Test of vector portal with dark fermions in NA64 Experiment

News, 22 July 2024

Scientists from the Laboratory of Theoretical Physics at JINR, research centres, and universities of Chile, Germany, and Russia presented the results of an experiment searching for dark sector particles in neutral meson decays in the NA64 Experiment at the Super Proton Synchrotron (SPS) at CERN.

The article details an experiment searching for dark sector particles in invisible (or semi-invisible) decays of neutral mesons M00, ?, ?′, ?, ? 2 (1270), which produced the charge-exchange reactions π-+(A,Z)→M0+(A,Z-1);M0→ invisible of high-energy pions (or kaons) on a nuclei target in the NA64 experiment at the CERN SPS. This reaction chain would lead to a striking signature of the signal event—the complete disappearance of the beam energy in the setup. Using data obtained from the measurements at IHEP (Protvino) and Fermilab (Batavia) we show that the integral cross sections ? for the production of the M0s slightly deviate from the phenomenological formula σ~Z2/3, where ? is the nuclei charge. In particular, the article presents formulas for the differential and integral cross sections that explicitly depend on the Mandelstam and ? variables. Derived formulas are used to predict the M0 yield as a function of beam energy for several target nuclei and to estimate the projection sensitivity for the proposed search in the dark vector portal model. Sensitivity to different decay modes of M0s is studied.

The full text of the article is available via the link. Among the authors is a senior researcher of the Laboratory of Theoretical Physics at JINR Alexey Zhevlakov.