2018 Impact factor 2.481
Hadrons and Nuclei
Eur. Phys. J. A 16, 549-561 (2003)
DOI: 10.1140/epja/i2002-10131-8

Lifetime of heavy hypernuclei and its implications on the weak $\mth{\Lambda N}$ interaction

W. Cassing1, L. Jarczyk2, B. Kamys2, P. Kulessa3, 4, H. Ohm3, K. Pysz3, 4, Z. Rudy2, 3, O.W.B. Schult3 and H. Ströher3

1  Institut für Theoretische Physik, Justus Liebig Universität Giessen, D-35392 Giessen, Germany
2  M. Smoluchowski Institute of Physics, Jagellonian University, PL-30059 Cracow, Poland
3  Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich, Germany
4  H. Niewodniczanski Institute of Nuclear Physics, PL-31342 Cracow, Poland

h.stroeher@fz-juelich.de

(Received: 8 August 2002 / Revised version: 20 December 2002 / Published online: 25 March 2003)

Abstract
The lifetime of the $\Lambda$-hyperon in heavy hypernuclei measured in proton-Au, -Bi and -U collisions by the COSY-13 Collaboration at COSY-Jülich has been analyzed to yield $\tau_{\Lambda}= (145 \pm 11$) ps. This value for $\tau_{\Lambda}$ is compatible with the lifetime extracted from antiproton annihilation on Bi and U targets, albeit much more accurate. Theoretical models based on the meson exchange picture and assuming the validity of the phenomenological $\Delta
I =1/2$ rule predict the lifetime of heavy hypernuclei to be significantly larger (2-3 standard deviations). Such large differences indicate that at least one of the assumptions in these models is not fulfilled. A much better reproduction of the lifetimes of heavy hypernuclei is achieved in the phase space model, if the $\Delta
I =1/2$ rule is discarded in the nonmesonic $\Lambda$ decay.

PACS
13.30.-a - Decays of baryons.
13.75.Ev - Hyperon-nucleon interactions.
21.80.+a - Hypernuclei.
25.80.Pw - Hyperon-induced reactions.

© Società Italiana di Fisica, Springer-Verlag 2003