Precision Measurements of the Timelike Electromagnetic Form Factors of the Pion, Kaon, and Proton

TL;DR

This paper reports precise measurements of the electromagnetic form factors of the pion, kaon, and proton at high timelike momentum transfer, providing the first such data for pions and kaons above 4 GeV^2.

Contribution

It presents the first measurements of the electromagnetic form factors of pions and kaons at |Q^2| > 4 GeV^2, using e+e- annihilation data at 3.671 GeV.

Findings

Measured F_pi(13.48 GeV^2) = 0.075+-0.008(stat)+-0.005(syst)

Measured F_K(13.48 GeV^2) = 0.063+-0.004(stat)+-0.001(syst)

Proton magnetic form factor G^p_M(13.48 GeV^2) = 0.014+-0.002(stat)+-0.001(syst)

Abstract

Using 20.7 pb^-1 of e+e- annihilation data taken at sqrt{s} = 3.671 GeV with the CLEO-c detector, precision measurements of the electromagnetic form factors of the charged pion, charged kaon, and proton have been made for timelike momentum transfer of |Q^2| = 13.48 GeV^2 by the reaction e+e- to h+h-. The measurements are the first ever with identified pions and kaons of |Q^2| > 4 GeV^2, with the results F_pi(13.48 GeV^2) = 0.075+-0.008(stat)+-0.005(syst) and F_K(13.48 GeV^2) = 0.063+-0.004(stat)+-0.001(syst). The result for the proton, assuming G^p_E = G^p_M, is G^p_M(13.48 GeV^2) = 0.014+-0.002(stat)+-0.001(syst), which is in agreement with earlier results.