3 research outputs found
Residual interaction effects on deeply bound pionic states in Sn and Pb isotopes
We have studied the residual interaction effects theoretically on the deeply
bound pionic states in Pb and Sn isotopes. We need to evaluate the residual
interaction effects carefully in order to deduce the nuclear medium effects for
pion properties, which are believed to provide valuable information on nuclear
chiral dynamics. The s- and p-wave interactions are used for the
pion-nucleon residual interactions. We show that the complex energy shifts are
around [(10-20)+i(2-7)]keV for 1s states in Sn, which should be taken into
account in the analyses of the high precision data of deeply bound pionic
states in Sn isotopes.Comment: REVTEX4, 6 pages, 5 tables, Submitted to Phys. Rev. C, Some
explanations are added in Version
Nuclear Quadrupole Effects in Deeply Bound Pionic Atoms
We have studied nuclear quadrupole deformation effects in deeply bound pionic
atoms theoretically. We have evaluated the level shifts and widths of the
hyperfine components using the first order perturbation theory and compared
them with the effects of neutron skin. We conclude that the nuclear quadrupole
deformation effects for deeply bound and states are very difficult to
observe and that the effects could be observed for states. We also
conclude that the deformation effects are sensitive to the parameters of the
pion-nucleus optical potential.Comment: Latex 11pages, Figures available on reques
Pionic atom unveils hidden structure of QCD vacuum
Modern theories of physics tell that the vacuum is not an empty space. Hidden
in the vacuum is a structure of anti-quarks and quarks . The
and pair has the same quantum number as the vacuum and
condensates in it since the strong interaction of the quantum chromodynamics
(QCD) is too strong to leave it empty. The condensation breaks the
chiral symmetry of the vacuum. The expectation value is an order
parameter. For higher temperature or higher matter-density,
decreases reflecting the restoration of the symmetry. In contrast to these
clear-cut arguments, experimental evidence is so far limited. First of all, the
is nothing but the vacuum itself. It is neither visible nor
perceptible. In this article, we unravel this invisible existence by high
precision measurement of pionic atoms, -meson-nucleus bound systems.
Using the as a probe, we demonstrate that is reduced in
the nucleus by a factor of 58 4% compared with that in the vacuum. This
reduction indicates that the chiral symmetry is partially restored due to the
extremely high density of the nucleus. The present experimental result clearly
exhibits the existence of the hidden structure, the chiral condensate, in the
vacuum