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in subjects: "Relativity Theory"

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E. Cartan moment of rotation in classical and quantum gravity. Final report

The geometric construction of the E. Cartan moment of rotation associated to the spacetime curvature provides a geometric interpretation of the gravitational field sources and describes geometrically how the sources are ``wired`` to the field in standard geometrodynamics. E. Cartan moment of rotation yields an alternate way (as opposed to using variational principles) to obtain Einstein equations. The E. Cartan construction uses in an essential way the soldering structure of the frame bundle un… more

Date: May 25, 1994

Creator: Kheyfets, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Round table discussion. Relativistic approaches to hadrons and nuclei at medium energies

The purpose of these discussions is to illuminate a variety of different approaches to the nonperturbative dynamics of hadrons and nuclei at medium energies.

Date: December 1, 1995

Creator: Coester, F.; Karmanov, V.A. & Lev, F.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Computing spacetime curvature via differential-algebraic equations

The equations that govern the behavior of physical systems can often solved numerically using a method of lines approach and differential-algebraic equation (DAE) solvers. For example, such an approach can be used to solve the Einstein field equations of general relativity, and thereby simulate significant astrophysical events. In this paper, we describe some preliminary work in which two model problems in general relativity are formulated, spatially discretized, and then numerically solved as … more

Date: January 1, 1996

Creator: Ashby, S. F.; Lee, S. L.; Petzold, L. R.; Saylor, P. E. & Seidel, E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Some thoughts on discrete physics and the reconstruction of quantum mechanics

The authors explore how relativistic quantum mechanics might be reconstructed on a finite and discrete basis, starting from the observation that strong interactions break scale invariance at the pion Compton wavelength and provide an event horizon for space-time description. Regions of this size act coherently, and can only be explored by studying the momentum and quantum number distribution of particles produced in high energy collisions that attempt to probe them. This leads to the concept of… more

Date: April 1, 1996

Creator: Noyes, H. Pierre

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Use of the Lorentz-Operator in Relativistic Quantum Mechanics to Guarentee a Single-Energy Root

The Lorentz-operator form of relativistic quantum mechanics, with relativistic wave equation i{h_bar}{partial_derivative}{psi}/{partial_derivative}t=(mc{sup 2}{gamma}+e{Phi}){psi}, is implemented to guarantee a single-energy root. The Lorentz factor as modified by Pauli's ansatz is given by {gamma}={radical}1+[{rvec {sigma}}{center_dot}(i{h_bar}{rvec {del}}+(e/c){rvec A})]{sup 2}/m{sup 2}c{sup 2}, such that the theory is appropriate for electrons. Magnetic fine structure in the Lorentz relativi… more

Date: August 1, 1998

Creator: Ritchie, A. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Electron-deuteron scattering in a relativistic theory of hadrons

The author reviews a three-dimensional formalism that provides a systematic way to include relativistic effects including relativistic kinematics, the effects of negative-energy states, and the boosts of the two-body system in calculations of two-body bound-states. He then explains how to construct a conserved current within this relativistic three-dimensional approach. This general theoretical framework is specifically applied to electron-deuteron scattering both in impulse approximation and w… more

Date: November 1, 1998

Creator: Phillips, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Massively parallel fast elliptic equation solver for three dimensional hydrodynamics and relativity

Through the work proposed in this document we expect to advance the forefront of large scale computational efforts on massively parallel distributed-memory multiprocessors. We will develop tools for effective conversion to a parallel implementation of sequential numerical methods used to solve large systems of partial differential equations. The research supported by this work will involve conversion of a program which does state of the art modeling of multi-dimensional hydrodynamics, general r… more

Date: January 1, 1995

Creator: Sholl, P. L.; Wilson, J. R.; Mathews, G. J. & Avila, J. H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Accretion onto black holes: The power generating mechanism

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The physical relationships among accretion disks, quasars, black holes, collimated radio sources and galactic dynamos previously has been only weakly related without explicit cause and effect. We have constructed a physical evolution from large, primordial density perturbations to {open_quotes}damped Lyman alpha clouds,{close_quotes} to galaxy formation… more

Date: December 31, 1998

Creator: Colgate, S.A.; Hills, J.G. & Miller, W.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Heavy mesons in a relativistic model

Motivated by the present interest in the heavy quark effective theory, the authors use the spectator equations to treat the mesonic bound states of heavy quarks. The kernel they use is based on scalar confining and vector Coulomb potentials. Wave functions are treated to leading order and energies to order 1/m{sub Q} in the heavy-light systems, and order 1/m{sub Q{sup 2}} in heavy-heavy systems. Their results are in reasonable agreement with experimental measurements. They estimate two of the p… more

Date: December 1, 1994

Creator: Zeng, J.; Orden, J. & Roberts, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

E=mc{sup 2}: A hands-on exploration of Einstein's famous formula. Technical Report, 09/01/92-03/04/98

The finished product is a museum exhibition of approximately 600 sq.ft. It consists of three exhibit elements and a colorful enclosure with text explanations, diagrams and photos. The combined exhibit elements, including an original video, explain in a hands-on, interactive way, the meaning of Einstein's famous equation E=mc{sup 2}.

Date: February 3, 2000

Creator: Malamud, Dr. Ernest; Snow, Dr. Gregory & O'Connor, Charles

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Interpreting the neutron's electric form factor: Rest frame charge distribution or foldy term?

The neutron's electric form factor contains vital information on nucleon structure, but its interpretation within many models has been obscured by relativistic effects. The author demonstrates that, to leading order in the relativistic expansion of a constituent quark model, the Foldy term cancels exactly against a contribution to the Dirac form factor F{sub 1} to leave intact the naive interpretation of G{sup n}{sub E} as arising from the neutron's rest frame charge distribution.

Date: December 1, 1998

Creator: Isgur, Nathan

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Consistent relativistic treatment of the structure of the deuteron and its electromagnetic interactions

Relativistic calculations of deuteron static properties, the triton binding energy, and deuteron form factors are presented. The results show that the covariant formalism is capable of replacing nonrelativistic quantum mechanics, at least for the description of two and three body systems, and that some significant new insights emerge when the dynamics is described relativistically.

Date: February 1, 1996

Creator: Gross, Franz

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Relativistic nuclear Hamiltonian and currents to (v/c){sub 2}.

Relativistic Hamiltonians are defines as the sum of relativistic one-body kinetic energies and many-body interactions and their boost corrections. The calculation of the latter from commutation relations of the Poincare group is reviewed. It is shown that the most important terms can be understood from classical relativistic mechanics. The constraints of relativistic covariance on the charge and current densities are examined. Nuclear charge and current operators that satisfy them up to order (… more

Date: August 1, 1995

Creator: Schiavilla, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Light-cone quark model predictions for radiative meson decays

The authors investigate the radiative decays of pseudoscalar ({pi}, {Kappa}, {eta}, {eta}{prime}), vector ({rho}, {Kappa}{sup *}, {omega}, {phi}) and axial vector ({Alpha}{sub 1}) mesons using a simple relativistic constituent quark model. For both simplicity and relativity, they take advantage of the distinguished features in the light-cone quantization method; (1) the Fock-state expansion of meson wavefunctions are not contaminated by the vacuum fluctuation, (2) the problem of assigning quant… more

Date: June 1, 1996

Creator: Choi, H.M. & Ji, Chueng-Ryong

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The effects of general relativity on core collapse supernovae

The effects of general relativity (GR) on the hydrodynamics and neutrino transport are examined during the critical shock reheating phase of core collapse supernovae. The authors find that core collapse computed with GR hydrodynamics results in a substantially more compact core structure out to the shock, the shock radius at stagnation being reduced by a factor of 2. The inflow speed of material behind the shock is also increased by a factor of 2 throughout most of the evolution. They have deve… more

Date: December 1, 1997

Creator: De Nisco, K. R.; Bruenn, S. W. & Mezzacappa, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Relativistic charge form factor of the deuteron

Relativistic integral representation in terms of experimental neutron-proton scattering phase shifts alone is used to compute the charge form factor of the deuteron G{sub Cd}(Q{sup 2}). The results of numerical calculations of {vert_bar}G{sub Cd}(Q{sup 2}){vert_bar} are presented in the interval of the four-momentum transfers squared 0 {<=} Q{sup 2} {<=} 35 fm{sup {minus}2}. Zero and the prominent secondary maximum in {vert_bar}G{sub Cd}(Q{sup 2}){vert_bar} are the direct consequences of … more

Date: December 1, 1997

Creator: Afanasev, Andrei V.; Afanasev, V.D. & Trubnikov, S.V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Relativistic calculation of the triton binding energy and its implications

First results for the triton binding energy obtained from the relativistic spectator or Gross equation are reported. The Dirac structure of the nucleons is taken into account. Numerical results are presented for a family of realistic OBE models with off-shell scalar couplings. It is shown that these off-shell couplings improve both the fits to the two-body data and the predictions for the binding energy.

Date: July 1, 1996

Creator: Stadler, Alfred & Gross, Franz

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Gravitational coupling to two-particle bound states and momentum conservation in deep inelastic scattering

The momentum conservation sum rule for deep inelastic scattering (DIS) from composite particles is investigated using the general theory of relativity. For two 1+1 dimensional examples, it shown that covariant theories automatically satisfy the DIS momentum conservation sum rule provided the bound state is covariantly normalized. Therefore, in these cases, the two DIS sum rules for baryon conservation and momentum are equivalent.

Date: August 1, 1999

Creator: Batiz, Zoltan & Gross, Franz

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effects of relativistic dynamics in pp {r_arrow} pp{pi}{sup 0} near threshold

The cross-section for threshold {pi}{sup 0} production in proton-proton collisions is evaluated in the framework of the covariant spectator description. The negative energy intermediate states are included non-perturbatively and seen to yield a considerably smaller contribution, when compared to perturbative treatments. A family of OBE-models with different off-shell scalar coupling is considered.

Date: February 1, 1997

Creator: J. Adam, Jr.; Stadler, Alfred; Pena, M. T. & Gross, Franz

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Relativistic theory of few body systems and their electromagnetic interactions

Recent results obtained from the manifestly covariant spectator theory are summarized. A recent unpublished best fit to NN scattering using 13 OBE parameters gives x{sup 2}=2.25 and a triton binding energy of {minus}8.491 MeV. This agreement is possible because of the existence of off-shell coupling of the phenomenological, intermediate range effective scalar exchanges (both isoscalar and isovector). The previously published results for the deuteron form factors are reviewed, and new, prelimina… more

Date: May 1, 1998

Creator: Gross, Franz

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Non-perturbative dynamics of the heavy-light quark system in the non-recoil limit

Starting from the relativistic gauge-invariant quark-antiquark Green function the authors obtain the relevant interaction in the one-body limit, which can be interpreted as the kernel of a non-perturbative Dirac equation. They study this kernel in different kinematic regions, reproducing, in particular, for heavy quark the potential case and sum rules results. They discuss the relevance of the result for heavy-light mesons and the relation with the phenomenological Dirac equations used up to no… more

Date: March 1, 1997

Creator: Brambilla, N. & Vairo, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Low energy theorem for scalar and vector interactions of a composite spin-1/2 system

Scalar and vector interactions, with the scalar interaction coupled to a composite spin-1/2 system so as to cause a shift of its mass, are shown to obey a low-energy theorem which guarantees that the second order interaction due to z-graphs is the same as for a point Dirac particle. Off-shell and contact interactions appropriate to the composite system cancel and this is verified in a model of a composite fermion. The result provides a justification for the use of the Dirac equation as it has b… more

Date: July 1, 1994

Creator: Wallace, S. J.; Gross, Franz & Tjon, J. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Normalization of the covariant three-body bound state vertex function

The normalization condition for the relativistic three nucleon Bethe-Salpeter and Gross bound state vertex functions is derived, for the first time, directly from the three body wave equations. It is also shown that the relativistic normalization condition for the two body Gross bound state vertex function is identical to the requirement that the bound state charge be conserved, proving that charge is automatically conserved by this equation.

Date: February 1, 1997

Creator: J. Adam, Jr.; Gross, Franz; Savkli, Cetin & Orden, J.W. Van

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Baryon current matrix elements in a light-front framework

Current matrix elements and observables for electro- and photo-excitation of baryons from the nucleon are studied in a light-front framework. Relativistic effects are estimated by comparison to a nonrelativistic model, where the authors use simple basis states to represent the baryon wavefunctions. Sizeable relativistic effects are found for certain transitions, for example, to radial excitations such as that conventionally used to describe to the Roper resonance. A systematic study shows that … more

Date: November 1, 1994

Creator: Capstick, S. & Keister, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department