Observation of e⁺e^-→■-+c.c.

摘要

Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢ detector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb-1, the process e+e-→■+ c.c. is observed for the first time with a statistical significance of 11.5σ. The average Born cross sections in the energy ranges of（4.160, 4.380） GeV,（4.400, 4.600） GeV and（4.610, 4.700） GeV are measured to be（21.5±5.7±1.2） fb,（46.3±10.6±2.5） fb and （59.0±9.4±3.2） fb, respectively, where the first uncertainties are statistical and the second are systematic. The line shapes of the ■ and ppπ- invariant mass spectra are consistent with phase space distributions, indicating that no hexaquark or di-baryon state is observed.

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