Description
The current generation of short baseline neutrino experiments is
approaching intrinsic source limitations in the knowledge of flux,
initial neutrino energy and flavor. A dedicated facility based on
conventional accelerator techniques and existing infrastructures
designed to overcome these impediments would have a remarkable impact
on the entire field of neutrino oscillation physics. It would improve
by about one order of magnitude the precision on $\nu_\mu$ and $\nu_e$
cross sections, enable the study of electroweak nuclear physics at the
GeV scale with unprecedented resolution and advance searches for
physics beyond the three-neutrino paradigm. In turn, these results
would enhance the physics reach of the next generation long baseline
experiments (DUNE and Hyper-Kamiokande) on CP violation and their
sensitivity to new physics. In this document, we present the physics
case and technology challenge of high precision neutrino beams based
on the results achieved by the ENUBET Collaboration in 2016-2018. We
also set the R\&D milestones to enable the construction and running of
this new generation of experiments well before the start of the DUNE
and Hyper-Kamiokande data taking. We discuss the implementation of
this new facility at three different level of complexity: $\nu_\mu$
narrow band beams, $\nu_e$ monitored beams and tagged neutrino
beams. We also consider a site specific implementation based on the
CERN-SPS proton driver providing a fully controlled neutrino source to
the ProtoDUNE detectors at CERN.
