Search for double-beta decay of $$\mathrm {^{130}Te}$$ to the $$0^+$$ states of $$\mathrm {^{130}Xe}$$ with CUORE
Authors: Adams D. Q. , Alduino C. , Alfonso K. , Avignone F. T. III , Azzolini O. , Bari G. , Bellini F. , Benato G. , Biassoni M. , Branca A. , Brofferio C. , Bucci C. , Camilleri J. , Caminata A. , Campani A. , Canonica L. , Cao X. G. , Capelli S. , Cappelli L. , Cardani L. , Carniti P. , Casali N. , Celi E. , Chiesa D. , Clemenza M. , Copello S. , Cosmelli C. , Cremonesi O. , Creswick R. J. , D’Addabbo A. , Dafinei I. , Davis C. J. , Dell’Oro S. , Domizio S. Di , Dompè V. , Fang D. Q. , Fantini G. , Faverzani M. , Ferri E. , Ferroni F. , Fiorini E. , Franceschi M. A. , Freedman S. J. , Fu S. H. , Fujikawa B. K. , Giachero A. , Gironi L. , Giuliani A. , Gorla P. , Gotti C. , Gutierrez T. D. , Han K. , Heeger K. M. , Huang R. G. , Huang H. Z. , Johnston J. , Keppel G. , Kolomensky Yu. G. , Ligi C. , Ma L. , Ma Y. G. , Marini L. , Maruyama R. H. , Mayer D. , Mei Y. , Moggi N. , Morganti S. , Napolitano T. , Nastasi M. , Nikkel J. , Nones C. , Norman E. B. , Nucciotti A. , Nutini I. , O’Donnell T. , Ouellet J. L. , Pagan S. , Pagliarone C. E. , Pagnanini L. , Pallavicini M. , Pattavina L. , Pavan M. , Pessina G. , Pettinacci V. , Pira C. , Pirro S. , Pozzi S. , Previtali E. , Puiu A. , Rosenfeld C. , Rusconi C. , Sakai M. , Sangiorgio S. , Schmidt B. , Scielzo N. D. , Sharma V. , Singh V. , Sisti M. , Speller D. , Surukuchi P. T. , Taffarello L. , Terranova F. , Tomei C. , Vetter K. J. , Vignati M. , Wagaarachchi S. L. , Wang B. S. , Welliver B. , Wilson J. , Wilson K. , Winslow L. A. , Zimmermann S. , Zucchelli S. 
Published: July 2021

The CUORE experiment is a large bolometric array searching for the lepton number violating neutrino-less double beta decay ($$0\nu \beta \beta $$

0
ν
β
β

) in the isotope $$\mathrm {^{130}Te}$$

130

Te

. In this work we present the latest results on two searches for the double beta decay (DBD) of $$\mathrm {^{130}Te}$$

130

Te

to the first $$0^{+}_2$$

0
2
+

excited state of $$\mathrm {^{130}Xe}$$

130

Xe

: the $$0\nu \beta \beta $$

0
ν
β
β

decay and the Standard Model-allowed two-neutrinos double beta decay ($$2\nu \beta \beta $$

2
ν
β
β

). Both searches are based on a 372.5 kg$$\times $$
×
yr TeO$$_2$$

2

exposure. The de-excitation gamma rays emitted by the excited Xe nucleus in the final state yield a unique signature, which can be searched for with low background by studying coincident events in two or more bolometers. The closely packed arrangement of the CUORE crystals constitutes a significant advantage in this regard. The median limit setting sensitivities at 90% Credible Interval (C.I.) of the given searches were estimated as $$\mathrm {S^{0\nu }_{1/2} = 5.6 \times 10^{24} \, \mathrm {yr}}$$

S

1
/
2

0
ν

=
5.6
×

10
24

yr

for the $${0\nu \beta \beta }$$

0
ν
β
β

decay and $$\mathrm {S^{2\nu }_{1/2} = 2.1 \times 10^{24} \, \mathrm {yr}}$$

S

1
/
2

2
ν

=
2.1
×

10
24

yr

for the $${2\nu \beta \beta }$$

2
ν
β
β

decay. No significant evidence for either of the decay modes was observed and a Bayesian lower bound at $$90\%$$

90
%

C.I. on the decay half lives is obtained as: $$\mathrm {(T_{1/2})^{0\nu }_{0^+_2} > 5.9 \times 10^{24} \, \mathrm {yr}}$$

(

T

1
/
2

)

0
2
+

0
ν

>
5.9
×

10
24

yr

for the $$0\nu \beta \beta $$

0
ν
β
β

mode and $$\mathrm {(T_{1/2})^{2\nu }_{0^+_2} > 1.3 \times 10^{24} \, \mathrm {yr}}$$

(

T

1
/
2

)

0
2
+

2
ν

>
1.3
×

10
24

yr

for the $$2\nu \beta \beta $$

2
ν
β
β

mode. These represent the most stringent limits on the DBD of $$^{130}$$

130

Te to excited states and improve by a factor $$\sim 5$$

∼
5

the previous results on this process.