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Title: A single particle energies

We consider the binding energies of {Lambda} hypernuclei (HN), in particular the single-particle (s.p.) energy data, which have been obtained for a wide range of HN with mass numbers A {le} 89 and for orbital angular momenta {ell}{sub {Lambda}} {le} 4. We briefly review some of the relevant properties of A hypernuclei. These are nuclei {sub {Lambda}}{sup A}Z with baryon number A in which a single {Lambda} hyperon (baryon number = 1) is bound to an ordinary nucleus {sup A}Z consisting of A - 1 nucleons = Z protons + N neutrons. The {Lambda} hyperon is neutral, has spin 1/2, strangeness S = {minus}1, isospin I = O and a mass M{sub {Lambda}} = 1116 MeV/c{sup 2}. Although the {Lambda} interacts with a nucleon, its interaction is only about half as strong as that between two nucleons, and thus very roughly V{sub {Lambda}N} {approx} 0.5 V{sub NN}. As a result, the two-body {Lambda}N system is unbound, and the lightest bound HN is the three-body hypertriton {sub {Lambda}}{sup 3}H in which the {Lambda} is bound to a deuteron with the {Lambda}-d separation energy being only {approx} 0.1 MeV corresponding to an exponential tail of radius {approx} 15 fm! In strong interactionsmore » the strangeness S is of course conserved, and the {Lambda} is distinct from the nucleons. In a HN strangeness changes only in the weak decays of the {Lambda} which can decay either via ``free`` pionic decay {Lambda} {yields} N + {pi} or via induced decay {Lambda} + N {yields} N + N which is only possible in the presence of nucleons. Because of the small energy release the pionic decay is strongly suppressed in all but the lightest HN and the induced decay dominates. However, the weak decay lifetime {approx} 10{sup {minus}10}s is in fact close to the lifetime of a free {Lambda}. Since this is much longer than the strong interaction time {approx} 10{sup {minus}22}s we can ignore the weak interactions when considering the binding of HN, just as for ordinary nuclei.« less
Authors:
 [1] ; ;  [2]
  1. Illinois Univ., Chicago, IL (United States). Dept. of Physics|[Argonne National Lab., IL (United States)
  2. Jamia Millia Islamia, New Delhi (India). Dept. of Physics
Publication Date:
OSTI Identifier:
10193174
Report Number(s):
ANL/PHY/CP--80702; CONF-9306259--1
ON: DE93041163; CNN: Grant INT-9216662; TRN: 94:000022
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: 17. international workshop on condensed matter theories,Nathiagali (Pakistan),18-24 Jun 1993; Other Information: PBD: [1993]
Research Org:
Argonne National Lab., IL (United States)
Sponsoring Org:
USDOE, Washington, DC (United States);National Science Foundation, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; LAMBDA PARTICLES; BINDING ENERGY; HYPERNUCLEI; NUCLEAR FORCES; HELIUM 5; NUCLEAR MATTER; WEAK PARTICLE DECAY 663110; GENERAL AND AVERAGE PROPERTIES OF NUCLEI AND NUCLEAR ENERGY LEVELS