Constraints On The Dark Matter Interpretation N -> Chi Plus E(+)E(-) Of The Neutron Decay Anomaly With The Perkeo Ii Experiment

Discrepancies from in-beam- and in-bottle-type experiments measuring the neutron lifetime are on the 4 sigma standard deviation level. In a recent publication Fornal and Grinstein proposed that the puzzle could be solved if the neutron would decay on the one percent level via a dark decay mode, one possible branch being n -> chi + e(+)e(-). With data from the PERKEO II experiment we set limits on the branching fraction and exclude a one percent contribution for 95% of the allowed mass range for the dark matter particle.