Ram Lal Awasthi, M. K. Parida, Sudhanwa Patra
In the conventional TeV scale parity restoring left-right model, new dominant contribution to neutrinoless double beta decay runs into conflict with light neutrino mass predictions through popular seesaw mechanisms. We evade this difficulty by using a class of left-right gauge theories with high scale parity restoration but TeV scale $W_R, Z_R$ gauge bosons and extended seesaw mechanism for neutrino masses. Most dominant new contribution to neutrinoless double beta decay is noted to occur via $W_L^{-}W_L^{-}$ mediation involving lighter sterile neutrino exchanges. The next dominant contribution is found to be through $W_L^{-}W_R^{-}$ mediation involving both light and heavy right-handed neutrino or sterile neutrino exchanges. The quark-lepton symmetric origin of the Dirac neutrino mass matrix is also found to play a crucial role in determining these results while predicting lepton flavor violating branching ratios for $\tau \rightarrow e + \gamma$, $\tau \rightarrow \mu + \gamma$, and $\mu \rightarrow e + \gamma$ accessible to ongoing search experiments. The underlying non-unitarity matrix is found to manifest in the predictions of substantial CP-violating effects even when the leptonic Dirac phase $\delta_{\rm CP} \simeq 0, \pi, 2 \pi$. Finally we explore a possible origin of the model in non-supersymmetric SO(10) grand unified theory where, in addition to low mass $W_R^\pm$ and $Z_R$ bosons accessible to Large Hadron Collider, the model is found to predict observable neutron-antineutron oscillation and lepto-quark gauge boson mediated rare kaon decay with ${Br} (K_{\rm L} \rightarrow \mu\, \bar{e}) \simeq (10^{-9}- 10^{-11})$.
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http://arxiv.org/abs/1302.0672
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