Recent results from the NA48 experiment at CERN

Sergey Shkarovskiy

doi:10.1088/1742-6596/934/1/012031

Abstract

The NA48/2 experiment presents a final result of the charged kaon semileptonic decays form factors measurement based on 4.28 million and 2.91 million selected decays collected in 2004. The result is competetive with other measurements in mode and has a smallest uncertainty for , that leads to the most precise combined result and allows to reduce the form factor uncertainty of |VUS|. The NA48/2 experiment at CERN collected a very large sample of charged kaon decays into multiple final states. From this data sample we have reconstructed about 1663 events of the very rare decay K± → μ±νe+e− over almost negligible background in the region with m(e+e−) above 140 MeV, which is of great interest in Chiral Perturbation Theory. We present the mee spectrum and a model-independent measurement of the decay rate for this region.

Highlights

NA62 is a fixed target experiment located at the North Area of the European Center for Nuclear
NA62 took over the NA48[1] experiment physics program and in 2007 acquired for the first time data using the same beam line and apparatus as in NA48
Starting from 2008 the experiment underwent an intense phase of R&D finalized to the upgrade of the apparatus to push further the physics sensitivity

Summary

The NA62 Experiment

NA62 is a fixed target experiment located at the North Area of the European Center for Nuclear. The proton beam from the SPS accelerator is used to produce a secondary hadron beam and to perform flavor physics studies mainly in the charged kaon sector. NA62 took over the NA48[1] experiment physics program and in 2007 acquired for the first time data using the same beam line and apparatus as in NA48. The purpose of the run was to study the lepton universality through the measurement of the RK. Starting from 2008 the experiment underwent an intense phase of R&D finalized to the upgrade of the apparatus to push further the physics sensitivity. The new detector was optimized for the precise measurement of the K+ → π+ννbranching ratio and has taken data for the first time in 2014/2015

Measurement of the πo Transition Form Factor

The NA62 apparatus in 2007

Event selection and preliminary results

Measurement strategy and NA62 apparatus

Findings

Data Quality in 2015 and Perspective