Abstract

We extend the recently developed Jacobi no-core shell model to hypernuclei. Based on the coefficients of fractional parentage for ordinary nuclei, we define a basis where the hyperon is the spectator particle. We then formulate transition coefficients to states that single out a hyperon–nucleon pair which allow us to implement a hypernuclear many-baryon Hamiltonian for p-shell hypernuclei. As a first application, we use the basis states and the transition coefficients to calculate the ground states of ^{4}_{varLambda }hbox {He}, ^{4}_{varLambda }hbox {H}, ^{5}_{varLambda }hbox {He}, ^{6}_{varLambda }hbox {He}, ^{6}_{varLambda }hbox {Li}, and ^{7}_{varLambda }hbox {Li} and, additionally, the first excited states of ^{4}_{varLambda }hbox {He}, ^{4}_{varLambda }hbox {H}, and ^{7}_{varLambda }hbox {Li}. In order to obtain converged results, we employ the similarity renormalization group (SRG) to soften the nucleon–nucleon and hyperon-nucleon interactions. Although the dependence on this evolution of the Hamiltonian is significant, we show that a strong correlation of the results can be used to identify preferred SRG parameters. This allows for meaningful predictions of hypernuclear binding and excitation energies. The transition coefficients will be made publicly available as HDF5 data files.

Highlights

  • A direct use of hypernuclear data requires solving the hypernuclear many-body problem many times and, calls for a very efficient calculation scheme

  • In order to obtain converged results, we employ the similarity renormalization group (SRG) to soften the nucleon–nucleon and hyperon-nucleon interactions. The dependence on this evolution of the Hamiltonian is significant, we show that a strong correlation of the results can be used to identify preferred SRG parameters

  • We explicitly checked that NN and YN scattering observables remain unchanged by this unitary transformation

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Summary

Introduction

A direct use of hypernuclear data requires solving the hypernuclear many-body problem many times and, calls for a very efficient calculation scheme. Nuclear lattice effective field theory (NLEFT) has been extended to hypernuclei using the impurity lattice Monte Carlo technique [32] This first study has been performed with somewhat simplified (spin-independent) interactions, that method promises the application of free-space interactions up to medium-heavy hypernuclei. The NCSM requires a further softening of the nucleon-nucleon (NN) and YN interactions To this aim, we apply the similarity renormalization group (SRG) to the NN and YN potentials [43,44]. We apply the similarity renormalization group (SRG) to the NN and YN potentials [43,44] This method has the advantage that an effective interaction can be systematically derived from the starting NN and YN interactions, which can be well employed in momentum space and HO space.

NCSM basis in Jacobi coordinates
Separation of NN and YN pairs
SRG evolution for chiral NN and YN interactions
Results
Extrapolation of the binding energies
Effects of NN chiral interactions on BΛ
Effects of the NLO YN interactions on BΛ
Correlation of Λ-separation energies
Conclusions
Full Text
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