Doctor of Philosophy (PhD), Ohio University, 2024, Physics and Astronomy (Arts and Sciences)

We present two topics relevant to the advancement of the field of Relativistic Heavy Ion collision physics: a novel technique development for calibrating a detector in sPHENIX and a physics analysis using PHENIX data with the goal of studying the possibility of jetquenching in so-called small collision systems. Calibrating the electromagnetic calorimeter (EMCal) of the sPHENIX experiment to the electromagnetic scale is an important task which will allow many important analyses to succeed. The established known mass of the π0 particle is utilized for development of a new technique to perform calibration of the sPHENIX EMCal. The sPHENIX experiment uses many different methods and particles to calibrate the detectors, which complement each other. This pi0-method is one of the methods that has been used to successfully calibrate the sPHENIX electromagnetic calorimeter to its electromagnetic scale in the first sPHENIX running period 2023. The second part of this work is about studying the possibility of production of quark-gluon plasma (QGP), a state of matter that is a regular occurrence in ultrarelativistic high-energy heavy-ion collisions at RHIC and LHC. However, the same cannot be definitively said for small collision systems. However, multiple recent research results have indicated the presence of QGP formation in small collision systems. We employ an analysis of two-particle jet correlations between pi0-h particles using PHENIX data to investigate whether a jet suppression signal using the new observable RI exists. Several small collision systems were investigated, including d+Au, 3He+Au, and primarily, peripheral centrality (65-70%) Au+Au collisions, which serve as proxies for small systems in terms of the number of nucleons involved during the collision. This study focuses on the latter. Our study aims to examine the Au+Au collision system with two different system sizes: one involving nearly central collisions where QGP formation is expecte (open full item for complete abstract)

Committee: Justin Frantz Dr. (Advisor) Subjects: Physics

PHD, Kent State University, 2024, College of Arts and Sciences / Department of Physics

Numerous previous investigations of in-medium quarkonium suppression have tacitly relied on an adiabatic approximation, presuming that the potential governing heavy quark interactions evolves slowly with time. In this adiabatic scenario, one can decouple the calculation of the in-medium breakup rate and the temporal evolution of the medium, combining them only at the conclusion of the analysis. We relax this assumption by solving the 3d Schr¨odinger equation in real-time in order to compute quarkonium suppression dynamically. We introduce a method for reducing anisotropic heavy-quark potentials to isotropic potentials by using an effective screening mass that depends on the quantum numbers l and m of a given state. We demonstrate that using the resulting 1D effective potential model, one can solve a 1D Schr¨odinger equation and reproduce the full 3D results for the energies and binding energies of low-lying heavy-quarkonium bound states to relatively high accuracy. We introduce a framework called Heavy Quarkonium Quantum Dynamics (HQQD) which can be used to compute the dynamical suppression of heavy quarkonia propagating in the quark-gluon plasma using real-time in-medium quantum evolution. Using HQQD we compute large sets of real-time solutions to the Schr¨odinger equation using a realistic in-medium complex-valued potential. We sample 2 million quarkonia wave packet trajectories and evolve them through the QGP using HQQD to obtain their survival probabilities. Using the potential non-relativistic quantum chromodynamics (pNRQCD) effective field theory, we derive a Lindblad equation for the evolution of the heavy-quarkonium reduced density matrix that is accurate to next-to-leading order (NLO) in the ratio of the binding energy of the state to the temperature of the medium. The resulting NLO Lindblad equation can be used to more reliably describe heavy-quarkonium evolution in the quark-gluon plasma at low temperatures compared to the leading-order tr (open full item for complete abstract)

Committee: Michael Strickland (Advisor); Spyridon Margetis (Committee Chair); Soumitra Basu (Committee Member); John Portman (Committee Member); Barry Dunietz (Committee Member); Declan Keane (Committee Member) Subjects: Nuclear Physics; Physics; Theoretical Physics

PHD, Kent State University, 2023, College of Arts and Sciences / Department of Physics

In the field of high-energy nuclear physics, ultrarelativistic heavy-ion collisions serve as a one-of-a-kind laboratory for investigating the extreme properties of matter. These collisions involve massive nuclei, such as lead or gold, colliding with energies in the trillions of electron volts per nucleon range. These collisions produce an environment where the strong force, as described by quantum chromodynamics (QCD), is the dominant force. In particular, the collisions generate a state of matter known as the quark-gluon plasma (QGP), which is characterized by a state of quarks and gluons that is not confined inside hadrons such as protons and neutrons. The QGP is an intriguing state of matter that provides insights into the behavior of dense astrophysical objects and the early universe. It is produced when the energy density of the collision reaches a critical threshold, resulting in the transition from the confined to the unconfined state of quarks and gluons. The QGP is a hot and dense system, with temperatures on the order of trillions of Kelvin and densities several orders of magnitude greater than the density of atomic nuclei in ordinary matter. In the initial phases of a heavy-ion collision, the system is far from thermal equilibrium and possesses a highly anisotropic pressure. The pressure anisotropy results from the longitudinal expansion being more rapid than the transverse expansion. The dynamics of the system cannot be adequately described by ideal hydrodynamics, which assumes local isotropic thermal equilibrium at all times. To account for the pressure anisotropy and non-equilibrium nature of the QGP, a framework known as anisotropic hydrodynamics has been developed. Anisotropic hydrodynamics (aHydro) is a useful tool for describing the evolution of the QGP, especially during the early non-equilibrium evolution of the QGP. It goes beyond the ideal hydrodynamic limit by incorporating dissipative transport coefficients, such as shear viscosity, which (open full item for complete abstract)

Committee: Michael Strickland (Advisor); Declan Keane (Committee Member); Mina Katramatou (Committee Member); Diana Goncalves Schmidt (Committee Member); Ruoming Jin (Committee Member) Subjects: Nuclear Physics; Particle Physics; Physics; Theoretical Physics

Doctor of Philosophy, The Ohio State University, 2023, Physics

The advent of multiple successfully calibrated models for relativistic heavy-ion collisions demands a clear strategy based on rigorous statistical principles to utilize them all in understanding the nature of the quark-gluon plasma. The successful calibration of the viscous anisotropic hydrodynamic model in this thesis adds another serious competitor to the arena and emphasizes, even more, the importance of such a unifying strategy. In our work, we have identifed the need for massive computational resources as one of the main challenges to studying relativistic heavy-ion collisions using multiple simulation models. We introduce multiple novel computational tools that can be used in our feld of study to ease this computational burden. Lastly, we discuss a novel Bayesian model mixing tool developed by us, Taweret, which can combine multiple diferent simulations to obtain more accurate predictions. For the frst time, we apply these model mixing techniques to locally mix two models from relativistic heavy-ion collisions with mixing weights that vary with collision centrality. Furthermore, we perform a Bayesian parameter estimation with the mixed model to infer the properties of the quark-gluon plasma considering both the experimental and modeling uncertainties. It is our hope that this work provides clear directions for future studies of the quark-gluon plasma fluid created in laboratory experiments, making use of multiple models and the full set of experimental data.

Committee: Ulrich Heinz (Advisor) Subjects: Physics

Bachelor of Science (BS), Ohio University, 2023, Physics

The field of subatomic particles has existed for over a hundred years now. From the discovery of the electron that sparked the field, to the discovery of the Higgs Boson, physicists have always wanted to uncover the subatomic structure of the atoms, nuclei, and their constituents at smaller and smaller levels. By the 1930s, the proton, neutron, and electron had been discovered. These protons and neutrons are types of hadrons, and many different types of hadrons had been discovered by the 1960s. In 1964, Murray Gell-man and George Zweig independently proposed the quark model to explain the different hadrons. A quark is a particle that makes up a hadron, accounting for the many different types of hadrons that had been discovered; the other hadrons were composed of 2 or 3 of the 6 quarks. These include the up, down, top, bottom, charm, and strange quarks. The proton is made of 2 up quarks and 1 down quark, while the π0 particle is made of an up and an anti-up, or a down and an anti-down quark, for example. Advancements in technology allowed physicists to be able to accelerate particles and smash them together in particle accelerators and colliders. These new machines were how physicists were able to split open atoms, and the hadrons inside, to uncover these quarks. In the search for these different quarks, other particles were being discovered as well. This included the 6 leptons, the electron, the tau, and the muon, and their neutrino counterparts. The leptons are grouped separately from quarks because they participate only in electroweak interactions, while quarks also participate in strong interactions. Electroweak interactions describe the interactions caused by the electromagnetic force and the weak nuclear force. The strong interactions describe those caused by the strong nuclear force. These 3 forces, along with gravity, are the four fundamental forces of the universe, with the strong force being the strongest force and responsible for most of the energy in (open full item for complete abstract)

Committee: Justin Frantz (Advisor) Subjects: Nuclear Physics; Physics; Plasma Physics

PHD, Kent State University, 2021, College of Arts and Sciences / Department of Physics

The goal of high-energy nuclear physics is to understand the dynamics and properties of the various forms and phases of the strongly-interacting matter. Heavy-ion collision experiments are performed to deposit a large energy density in a very small volume of space and generate a form of extremely hot matter called the quark-gluon plasma (QGP). The behavior of the generated matter shows signatures of collectivity allowing phenomenological models based on statistical or fluid dynamical descriptions to be used successfully to analyze the outcomes the experiments. However, the very short lifetime and the extreme conditions of the QGP call for the construction of theoretical models based on the physics of nonequilibrium systems. Understanding the properties of QGP requires the study of collective excitations in the emergent many-body dynamics of the quarks and gluons as the fundamental objects in the theory of quantum chromodynamics. In this dissertation, the collective excitations of the nonequilibrium QGP are studied by calculating the quark and gluon self-energies within the hard loop effective theory. By extracting the solutions of the gluon dispersion relation in the complex plane, the presence of unstable modes in the momentum-anisotropic QGP is studied. The quark self-energy is also used to calculate the rate of photon emission from QGP in the subsequent studies performed as part of this dissertation. Electromagnetic probes (photons and dileptons) are considered among the best observables for extracting information about the early stages of evolution of the strongly interacting matter produced in heavy-ion collisions. In contrast to the hadrons, the emitted photons and leptons are not distorted by a strong coupling to the medium and they can escape the system with much larger mean free paths. Since the dilepton and photon emission rates from QGP are directly affected by the momentum distribution of the partonic degrees of freedom, their emission patter (open full item for complete abstract)

Committee: Michael Strickland Dr. (Advisor); Declan Keane Dr. (Committee Member); Jonathan Selinger Dr. (Committee Member); Barry Dunietz Dr. (Committee Member); Gang Yu Dr. (Committee Member) Subjects: Nuclear Physics; Particle Physics; Physics

Doctor of Philosophy, The Ohio State University, 2021, Physics

One of the primary goals of nuclear physics is studying the phase diagram of Quantum Chromodynamics, where a hypothetical critical point serves as a landmark. A systematic model-data comparison of heavy-ion collisions at center-of-mass energies between 1 and 100 GeV per nucleon is essential for locating the critical point and the phase boundary between the deconfined quark-gluon plasma and the confined hadron resonance gas. At these energies the net baryon density of the system can be high and critical fluctuations can become essential in the presence of the critical point. Simulating their dynamical evolution thus becomes an indispensable part of theoretical modeling. In this thesis we first present the (3+1)-dimensional relativistic hydrodynamic code BEShydro, which solves the equations of motion of second-order Denicol-Niemi-Molnar-Rischke theory, including bulk and shear viscous components as well as baryon diffusion current. We then study the effects caused by the baryon diffusion on the longitudinal dynamics and on the phase diagram trajectories of fluid cells at different space-time rapidities of the system, and how they are affected by critical dynamics near the critical point. We finally explore the evolution of non-hydrodynamic slow processes describing long wavelength critical fluctuations near the critical point, by extending the conventional hydrodynamic description by coupling it to additional explicitly evolving slow modes, and their back-reaction to the bulk matter properties.

Committee: Ulrich Heinz (Advisor); Richard Furnstahl (Committee Member); Michael Lisa (Committee Member); Jay Gupta (Committee Member) Subjects: Nuclear Physics

Doctor of Philosophy, The Ohio State University, 2021, Physics

The study of heavy-ion collisions presents a challenge to both theoretical and experimental nuclear physics. Due to the extremely short (10^{-23} s) lifetime and small size (10^{-14} m) of the collision system, disentangling information provided by experimental observables, and progress in physical insight, requires the careful application of plausible reasoning. I apply a program of statistical methodologies, primarily Bayesian, to quantify properties of the medium in specific models, as well as compare and criticize differing models of the system. Of particular interest are estimations of the specific shear and bulk viscosities, where we find that information carried by the experimental data is still limited. In particular we find a large sensitivity to prior assumptions at high temperatures. Moreover, sensitivities to model assumptions are present at low temperatures, and this source of model uncertainty is propagated with model averaging and model mixing.

Committee: Ulrich Heinz (Advisor) Subjects: Nuclear Physics; Physics

PHD, Kent State University, 2019, College of Arts and Sciences / Department of Physics

Heavy ion collisions allow us to study the formation and characteristics of Quark-Gluon Plasma (QGP), a state of matter now known to exist at very high temperature and/or very high energy density. QGP also existed around a millionth of a second after the Big Bang, and it may persist today at the center of compact stars. A brief time (a few fm/c) after the QGP phase is achieved in a heavy ion collision, the hadronization process starts to take place. This leads to the production of particles such as protons, pions, etc., which can be observed by particle detectors. What symmetry or asymmetry went into the motion of particles during the collision process? There are other interesting, yet unanswered questions, such as what is the order of the phase transition between the QGP and hadronic phases? Such questions intrigue many high-energy nuclear physics researchers. The Relativistic Heavy Ion Collider (RHIC) located at Brookhaven National Laboratory began operation in the year 2000 in a mission to produce controlled heavy ion collisions and QGP. The STAR (Solenoidal Tracker at RHIC) collaboration operates one of four experiments at RHIC, and STAR is at present the only remaining experiment taking data. The Beam Energy Scan (BES) program at RHIC explores collisions over the widest possible range of beam energies, and allows us to study the properties of the Quantum Chromodynamics (QCD) phase diagram in the regions where a first-order phase transition and a critical point may exist. Phase-I of this program (BES-I) collected data during 2011-2014 and interesting results have been observed. For example, there is a minimum in an azimuthal anisotropy parameter called directed flow (v1) for protons and other baryons at collision energies of √sNN = 10-20 GeV, and it qualitatively resembles the predicted signature of a softening of the equation of state associated with the first-order phase transition. To better identify this softest point, we need to make measurements of d (open full item for complete abstract)

Committee: Declan Keane (Advisor); Spyridon Margetis (Committee Member); Michael Strickland (Committee Member); Diane Stroup (Committee Member); Arvind Bansal (Committee Chair) Subjects: Nuclear Physics; Physics

PHD, Kent State University, 2019, College of Arts and Sciences / Department of Physics

Relativistic heavy-ion collision experiments are currently the only controlled way to generate and study matter in the most extreme temperatures (T ~10e+12 K). At these temperatures matter undergoes a phase transition to an exotic phase of matter called the quark-gluon plasma (QGP). The QGP is an extremely hot and deconfined phase of matter where sub-nucleonic constituents (quarks and gluons) are asymptotically free. The QGP phase is important for different reasons. First of all, our universe existed in this phase up to approximately t ~10e-5 s after the Big Bang, before it cools down sufficiently to form any kind of quark bound states. In this regard, studying the QGP provides us with useful information about the dynamics and evolution of the early universe. Secondly, high-energy collisions serve as a microscope with a resolution on the order of 10e-15 m (several orders of magnitude more powerful than the best ever developed electron microscopes). With this fantastic probe, penetrating into the detailed structure of nucleons, and the discovery of new particles and fundamental phases are made possible. The dynamics of the QGP is based on quantum chromodynamics (which governs the interactions of quarks and gluons) and the associated force is "strong force". The strong collective behaviors observed experimentally inspired people to use dissipative fluid dynamics to model the dynamics of the medium. The QGP produced in heavy-ion collisions, experiences strong longitudinal expansion at early times which leads to a large momentum-space anisotropy in the local rest frame distribution function. The rapid longitudinal expansion casts doubt on the application of standard viscous hydrodynamics (vHydro) models, which lead to unphysical predictions such as negative pressure, negative one-particle distribution function, and so on. Anisotropic hydrodynamics (aHydro) takes into account the strong momentum-space anisotropy in the leading order distribution function in a consistent (open full item for complete abstract)

Committee: Michael Strickland (Advisor); Declan Keane (Committee Member); Khandker Quader (Committee Member); Xiaoyu Zheng (Committee Member); Peter Palffy-Muhoray (Committee Member) Subjects: Fluid Dynamics; Particle Physics; Physics; Plasma Physics; Theoretical Physics

MS, Kent State University, 2018, College of Arts and Sciences / Department of Physics

Since the 1960s, it has been known that the protons and neutrons in nuclei are composed of more fundamental particles called quarks. To date, there is no evidence that quarks have a substructure. Experiments at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab, on Long Island, New York, study the particle emerging from very energetic collisions between heavy nuclei like gold (each made up of 197 protons and neutrons), and offer a unique means for investigating the properties of quarks and the particles associated with the forces between quarks. The most high-profile scientific breakthrough so far at the RHIC accelerator was the discovery of quark-gluon plasma (QGP). The existence of this new phase of matter had been predicted on theoretical grounds, and it is believed to have existed briefly during the first microsecond after the Big Bang. Its discovery was further confirmation of the Standard Model – a unified description of matter in terms of quarks, particles in the electron family (leptons), and the fields mediating their interactions. Until recently, the available evidence always pointed to a smooth transition between ordinary matter and QGP, unlike the familiar discontinuous change of state (phase transition) when ice turns to liquid water, or when liquid water turns to steam. Changes of phase like in water are called first-order phase transitions. Theorists had anticipated that the normal maximum energy of the RHIC accelerator is too high to observe a first- order phase transition, and they predicted that it might be seen at a lower energy. This insight prompted a multi-year effort at RHIC, known as the Beam Energy Scan (BES), to investigate a wide range of beam energies and search for such phenomena. One of the challenges that arise in interpreting BES measurements is to investigate if a bombarding energy exists where a maximum occurs in the nuclear compression during the early stages of the collision. Naively, one might expect compressio (open full item for complete abstract)

Committee: Keane Declan (Advisor); Spyridon Margetis (Advisor); Mina Katramatou (Committee Member) Subjects: Nuclear Physics; Physics

PHD, Kent State University, 2017, College of Arts and Sciences / Department of Physics

Quantum Chromodynamics (QCD), the theory of the strong interaction between quarks and gluons, predicts that at extreme conditions of high temperature and/or density, quarks and gluons are no longer confined within individual hadrons. This new deconfined state of quarks and gluons is called Quark-Gluon Plasma (QGP). The Universe was in this QGP state a few microseconds after the Big Bang. The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) on Long Island, NY was built to create and study the properties of QGP. Due to their heavy masses, quarks with heavy flavor (charm and bottom) are mainly created during the early, energetic stages of the collisions. Heavy flavor is considered to be a unique probe for QGP studies, since it propagates through all phases of a collision, and is affected by the hot and dense medium throughout its evolution. Initial studies, via indirect reconstruction of heavy flavor using their decay electrons, indicated a much higher energy loss by these quarks compared to model predictions, with a magnitude comparable to that of light quarks. Mesons such as D0 could provide information about the interaction of heavy quarks with the surrounding medium through measurements such as elliptic flow. Such data help constrain the transport parameters of the QGP medium and reveal its degree of thermalization. Because heavy hadrons have a low production yield and short lifetime (e.g. ct = 120µm for D0), it is very challenging to obtain accurate measurements of open heavy flavor in heavy-ion collisions, especially since the collisions also produce large quantities of light-flavor particles. Also due to their short lifetime, it is difficult to distinguish heavy-flavor decay vertices from the primary collision vertex; one needs a very high precision vertex detector in order to separate and reconstruct the decay of the heavy flavor particles in the presence of thousands of other particles produced in each collision. The STAR (open full item for complete abstract)

Committee: Spyridon Margetis Prof. (Advisor); Declan Keane Prof. (Advisor); Veronica Dexheimer (Committee Member); Songping Huang (Committee Member); Mietek Jaroniec (Committee Member) Subjects: Nuclear Physics; Particle Physics; Physics

Doctor of Philosophy, The Ohio State University, 2017, Physics

Local momentum anisotropies are large in the early stages of the quark-gluon plasma created in relativistic heavy-ion collisions, due to the extreme difference in the initial longitudinal and transverse expansion rates. In such situations, fluid dynamics derived from an expansion around an isotropic local equilibrium state is bound to break down. Instead, we resum the effects of the slowest nonhydrodynamic degree of freedom (associated with the deviation from momentum isotropy) and include it at leading order, defining a local anisotropic quasi-equilibrium state, thereby treating the longitudinal/transverse pressure anisotropy nonperturbatively. Perturbative transport equations are then derived to deal with the remaining residual momentum anisotropies. This procedure yields a complete transient effective theory called viscous anisotropic hydrodynamics. We then show that the anisotropic hydrodynamic approach, especially after perturbative inclusion of all residual viscous terms, dramatically outperforms viscous hydrodynamics in several simplified situations for which exact solutions exist but which share with realistic expansion scenarios the problem of large dissipative currents. Simulations of the full three-dimensional dynamics of the anisotropic quark-gluon plasma are then presented.

Committee: Ulrich Heinz (Advisor); Michael Lisa (Committee Member); Yuri Kovchegov (Committee Member); Junko Shigemitsu (Committee Member) Subjects: Physics

Doctor of Philosophy, Case Western Reserve University, 2017, Physics

Ultra High Energy Cosmic Rays (UHECRs) and hadronic interactions (HIs) are fundamentally linked. Although typically HIs are studied using symmetrical heavy ion collisions, such as gold (Au) and lead (Pb), there are increasing inquiries into the behavior of asymmetrical collisions, such as p + Au. These inquires arise from the fact that the onset of collective behavior, e.g. flow, is not confined to central heavy ion collisions. Since there is increasing confidence in evidence for of quark-gluon plasma (QGP) formation at the lower collision energies used at RHIC, and since UHECR collision energies are an order of magnitude higher(~ 100 T eV ) than that at LHC, it stands to reason that, although the interacting hadrons may be lighter, there may be QGP formation occurring during the initial UHECR collision. In this work we explore the possibility that the formation of QGP during the first interactions of UHECRs may result in observable signatures in ground profile and shower particle composition that could conceivably be detectable by an air shower array experiment such as the Pierre Auger Observatory. Knowledge of whether QGP formation affects the properties of UHECR development will further the understand- ing of both UHECR behavior and high energy hadronic interaction behavior. Results show potential for QGP detection at 100 PeV initial energy at an initial interaction event height of 12 km through a &mu ± excess at 10 GeV between 100 - 300 m from the shower core favoring QGP forming events. Higher initial heights of 24 and 36 km at a 100 PeV initial energy show no significant potential for QGP detection.

Committee: Corbin Covault (Advisor); John Ruhl (Committee Member); Harsh Mathur (Committee Member); Stacy McGaugh (Committee Member) Subjects: Astrophysics; Particle Physics; Physics

PHD, Kent State University, 2016, College of Arts and Sciences / Department of Physics

Heavy ion collisions at RHIC provide a unique environment to probe into the understanding of nuclear matter under extreme high temperature and density conditions. Among the many insights that can be provided is the further understanding of the QCD (Quantum Chromo Dynamics) phase diagram and equation of state, as well as search for evidence of the QCD critical point and chiral symmetry restoration. Production of heavy quarks in high-energy nuclear collisions at RHIC occurs mainly through gluon fusion and quark anti-quark annihilation; and while heavy flavor production may be somewhat enhanced due to final state interactions via thermal processes these channels are greatly suppressed due to the heavy quark masses. Thus heavy flavor provides an ideal probe in the study of the hot and dense medium created in high-energy collisions as it is produced early in the evolution of the collision, and hence is sensitive to the collision dynamics of the partonic matter at early stages. Previous measurements of collective motion (flow) in light quarks (u,d,s) at RHIC suggest that partonic collectivity has been achieved in the collisions. These results also seem to suggest that the dense matter produced during collisions thermalizes at very high temperatures and form a strongly coupled Quark Gluon Plasma (QGP) whose behavior is compatible with viscous hydrodynamic models with a low shear-viscosity-to-entropy-density (η/s) ratio. The question remains as to whether or not this collective behavior applies to heavy flavor and a detailed description of the behavior of heavy flavor is essential to understand the underlying dynamics, distinguish between different energy loss mechanisms, and constrain theoretical models. In particular, if the elliptic flow of charm quarks is found to be comparable to that of lighter matter this would be indicative of frequent interactions between all quarks and would strongly support the discovery of QGP at RHIC. Understanding how this collecti (open full item for complete abstract)

Committee: Margetis Spyridon Prof. (Advisor); Xin Dong Dr. (Advisor) Subjects: Nuclear Physics; Physics

BS, Kent State University, 2016, College of Arts and Sciences / Department of Physics

I discuss the historical and physical significance of bottomonium suppression in heavy ion collision-produced quark-gluon plasma. I use a computational technique, the finite-difference time-domain method, to solve the Schrodinger equation for a complex valued potential and obtain collision temperature-dependence of bottomonium's binding energy. Along the way, I review fundamentals of quantum theory, I present a 1-dimensional algorithm for the finite-difference time-domain method, and I test outputs of that algorithm by comparing them with known analytic solutions of the Schrodinger equation for a simple potential.

Committee: Michael Strickland (Advisor) Subjects: High Temperature Physics; Particle Physics; Physics

Bachelor of Sciences, Ohio University, 2016, Physics and Astronomy

Over the past 15 years, we have seen much evidence of the existence of quark gluon plasma. This evidence was established through Au+Au and Pb+Pb collisions at the Relativistic Heavy Ion Collider (RHIC). In recent studies, it was confirmed that deuteron and gold nuclei collisions might also produce the quark gluon plasma, albeit in much smaller quantities. To further test this trend, helium-3 nuclei were collided with gold nuclei to study the quark gluon plasma signatures. In this study, p0 - h± azimuthal angular correlations and trigger yields in He+Au collisions are measured at 200 GeV and compared to d+Au collisions and p+p collisions at the same energy. To analyze the data we use IAA plots and RI (double ratio) plots, the latter being originally proposed by Bing Xia [1]. In d+Au and Au+Au collisions we see a suppression of the RI in high momentum regions and an enhancement of the RI in low momentum regions. The enhancement and suppression is a result of jet quenching due to the quark gluon plasma being created in both of these collisions. While the IAA plots for He+Au collisions conformed to the trend set by Au+Au and d+Au collisions, the RI plots deviated from the trend. Instead, we found suppression in low momentum regions and an enhancement in high momentum regions. In an effort to explain this deviation, detector modifications were checked and the effect of hydrodynamic flow was also checked. While there is a possibility that the geometry of helium-3 may have affected hydrodynamic flow, simulations implied that this is not the case. This result implies that these collisions should be looked into further.

Committee: Justin Frantz Dr. (Advisor) Subjects: Physics

Doctor of Philosophy (PhD), Ohio University, 2014, Physics and Astronomy (Arts and Sciences)

Various quark gluon plasma signatures have been experimentally established in Au+Au and Pb+Pb collisions at RHIC and LHC, such as elliptical flow and jet quenching. For decades, the quark gluon plasma was believed not to be created in p+A collisions. However, recent experimental discoveries of collective flow in p+Pb and d+Au collisions indicate a hot nuclear medium and a thermal equilibrium in such small systems. An energy loss analysis would be a good alternative measurement for such pictures. Di-hadron correlation measurements are widely used in jet analysis. In this study, π0 - h± azimuthal correlations and the per trigger yields in d+Au collisions at √SNN = 200 GeV are measured and compared with p+p collisions at the same energy. In order to cancel out part of the systematic uncertainties and measure the subtle jet modifications, a new quantity RI is proposed and measured from data. In central d+Au collisions, RI shows a clear suppression in large zT regions and a delicate enhancement of about 2s in low zT regions. Such jet modifications are qualitatively similar, but in a much smaller scale, to the ones observed in central Au+Au collisions, which are attributed to the jet quenching and energy loss in a quark gluon plasma created in central Au+Au collisions. No theory is available to explain this new experimental phenomenon. To constrain the cold nuclear matter effects, we perform a series of simulations to investigate the possible physics origin of these modifications. Various kT setting in Pythia and Hijing simulations are not able to reproduce the features observed in data. Also, the gluon jet mixing and nuclear modification of the parton distribution unctions are studied. None of them are sufficient to explain the RI modification observed in central d+Au collisions. No significant away-side IdA modifications is observed in peripheral d+Au collisions. This result suggests that previous unexpected RdA enhancement in peripheral d+Au collisions from π0 (open full item for complete abstract)

Committee: Justin Frantz (Advisor); Brune Carl (Committee Member); Hicks Kenneth (Committee Member); Masson Eric (Committee Member) Subjects: Nuclear Physics; Physics

PhD, University of Cincinnati, 2009, Arts and Sciences : Physics

The purpose of this study is to examine the adiabatic dynamics of heavy mesons consisting of one light quark and one heavy quark at non-zero temperature by using a conjectured equivalence between a string theory in an anti-de Sitter gravitational background with a black hole and a Yang-Mills theory at non-zero temperature. We do this by analyzing the string configurations equivalent to the mesons. We show that for certain mesons, there is a critical velocity where an adiabatically forced meson will become “dressed,” i.e., it will cease to gain momentum by increasing its speed and will instead increase its mass and slow down. The string associated with such a dressed meson assumes “drooped” configuration in which the string hangs down towards the black hole. Then at a subsequent lower velocity, the frequency of the first excited mode of the drooping string vanishes and the string becomes unstable. We present evidence that, at this instability, the two quarks of the meson dissociate and start to feel a drag force from the color degrees of freedom in the Yang-Mills thermal bath. We also discover new heavy-light stationary string configurations as well as new “glueball” string solutions.

Committee: Philip Argyres PhD (Committee Chair); Kay Kinoshita PhD (Committee Member); Frank Pinski PhD (Committee Member); L.C.R. Wijewardhana PhD (Committee Member) Subjects: Particle Physics; Physics

PHD, Kent State University, 2011, College of Arts and Sciences / Department of Physics

My area of research is experimental nuclear physics, more specifically heavy ion collisions at velocities close to the speed of light. The data analyzed comes from the STAR experiment at the Relativistic Heavy Ion Collider (RHIC), located at Brookhaven National Laboratory (BNL) in Upton, NY. At RHIC, two beams of ions travel at velocities close to the speed of light in opposite directions in a 2.4 mile ring and these beams cross at six points. RHIC has now two large experiments STAR and PHENIX. This work is done using the data collected by the STAR (Solenoidal Tracker at RHIC) detector during the year 2007 run. Collisions of heavy ions that are traveling close to the speed of light create extreme temperatures and densities, and they might produce a new form of nuclear matter. This form of matter might have existed just a few microseconds after the Big Bang. Understanding how nuclear matter behaves under these conditions might help us to know how matter behaved at the beginning of the Universe as well as to study exotic objects in the cosmos. At sufficiently high temperature and/or high densities it is believed that the protons and neutrons inside the nuclei melt to form a soup of quarks, antiquarks and gluons, called the Quark-Gluon Plasma (QGP). During the collision, thousands of new particles form due to nuclear interactions and this “fireball” expands and cools. The STAR detector can be used to search these particle tracks to look for clues about QGP creation. Striking observations from RHIC, such as partonic collectivity and jet quenching have led us to the conclusion that strongly interacting, deconfined partonic matter (sQGP) is created in Au+Au collisions at sqrt{sNN} = 200 GeV. The properties of this new matter, however are still not well understood, especially the production and properties of heavy quarks like charm and beauty. The energy loss of charm quarks showed an anomalous behavior in previous studies, which used an indirect method based on th (open full item for complete abstract)

Committee: Spyridon Margetis Dr. (Advisor); Declan Keane Dr. (Committee Member); Mark Manley Dr. (Committee Member); Sonia Kabana Dr. (Committee Member); Robert Twieg Dr. (Committee Member); Jin Ruoming Dr. (Committee Member) Subjects: Nuclear Physics