111 research outputs found
The Quest for Pionic and Kaonic Nuclear Bound Systems Following Yukawa and Tomonaga
After sketching some historical events related to Yukawa and Tomonaga
concerning the birth of mesons, the author describes recent developments in the
spectroscopy of pion-nucleus bound states via "pion-transfer" reactions. The
role of pions as Nambu-Goldstone bosons in nuclear media is emphasized by
recently obtained experimental evidence for the partial restoration of chiral
symmetry breaking. New light is shed on Kbar mesons, which play a unique role
in forming dense nuclear systems. The basic unit, K- pp, is predicted to
possess a molecular structure with quasi-Lambda(1405) as an "atomic
constituent". We find here "super strong nuclear force" produced by a migrating
real Kbar meson in the Heitler-London-Heisenberg scheme in place of the normal
nuclear force mediated by Yukawa's virtual mesons.Comment: 20 pages, 11 figures. Prog. Theor. Phys., in pres
The Quest for Pionic and Kaonic Nuclear Bound Systems Following Yukawa and Tomonaga
After sketching some historical events related to Yukawa and Tomonaga
concerning the birth of mesons, the author describes recent developments in the
spectroscopy of pion-nucleus bound states via "pion-transfer" reactions. The
role of pions as Nambu-Goldstone bosons in nuclear media is emphasized by
recently obtained experimental evidence for the partial restoration of chiral
symmetry breaking. New light is shed on Kbar mesons, which play a unique role
in forming dense nuclear systems. The basic unit, K- pp, is predicted to
possess a molecular structure with quasi-Lambda(1405) as an "atomic
constituent". We find here "super strong nuclear force" produced by a migrating
real Kbar meson in the Heitler-London-Heisenberg scheme in place of the normal
nuclear force mediated by Yukawa's virtual mesons.Comment: 20 pages, 11 figures. Prog. Theor. Phys., in pres
Super strong nuclear force caused by migrating Kbar mesons - Revival of the Heitler-London-Heisenberg scheme in kaonic nuclear clusters
We have studied the structure of K- pp comprehensively by solving this
three-body system in a variational method, starting from the Ansatz that the
Lambda(1405) resonance (~ Lambda*) is a K-p bound state. The structure of K-pp
reveals a molecular feature, namely, the K- in Lambda* as an "atomic center"
plays a key role in producing strong covalent bonding with the other proton. We
point out that strongly bound Kbar nuclear systems are formed by ``super
strong" nuclear force due to migrating real bosonic particles Kbar a la
Heitler-London-Heisenberg, whereas the normal nuclear force is caused by
mediating virtual pions. We have shown that the elementary process, p + p -->
K+ + Lambda* + p, which occurs in a short impact parameter and with a large
momentum transfer, leads to unusually large self-trapping of Lambda* by the
involved proton, since the Lambda*-p system exists as a compact doorway state
propagating to K-pp.Comment: 11 pages, 5 figure
K-K-pp - an important gateway toward multi-kaonic nuclei
Based on our Faddeev-Yakubowsky calculations of four-body kaonic nuclear
systems it was revealed that the structure of K-K-pp is well approximated by
two Lambda*=K-p's with strong mutual attraction. It is vitally important to
study this nucleus, as it is an essential gateway toward multi-Lambda* nuclei.
Two experimental proposals are presented: i) production of K-K-pp by p+p
reactions at T_p = 7 GeV, and ii) search for K-K-pp from the invariant mass of
M(Lambda-Lambda) around 2.6 GeV/c2 in high-energy HI reactions.Comment: 4 pages, 4 figure
Resonant formation of Lambda(1405) by stopped-K- absorption in deuteron
To solve the current debate on the position of the quasi-bound K^-p state,
namely, "Lambda(1405) or Lambda*(1420)", we propose to measure the T_{21} =
T_{Sigma-pi \leftarrow Kbar-N} Sigma-pi invariant-mass spectrum in stopped-K-
absorption in deuteron, since the spectrum, reflecting the soft and hard
deuteron momentum distribution, is expected to have a narrow quasi-free
component with an upper edge of M = 1430 MeV/c^2, followed by a significant
"high-momentum" tail toward the lower mass region, where a resonant formation
of Lambda(1405) of any mass and width in a wide range is revealed. We introduce
a "deviation" spectrum as defined by DEV = OBS (observed or calculated) / QF
(non-resonant quasi-free), in which the resonant component can be seen as an
isolated peak free from the QF shape.Comment: 7 pages, 6 figure
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