New experimental limits on the Pauli-forbidden transitions in 12C nuclei obtained with 485 days Borexino data

New experimental limits on the Pauli-forbidden transitions in ¹²C nuclei obtained with 485 days Borexino data
G. Bellini et al. (Borexino Collaboration)
Phys. Rev. C 81, 034317 – Published 29 March 2010

doi:10.1103/PhysRevC.81.034317
(local copy; preprint on arXiv)

Abstract

The Pauli exclusion principle (PEP) has been tested for nucleons (n,p) in ¹²C with the Borexino detector. The approach consists of a search for γ, n, p, and β^± emitted in a non-Paulian transition of 1P_3/2-shell nucleons to the filled 1S_1/2 shell in nuclei. Due to the extremely low background and the large mass (278 tons) of the Borexino detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established:
$\tau(^{12}C\rightarrow^{12}\tilde{C}+\gamma)\geq5.0\times10^{31}$ $yr$ ,
$\tau(^{12}C\rightarrow^{11}\tilde{B}+p)\geq8.9\times10^{29}$ $yr$ ,
$\tau(^{12}C\rightarrow^{11}\tilde{C}+n)\geq3.4\times10^{30}$ $yr$ ,
$\tau(^{12}C\rightarrow^{12}\tilde{N}+e^{-}+\tilde{\nu}_{e})\geq3.1\times10^{30}$ $yr$ ,
$\tau(^{12}C\rightarrow^{12}\tilde{B}+e^{+}+\nu_{e})\geq2.1\times10^{30}$ $yr$ ,
all at 90% C.L. The corresponding upper limits on the relative strengths for the searched non-Paulian electromagnetic, strong and weak transitions have been estimated as $\delta^{2}_{\gamma}\leq2.2\times10^{-57}$ , $\delta^{2}_{N}\leq4.1\times10^{-60}$ , and $\delta^{2}_{\beta}\leq2.1\times10^{-35}$ .