The NEXT generation of neutrinoless double beta decay experiments

Neutrinos, unlike the other fermions, could be Majorana particles, that is, truly neutral particles identical to their antiparticles. This would have deep consequences in particle physics and cosmology. A unique signature of Majorana neutrinos is the observation of neutrinoless double beta decays (ββ0ν). The discovery of neutrino oscillations — which has shown that neutrinos have masses — and the possible evidence of a ββ0ν signal in the Heildelberg-Moscow experiment have revolutionized the double beta decay comunity. A new generation of experiments with improved sensitivity is currently under design and construction. This paper reviews some of these proposals, with special emphasis in NEXT, that aims at building a 100-kg, high-pressure gas xenon TPC to be hosted in the new Canfranc Underground Laboratory (LSC), in Spain.