Neutrinoless double beta decay and lepton number violation at the LHC

Abstract

We compare the discovery potential of the LHC for lepton number violating (LNV) signals with the sensitivity of current and future double beta decay experiments, assuming $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay is dominated by heavy particle exchange. We consider charged scalar, leptoquark and diquark mechanisms of $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay, covering the $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay operators with both, the smallest and largest, possible rates. We demonstrate, if $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay were found with a half-life below ${10}^{26}--{10}^{27}\text{ }\mathrm{\text{years}}$ a positive signal should show up at the LHC, except for some particular cases of the leptoquark mechanism, and vice versa, if the LHC does not find any hints for LNV, a ``short-range'' explanation for a finite $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay half-life will be ruled out in most cases. We argue, if a positive LNV signal were found at the LHC, it is possible to identify the dominant contribution to $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$. Two different kinds of observables which could provide such ``model discriminating'' power are discussed: different invariant mass peaks and the charge asymmetry.