A Mass Formula from Light to Hypernuclei

Abstract

Simultaneous description of ordinary and hypernuclei masses by a single mass formula has been a great challenge in nuclear physics. Hyperon-separation energies of about forty Lambda($\Lambda$), three Lambda-Lambda($\Lambda\Lambda$), one Sigma($\Sigma$) and seven Cascade($\Xi$) hypernuclei have been experimentally found. Many of these nuclei are of light masses. We prescribe a new mass formula, called BWMH, which describes the normal and hypernuclei on the same footing. It is based on the modified-Bethe-Weizs\"acker mass formula (BWM). BWM is basically an extension of the Bethe-Weizs\"acker mass formula (BW) for light nuclei. The parameters of BWM were optimized by fitting about 3000 normal nuclei available recently. The original Bethe-Weizs\"acker mass formula (BW) was designed for medium and heavy mass nuclei and it fails for light nuclei. Two earlier works on hypernuclei based on this BW show some limitations. The BWMH gives improved agreement with the experimental data for the line of stability, one-neutron separation energy versus neutron number spectra of normal nuclei, and the hyperon-separation energies from hypernuclei. The drip lines are modified for addition of a $\Lambda$ hyperon in a normal nucleus.Comment: Presented at the "XXIX Mazurian Lakes Conference on Physics: Nuclear Physics and the Fundamental Processes, Piaski, Poland, August 30 - September 6, 2005." (7 pages, 1 Table, 1 Figure