Observation of the radiative kaon decay K{sup -} {sup {yields}} {mu}{sup -}{pi}{sup 0}{gamma}{nu}

• Published in: Physics of atomic nuclei 2007-01, Vol.70 (1)
• Main Authors: Tchikilev, O. G., Akimenko, S. A., Britvich, G. I., Datsko, K. V., Filin, A. P., Inyakin, A. V., Khmelnikov, V. A., Konstantinov, A. S., Korolkov, I. Ya, Leontiev, V. M., Novikov, V. P., Obraztsov, V. F., Polyakov, V. A., Romanovsky, V. I., Shelikhov, V. I., Uvarov, V. A., Yushchenko, O. P., Bolotov, V. N., Laptev, S. V., Duk, V. A.
• Format: Article
• Language: English
• Subjects: ANGULAR DISTRIBUTION; ASYMMETRY; FORECASTING; GAMMA RADIATION; KAONS; KAONS MINUS; MEV RANGE; MUONS MINUS; NEUTRINOS; PARTICLE DECAY; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; PIONS NEUTRAL; PROTONS; RADIATIVE DECAY; SPECTROMETERS; SYNCHROTRONS
• ISSN: 1063-7788; 1562-692X
• DOI: 10.1134/S1063778807010048

Using data collected with the ISTRA+ spectrometer during the 2001 run of the U-70 proton synchrotron in Protvino, the first observation of the radiative kaon decay K{sup -} {sup {yields}} {mu}{sup -}{pi}{sup 0}{gamma}{nu} is reported. The ratio Br(K{sub {mu}}{sub 3{gamma}}, 5 < E*{sub {gamma}} < 30 MeV)/Br(K{sub {mu}}{sub 3}) is found to be [0.270 {+-} 0.029(stat.) {+-} 0.026(syst.)]% and the ratio Br(K{sub {mu}}{sub 3{gamma}}, 30 < E*{sub {gamma}} < 60 MeV)/Br(K{sub {mu}}{sub 3}) = [0.0448 {+-} 0.0068(stat.) {+-} 0.0099(syst.)]%. These ratios are consistent with the theoretical predictions 0.21 and 0.047%, respectively. The measured angular distribution asymmetry for the region 5 < E*{sub {gamma}} < 30 MeV, A(cos {theta}*{sub {mu}}{sub {gamma}}) = 0.093 {+-} 0.141, is two standard deviations away from the theoretical prediction of 0.354. The measured asymmetry in the T-odd variable {xi} = p{sub {gamma}} . (p{sub {mu}} x p{sub {pi}})/m{sub K}{sup 3} is -0.03 {+-} 0.13.