Possible collective band in neutron-rich $^{119}$Sn

Abstract Excited states of $^{119}$Sn have been studied using an in-beam $\gamma$-ray spectroscopic technique following the incomplete fusion of $^{7}$Li on an $^{116}$Cd target at a beam energy of 42 MeV. A new bandlike structure is proposed to be arised from deformed two-particle-two-hole (2p-2h) proton excitations across the $Z$ = 50 closed shell based on the systematics of the odd-$A$ Sn isotopes and the configuration-fixed constrained triaxial relativistic mean-field calculations. This observation extends the boundaries of the deformed 2p-2h collective band to $A$ = 119 in the Sn isotopes.