Measurement of $e^{+}{e}^{-}\to K^{+}{K}^{-}$ cross section at $\sqrt{s}=2.00-3.08$ GeV

Abstract

The cross section of the process $e^{+}{e}^{-}\to K^{+}{K}^{-}$ is measured at a number of center-of-mass energies $\sqrt{s}$ 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 $M=2239.2\pm 7.1\pm 11.3$~and a width of $\Gamma =139.8\pm 12.3\pm 20.6$ MeV, where the first uncertainties are statistical and the second ones are systematic. In addition, the time-like electromagnetic form factor of the kaon is determined at the individual center-of-mass energy points.

8 figures