Search for K + → π + νν̄ at the NA62 experiment

Looking for phenomena beyond the Standard Model (SM) in rare decays is a complementary approach to direct searches for New Physics (NP) at colliders. One of the theoretically cleanest processes is the ultra rare decay K+ → π+νν̄. The goal of the NA62 experiment at CERN SPS is to measure the branching ratio (BR) of this decay with 10% precision. The experiment has been launched in 2014. In 2015, the detector was commissioned at a low intensity beam. The experimental setup is described and performances achieved in 2015 are discussed in view of the final measurement.