2,739 research outputs found
Theoretical Response to the Discovery of Deeply Bound Pionic States in 208Pb(d,3He) reactions
Recently, deeply bound pionic states were found experimentally in (d, He)
reactions on Pb. They found an isolated peak structure in the bound
region below the pion production threshold. We study theoretically these
excitation functions in (d, He) reactions on Pb at T=600 MeV.
We found very good agreement with the (d, He) excitation functions and
could identify the underlying structures of the pionic states. We study the
energy dependence of the (d, He) reactions and the change of the excitation
functions with the incident energy.Comment: 5 pages, Latex, Figures available on request, Z.Phys.A.accepte
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
Spectral sum for the color-Coulomb potential in SU(3) Coulomb gauge lattice Yang-Mills theory
We discuss the essential role of the low-lying eigenmodes of the
Faddeev-Popov (FP) ghost operator on the confining color-Coulomb potential
using SU(3) quenched lattice simulations in the Coulomb gauge. The
color-Coulomb potential is expressed as a spectral sum of the FP ghost operator
and has been explored by partially summing the FP eigenmodes. We take into
account the Gribov copy effects that have a great impact on the FP eigenvalues
and the color-Coulomb potential. We observe that the lowest eigenvalue vanishes
in the thermodynamic limit much faster than that in the Landau gauge. The
color-Coulomb potential at large distances is governed by the near-zero FP
eigenmodes; in particular, the lowest one accounts for a substantial portion of
the color-Coulomb string tension comparable to the Wilson string tension.Comment: 14 pages, 14 figure
QCD Phase Transition at Finite Temperature in the Dual Ginzburg-Landau Theory
We study the pure-gauge QCD phase transition at finite temperatures in the
dual Ginzburg-Landau theory, an effective theory of QCD based on the dual Higgs
mechanism. We formulate the effective potential at various temperatures by
introducing the quadratic source term, which is a new useful method to obtain
the effective potential in the negative-curvature region. Thermal effects
reduce the QCD-monopole condensate and bring a first-order deconfinement phase
transition. We find a large reduction of the self-interaction among
QCD-monopoles and the glueball masses near the critical temperature by
considering the temperature dependence of the self-interaction. We also
calculate the string tension at finite temperatures.Comment: 13 pages, uses PHYZZX ( 5 figures - available on request from
[email protected]
Pionic Atom Spectroscopy in the (d,3He) reaction at finite angles
We study the formation of deeply bound pionic atoms in the (d,3He) reactions
theoretically and show the energy spectra of the emitted 3He at finite angles,
which are expected to be observed experimentally. We find that the different
combinations of the pion-bound and neutron-hole states dominate the spectra at
different scattering angles because of the matching condition of the reaction.
We conclude that the observation of the (d,3He) reaction at finite angles will
provide the systematic information of the pionic bound states in each nucleus
and will help to develop the study of the pion properties and the partial
restoration of chiral symmetry in nuclei.Comment: 7 pages, 4 figures, 1 tabl
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