Determination of V$^_{ud}$ from mirror transitions and the role of atom and ion traps

The Vud element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix has traditionally been determined from the analysis of data in three semileptonic processes, namely, nuclear superallowed 0+ ! 0+ transitions, neutron decay and pion beta decay. It has recently been shown that the value of |Vud| can independently be determined from the analysis of T=1/2 nuclear mirror transitions and that this value is more precise than the pion result, competitive with the neutron result and consistent with that from 0+ ! 0+ transitions. The extraction of |Vud| from mirror transitions requires (like the neutron decay) the knowledge of the associated Gamow-Teller/Fermi mixing ratios which can directly be obtained from beta decay correlation measurements. Such measurements have recently been performed with high precision using atom traps. We review here recent achievements obtained in beta decay correlation measurements using atom and ion traps and discuss their potential for the determination of GT/F mixing ratios in mirror transitions with the aim to further improve the extraction of |Vud|