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Talk presented at the Initial Stages of High-Energy Nuclear Collisions 2023 conference

Talk presented at the Winter Workshop on Nuclear Dynamics 2023 conference

Talk presented at the Deep-Inelastic Scattering 2022 conference

Talk presented at the Lomonosov Conference on Elementary Particle Physics 2021

We identify accelerator and beam conditions at the Electron-Ion Collider (EIC) that need to be included in physics and detector simulations. For our studies, we implement accelerator and beam effects in the Pythia 8 Monte Carlo event generator and examine their influence on the measurements in the central and far-forward regions of the detector. In our analysis, we demonstrate that the accelerator and beam effects can be also studied accurately by modifying the Monte Carlo input to detector simulations, without having to implement the effects directly in the event generators.

This document outlines the procedure for generating, executing and analyzing simulation data using PISA within the PHENIX framework.

Talk presented at the Quark Matter 2018 conference

Talk presented at the International Workshop on Forward Physics and QCD with LHC, EIC and Cosmic Rays, held at JLAB January 20-23, 2021

Talk given at the Hard Probes 2018 conference

As software systems change and evolve over time regression tests have to be run to validate these changes. Regression testing is an expensive but essential activity in software maintenance. The purpose of this paper is to compare a new regression test selection model called ReTSE with Pythia. The ReTSE model uses decomposition slicing in order to identify the relevant regression tests. Decomposition slicing provides a technique that is capable of identifying the unchanged parts of a system. Pythia is a regression test selection technique based on textual differencing. Both techniques are compare using a Power program taken from Vokolos and Frankl’s paper. The analysis of this comparison has shown promising results in reducing the number of tests to be run after changes are introduced.

Jets are a dominant feature of high energy particle interactions and can be interpreted in terms of the fragmentation of quarks and gluons produced in a hard scattering process. Jets provide important tools for studying hot and dense Quantum Chromodynamics (QCD) matter that is created in high energy collisions of heavy nuclei. In heavy ion collisions, such as Cu+Au, large transverse momentum partons traverse the colored Quark-Gluon Plasma (QGP) medium and lose energy which modifies the jet structure relative to jets generated in the vacuum. Jet production in relativistic heavy ion collisions is investigated using the Cu+Au collisions at √sNN = 200 GeV

High-$p_\mathrm{T}$ processes in proton- and deuteron-nucleus collisions at TeV energies are the best presently available way to study the partonic structure of the nucleus in a high-density regime. Jet production over a wide range of phase space can significantly constrain the current knowledge of nuclear parton distribution functions (nPDFs), which are substantially less well understood than the corresponding PDFs in protons and which have only recently begun to be treated in a spatially-dependent way. An accurate knowledge of nPDFs is crucial for a definitive control of perturbative processes in a cold nuclear environment, since high-$p_\mathrm{T}$ probes are used to quantitatively investigate the hot QCD matter created in ultrarelativistic nucleus-nucleus collisions. Furthermore, jets from low Bjorken-$x$ partons can probe the transition from the dilute to saturated nuclear regimes. Jet production is investigated in $d$+Au collisions at $\sqrt{s} = 200$ GeV with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), and in $p$+Pb collisions at $\sqrt{s} = 5.02$ TeV with the ATLAS detector at the Large Hadron Collider (LHC). The measurements shown here utilize $\int\mathcal{L}dt = 23$ nb$^{-1}$ and $0.2$ pb$^{-1}$ of 200 GeV $d$+Au and $pp$ data, respectively, recorded in 2007-8 at RHIC and $\int\mathcal{L}dt = 31$ nb$^{-1}$ and $4.1$ pb$^{-1}$ of $5.02$ TeV $p$+Pb and $2.76$ TeV $pp$ data, respectively, recorded in 2013 at the LHC. Jets are reconstructed using the $\sigma=0.3$ Gaussian filter and $R=0.4, 0.6$ anti-$k_\mathrm{T}$ algorithms. Inclusive, centrality-dependent jet yields within $\left|\eta\right| < 0.35$ and $10\ \mathrm{GeV}\ < p_\mathrm{T} < 40$ GeV in 200 GeV $d$+Au and $pp$ collisions are presented. The jet yield in $d$+Au collisions relative to the geometric expectation is found to be slightly suppressed ($\approx0.9$) in central events and moderately enhanced ($\approx1.3$) in peripheral events, with no modification when averaged over all $d$+Au events. Separately, inclusive, centrality-dependent jet yields within $\left|y^*\right| < 4.4$ and $25\ \mathrm{GeV}\ < p_\mathrm{T} < 800$ GeV in 5.02 TeV $p$+Pb and 2.76 TeV $pp$ collisions are presented. The event centrality in $p$+Pb collisions is determined by the sum of the transverse energy in the Pb-going forward calorimeter, $\Sigma{E}_\mathrm{T}^\mathrm{Pb}$, and the mean number of participating nucleons $N_\mathrm{part}$ is estimated using the Glauber and Glauber-Gribov models of semiclassical $p$+A collisions. The jet yield in $p$+Pb collisions relative to the geometric expectation is found to be suppressed in central events and enhanced in peripheral events. The modifications are found to be stronger at higher-$p_\mathrm{T}$ and at more forward (downstream proton) rapidities. Furthermore, it is observed that for each centrality selection, the modification at all rapidities is consistent with a simple function of the total jet energy only. The implications of the results are discussed, including a comparison of the modifications between RHIC and LHC energies.

The properties of the system must be inferred from the remnants of the collision which reach detectors a few meters away from the collision region. The non-interacting pieces of the Au nuclei continue forward in the beam direction after the collision, but in the collision region energy is scattered perpendicular to the beam direction. In this present work we are interested in the particles which are the remains of inelastic parton and the nucleon scattering of the collision. We investigate jet-like azimuthal correlations between two particles where one or both is identified at intermediate pT. Two particle correlations provide additional information hence one can discriminate between particle production mechanisms than single particle observables.

This dissertation presents the measurement of electrons from heavy flavor decays in proton + proton collisions at RHIC at colli­sion energy √s = 200 GeV over a wide range of transverse moment (0.4 < pr < 5 GeV/c). Two independent analysis techniques of signal extraction were performed. This is the first measure­ment of the Open Charm cross section at this collision energy and it is an important baseline measurement for comparison with nucleus + nucleus collisions.

This thesis summarizes the analysis of non-photonic single elec­trons from Au-Au collisions at √sNN = 200GeV at RHIC Run-2. From the fully corrected inclusive electron spectra in various Au-Au centrality classes, we subtract background cocktails of elec­trons, from photonic sources. The remaining non-photonic elec­trons originate from heavy flavor decays. With the corresponding measurement from p + p collisions at 200 GeV as reference, we calculate the nuclear modification factor Raa as function of px in various Au + Au centrality classes.

One of the unique features of PHENIX detector is the muon tracking and identification system. In the collisions of polarized protons, the muon arms can explore the polarization of quarks and gluons in the proton through W boson production, the Drell - Yan process and open heavy flavor production. This thesis reports the performance of the muon spectrometer during the first data taking period and also the production cross section for J/Psi in proton-proton collision at √sNN = 200 GeV which is in good agreement with the color evaporation model and QCD predictions.