Some recent DAMA/NaI results on
Charge-Non-Conserving processes

The electric charge conservation is a fundamental law of quantum electrodynamics; nevertheless, because there is the possibility that it may be broken in future unified gauge theories, many efforts have been devoted to test it with different procedures by various experimental groups.

In particular, by using the ~100 kg NaI(Tl), we have achieved the new results summarized in the following:

  • 1999 - Limit on electron stability - considering for the first time L-shell electrons in the Iodine atoms- (exposure 19511 kg day) studying the process:
    e- → 3ν, majoron + ν or anything invisible:
    τ > 4.2 x 1024 y at 68% C.L.;

  • 1999 - New lifetime limits on the charge non-conserving electron capture with excitation of 127I and 23Na nuclear levels have been established by using a exposure of 34866 kg day. These new limits are in the range:
    (1.5-2.4) x 1023 y,

    (up to two orders of magnitude higher than the ones previously available).
    Stringent restrictions on the relative strengths of the charge non-conserving (CNC) processes are derived (90% C.L.):
    (εW)2 < 9.6 x 10 -26 and (εγ)2 < 1.2 x 10-40