Measurement of e + e − → K + K − π 0 cross section and observation of a resonant structure

Based on e + e − collision data collected by the BESIII detector at the BEPCII collider at center-of-mass energies from 2.000 to 3.080 GeV, a partial-wave analysis is performed for the process e + e − → K + K − π 0 . The Born cross section of the process e + e − → K + K − π 0 and its subprocesses e + e − → ϕπ 0 , K *+ (892) K − and K_2^∗ + (1430) K − are measured. The results for e + e − → K + K − π 0 and ϕπ 0 are consistent with the BaBar measurements and with improved precision. By analyzing the cross sections of the subprocesses e + e − → K *+ (892) K − and K_2^∗ + (1430) K − , a structure with mass M R = (2190 ± 19 ± 37) MeV/ c 2 and width Γ R = (191 ± 28 ± 60) MeV is observed with a combined statistical significance of 7.1 σ . The measured resonance parameters suggest it can be identified as the ϕ (2170), thus the results provide valuable input to understand the internal nature of this state.