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in subjects: "Correlation Functions"

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Pion correlations as a function of atomic mass in heavy ion collisions

The method of two pion interferometry was used to obtain source-size and lifetime parameters for the pions produced in heavy ion collisions. The systems used were 1.70 {center dot} A GeV {sup 56}Fe + Fe, 1.82 {center dot} A GeV {sup 40}Ar + KCl and 1.54 {center dot} A GeV {sup 93}Nb + Nb, allowing for a search for dependences on the atomic number. Two acceptances (centered, in the lab., at {approximately} 0{degrees} and 45{degrees}) were used for each system, allowing a search for dependences o… more

Date: November 26, 1989

Creator: Chacon, A.D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

The interpretation of reflectometry measurements of plasma fluctuations

Wave reflections from density fluctuations with magnitudes and frequencies typical of drift waves have been investigated. Both drift waves and the reflected phase and amplitude depend on the density gradient scale length, and this common feature implies that both the angular deviation of a normally propagating wave and the phase change on reflection are of order unity. Thus the surface will always appear rough'' and amplitude variations will always be large. For smaller amplitude waves numerica… more

Date: October 1, 1991

Creator: Bretz, N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Lattice gaugefixing and other optics in lattice gauge theory

We present results from four projects. In the first, quark and gluon propagators and effective masses and {Delta}I = 1/2 Rule operator matching coefficients are computed numerically in gaugefixed lattice QCD. In the second, the same quantities are evaluated analytically in the strong coupling, N {yields} {infinity} limit. In the third project, the Schwinger model is studied in covariant gauges, where we show that the effective electron mass varies with the gauge parameter and that longitudinal … more

Date: June 1, 1992

Creator: Yee, Ken.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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An iterative algorithm to produce a positive definite correlation matrix from an approximate correlation matrix (with a program user's guide)

This report contains an explanation of an algorithm that, when executed, will operate on any symmetric approximate correlation matrix by iteratively adjusting the eigenvalues of this matrix. The objective of this algorithm is to produce a valid, positive definite, correlation matrix. Also a description of a program (called POSDEF) which implements the algorithm is given.

Date: June 1, 1982

Creator: Iman, R.L. & Davenport, J.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Bose-Einstein correlations in e/sup +/e/sup -/ collisions

The MARK II detector is used to study the Bose-Einstein correlation between pairs and triplets of charged pions produced in hadronic decays of the J)psi), the ..sqrt..s = 4 to 7 GeV continuum above the J)psi), two photon events at ..sqrt..s = 29 GeV, and e/sup )plus/)e/sup )minus/) annihilation events at ..sqrt..s = 29 GeV as a function of Q/sup 2/, the four-momentum transfer squared. After corrections for Coulomb effects and pion misidentification, we find a nearly full Bose-Einstein enhanceme… more

Date: December 1, 1987

Creator: Juricic, I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Unusual initial and final state effects in quantum chromodynamics

We have constructed a number of fundamental tests which can be used to probe discrete symmetries, and their possible violations, in the required new physics'' beyond the standard model. On-going experiments with unpolarized e{sup {minus}}e{sup +} collisions contain many events for the production-decay sequence e{sup {minus}}e{sup +} {yields} Z{degrees}, {gamma}* {yields} {tau}{sup {minus}}{tau}{sup +} {yields} (A{sup {minus}X}) (B{sup +}X). From the beam referenced spin-correlation function for… more

Date: December 1, 1991

Creator: Nelson, C.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Static and dynamic spin fluctuations in the spin glass doping regime in La sub 2-x Sr sub x CuO sub 4+y

We review the results of neutron scattering studies of the static and dynamic spin fluctuations crystals of La{sub 2-x}Sr{sub x}CuO{sub 4+{delta}} in the doping regime intermediate between the Neel and superconducting regions. In this regime the in-plane resistance is linear in temperature down to {approximately}80 K with a crossover due to logarithmic conductance effects at lower temperatures. The static spin correlations are well-described by a simple model in which the inverse correlation le… more

Date: January 1, 1991

Creator: Birgeneau, R.J.; Belk, N.; Kastner, M.A.; Keimer, B. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics); Endoh, Y. (Tohoku Univ., Sendai (Japan). Dept. of Physics); Erwin, R.W. (National Inst. of Standards and Technology, Gaithersburg, MD (United States)) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Microscopic calculations of nuclear structure and nuclear correlations

A major goal in nuclear physics is to understand how nuclear structure comes about from the underlying interactions between nucleons. This requires modelling nuclei as collections of strongly interacting particles. Using realistic nucleon-nucleon potentials, supplemented with consistent three-nucleon potentials and two-body electroweak current operators, variational Monte Carlo methods are used to calculate nuclear ground-state properties, such as the binding energy, electromagnetic form factor… more

Date: January 1, 1992

Creator: Wiringa, R.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Correlation theory applied to the static and dynamic properties of EuO and EuS

The paramagnetic scattering was recently measured for EuO. It was found that spin-wave-like excitations develop for wave vectors approaching the zone boundary. The spectrum was found to be well described by damped harmonic oscillators (also called the two-pole-approximation). This approximation was used previously in the correlation theory primarily to calculate static properties. Selfconsistent dynamic and static calculations have been performed for EuO, which is an ideal Heisenberg magnet wit… more

Date: October 1, 1981

Creator: Lindgard, P.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Interferometric studies from p-p-fragment coincidences

Exclusive p-p correlations from the {sup 58}Ni + {sup 58}Ni reaction have been measured at an incident energy of 850 MeV. The enhancement in the p-p correlation function for small {Delta}p is satisfactorily explained by p-p final-state interaction effects. the observed enhancement is found to depend on the relative angle between the fragment and p-p c.m. velocities. The observed dependence of the p-p coincidence yield on the orientation of {Delta}p with respect to the plane spanned by the fragm… more

Date: January 1, 1991

Creator: Korolija, M. (Institut Rudjer Boskovic, Zagreb (Yugoslavia) Joint Inst. for Heavy Ion Research, Oak Ridge, TN (United States)); Shapira, D.; Gomez del Campo, J.; Kim, H.J. (Oak Ridge National Lab., TN (United States)); Cindro, N. (Institut Rudjer Boskovic, Zagreb (Yugoslavia)); Teh, K. (Joint Inst. for Heavy Ion Research, Oak Ridge, TN (United States)) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Improved methods for computing masses from numerical simulations

An important advance in the computation of hadron and glueball masses has been the introduction of non-local operators. This talk summarizes the critical signal-to-noise ratio of glueball correlation functions in the continuum limit, and discusses the case of (q{bar q} and qqq) hadrons in the chiral limit. A new strategy for extracting the masses of excited states is outlined and tested. The lessons learned here suggest that gauge-fixed momentum-space operators might be a suitable choice of int… more

Date: November 22, 1989

Creator: Kronfeld, A.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Interparticle interactions and polarization effects in colloids

The physics of simple colloidal systems is usually dominated by three independent length scales: the particle size, the average interparticle distance, and the range of the interparticle potential. The dispersed particles typically have characteristic dimensions in the range 5 to 100 nm, often with spherical or cylindrical symmetry. Dispersion densities vary over volume fractions ranging from 0.5 to 10/sup -4/, with the corresponding mean interparticle distances ranging from about 1 to 10 diame… more

Date: January 1, 1987

Creator: Hayter, J. B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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On the causes of compositional order in the Ni sub c Pt sub (1-c) alloys

We review, briefly, the arguments which gave rise to the current controversy concerning the origin of compositional order in Ni{sub c}Pt{sub 1-c} alloys. We note that strain fluctuations play an important role in determining the state of compositional order in this system and outline a theoretical framework that takes account of them. 29 refs., 4 figs.

Date: January 1, 1991

Creator: Gyorffy, B.L. (Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.); Pinski, F.J. (Cincinnati Univ., OH (United States). Dept. of Physics); Ginatempo, B. (Messina Univ. (Italy). Ist. di Fisica Teorica); Johnson, D.D. (Sandia National Labs., Albuquerque, NM (United States)); Staunton, J.B. (Warwick Univ., Coventry (United Kingdom). Dept. of Physics); Shelton, W.A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Some exact results for the two-point function of an integrable quantum field theory

The two point correlation function for the quantum nonlinear Schroedinger (delta-function gas) model is studied. An infinite series representation for this function is derived using the quantum inverse scattering formalism. For the case of zero temperature, the infinite coupling (c ..-->.. infinity) result of Jimbo, Miwa, Mori and Sato is extended to give an exact expression for the order 1/c correction to the two point function in terms of a Painleve transcendent of the fifth kind.

Date: February 1, 1981

Creator: Creamer, D.B.; Thacker, H.B. & Wilkinson, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Meson and baryon correlation studies using the PEP-TPC/2. gamma. Facility

Results on vector meson, and strange and charmed-baryon production are presented for data taken during the period 1982--1986 using the TPC/2{gamma} detector at PEP. Vector mesons ({rho}{sup 0}, K{sup *} and {phi}) with 0, 1 and 2 strange quarks are used to obtain redundant measures of strange-quark suppression and of the vector to pseudoscalar ratio in hadronization. Measurements of the production rates of {Lambda}, {Xi}{sup {minus}}, {Omega} and {Xi}{sup *0} hyperons and for the {Lambda}{sub c… more

Date: March 1, 1991

Creator: Ronan, M.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Magnetic excitations above the critical temperature

No Description Available.

Date: October 1, 1975

Creator: Swanson, P. A.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Search for the quark-gluon plasma (1989): The NA35 experiment at the CERN SPS

Results from the NA35 experiment at the CERN SPS are described in the context of possible formation and identification of a quark-gluon plasma (QGP). Evidence is presented that the initial energy density and temperature are sufficient for the QGP to be produced, and that hydrodynamic flow occurs in the expansion stage. Evidence for an unexpectedly large pion source size and for enhanced strangeness production is presented, and discussed in terms of QGP formation. Plans for experiments in 1990--… more

Date: September 1, 1989

Creator: Pugh, H.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Introduction to lattice gauge theory

The lattice formulation of Quantum Field Theory (QFT) can be exploited in many ways. We can derive the lattice Feynman rules and carry out weak coupling perturbation expansions. The lattice then serves as a manifestly gauge invariant regularization scheme, albeit one that is more complicated than standard continuum schemes. Strong coupling expansions: these give us useful qualitative information, but unfortunately no hard numbers. The lattice theory is amenable to numerical simulations by which… more

Date: January 1, 1987

Creator: Gupta, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Jet physics at PEP and PETRA

Recent data on the fragmentation of quarks at PEP and PETRA energies is discussed in the context of phenomenological models of parton fragmentation. Emphasis is placed on the experimental evidence for parton showers as compared to a fixed order QCD treatment, on new data on inclusive hadron production and on detailed studies of baryon production in jets. 63 refs., 22 figs., 3 tabs.

Date: September 1, 1987

Creator: Hofmann, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Cosmological Analysis From Large-Scale Anisotropic Correlation Function of the Sloan Digital Sky Survey

No Description Available.

Date: March 1, 2008

Creator: Okumura, Teppei & U., /Nagoya

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Neutral Kaon Interferometry in Au+Au collisions at sqrt(s_NN) =200 GeV

We present the first statistically meaningful results fromtwo-K0s interferometry in heavy-ion collisions. A model that takes theeffect of the strong interaction into account has been used to fit themeasured correlation function. The effects of single and coupled channelwere explored. At the mean transverse mass m_T = 1.07 GeV, we obtain thevalues R = 4.09 +- 0.46 (stat.) +- 0.31 (sys) fm and lambda = 0.92 +-0.23 (stat) +- 0.13 (sys), where R and lambda are the invariant radiusand chaoticity par… more

Date: August 5, 2006

Creator: Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

QCD Evolution of the Transverse Momentum Dependent Correlations

We study the QCD evolution for the twist-three quark-gluon correlation functions associated with the transverse momentum odd quark distributions. Different from that for the leading twist quark distributions, these evolution equations involve more general twist-three functions beyond the correlation functions themselves. They provide important information on nucleon structure, and can be studied in the semi-inclusive hadron production in deep inelastic scattering and Drell-Yan lepton pair produ… more

Date: December 10, 2008

Creator: Zhou, Jian; Liang, Zuo-Tang & Yuan, Feng

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Chemical reaction rates using the semiclassical Van-Vleck initialvalue representation

A semiclassical IVR formulation using the Van-Vleck propagator has been used to calculate the flux correlation function and thereby reaction rate constants. This Van-Vleck formulation of the flux-flux correlation function is computationally as simple as the classical Wigner model. However unlike the latter, it has the ability to capture quantum interference/coherence effects. Classical trajectories are evolved starting from the dividing surface that separates reactants and products, and are evo… more

Date: November 29, 2006

Creator: Venkataraman, Charulatha & Miller, William H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Test of the consistency of various linearized semiclassical initial value time correlation functions in application to inelastic neutron scattering from liquid para-hydrogen

The linearized approximation to the semiclassical initial value representation (LSC-IVR) is used to calculate time correlation functions relevant to the incoherent dynamic structure factor for inelastic neutron scattering from liquid para-hydrogen at 14 K. Various time correlations functions were used which, if evaluated exactly, would give identical results, but they do not because the LSC-IVR is approximate. Some of the correlation functions involve only linear operators, and others involve n… more

Date: March 15, 2008

Creator: Miller, William; Liu, Jian & Miller, William H.

Item Type: Article

Partner: UNT Libraries Government Documents Department