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We report results on 1220 electron pairs produced from a 207Pb beam at 160 A GeV in nuclear emulsion with invariant mass Q ranging between 1 and 100 MeV and lifetime τ between 10−15 s and 10−12 s. These electron pairs were produced at a distance of more than 50 µm from the primary interactions—this distance eliminates contamination due to Dalitz pairs. After subtracting the background pairs from the materialization of photons and also due to the decay of π0 → 2γ from the data, they exhibit enhancement at low mass Q = 6–20 MeV with narrow peaks at 7 ± 1 MeV, 19 ± 1 MeV and τ ⩽ 10−13 s.

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