12,421 research outputs found
Spontaneous Breaking of Chiral Symmetry as a Consequence of Confinement
We show that at the leading order in the large- expansion a lattice QCD
motivated linear rising confinement potential at large distances leads to a
non-local four-quark interaction that realizes spontaneous breaking of chiral
symmetry (SBCS) in the same way the Nambu-Jona-Lasinio model does. The
dynamical quark mass , which represents the solution of the gap-equation, is
proportional to the square root of the string tension and takes the
form at the leading order in the large- expansion
with GeV. The Nambu-Jona-Lasinio phenomenological constant
, which is responsible for SBCS, is expressed in terms of the string
tension and the confinement radius.Comment: 10 pages, 0 figures, latex, IK-TUW-Preprint 930540
Ordering variable for parton showers
The parton splittings in a parton shower are ordered according to an ordering
variable, for example the transverse momentum of the daughter partons relative
to the direction of the mother, the virtuality of the splitting, or the angle
between the daughter partons. We analyze the choice of the ordering variable
and conclude that one particular choice has the advantage of factoring softer
splittings from harder splittings graph by graph in a physical gauge.Comment: 28 pages, 5 figure
Investigation of the composition of the Luna 16 lunar sample
The concentrations of aluminum, manganese, sodium, chromium, iron, cobalt, and 12 rare earth elements were determined by neutron activation analysis using slow neutrons. Oxygen and silicon were determined using a fast neutron generator. Mossbauer spectroscopy was used to investigate iron compounds in Luna 16 regolith samples from the upper part of the core
Four-jet angular distributions and color charge measurements: leading order versus next-to-leading order
We present the next-to-leading order perturbative QCD prediction to the
four-jet angular distributions used by experimental collaborations at LEP for
measuring the QCD color charge factors. We compare our results to ALEPH data
corrected to parton level. We perform a leading order ``measurement'' of the
QCD color factor ratios by fitting the leading order perturbative predictions
to the next-to-leading order result. Our result shows that in an experimental
analysis for measuring the color charge factors the use of the O()
QCD predictions instead of the O() results may shift the center of
the fit by a relative factor of 1+2\as in the direction.Comment: 14 pages, 10 tables, 5 figures, revtex, eps style
Plastid developement and capacity of carboxylating enzymes in normal and mutant maize leaves under different illumination intensity
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