Effect of Majorana component in the Λ-nucleon potential on the BΛ value of 5ΛHe

Distortion effects in light hypernuclei

“…In the present study, which fairly well described the s-shell nuclei, we find that the Ba-value of the s-shell hypernuclei is not simultaneously reproduced by the Yamamoto-Bando AN-force with a common value for the parameter kF. However, adopting kv = 0.9 fm-~ in our studies of the s-shell hypernuclei, our dynamical approaches do not show the strong overbinding of ]He as encountered in previous studies [2,15,16]. Nevertheless, as the Fermi-momentum is not well-defined in light nuclei, we do not think that our study allows for quantitative conclusions about the ]He overbinding problem.…”

“…This, however, should not be expected as the Fermi-momentum -if well defined at all in these light systems -should be somewhat different for these hypernuclei. Nevertheless, we like to point out that our calculations do not show the strong overbinding of 5AHe as encountered in previous studies [2,15,16]. In contrast, if we again assume a linear dependence of the BA-value on kF, a static approach, in which we use the Yamamoto-Bando AN-interaction with a common value for the parameter k F for all s-shell hypernuclei, shows the strong overbinding of the 5AHe hypernucleus compared to the other s-shell hypernuclei.…”

“…Therefore we have repeated parts of our calculations using AN-forces from the literature which do not depend on additional 'free parameters'. We found that the two-Gaussian force given in [14] does not bind the ~H hypernucleus, while the force of [2] overbinds the hypernuclei 4AH and 5He noticeably. Due to these noticeable shortcomings, we have not adopted these interactions to study the distorsion effects in hypernuclei, although these choices had allowed us to avoid the ambiguities in our studies introduced by the dependence of the Yamamoto-Bando force on the fermi momentum.…”

“…Several previous studies of s-shell hypernuclei encountered an overestimation of the Ba-value in ]He [2,15,16]. This 'SHe overbinding problem' states too strong a binding of the A-particle in ]He compared to the other s-shell hypernuclei if the same AN-interaction as well as reasonable NN-forces are adopted.…”

“…We therefore do not believe that the consideration of D-state admixtures in the nuclear wave functions changes the essential results of our studies. The multichannel RGM study [1][2][3][4][5][6][7][8] as well as a variational approach [-9] to the 5He hypernucleus suggest that besides the effects of a D-state admixture in the nuclear wave functions nuclear rearrangement effects caused by the NN-tensor force should also be taken into account in studies of s-shell hypernuclei which want to tackle the 5He overbinding problem consistently. For RGM type calculations this means, however, that one cannot use the standard effective NN-interactions which are usually central and designed to reproduce the properties of s-shell nuclei without the consideration of a D-state.…”