We present the first microscopic description of proton radioactivity in $^{ 149}$Lu, the most oblate deformed proton emitter known, using a deformed microscopic optical potential derived from $ab\ initio$ nuclear matter calculations. We predict a novel angular-dependent phenomenon unprecedented in spherical proton emitters: the disappearance of classically allowed regions at small polar angles $(\theta\leq 21^\circ)$. Combining the Wentzel-Kramers-Brillouin penetration probabilities and the assault frequency of the emitted proton estimated with a new harmonic-oscillator-inspired scheme, our framework yields a half-life $T_{ 1/2}=467^{ +143}_{ -108}$ ns for $^{ 149}$Lu, in excellent agreement within uncertainties with the experimental value $450^{ +170}_{ -100}$ ns. Deformation analysis rigorously excludes configurations with $|\beta_2|\geq 0.32$. Extensions to $^{ 150, 151}$Lu and their isomers also achieve excellent agreement with experimental half-life data. We further predict $^{ 148}$Lu as another highly oblate $(\beta_2 = -0.166)$ proton emitter with a half-life of 4.42 ns. This work validates deformed microscopic optical potentials as a robust predictive tool for drip-line proton emitters and provides quantitative evidence for deformation effects in exotic decays.
Categories: nucl-th nucl-ex