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Register a new userNucleon and dinucleon decays to leptonic final states in a left-right symmetric model with large extra dimensions
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Sudhakantha Girmohanta
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We consider baryon-number-violating nucleon and dinucleon decays to leptonic final states in the context of a left-right symmetric (LRS) model with large extra dimensions. Specifically, we study (a) nucleon to trilepton decays with $Delta B=-1$ and $Delta L=-3$, and (b) dinucleon to dilepton decays with $Delta B=-2$ and $Delta L=-2$. In the LRS model, $B-L$ is gauged and is spontaneously broken by a Higgs vacuum expectation value $v_R$, which characterizes the scale at which processes violating $B-L$ occur. We show that together with the lower bound on $v_R$ from experimental limits on $n$-$bar n$ oscillations, constraints from searches for other nucleon decay modes imply sufficient suppression of these nucleon to trilepton and dinucleon to dilepton decay modes in this model to agree with experimental bounds.
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It is known that limits on baryon-violating nucleon decays do not, in general, imply corresponding suppression of $n - bar n$ transitions. In the context of a model with fermions propagating in higher dimensions, we investigate a related question, namely the implications of limits on $Delta L=-1$ proton and bound neutron decays mediated by four-fermion operators for rates of nucleon decays mediated by $k$-fermion operators with $k =6$ and $k=8$. These include a variety of nucleon and dinucleon decays to dilepton and trilepton final states with $Delta L=-3, -2, 1$, and $2$. We carry out a low-energy effective field theory analysis of relevant operators for these decays and show that, in this extra-dimensional model, the rates for these decays are strongly suppressed and hence are in accord with experimental limits.
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