Proton radii of 4,6,8He isotopes from high-precision nucleon-nucleon interactions

Recently, precision laser spectroscopy on He-6 atoms determined accurately the isotope shift between He-4 and He-6 and, consequently, the charge radius of He-6. A similar experiment for He-8 is under way. We have performed large-scale ab initio calculations for He-4,He-6,He-8 isotopes using high-precision nucleon-nucleon (NN) interactions within the no-core shell model (NCSM) approach. With the CD-Bonn 2000 NN potential we found point-proton root-mean-square (rms) radii of He-4 and He-6 1.45(1) fm and 1.89(4), respectively, in agreement with experiment and predict the He-8 point-proton rms radius to be 1.88(6) fm. At the same time, our calculations show that the recently developed nonlocal INOY NN potential gives binding energies closer to experiment, but underestimates the charge radii.