Search for R-Parity Violating Production of Single Sneutrinos in e+e- Collisions at sqrt(s) = 189-209GeV

A search for single sneutrino production under the assumption that R-parity is violated via a single dominant $LL\bar{E}$ coupling is presented. This search considers the process ${\rm e} \gamma {\smash{\mathop{\to}}} \tilde{\nu}\ell$ and is performed using the data collected by the ALEPH detector at centre-of-mass energies from 189 GeV up to 209 GeV corresponding to an integrated luminosity of 637.1 $\mathrm{pb}^{-1}$. The numbers of observed candidate events are in agreement with Standard Model expectations and 95% confidence level upper limits on five of the $LL\bar{E}$ couplings are given as a function of the assumed sneutrino mass.