Radiative Decay Width Measurements of Neutral Kaon Excitations Using the Primakoff Effect

TL;DR

This study measures the radiative decay widths of neutral kaon excitations using the Primakoff effect, providing first experimental data to test quark-model predictions of meson properties.

Contribution

First measurements of radiative widths for K1(1400) and K1(1270) using Primakoff effect, enabling validation of quark-model predictions.

Findings

Measured Gamma_r(K1(1400)) = 280.8 keV

Measured Gamma_r(K1(1270)) = 73.2 keV

Set upper limits for Gamma_r(K*(1410)) and Gamma_r(K2*(1430))

Abstract

We produce a sample consisting of 147 candidate events, with minimal backgrounds, of the mixed axial vector pair K1(1270)-K1(1400) by exciting Kl's in the Coulomb field of lead and report the first measurements of the radiative widths Gamma_r(K1(1400)) = 280.8+-23.2(stat)+-40.4(syst) keV and Gamma_r(K1(1270)) = 73.2+- 6.1(stat)+-28.3(syst) keV. We also place 90% CL upper limits Gamma_r(K*(1410)) < 52.9 keV for the vector state and Gamma_r(K2*(1430)) < 5.4 keV for the tensor state. These measurements allow for significant tests of quark-model predictions of radiative widths for the low-lying vector mesons.