A model of n - n ^ { \prime } ( neutron-mirror neutron ) oscillations is proposed under the framework of the mirror matter theory with slightly broken mirror symmetry .
It resolves the neutron lifetime discrepancy , i.e. , the 1 % difference in neutron lifetime between measurements from “ beam ” and “ bottle ” experiments .
In consideration of the early universe evolution , the n - n ^ { \prime } mass difference is determined to be about 2 \times 10 ^ { -6 } eV/c ^ { 2 } with the n - n ^ { \prime } mixing strength of about 2 \times 10 ^ { -5 } .
The picture of how the mirror-to-ordinary matter density ratio is evolved in the early universe into the observed dark-to-baryon matter density ratio of about 5.4 is presented .
Reanalysis of previous data and new experiments that can be carried out under current technology are discussed and recommended to test this proposed model .
Other consequences of the model on astrophysics and possible oscillations of other neutral particles are discussed as well .