Tilting instability in negative-γ rotating nuclei

Based on the cranking model and the random phase approximation, we point out that the wobbling excitation on top of the s band in ^{182}Os is stable against angular momentum tilting. This is consistent with the general trend that the wobbling excitations in \gamma<0 rotating nuclei are more stable than those in \gamma>0 ones found in our previous studies. In higher N isotopes known to be \gamma soft, however, a different type of tilting instability is expected. Its possible correspondence to the experimental data is also discussed.