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B$_\Lambda$($^5_\Lambda$He) from short range effective theory

Not scheduled
15m
2nd Floor

2nd Floor

Renaissance Portsmouth-Norfolk Waterfront Hotel 425 Water Street Portsmouth, VA 23704
Abstract Submission

Speaker

Dr Lorenzo Contessi (Racah Institute of Physics, The Hebrew University, Jerusalem, Israel)

Description

We present an effective field theory (EFT) at leading order to describe light single-$\Lambda$ hypernuclei [1]. Owing to the weak $\Lambda$ binding and to the $\Lambda$-n short interaction range, meson exchange forces are approximated by contact interactions within a pion-less EFT where the only degrees of freedom are baryons. At leading order the theory contains both 2-body (singlet and triplet) and three 3-body interactions, a total of 5 terms associated with 5 coupling strengths or low energy constants (LECs). We adjust the 2-body LECs from available data that constrain the $\Lambda$-n scattering lengths. Because of the limited 3-body data, both 3-body and 4-body hypernuclear binding energies and excitation energies are used to adjust the 3-body LECs. To calculate the binding energies for the A-body systems with A>2, we have expanded the wave-function using a Gaussian basis. The stochastic variational method was employed to select the non-linear parameters. The resulting EFT is then applied to calculate the $\Lambda$ binding energy in $ ^5 \Lambda $He, where the adjusted 3-body interactions largely resolve the known overbinding problem of $ ^5 _\Lambda $He [2]. [1] L. Contessi, N. Barnea, A. Gal (in preparation). [2] R.H. Dalitz, R.C. Herndon, Y.C. Tang, Nucl. Phys. B 47 (1972) 109.

Primary author

Dr Lorenzo Contessi (Racah Institute of Physics, The Hebrew University, Jerusalem, Israel)

Co-authors

Prof. Avraham Gal (Racah Institute of Physics, The Hebrew University, Jerusalem, Israel) Prof. Nir Barnea (Racah Institute of Physics, The Hebrew University, Jerusalem, Israel)

Presentation materials

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