Humanity discovered that this Universe is made of particles and has developed particle physics over more than a century. To date we know this universe is made of fundamental particles, which are called Leptons and Quarks. Neutrino is a group of particles belongs Leptons. Since they don't interact with electromagnetic force nor with strong force, they can penetrate even the earth easily. However, physicists have found ways to catch them by means of various neutrino sources and huge detectors with kilo-tons of masses.
Particle physics has been greatly progressed with an employment of particle collider. The state-of-the-art collider is the Large Hadron Collider (LHC) at CERN with a collision energy of 13.6 TeV. At the colliders, wide range of particles can be studied from quarks to hypothetical dark matter, but they miss neutrino physics. In 50 years of history of particle colliders, no neutrino had been detected. This is due to the elusive nature of neutrinos and also the high radiation environment at the colliders. Neutrinos have been regarded as invisible at colliders. While, neutrinos from the LHC is expected to be at the highest energies that human can produce, and no data is currently available at the energies around 1 TeV. This can be a great opportunity for new discoveries.
This ERC-FASERnu project aims to detect and study high energy neutrinos at the LHC. We identified a suitable experimental location 480-m downstream of the proton-proton interaction point, where we can mitigate the problem of high background radiation. We then employ a 1.1-tons nano-resolution neutrino detector with a sensitivity to separate different neutrino species (electron-, mu- and tau-neutrinos) and heavy quark species (charm, beauty). By taking data in the LHC operation in 2022-2025, we can collect about 10000 neutrino interactions. This data samples allows us to study the Lepton Flavor Universality, which has doubted due to recently identified anomalies, with neutrinos. Furthermore, by studying heavy quark production channels, FASERnu can study time-reversal process of heavy meson decays, in which a hint of beyond-standard-model phenomena is observed. This project not only contribute in neutrino physics, but also has implications in QCD and cosmic-ray physics. It is worth noting also that FASERnu will be the only neutrino experiment performed in Europe in this decade using an accelerator.
In the last years, the European strategy of particle physics was reported. The key message was to exploit the LHC as much as possible and plan for the Future Circular Collider. So far, the LHC and neutrino experiments are two separate lines of research, however, FASERnu will bring them together and pioneer a new research domain. Therefore, FASERnu will perfectly fit with the European strategy, and extend the discovery potential of the LHC in a new direction.
