Confirmation of a soft photon signal in excess of Q.E.D. expectations in pi p interactions at 280 GeV/c

TL;DR

This study confirms a significant excess of soft photon production in pi p interactions at 280 GeV/c, exceeding Q.E.D. predictions, using a lead sheet detector setup at CERN.

Contribution

The paper provides experimental evidence of a soft photon excess in pi p interactions, confirming previous findings with a different detection method.

Findings

Soft photon signal is 7.8 times the Q.E.D. prediction.

Results confirm previous observations of soft photon excess.

Photon detection via e+e- pairs in lead sheet.

Abstract

Photons produced in pi p interactions at 280 GeV/c were detected by reconstructing the e+e- pairs produced via the materialisation of the photons in a 1 mm thick lead sheet placed in front of the MWPCs of the OMEGA spectrometer at CERN. A soft photon signal 7.8 +/- 1.5 times the Q.E.D. inner bremsstrahlung prediction was observed confirming the results of a previous experiment.