Improved Limit on Neutrinoless Double-Beta Decay in ^{130} Te with CUORE.

Area of Science:

• Particle Physics
• Nuclear Physics
• Astroparticle Physics

Background:

• Neutrinoless double-beta decay (0νββ) is a hypothetical process that violates lepton number conservation.
• Observing 0νββ decay would prove that neutrinos are Majorana particles and provide insights into the matter-antimatter asymmetry in the universe.
• ^{130}Te is a promising isotope for 0νββ decay searches due to its relatively high Q-value.

Purpose of the Study:

• To search for neutrinoless double-beta decay in ^{130}Te using the CUORE detector.
• To improve the sensitivity and exclusion limits compared to previous searches.
• To constrain the effective Majorana neutrino mass.

Main Methods:

• Utilized the Cryogenic Underground Observatory for Rare Events (CUORE) detector, a bolometric experiment.
• Achieved a total exposure of 372.5 kg·yr, a fourfold increase over previous results.
• Implemented lower trigger thresholds and refined analysis techniques to reduce background and enhance sensitivity.

Main Results:

• Observed a background rate of (1.38±0.07)×10^{-2} counts/(keV·kg·yr) in the region of interest.
• Attained a median exclusion sensitivity of 1.7×10^{25} yr.
• Set a 90% credibility interval Bayesian lower limit of 3.2×10^{25} yr on the ^{130}Te half-life for 0νββ decay.

Conclusions:

• No evidence for neutrinoless double-beta decay in ^{130}Te was found.
• The results provide the most stringent limit to date on the half-life of this decay.
• Derived an upper limit on the effective Majorana neutrino mass between 75-350 meV, contingent on nuclear matrix element calculations.