Evidence for an excess of soft photons in hadronic decays of Z(0)

Soft photons inside hadronic jets converted in front of the DELPHI main tracker (TPC) in events of qq disintegrations of the Z0 were studied in the kinematic range 0.2hadronic bremsstrahlung (which is not included in the Monte Carlo) is (0.340±0.001±0.038)×10-3 γ/jet. The ratio of the excess to the predicted bremsstrahlung rate is then (3.4±0.2±0.8), which is similar in strength to the anomalous soft photon signal observed in fixed target experiments with hadronic beams.