6533b824fe1ef96bd1280909

RESEARCH PRODUCT

Impact of the quenching of gA on the sensitivity of 0νββ experiments

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Detection of the neutrinoless $\ensuremath{\beta}\ensuremath{\beta}$ ($0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) decay is of high priority in the particle- and neutrino-physics communities. The detectability of this decay mode is strongly influenced by the value of the weak axial-vector coupling constant ${g}_{A}$. The recent nuclear-model analyses of $\ensuremath{\beta}$ and $\ensuremath{\beta}\ensuremath{\beta}$ decays suggest that the value of ${g}_{A}$ could be dramatically quenched, reaching ratios of ${g}_{A}^{\mathrm{free}}/{g}_{A}\ensuremath{\approx}4$, where ${g}_{A}^{\mathrm{free}}=1.27$ is the free, neutron-decay, value of ${g}_{A}$. The effects of this quenching appear devastating for the sensitivity of the present and future $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ experiments since the fourth power of this ratio scales the $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ half-lives. This, in turn, could lead to some two orders of magnitude less sensitivity for the $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ experiments. In the present article it is shown that by using a consistent approach to both the two-neutrino $\ensuremath{\beta}\ensuremath{\beta}$ and $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decays by the proton-neutron quasiparticle random-phase approximation, the feared two-orders-of-magnitude reduction in the sensitivity of the $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ experiments actually shrinks to a reduction by factors in the range $2\text{--}6$. This certainly has dramatic consequences for the potential to detect the $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay.