New Experimental Limits on the Pauli-Forbidden Transitions in 12C Nuclei Obtained with 485 Days Borexino Data

The Pauli exclusion principle (PEP) has been tested for nucleons (n, p) in C with the Borexino detector.The approach consists of a search for γ, n, p and β emitted in a non-Paulian transition of 1P3/2shell nucleons to the filled 1S1/2 shell in nuclei. Due to the extremely low background and the large mass (278 t) of the Borexino detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established: τ (C → C̃ + γ) ≥ 5.0 · 10 y, τ (C → B̃ + p) ≥ 8.9 · 10 y, τ (C → C̃ + n) ≥ 3.4 · 10 y, τ (C → Ñ + e + ν̃e) ≥ 3.1 · 10 30 y and τ (C → B̃ + e + νe) ≥ 2.1 · 10 30 y, 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: δ γ ≤ 2.2 · 10 , δ N ≤ 4.1 · 10 −60 and δ β ≤ 2.1 · 10 .