QNP2022 - The 9th International Conference on Quarks and Nuclear Physics

Recent pionless EFT studies of $\Lambda$ and $\Lambda\Lambda$ few-body hypernuclei

Sep 8, 2022, 1:20 PM

25m

online

oral presentation Nuclear Strangeness

Speaker

Martin Schäfer (Racah Institute od Physics, The Hebrew University of Jerusalem)

Description

We report on our recent leading order pionless effective field theory (LO pionless EFT) studies [1,2,3,4,5] of light single- and double-Lambda hypernuclei. These systems are within the focus of current experimental interest since their spectra provide strong constraints in a study of the 2- and 3-body interaction between $\Lambda$ hyperons and nucleons. Application of LO pionless EFT, fitted to available low-energy data, reveals excited state of hypertriton ${\rm ^3_\Lambda H^*}~(J^\pi=3/2^+)$ in a form of a virtual state and predicts possible broad $\Lambda nn~(J^\pi =1/2^+)$ resonance [2,3] with the resonance energy strongly dependent on the size of $\Lambda N$ scattering length. Considering $\Lambda N$ charge symmetry breaking (CSB) and partially conserved baryon-baryon SU(3) flavor symmetry we deduce from the experimental CSB in $\rm ^4_\Lambda H− ^4_\Lambda He$ hypernuclei in-medium $\Lambda$ isospin $I=1$ admixture amplitude [5]. Our result is in agreement with the free-space value ≈1.5% inferred by Dalitz and von Hippel [6] and recent QCD+QED lattice calculations [7]. Extending LO pionless EFT to the double-$\Lambda$ sector we firmly predict bound ${\rm ^5_{\Lambda \Lambda} H~/~^5_{\Lambda \Lambda} He }~(J^\pi = 1/2^+)$ isospin doublet, while four-body ${\rm ^4_{\Lambda \Lambda} H }~(J^\pi =1^+)$ hypernucleus is found on the verge of binding, strongly dependent on the strength of $\Lambda \Lambda$ interaction [1].

References

[1] L. Contessi, M. Schafer, N. Barnea, A. Gal, and J. Mares, Phys. Lett. B 797, 134893 (2019).
[2] M. Schafer, B. Bazak, N. Barnea, and J. Mares, Phys.Lett. B 808 135614 (2020).
[3] M. Schafer, B. Bazak, N. Barnea, and J. Mares, Phys. Rev. C 103, 025204 (2021).
[4] M. Schafer, B. Bazak, N. Barnea, A. Gal, and J. Mares, Phys. Rev. C 105 015202 (2022).
[5] M. Schafer, N. Barnea, and A. Gal, arXiv nucl-th: 2202.07460 (2022).
[6] R. H. Dalitz and F. von Hippel, Phys. Lett 10, 153 (1964).
[7] Z. R. Kordov, R. Horsley, Y. Nakamura et al. Phys. Rev. D 101, 034517 (2020).

Presentation materials

QNP2022.pdf