68,051 research outputs found
Effective Operator Treatment of the Lipkin Model
We analyze the Lipkin Model using effective operator techniques. We present
both analytical and numerical results for effective Hamiltonians. The accuracy
of the cluster approximation is investigated.Comment: To appear in Phys.Rev.
Diffractive heavy pseudoscalar-meson productions by weak neutral currents
A first theoretical study for neutrino-induced diffractive productions of
heavy pseudoscalar-mesons, \eta_c and \eta_b, off a nucleon is performed based
on factorization formalism in QCD. We evaluate the forward diffractive
production cross section in perturbative QCD in terms of the light-cone wave
functions of Z boson and \eta_{c,b} mesons, and the gluon distribution of the
nucleon. The diffractive production of \eta_c is governed by the axial vector
coupling of the longitudinally polarized Z boson to Q\bar{Q} pair, and the
resulting \eta_c production cross section is larger than the J/\psi one by one
order of magnitude. The bottomonium \eta_b production, which shows up for
higher beam energy, is also discussed.Comment: 5 pages with 3 embedded figures. Talk presented at the 15th
International Spin Physics Symposium, Spin 2002, Brookhaven National
Laboratory, September 9-14, 200
Structure of the constituent quark and quark distributions of hadrons
We study the structure of constituent quarks by dressing bare quarks with the
Goldstone bosons and its implications for quark distribution functions of
hadrons , and . In particular we discuss effects of
the dressing on the nucleon spin structure, and find that contributions to
chiral-odd is quite different from those to , which can be
measured in the semi-inclusive polarized deep inelastic scattering.Comment: 7 pages, LaTeX, 4 figures are included using epsfig.sty, talk
presented at QULEN97, to appear in the proceedings, Complete PS fils is also
available at http://WWW.physik.tu-muenchen.de/~ksuzuki/publication.htm
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