370 research outputs found
New approach to He charge distribution
We present a study of the He charge distribution based on realistic
nucleonic wave functions and incorporation of the nucleon's quark substructure.
The central depression of the proton point density seen in modern four-body
calculations is too small by itself to lead to a correct description of the
charge distribution. We utilize six-quark structures calculated in the
Chromodielectric Model for N-N interactions, and we find a swelling of the
proton charge distribution as the internucleon distance decreases. These charge
distributions are combined with the He wave function using the Independent
Pair Approximation and two-body distributions generated from Green's Function
Monte Carlo calculations. We obtain a reasonably good fit to the experimental
charge distribution without including meson exchange currents.Comment: 9 pages, LaTeX, 4 figures (Figures 1 and 2 doesn't exist as
postscript files : they are only available on request
The Spiritual Life in the Twenty-first Century: Solidarity with the Victims of Violence
In order to give a religious answer to the question, ʻWhat is religiouslife?ʼ in the twenty-first century I propose to give a meditation on thefamous story of the Good Samaritan. Clearly this story concerns itselfsolidarity with a victim, and so it presents itself as very germane to theposition I wish to explore. At the same time it has some surprising twiststhat can help us to understand the implications of trying to live a religiouslife based upon the relationship with a victim
Organocatalysis with Endogenous Compounds: Towards Novel Non-enzymatic Reactions
The aldol reaction of the endogeneous compounds acetone and methylglyoxal has been studied using organocatalysis in relation to biologically relevant non-enzymatic reactions. Under preparative conditions, 3-hydroxy-2,5-hexadione, known as Henze’s ketol, is formed in high yield and with enantioselectivities up to 88% ee. Furthermore, Henze’s ketol is also formed under simulated physiological conditions at micromolar scale, indicating that this reaction might take place in living organisms
Parton Distributions for the Octet and Decuplet Baryons
We calculate the parton distributions for both polarized and unpolarized
octet and decuplet baryons, using the MIT bag, dressed by mesons. We show that
the hyperfine interaction responsible for the and splittings leads to large deviations from SU(3) and SU(6) predictions.
For the we find significant polarized, non-strange parton
distributions which lead to a sizable polarization in polarized,
semi-inclusive scattering. We also discuss the flavour symmetry violation
arising from the meson-cloud associated with the chiral structure of baryons.Comment: 29 pages, 15 figure
Lambda Polarization in Polarized Proton-Proton Collisions at RHIC
We discuss Lambda polarization in semi-inclusive proton-proton collisions,
with one of the protons longitudinally polarized. The hyperfine interaction
responsible for the - and - mass splittings gives
rise to flavor asymmetric fragmentation functions and to sizable polarized
non-strange fragmentation functions. We predict large positive Lambda
polarization in polarized proton-proton collisions at large rapidities of the
produced Lambda, while other models, based on SU(3) flavor symmetric
fragmentation functions, predict zero or negative Lambda polarization. The
effect of and decays is also discussed. Forthcoming
experiments at RHIC will be able to differentiate between these predictions.Comment: 18 pages, 5 figure
Structure and Production of Lambda Baryons
We discuss the quark parton structure of the baryon and the
fragmentation of quarks into baryons. We show that the hyperfine
interaction, responsible for the - and - mass
splittings, leads not only to sizeable SU(3) and SU(6) symmetry breaking in the
quark distributions of the , but also to significant polarized
non-strange quark distributions. The same arguments suggest flavor asymmetric
quark fragmentation functions and non-zero polarized non-strange quark
fragmentation functions. The calculated fragmentation functions give a good
description of all measured observables. We predict significant positive
polarization in semi-inclusive DIS experiments while models based on
SU(3) flavor symmetry predict zero or negative polarization. Our
approach also provides a natural explanation for the dependence of the maximum
of the spectrum on the mass of the particles produced in
annihilation.Comment: 24 pages, 9 figures, minor change
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