Measurement of e+e- → π+π- φ (3686) from 4.008 to 4.600 GeV and observation of a charged structure in the π± φ(3686) mass spectrum


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Ablikim M., Achasov M., Ahmed S., Ai X., Albayrak O., Albrecht M., ...More

Physical Review D, vol.96, no.3, 2017 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 96 Issue: 3
  • Publication Date: 2017
  • Doi Number: 10.1103/physrevd.96.032004
  • Journal Name: Physical Review D
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Ankara University Affiliated: Yes

Abstract

We study the process e+e- → π+π- φ (3686) using 5.1 fb-1 of data collected at 16 center-of-mass energy (√s) points from 4.008 to 4.600 GeV by the BESIII detector operating at the BEPCII collider. The measured Born cross sections for e+e- → π+π- φ(3686) are consistent with previous results, but with much improved precision. A fit to the cross section shows contributions from two structures: the first has M = 4209.5 ± 7.4 ±1.4 MeV=c2 and Λ = 80.1 ± 24.6 ± 2.9 MeV, and the second has M = 4383.8 ± 4.2 ± 0.8 MeV=c2 and F = 84.2 ± 12.5 ±2.1 MeV, where the first errors are statistical and the second systematic. The lower-mass resonance is observed in the process e+e- → π+π- φ(3686) for the first time with a statistical significance of 5.8σ. A charged charmoniumlike structure is observed in the π± φ(3686) invariant mass spectrum for data at √s = 4.416 GeV. A fit with an S-wave Breit-Wigner function yields a mass M = 4032.1 ± 2.4 MeV=c2, where the errors are statistical only. However, there are still unresolved discrepancies between the fit model and data. The width of the intermediate state varies in a wide range for different kinematic regions within the data set. Therefore, no simple interpretation of the data has been found, and a future data sample with larger statistics and more theoretical input will be required to better understand this issue.