Measurement of the double-beta decay half-life and search for the neutrinoless double-beta decay of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Ca</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>48</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math>with the NEMO-3 detector

The NEMO-3 experiment at the Modane Underground Laboratory investigates the double-beta decay of $^{48}\mathrm{Ca}$. Using 5.25 yr of data recorded with a 6.99 g sample of $^{48}\mathrm{Ca}$, approximately 150 double-beta decay candidate events are selected with a signal-to-background ratio greater than 3. The half-life for the two-neutrino double-beta decay of $^{48}\mathrm{Ca}$ is measured to be ${T}_{1/2}^{2\ensuremath{\nu}}=[6.{4}_{\ensuremath{-}0.6}^{+0.7}{(\mathrm{stat})}_{\ensuremath{-}0.9}^{+1.2}(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}1{0}^{19}\text{ }\text{ }\mathrm{yr}$. A search for neutrinoless double-beta decay of $^{48}\mathrm{Ca}$ yields a null result, and a corresponding lower limit on the half-life is found to be ${T}_{1/2}^{0\ensuremath{\nu}}&gt;2.0\ifmmode\times\else\texttimes\fi{}1{0}^{22}\text{ }\text{ }\mathrm{yr}$ at 90% confidence level, translating into an upper limit on the effective Majorana neutrino mass of $⟨{m}_{\ensuremath{\beta}\ensuremath{\beta}}⟩&lt;6.0--26\text{ }\text{ }\mathrm{eV}$, with the range reflecting different nuclear matrix element calculations. Limits are also set on models involving Majoron emission and right-handed currents.