Gauged $L^{}_{\mu}{-}L^{}_{\tau}$ at a muon collider

Understand

We investigate the sensitivity of the projected TeV muon collider to the gauged $L^{}_{\mu}$-$L^{}_{\tau}$ model.

• Two processes are considered: $Z'$-mediated two-body scatterings $\mu^+ \mu^- \to \ell^+ \ell^-$ with $\ell = \mu$ or $\tau$, and scattering with initial state photon emission, $\mu^+ \mu^- \to \gamma Z',~Z' \to \ell \overline{\ell}$, where $\ell$ can be $\mu$, $\tau$ or $\nu_{\mu/\tau}$.
• We quantitatively study the sensitivities of these two processes by taking into account possible signals and relevant backgrounds in a muon collider experiment with a center-of-mass energy $\sqrt{s} = 3~{\rm TeV}$ and a luminosity $L=1~{\rm ab^{-1}}$.
• For two-body scattering one can exclude $Z'$ masses $M^{}_{Z'} \lesssim 100~{\rm TeV}$ with $\mathcal{O}(1)$ gauge couplings.