Radiative widths of neutral kaon excitations

摘要

We observe 147 events of the axial vector pair K_1(1270)-K_1(1400) produced in the Coulomb field of a Pb target and measure the radiative widths Γ(K_1(1400) → K~0 + γ) = 280.8 ± 23.2(stat.) ± 40.4(syst.) keV and Γ(K_1(1270) → K~0 + γ) = 73.2 ± 6.1(stat.) ± 28.3(syst.) keV. These first measurements are lower than the quark-model predictions. We also place upper limits on the radiative widths for K~* (1410) and K_2~* (1430) and find that the latter is very small in accord with SU(3) invariance in the naive quark model.