Abstract

The decays $\chi_{c1} \rightarrow J/\psi \mu^+ \mu^-$ and $\chi_{c2} \rightarrow J/\psi \mu^+ \mu^-$ are observed and used to study the resonance parameters of the $\chi_{c1}$ and $\chi_{c2}$ mesons. The masses of these states are measured to be m(\chi_{c1}) = 3510.71 \pm 0.04(stat) \pm 0.09(syst)MeV , m(\chi_{c2}) = 3556.10 \pm 0.06(stat) \pm 0.11(syst)MeV , where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. The momentum-scale uncertainties largely cancel in the mass difference m(\chi_{c2}) - m(\chi_{c1}) = 45.39 \pm 0.07(stat) \pm 0.03(syst)MeV . The natural width of the $\chi_{c2}$ meson is measured to be $$\Gamma(\chi_{c2}) = 2.10 \pm 0.20(stat) \pm 0.02(syst)MeV .$$ These results are in good agreement with and have comparable precision to the current world averages.

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [193 KiB]
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	Fig3_supp.pdf [9 KiB] HiDef png [174 KiB] Thumbnail [155 KiB] *C file

Created on 26 April 2024.