3,133 research outputs found
On the determination of the pion effective mass in nuclei from pionic atoms
The binding energies of the deeply bound 1s and 2p states in pionic atoms of
Pb, recently established experimentally in the Pb(d,He)
reaction, have been used by several groups to derive the pion effective mass in
nuclear matter. We show that these binding energies are fully consistent with
`normal' pionic atoms and that the real part of the pion-nucleus potential at
the center of Pb is 283 MeV and not 20 MeV as suggested
previously.Comment: 8 pages, Revtex, 2 figures, accepted by Physics Letters
Properties of Color-Coulomb String Tension
We study the properties of the color-Coulomb string tension obtained from the
instantaneous part of gluon propagators in Coulomb gauge using quenched SU(3)
lattice simulation.
In the confinement phase, the dependence of the color-Coulomb string tension
on the QCD coupling constant is smaller than that of the Wilson loop string
tension. On the other hand, in the deconfinement phase, the color-Coulomb
string tension does not vanish even for , the temperature
dependence of which is comparable with the magnetic scaling, dominating the
high temperature QCD. Thus, the color-Coulomb string tension is not an order
parameter of QGP phase transition.Comment: 17 pages, 5 figures; one new figure added, typos corrected, version
to appear in PR
Infrared behavior of the Faddeev-Popov operator in Coulomb gauge QCD
We calculate the eigenvalue distribution of the Faddeev-Popov operator in
Coulomb gauge QCD using quenched SU(3) lattice simulation. In the confinement
phase, the density of the low-lying eigenvalues increases with lattice volume,
and the confinement criterion is satisfied. Moreover, even in the deconfinement
phase, the behavior of the FP eigenvalue density is qualitatively the same as
in the confinement phase. This is consistent with the fact that the
color-Coulomb potential is not screened in the deconfined phase.Comment: 10 pages, 10 figure
Scaling study of the gluon propagator in Coulomb gauge QCD on isotropic and anisotropic lattices
We calculate the transverse and time-time components of the instantaneous
gluon propagator in Coulomb gauge QCD by using an SU(3) quenched lattice
simulation on isotropic and anisotropic lattices. We find that the gluon
propagators suffer from strong discretization effects on the isotropic lattice;
on the other hand, those on the anisotropic lattices give a better scaling.
Moreover, on these two type of lattices the transverse parts are significantly
suppressed in the infrared region and have a turnover at about 500 [MeV]. The
high resolution to the temporal direction due to the anisotropy yields small
discretization errors for the time-time gluon propagators, which also show an
infrared enhancement as expected in the Gribov-Zwanziger confinement scenario.Comment: 29 pages, 18 figure
Radiative production of the Lambda(1405) resonance in K collisions on protons and nuclei
We have carried a theoretical study of the K^- p\to M B \gamma reaction with
M B = K^-p, \bar{K}^0 n, \pi^- \Sigma^+, \pi^+ \Sigma^-, \pi^0 \Sigma^0, \pi^0
\Lambda, for K^- lab. momenta between 200 and 500 MeV/c, using a chiral unitary
approach for the strong K^-p interaction with its coupled channels. The
\Lambda(1405) resonance, which is generated dynamically in this approach, shows
up clearly in the d\sigma/dM_I spectrum, providing new tests for chiral
symmetry and the unitary approach, as well as information regarding the nature
of the resonance. The photon detection alone, summing all channels, is shown to
reproduce quite accurately the strength and shape of the \Lambda(1405)
resonance. Analogous reactions in nuclei can provide much information on the
properties of this resonance in a nuclear medium.Comment: 11 pages, 3 postscripts figure
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