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

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

M. Ablikim et al. (BESIII Collaboration)

Phys. Rev. D 99, 032001 – Published 4 February 2019

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 $M = 2239.2 \pm 7.1 \pm 11.3 MeV / c^{2}$ and a width of $Γ = 139.8 \pm 12.3 \pm 20.6 MeV$ , 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.

Received 21 November 2018

DOI:https://doi.org/10.1103/PhysRevD.99.032001

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Published by the American Physical Society