Current status of superallowed $0^+$$\rightarrow 0^+$ nuclear $\beta$ decay and the value of $V_{ud}$

Currently, the results from superallowed $0^+$$\rightarrow 0^+$ nuclear $\beta$ decays provide the most precise value for $V_{ud}$, the up-down element of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix. According to the most recent critical survey of world data [1], the $ft$ values for 14 of these superallowed transitions have been established to a precision of order 0.1\% or better. These results, which cover a wide range of parent nuclei from $^{10}$C to $^{74}$Rb, constitute a very robust data set. After radiative and isospin-symmetry-breaking corrections have been applied, the resulting corrected ${\cal F} t$ values are all consistent with one another, demonstrating agreement with conservation of the vector current (CVC). With CVC upheld, the ${\cal F} t$-value results can then be averaged to obtain a value for $G_V$, the vector coupling constant, and for $V_{ud}$. Since the last survey closed, new measurements have appeared, which do not significantly change the conclusions in [1] but do reflect constructively on isospin symmetry breaking and on possible scalar currents. Up-to-date outcomes will be presented. \newline [1] J.C. Hardy and I.S. Towner, Phys. Rev. C 91, 025501 (2015).