Abstract:
We report on the recent activity of the NA64 experiment at the SPS of CERN. The NA64 experiment uses a beam dump setup to conduct missing energy searches with a high intensity electron beam.
In 2016 and 2017 separate dedicated searches for two mediators between standard model and dark sector, a new light vector boson A’ and a new short-lived neutral boson X, were performed. The A’ was proposed as a possible explanation for magnetic moment anomalies of muons. It could be created in electron on target reactions e−Z→e−ZA′ and supposedly decay invisible into lighter dark sector particles (A′→χχ). The X is motivated by an excess of e+e−-pairs in 8Be* excited state nuclear transitions. It could be produced in bremsstrahlung interactions e−Z→e−ZX and decay into standard model leptons (X→e+e−).
We show the experimental setup and the analysis strategies of the searches for both bosons. We present the data from 2016 and take a first glance at the data recorded in 2017.