques, which allows for consistent treatment of the experimental uncertainties and tests the completeness of the available hydrodynamic frameworks. Using relativistic fluid framework Fluid${\it u}$M with PCE coupled to \trento initial state and FastReso decays, we analyse \pt distribution of identified charged hadrons measured in heavy-ion collisions at top RHIC and the LHC energies, and identify an excess of pions produced below $p_{\rm T}\approx500$ MeV$/c$. Our results provide new input for the interpretation of the pion excess as either missing components in the thermal particle yield description or as an evidence for a different particle production mechanism.

hep-ph↗