John W. Negele

Neutron star matter at sub-nuclear densities

An extremely simple form for the energy density of a nuclear many-body system derived from the two-body nucleon-nucleon interaction is used to determine the ground state configuration of matter at sub-nuclear density. As the baryon density is increased, nuclei become progressively more neutron rich until neutrons eventually escape, yielding a Coulomb lattice of bound neutron and proton clusters surrounded by a dilute neutron gas. The clusters enlarge and the lattice constant decreases with increasing density, approaching a completely uniform state near nuclear density.

CONTRIBUTIONS OF NEUTRONS TO ELASTIC ELECTRON SCATTERING FROM NUCLEI.

Abstract Previously ignored contributions from the neutron charge from factor and the spin-orbit interaction in spin unsaturated shells are investigated. It is shown that at q = 3 fm−1 approximately 30% of the total cross section in heavy nuclei arises from neutrons and that the seemingly anomalous decrease of the rms charge radius from 40Ca to 48Ca is caused by the f 7 2 neutrons. The uncertainty in the neutron charge form factor presents a serious difficulty in making accurate comparisons to theoretical models.

Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions

We present high statistics results for the structure of the nucleon from a mixed-action calculation using 2+1 flavors of asqtad sea and domain-wall valence fermions. We perform extrapolations of our data based on different chiral effective field theory schemes and compare our results with available information from phenomenology. We discuss vector and axial form factors of the nucleon, moments of generalized parton distributions, including moments of forward parton distributions, and implications for the decomposition of the nucleon spin.

Chiral Extrapolation of Lattice Moments of Proton Quark Distributions

We present the resolution of a long-standing discrepancy between the moments of parton distributions calculated from lattice QCD and their experimental values. We propose a simple extrapolation formula for the moments of the nonsinglet quark distribution u-d, as a function of quark mass, which embodies the general constraints imposed by the chiral symmetry of QCD. The inclusion of the leading nonanalytic behavior leads to an excellent description of both the lattice data and the experimental values of the moments.

Evidence for the role of instantons in hadron structure from lattice QCD.

Cooling is used as a filter on a set of gluon fields sampling the Wilson action to selectively remove essentially all fluctuations of the gluon field except for the instantons. The close agreement between quenched lattice QCD results with cooled and uncooled configurations for vacuum correlation functions of hadronic currents and for density-density correlation functions in hadronic bound states provides strong evidence for the dominant role of instantons in determining light hadron structure and quark propagation in the QCD vacuum.

Moments of nucleon generalized parton distributions in lattice QCD

Calculation of the moments of generalized parton distributions in lattice QCD requires more powerful techniques than those previously used to calculate the moments of structure functions. Hence, we present a novel approach that exploits the full information content from a given lattice configuration by measuring an overdetermined set of lattice observables to provide maximal statistical constraints on the generalized form factors at a given virtuality t. In an exploratory investigation using unquenched QCD configurations at intermediate sea quark masses, we demonstrate that our new technique is superior to conventional methods and leads to reliable numerical signals for the

Light hadron spectroscopy using domain wall valence quarks on an Asqtad sea

n=2

Moments of nucleon light cone quark distributions calculated in full lattice QCD

flavor singlet generalized form factors up to

Nucleon Axial Charge in Full Lattice QCD

3{\mathrm{GeV}}^{2}.

The determination of the nuclear charge distribution of 208Pb from elastic electron scattering and muonic X-rays

The contribution from connected diagrams in the flavor singlet sector to the total quark angular momentum is measured to an accuracy of the order of 1%.