Scattering of few nucleons in NLO Pionless Effective Field Theory - n-d, n-3H, and n-3He elastic scattering

  Martin Schäfer  
Racah Institute of Physics, The Hebrew University, Jerusalem

Pionless effective field theory (EFT) represents a highly convenient tool which allows us to describe nucleon interactions at low energies using a minimal set of input parameters.  Pionless EFT at leading order has been used to study various systems up to 16O, however, only with little success, rendering A > 4 nuclei unbound. Higher orders of the theory have been tested only in A<=3 nuclear systems so far, predominantly, due to nontrivial requirement of their perturbative inclusion. At three-body level, it has been shown that considering sub-leading terms systematically improves predictive power of the theory. Experimentally observed binding of A > 4 nuclei is thus expected to be restored at higher orders.

In our work, we applied few-body approach based on the Stochastic Variational Method with a correlated Gaussian basis and a harmonic oscillator trap, which enabled us to study systems with A > 3. In this framework, we performed fully perturbative calculations within next-to-leading order (NLO) pionless EFT where calculations of A=4 systems were performed for the first time. Our microscopic predictions of low-momentum n-d, n-3H, and n-3He elastic scattering (scattering length and effective range) were compared to available experimental data.