Possible multiple chiral doublet bands in odd-odd 128La

High-spin states of 128La have been populated by the 118Sn(14N, 4n)128La reaction at a beam energy of 69 MeV. The previously known level scheme of 128La is extended with the addition of 27 gamma transitions. A new negative-parity band with the same pi h11/2 (R) nu d5/2 configuration as that of the yrare band is observed in 128La. This pair of negative-parity bands is suggested to be candidate chiral doublet bands, which is supported by the particle rotor model calculations. Meanwhile, the newly identified negative-parity chiral doublet bands together with the previously known pair of positive-parity chiral doublet bands constitute a case of multiple chiral doublet bands in the odd-odd nucleus 128La. Furthermore, systematic studies of multiple chiral doublet bands are presented in this work.