Production of χc1 in e +e − collision
DOI:
https://doi.org/10.31349/SuplRevMexFis.3.0308059Keywords:
e e − annihilation, charmonium, electronic width, BESIII, two-photon processAbstract
The direct production of the charmonium state χc1 in electron positron annihilation is searched by using e +e − collision data at four centerof-mass energies, 3.5080, 3.5097, 3.5104 and 3.5146 GeV collected with the BESIII detector at the BEPC-II collider. By combining the 4 data samples, the χc1 signal is observed with a significance of 5.1σ. An interference pattern between the signal process of e +e − → χc1 → γJ/ψ → γµ+µ − and the background process of e +e − → γISRJ/ψ → γISRµ +µ − is identified. This is the first observation of a C-even state produced directly in e +e − annihilation. At 68.3% confidence level, the electronic width of χc1 is determined to be Γee = (0.12+0.13 −0.08) eV.
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