Parity-transfer ({}¹⁶{rm O},{}¹⁶{rm F}(0^-,{rm g.s.})) reaction as a selective probe of isovector 0^- states in nuclei

We demonstrate that the parity-transfer $({}^{16}{\rm O},{}^{16}{\rm F}(0^-,{\rm g.s.}))$ reaction provides a selective probe of isovector $0^-$ excitations in nuclei. This reaction selectively populates unnatural-parity states through a $0^+ \to 0^-$ transition in the projectile. The excitation-energy spectrum of $^{12}\mathrm{B}$ was reconstructed via the ${}^{12}{\rm C}({}^{16}{\rm O},{}^{16}{\rm F}(0^-,{\rm g.s.}))$ reaction at 247~MeV/u from the coincident detection of the ${}^{15}\mathrm{O}+p$ decay products of ${}^{16}\mathrm{F}$. The known $0^{-}$ state at $E_x = 9.3~{\rm MeV}$ was clearly observed with a strongly enhanced forward cross section, establishing the selectivity of the reaction. Structures observed at $E_x = 6.6 \pm 0.4$ and $14.8 \pm 0.3~{\rm MeV}$ exhibit forward-peaked angular distributions and are suggested to contain significant $0^-$ strength. These results demonstrate that the parity-transfer reaction provides a powerful probe of $0^-$ excitations and highlight its potential for systematic studies of spin-isospin modes, including pion-related dynamics, in nuclei.