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Study of hyperon-nucleon interactions with d(e,e'K) reactions.

Description: The dependence of the d(e,e{prime}K{sup +}) reaction cross sections on the hyperon-nucleon interactions is investigated. It is shown that the data obtained with Longitudinal-Transverse separation or polarized photons can distinguish a class of Nijmegen models of hyperon-nucleon interactions which are {chi}{sup 2}-equivalent in fitting the existing 35 data points of hyperon-nucleon reactions.
Date: January 29, 1998
Creator: Lee, T.-S. H.
Partner: UNT Libraries Government Documents Department

A meson exchange model for the YN interaction

Description: We present a new model for the hyperon-nucleon (Lambda N, Sigma N) interaction, derived within the meson exchange framework. The model incorporates the standard one boson exchange contributions of the lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) symmetry relations. In addition - as the main feature of the new model - the exchange of two correlated pions or kaons, both in the scalar-isoscalar (sigma) and vector-isovector (rho) channels, is included.
Date: September 1, 2001
Creator: Haidenbauer, J.; Melnitchouk, W. & Speth, J.
Partner: UNT Libraries Government Documents Department

THE STORY OF SIGMA HYPERNUCLEI - A MODERN FABLE.

Description: The reality of {Sigma} hypernuclei has been the subject of intense concern among experimenters and theoreticians for more than 20 years. The possible existence of {Sigma} hypernuclei was first suggested by a pioneering experiment on a {sup 9}Be target at the CERN PS. There were reported to be two narrow ({Gamma} < 8 MeV) peaks in the continuum region. This finding was quite unexpected since the widths of {Sigma} states were believed to be large due to the strong conversion process. It is obvious that if such relatively long-lived systems were confirmed unambiguously by experiment, their masses and widths provide important constraints on the {Sigma}N effective interaction and its relation to the {Lambda}N and NN interactions. Since the {Sigma} carries isospin, the role of isospin and isospin conservation in hadronic reactions could be explored. This report stimulated a number of subsequent experiments at the BNL-AGS and KEK, along with further experiments with a specially created short kaon beam at the CERN PS. Experimental data were reported for different targets at different momenta and at different conditions. Various tagging techniques were employed to suppress backgrounds, but always at the expense of a reduction in statistical quality. Because of problems with resolution and statistics, contradictions among the different sets of data resulted more often in clouding the issues than clarifying them. Thus, up until a few years ago, there was no statistically clear confirmation of this surprising finding. In the last few years, however, a series of definitive experiments has been performed at the BNL-AGS in an effort to resolve the discrepancies and settle the controversy. Besides repeating the initial experiment on Be, a target of {sup 6}Li was run. The earlier stopped kaon data on {sup 4}He was repeated in an in-flight experiment, and the suggestion of a {Sigma} bound state, ...
Date: February 19, 1999
Creator: CHRIEN,R.E.
Partner: UNT Libraries Government Documents Department

The Nijmegen hyperon-nucleon potentials

Description: The Nijmegen YN potential models are reviewed. Differences with the models constructed by the Juelich group are highlighted. A mini- review is given of the status of the scalar mesons and their relevance for the NN and YN interactions. Finally, the reactions {bar N}N {yields} {bar Y}Y are discussed.
Date: February 17, 1994
Creator: Timmermans, R.
Partner: UNT Libraries Government Documents Department

$lambda$$sup 0$ inclusive production in $Sigma$$sup -$-nucleus reactions

Description: A counter spark chamber experiment was done in the AGS 23- GeV/c charged hyperon beam to study $lambda$$sup 0$ inclusive production in reactions of $Sigma$$sup -$ on Al, Cu, W, and Pb. Preliminary results are reported on the missing mass spectra in the reaction $Sigma$$sup -$ + Nucleon $Yields$ $lambda$$sup 0$ + M$sup 2$/sub x/. The data are compared with the relevant triple Regge formalism. (auth)
Date: January 1, 1975
Creator: Arik, E.; Cleland, W.E. & Dris, M.
Partner: UNT Libraries Government Documents Department

Aspects of strangeness production with 15 -- 30 GeV proton beams

Description: We discuss the spectrum of physics questions related to strangeness which could be addressed with a 15--30 GeV proton storage ring. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hyper-fragments in p-nucleus collisions, and hyperon spin observables in inclusive production.
Date: April 1, 1992
Creator: Dover, C. B.
Partner: UNT Libraries Government Documents Department

BNL possibilities

Description: The Brookhaven National Laboratory AGS facility provides the intense kaon and pion beams necessary for detailed studies of the hyperon-nucleon interaction. A description of available beams is provided along with a summary of the current and future physics program.
Date: December 31, 1993
Creator: Pile, P. H.
Partner: UNT Libraries Government Documents Department

Aspects of strangeness production with 15 -- 30 GeV proton beams

Description: We discuss the spectrum of physics questions related to strangeness which could be addressed with a 15--30 GeV proton storage ring. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hyper-fragments in p-nucleus collisions, and hyperon spin observables in inclusive production.
Date: April 1, 1992
Creator: Dover, C.B.
Partner: UNT Libraries Government Documents Department

Physics opportunities with higher energy pion beams

Description: We provide a preview of the physics issues which could be addressed with intense beams of pions in the 1--2 GeV/c region. These include: the exploitation of the ({pi}{sup +}, K{sup +}) associated production reaction on proton and nuclear targets for high resolution studies of hypernuclear structure and decays, as well as {Lambda}-proton scattering, the use of pion reactions with hydrogen or deuterium targets to provide tagged {eta} beams for studies of rare decays, precision studies of baryon resonances which couple to the {pi}N system, and the exploration of pion elastic, inelastic, and charge exchange reactions above the (3,3)-resonance as a tool for the study of nuclear structure.
Date: December 1, 1992
Creator: Dover, C. B.
Partner: UNT Libraries Government Documents Department

Physics opportunities with higher energy pion beams

Description: We provide a preview of the physics issues which could be addressed with intense beams of pions in the 1--2 GeV/c region. These include: the exploitation of the ([pi][sup +], K[sup +]) associated production reaction on proton and nuclear targets for high resolution studies of hypernuclear structure and decays, as well as [Lambda]-proton scattering, the use of pion reactions with hydrogen or deuterium targets to provide tagged [eta] beams for studies of rare decays, precision studies of baryon resonances which couple to the [pi]N system, and the exploration of pion elastic, inelastic, and charge exchange reactions above the (3,3)-resonance as a tool for the study of nuclear structure.
Date: December 1, 1992
Creator: Dover, C.B.
Partner: UNT Libraries Government Documents Department

Hypernuclear interactions and the binding energies of and hypernuclei

Description: By use of variational calculations a reasonable hadronic description is obtained of the s-shell hypernuclei, of /sub /ZBe, and of the well depth, with N forces which are consistent with p scattering and which are quite strongly spin-dependent, with reasonable TPE NN forces with strongly repulsive dispersive-type NN forces. For the latter we also consider a spin-dependent version which is somewhat favored by our analysis. /sub /ZBe is treated as a 2ed + system and is significantly overbound, approx. =1 MeV, if only ed ed and ed potentials are used. An ed ed potential obtained from the NN forces nicely accounts for this overbinding. The hypernuclei /sub /WHe and /sub / Be are treated as ed + 2 and 2ed + 2 systems. Use of the /sub / Be event gives approx. =1.5 MeV too little binding for /sub /WHe. The S0 potential obtained from /sub / Be is quite strongly attractive, comparable to the N and also to the NN potential without OPE. 18 refs.
Date: January 1, 1988
Creator: Bodmer, A.R. & Usmani, Q.N.
Partner: UNT Libraries Government Documents Department

Nuclear and particle physics aspects of hyperon and antinucleon interactions

Description: A discussion is given of hyperon (Y) and antinucleon (anti N) interactions with nucleons and nuclei, emphasizing some of the future prospects for nuclear structure and elementary particle physics studies at LEAR or a future kaon factory. The topics addressed include: (1) production and decay of strange dibaryons; (2) spectroscopy of strangeness S = -2 many body systems; (3) N anti N annihilation mechanisms; and (4) inelastic anti N-nucleus scattering and spin-flip excitations in nuclei. 36 references.
Date: January 1, 1984
Creator: Dover, C.B.
Partner: UNT Libraries Government Documents Department

Binding energies of hypernuclei and. lambda. -nuclear interactions

Description: Variational calculations indicate that a reasonable description of ..lambda..p scattering and of ..lambda.. separation energies can be obtained in terms of ..lambda..N plus dispersive and TPE ..lambda..NN forces. Results for the ..lambda lambda.. interaction and for /sup 6//sub ..lambda../He obtained from an analysis of /sup 10//sub ..lambda lambda../Be are discussed. Coulomb and ..lambda..N charge symmetry breaking effects in the A = 4 hypernuclei are discussed.
Date: January 1, 1984
Creator: Bodmer, A.R. & Usmani, Q.N.
Partner: UNT Libraries Government Documents Department

Strangeness-exchange and strange nuclei

Description: The nuclear strangeness exchange reaction (K/sup -/,..pi../sup -/) is discussed. Possible reaction mechanisms are reviewed, and the spectroscopic ..lambda..-hypernuclear information derived from observation of strangeness exchange is discussed. The more general question of multiply-strange nuclei is introduced. 10 figures, 1 table, 32 references.
Date: January 1, 1978
Creator: Gal, A
Partner: UNT Libraries Government Documents Department

lambda. N effective interaction

Description: A combination of theoretical estimates, based on a ..lambda..N potential model, and phenomenological analysis of hypernuclear data is used to determine a set of four P/sub N/s/sub ..lambda../ two-body matrix elements which characterize the spin dependence of the ..lambda..N interaction in the p shell. The central spin-spin and the ..lambda.. spin-orbit matrix elements are most strongly constrained by existing data. The spin dependence is weak in the sense that s/sub ..lambda../ doublet splittings are predicted to be of order 100 keV except for the special case of /sub ..lambda..//sup 7/Li where the central spin-spin interaction dominates and the ground-state doublet separation is likely to be about 600 keV. The results of recent (K/sup -/, ..pi../sup -/..gamma..) experiments at the Brookhaven AGS are interpreted in terms of the ..lambda..N effective interaction.
Date: May 23, 1984
Creator: Millener, D.J.
Partner: UNT Libraries Government Documents Department