Double Beta Decay Constraint on Composite Neutrinos

Abstract

Neutrinoless double beta decay occurs through the magnetic coupling of dimension five, ${\lambda }_W/m_{\nu \ast }$, among the excited electron neutrino ${\nu }^{\ast }$, electron and $W$ boson if ${\nu }^{\ast }$ is a massive Majorana neutrino. (\lambda_W m_W / m_{\nu*}^2 |\frac{(m_*/m_W) +2}{(m_*/m_W +1)^2} -0.129{m_*/m_W} | <2.13\times 10^{-2}, where ${\lambda }_W$ is the relative strength, $m_{\nu \ast }$ is the composite scale and $m_{\ast }$ is the mass of excited neutrino. If the coupling is not small, i.e., ${\lambda }_W>1$ and $m_{\nu \ast }=m_{\ast }$, we find $m_{\ast }>3.4m_W$.

Comments: 10pages