First Results from CUORE: A Search for Lepton Number Violation via 0νββ Decay of Te130

Abstract

The CUORE experiment, a ton-scale cryogenic bolometer array, recently began operation at the Laboratori Nazionali del Gran Sasso in Italy. The array represents a significant advancement in this technology, and in this work we apply it for the first time to a high-sensitivity search for a lepton-number-violating process: ^{130}Te neutrinoless double-beta decay. Examining a total TeO_{2} exposure of 86.3 kg yr, characterized by an effective energy resolution of (7.7±0.5) keV FWHM and a background in the region of interest of (0.014±0.002) counts/(keV kg yr), we find no evidence for neutrinoless double-beta decay. Including systematic uncertainties, we place a lower limit on the decay half-life of T_{1/2}^{0ν}(^{130}Te)>1.3×10^{25} yr (90% C.L.); the median statistical sensitivity of this search is 7.0×10^{24} yr. Combining this result with those of two earlier experiments, Cuoricino and CUORE-0, we find T_{1/2}^{0ν}(^{130}Te)>1.5×10^{25} yr (90% C.L.), which is the most stringent limit to date on this decay. Interpreting this result as a limit on the effective Majorana neutrino mass, we find m_{ββ}<(110-520) meV, where the range reflects the nuclear matrix element estimates employed.

Breaking of the tetra-maximal neutrino mixing pattern

“…We introduce explicit breaking terms in such a way that one can explain large θ 12 as well as non-maximal values of θ 23 and δ, which are in well agreement with the latest global analysis data [2,9,10]. Moreover, although the predicted θ 13 within this mixing pattern is in compatible with the latest 3σ data, we show that such explicit breaking can also explain its best-fit value.…”

“…Within the symmetry, imposing ρ = σ = 90 • , we find that the leading order term of θ 12 is ∝ (m 2 + m 1 )/(m 2 − m 1 ) > 1 which enhances the evolution of θ 12 . On the other hand, θ 13 , θ 23 can not reach their current best-fit values i.e., θ 13 = 8.61 • (see dashed blue horizontal line), θ 23 = 49.6 • as can be seen from the left and right panels of the first row, respectively. A deviation of less than O(1 • ) have been identified for both the parameters.…”

“…The 0νββ decay (A, Z) −→ (A, Z + 2) + 2e − is the unique process which can probes the Majorana nature of massive neutrinos. The experiments that are currently searching for the signature of 0νββ-decay are GERDA Phase II [22], CUORE [23], SuperNEMO [24], KamLAND-Zen [25] and EXO [26]. However, this process violate lepton number by two-units.…”

Status of Neutrino Properties and Future Prospects—Cosmological and Astrophysical Constraints

“…We also specify the isotope used in each experiment. The current bounds are m ββ < 0.120 − 0.270 eV from Gerda Phase-II ( 76 Ge) [173,174] [177]. The next generation 0ν2β experiments, such as LEGEND, SuperNEMO, CUPID, SNO+, KamLAND2-Zen, nEXO, NEXT, PANDAX-III, aims to cover the entire region of IH, reaching a 3σ discovery sensitivity for m ββ of 20 meV or better, roughly an order of magnitude improvement with respect to the current limits (see [178] for a more detailed discussion and for a full list of references).…”

Lattice QCD Inputs for nuclear double beta decay

“…Because of these outstanding scientific motivations, a vigorous worldwide experimental program exists searching for 0νββ. Current experimental limits are very stringent [12][13][14][15][16][17][18][19][20][21][22][23][24]; for example, the 0νββ lifetime of 136 Xe is T 0ν 1/2 > 1.07 × 10 26 yr [16]. Next-generation, ton-scale, experiments aim to improve sensitivity by one or two orders of magnitude.…”