Speaker
Description
Two-neutrino double beta decay (2$\nu\beta\beta$) is a rare radioactive decay that is a weak process of second-order. It has been observed in neutrino-less double beta decay (0$\nu\beta\beta$) search experiments to verify the Majorana nature of neutrino. Precise observation of 2$\nu\beta\beta$ is important to reduce the theoretical uncertainty in the calculation of nuclear matrix elements required to obtain the effective Majorana mass from a lifetime of 0$\nu\beta\beta$. Also, 2$\nu\beta\beta$ itself is interesting because new physics could be hiding in the energy spectrum, for examples, Majoron emission mode 0$\nu\beta\beta$ and 2$\nu\beta\beta$ with neutrino-self-interaction.
KamLAND-Zen 800 is an experiment to search 0$\nu\beta\beta$ of $^{136}$Xe with ultra-pure large liquid scintillator detector, KamLAND. KamLAND-Zen 800 has been observing since 2019 with 750 kg of Xenon gas 91% enriched in $^{136}$Xe. We can analyze 2$\nu\beta\beta$ with high statistics.
I present the prospects of precisely measurement of 2$\nu\beta\beta$ half life and search for new physics in 2$\nu\beta\beta$ with KamLAND-Zen 800 in this presentation.
