New experimental limits on the Pauli-forbidden transitions inC12nuclei obtained with485days Borexino data

The Pauli exclusion principle (PEP) has been tested for nucleons ($n,p$) in ${}^{12}\mathrm{C}$ with the Borexino detector. The approach consists of a search for $\gamma$, $n$, $p$, and ${\beta }^{\pm }$ 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: $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{C}}+\gamma )⩾5.0\times {10}^{31}$ yr, $\tau ({}^{12}\mathrm{C}\to {}^{11}\tilde{\mathrm{B}}+p)⩾8.9\times {10}^{29}$ yr, $\tau ({}^{12}\mathrm{C}\to {}^{11}\tilde{\mathrm{C}}+n)⩾3.4\times {10}^{30}$ yr, $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{N}}+e^{-}+\widetilde{{\nu }_e})⩾3.1\times {10}^{30}$ yr, and $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{B}}+e^{+}+{\nu }_e)⩾2.1\times {10}^{30}$ 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 ${\delta }_{\gamma }^2⩽2.2\times {10}^{-57}$, ${\delta }_N^2⩽4.1\times {10}^{-60}$, and ${\delta }_{\beta }^2⩽2.1\times {10}^{-35}$.