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Full-Text Articles in Physics

First Measurement Of Near-Threshold J/ᴪ Exclusive Photoproduction Off The Proton, M. Ali, M. Amaryan, E.G. Anassontzis, Q. Zhou, X. Zhou, B. Zihlmann, Gluex Collaboration Jan 2019

First Measurement Of Near-Threshold J/ᴪ Exclusive Photoproduction Off The Proton, M. Ali, M. Amaryan, E.G. Anassontzis, Q. Zhou, X. Zhou, B. Zihlmann, Gluex Collaboration

Physics Faculty Publications

We report on the measurement of the γp -> J/ψp cross section from Eγ = 11.8 GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67 ± 0.39 GeV-2 at 10.7 GeV average energy. The LHCb pentaquark candidates P+c can be produced in the s channel of this reaction. We see no evidence for them and ...


Azimuthal Anisotropy In Cu+Au Collisions At √SNn = 200 Gev, L. Adamczyk, J. R. Adams, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, Renee H. Fatemi, Suvarna Ramachandran Jul 2018

Azimuthal Anisotropy In Cu+Au Collisions At √SNn = 200 Gev, L. Adamczyk, J. R. Adams, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at √sNN = 200 GeV for harmonics n = 1–4 in the pseudorapidity range |η| < 1. The directed flow in Cu+Au collisions is compared with the rapidity-odd and, for the first time, the rapidity-even components of charged particle directed flow in Au+Au collisions at √sNN = 20 GeV. The slope of the directed flow pseudorapidity dependence in Cu+Au collisions is found to be similar to that in Au+Au collisions, with the intercept shifted toward positive pseudorapidity values, i.e., the Cu-going direction. The mean transverse momentum projected onto the spectator plane ⟨px⟩ in Cu+Au collision also exhibits approximately linear dependence on pseudorapidity with the intercept at about ...


Pulse Height Spectra Analysis Of A Neutron Energy Tuning Assembly, Jason R. Stickney Mar 2018

Pulse Height Spectra Analysis Of A Neutron Energy Tuning Assembly, Jason R. Stickney

Theses and Dissertations

An energy tuning assembly (ETA) was previously designed and built for the purpose of irradiating samples with a combination of a thermonuclear and a prompt fission neutron spectrum. Initial research was performed to characterize the performance of the ETA at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron using 33 MeV deuteron breakup on tantalum as the neutron source. This research analyzes detector responses collected from three EJ-309 detectors used to characterize the ETA generated neutron field. A signal processing chain was developed to reduce the full waveform data into a pulse height spectrum. The primary goal was to develop a ...


Systematic Study Of High-Pt Di-Jet Correlations In Nuclear Collisions With The Phenix Experiment At Rhic , Nathan Conrad Grau Jan 2005

Systematic Study Of High-Pt Di-Jet Correlations In Nuclear Collisions With The Phenix Experiment At Rhic , Nathan Conrad Grau

Retrospective Theses and Dissertations

One major goal of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory on Long Island, New York, is to create and study the quark-gluon plasma (QGP). This state of matter results from the phase transition of Quantum Chromodynamics (QCD) at extremely high temperature (1012 K) and densities (100 times normal nuclear matter). Au ions are collided in an attempt to increase the temperature necessary to cross the phase boundary. To study the properties of this new matter, high energy jets are used as a probe. Jets are a collimated spray of hadrons resulting from the fragmentation of high-energy ...


Extraction Of Jet Properties From Two Particle Azimuthal Correlations In Pp And Auau Collisions At [Square Root Of S Subscript Nn] = 200 Gev , Paul Constantin Jan 2004

Extraction Of Jet Properties From Two Particle Azimuthal Correlations In Pp And Auau Collisions At [Square Root Of S Subscript Nn] = 200 Gev , Paul Constantin

Retrospective Theses and Dissertations

Two particle azimuthal correlation functions measured in pp and AuAu collisions at sNN = 200 GeV at midrapidity with the central arms of the PHENIX detector are analyzed in order to extract the properties of hadronic jets produced in QCD vacuum and highly excited QCD media, like the jet shape parameters jT and kT, the jet conditional yields (number of associated hadrons per high pT trigger hadron) and the jet fragmentation function.;The analysis of pp data starts with the measurement of the vacuum fragmentation function from which the pT dependence of the mean fragmentation momentum fraction 〈z〉 is extracted. We ...


Theoretical Models Of Many-Quark Bound States , Richard Jeffrey Lloyd Jan 2003

Theoretical Models Of Many-Quark Bound States , Richard Jeffrey Lloyd

Retrospective Theses and Dissertations

The foundations of Many-Fermion Dynamics (MFD) are developed with special attention paid to a treatment of color and flavor degrees of freedom. From these ingredients a framework was developed to calculate the properties of many-fermion bound states. The quark implementation of MFD (MFDq) was extensively tested on the 2-body problem against the established nucleon implementation of MFD (MFDn). We were able to perform a limited set of self-consistency checks of MFDq in the 4-body problem to test a proper treatment of all computed matrix elements.;Finally, calculations are presented using MFDn to predict the properties of 4-body charmonium bound states ...


Statistical And Thermal Properties Of Mesoscopic Systems: Application To The Many-Nucleon System , Bassam A. Shehadeh Jan 2003

Statistical And Thermal Properties Of Mesoscopic Systems: Application To The Many-Nucleon System , Bassam A. Shehadeh

Retrospective Theses and Dissertations

The dissertation investigates the statistical and thermal properties of mesoscopic systems and applies it to the multi-nucleon systems. The investigation was carried out using four approaches starting from the simplest and progressing to the more sophisticated. The first approach develops and employs the three-dimensional simple harmonic oscillator (3D-SHO) quantum statistics to obtain the thermal properties of multi-particle systems. The recently discovered method that relates the single particle oscillator properties to the multi particle oscillator is applied. The approach is successful in predicting observables at temperatures beginning slightly above the ground state domain for nuclear systems. The 3D-SHO potential function is ...


Antiprotons And Other Nuclear Matters , Brett Steven Fadem Jan 2002

Antiprotons And Other Nuclear Matters , Brett Steven Fadem

Retrospective Theses and Dissertations

We present antiproton invariant multiplicities from Experiment 941 using 12 and 19 GeV/c proton beams incident upon targets of Pb, Cu and Be. Since we are currently unable to calculate antiproton yields in this regime from first principles, we must rely on empirical data in order to answer questions involving antibaryon production at these energies. Typically, the motivation for studying this topic using proton-nucleus (p-A) collisions is to shed light on antiproton production in the more complicated collisions between heavy nuclei (A-A). For this reason, this thesis will use the measured target dependence to illuminate issues relating to annihilation ...


Hadron Structures And Decays Within Quantum Chromodynamics , Alaa Abd El-Hady Jan 1998

Hadron Structures And Decays Within Quantum Chromodynamics , Alaa Abd El-Hady

Retrospective Theses and Dissertations

We have evaluated the meson spectrum using a relativistic model based on reductions of Bethe-Salpeter equation. We included one gluon exchange from Quantum Chromodynamics (QCD) and phenomenological confinement in the interaction kernel. We used an ansatz for the running of the coupling constant with the meson masses. We fitted more than forty states ranging from a hundred MeV to a few GeV using seven parameters, with root mean square deviation from experimental data of 40-50 MeV. This establishes our successful QCD-based model for many applications which we investigate;We employed our model to examine the strong interaction medium effects on ...


Ambiguities In The Definition Of Spin-Dependent Parton Distributions , Yuen-Wing Law Jan 1998

Ambiguities In The Definition Of Spin-Dependent Parton Distributions , Yuen-Wing Law

Retrospective Theses and Dissertations

We investigate the ambiguities in defining polarized parton distributions. We point out that in addition to the well-known renormalization scheme dependence in the unpolarized case, there are extra ambiguities in defining polarized parton distributions. These include the definition of [gamma]5 in d-dimension and interpretation of the anomalous contribution. Here, a new renormalization/factorization scheme called UV Subtraction (UVS) is proposed. In the new UVS scheme, it exploits the freedom in renormalization to eliminate the ambiguities arising from [gamma]5 and anomalous contribution. We also discuss the consequences of these ambiguities on the calculable short-distance partonic hard parts and corresponding ...


Qcd Near The Light Front , Thomas John Fields Jan 1996

Qcd Near The Light Front , Thomas John Fields

Retrospective Theses and Dissertations

In this thesis, we propose a set of techniques to study the non-perturbative behavior of quantum field theories. These techniques include the use of near light front coordinates and a theory of effective Hamiltonians;Our ultimate goal will be to apply these methods to quantum electrodynamics (QED) and quantum chromodynamics (QCD). As a first test we will investigate simplified versions of QED and QCD with these methods over all ranges or their coupling constants;First, we solve the Schwinger model, which is QED in one space and one time dimension. We use this test model in both the massless and ...


Direct Photon Production In A Nuclear Environment , Xiaofeng Guo Jan 1996

Direct Photon Production In A Nuclear Environment , Xiaofeng Guo

Retrospective Theses and Dissertations

The photon is a very good probe of short distance physics in strong interactions. It can be produced directly at short-distance or through fragmentation processes. Through one-loop order in perturbation theory of quantum chromodynamics (QCD), this thesis provides complete analytic expressions for both the inclusive and the isolated prompt photon production cross sections in hadronic final states of e+e- annihilations. It is the first time that the full angular dependence of the cross sections is derived. Extraction of photon fragmentation functions from e+e- annihilations is addressed. Using e+e-→[gamma]+X as an example, this work demonstrates for ...


High-Spin [Gamma]-Ray Spectroscopy In 198bi, Superdeformation In 191au, And Multi-Photon Resonances In Low Energy E+E- Scattering , Duc Ta Vo Jan 1993

High-Spin [Gamma]-Ray Spectroscopy In 198bi, Superdeformation In 191au, And Multi-Photon Resonances In Low Energy E+E- Scattering , Duc Ta Vo

Retrospective Theses and Dissertations

The properties of low-and high-spin levels in [superscript]198Bi have been studied with the [superscript]181Ta([superscript]22Ne,5n)[superscript]198Bi reaction at 116 MeV and 120 MeV bombarding energies. Levels along and near the yrast lines, including one isomer, were established up to spin J ≈ 30\hbar. The main configurations of these states are suggested to be [pi] h[subscript]9/2 coupled to the known excited states in [superscript]197Pb. A sequence of states built on the excitation of the odd proton (coupled to one, two, or three quasi neutron-holes) was observed. In addition, at least two collective ...


Applications Of The Bethe-Salpeter Equation In Nuclear Physics , John R. Spence Jan 1989

Applications Of The Bethe-Salpeter Equation In Nuclear Physics , John R. Spence

Retrospective Theses and Dissertations

This work reports the study of techniques for solving the Bethe-Salpeter equation with a confinement kernel and reports the foundation of a program for constructing a relativistic model of the hadrons based upon the Bethe-Salpeter equation. The techniques described here represent a solution of the problem of constructing a relativistic model for the mesons. General methods are given for defining a confinement kernel in momentum space, of transforming the confinement kernel into an integrodifferential operator, and for solving the integral equations which result from applying these procedures to the Bethe-Salpeter equation;Momentum space eigenfunctions for charmonium are obtained and found ...


Nonstrange Baryon Properties From One-Gluon Exchange And Linear Confinement Between Quarks , Mark Linden Kiefer Jan 1983

Nonstrange Baryon Properties From One-Gluon Exchange And Linear Confinement Between Quarks , Mark Linden Kiefer

Retrospective Theses and Dissertations

We present a model of the quark structure of nonstrange baryons. We use quasi-quarks whose masses are roughly 1/3 the proton mass and which interact via one-gluon exchange and linear confining two-body potentials. The model is semirelativistic in that the quark kinetic energies and the one-gluon exchange potential include the lowest order, nonrelativistic terms plus the first order relativistic corrections. The three quark Hamiltonian is diagonalized in a harmonic oscillator basis using all states up to 6(omega) of excitation energy. The basis states have the center of mass motion explicitly factored out and are overall antisymmetric in the ...