Production of light hypernuclei with light-ion beams and targets

Abstract

Ion-ion collisions at relativistic energies have been shown recently to be a promising technique for the production of hypernuclei. In this article, we further investigate the production of light Λ hypernuclei by use of a hybrid dynamical model, cascade-coalescence followed by Fermi breakup. The predictions are then compared with the available experimental data. The dependence of the production cross section upon the beam energy, beam mass number as well as different projectiletarget combinations is investigated. In particular, we evaluate the yields and signal-over-background ratio in the invariant-mass spectrum for carbon projectiles impinging on hydrogen and carbon targets and various coincidence conditions in the experiment using the theoretical calculation as an input. It is found that comparing with carbon target, hydrogen target also leads to sizable hypernuclear yields, even for exotic species, and the hydrogen target could improve significantly signal-over-background ratio in some hypernuclear invariant mass studies.

Nonempirical Interactions for the Nuclear Shell Model: An Update

“…The cost of the EOM-CC calculations, however, presented a significant obstacle to widespread applications of this method. A much more efficient alternative is the recently introduced shell model coupled cluster (SMCC) method (179), which is formulated in Fock space and can be viewed as a non-unitary cousin of the IMSRG.…”

“…Instead of working with the wave operator, we may directly work with the generator G. Following the notation of Ref. (179), we write G as −S. We employ the iterative procedure laid out in section 3.1.1 to obtain an iterative expression for S:…”

“…Often, the iterations are better behaved with the help of a convergence factor, which we denote dt to connect with the formulation of Ref. (179). Multiplying the second term of Eq.…”

“…For the case of interest in the context of the shell model, with the dimension of the P space greater than one, the Baker-Campbell-Hausdorff expansion does not formally truncate (179). One approach to this issue is to truncate the series at a finite order of perturbation theory, or else at a finite power of G (see, e.g.…”

Strangeness in nuclei and neutron stars

“…In this context, also the investigation of neutron-deficient hypernuclei plays an important role. These hypernuclei are not measured at the moment, but future experiments planned at the FAIR facility by the R3B collaboration employing radioactive beams will study such hypernuclei [271].…”