Measurement of e(+) e(-) -> K+ K- cross section at root s=2.00-3.08 GeV

Abstract

The cross section of the process e(+) e(-) -> K+ K- is measured at a number of center-of-mass energies root s from 2.00 to 3.08 GeV with the BESIII detector at the Beijing Electron Positron Collider (BEPCII). The results provide the best precision achieved so far. A resonant structure around 2.2 GeV is observed in the cross section line shape. A Breit-Wigner fit yields a mass of M = 2239.2 +/- 7.1 +/- 11.3 MeV/c(2) and a width of Gamma = 139.8 +/- 12.3 +/- 20.6 MeV, where the first uncertainties are statistical and the second ones are systematic. In addition, the timelike electromagnetic form factor of the kaon is determined at the individual center-of-mass energy points.