A Search for $0^+$ States in $^{50}$Cr: Implications for the Superallowed $\beta$-decay of $^{50}$Mn

A Cr-52(p, t)Cr-50 two-neutron pickup reaction was performed using the Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium in Garching, Germany. Excited states in Cr-50 were observed up to an excitation energy of 5.3 MeV. Despite significantly increased sensitivity and resolution over previous work, no evidence of the previously assigned first excited 0(+) state was found. As a result, the 0(2)(+) state is reassigned at an excitation energy of E-x = 3895.0(5) keV in Cr-50. This reassignment directly impacts direct searches for a nonanalog Fermi beta(+) decay branch in Mn-50. These results also show better systematic agreement with the theoretical predictions for the 0(+) state spectrum in Cr-50 using the same formalism as the isospin-symmetry-breaking correction calculations for superallowed nuclei. The experimental data are also compared to ab-initio shell-model predictions using the IM-SRG formalism based on NN and 3N forces from chiral-EFT in the pf-shell for the first time.