Complex sentence: Subsequent data collected by the same experiment in 1977 revealed that the resonance had indeed been a fluctuation, but a new resonance at 9.5 GeV was discovered (using the same basic logic and greater statistical certainty), and the name Upsilon meson was reused.
Split into simpler sentences: Subsequent data collected by the same experiment in 1977 revealed that the resonance had indeed been a fluctuation. However, a new resonance at 9.5 GeV was discovered, using the same basic logic and greater statistical certainty, and the name Upsilon meson was reused.