Measurement of the direct emission and interference terms and search for CP violation in the decay K±→π±π0γ
Measurement of the direct emission and interference terms and search for CP violation in the decay K±→π±π0γ
复制标题
直接发射项和干扰项的测量以及在衰减 K±→π±π0γ 中寻找 CP 破坏
DOI：
10.1140/epjc/s10052-010-1349-8
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
NA482 Collaboration
中科院分区：
文献类型：
--
作者：
NA482 Collaboration
本文报道了在CERN SPS上用NA48/2实验测量k±→π±π0γ衰变的直接发射（DE）和干涉（INT）项。从2003年和2004年收集的数据中，大约选择了60万个这样的衰变候选者。DE和INT相对于内部轫致辐射（IB）贡献的相对量已经在emev: $$\begin{array}{l}\mathrm{Frac_{\mathrm{DE}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\[3pt]\quad =(3.32\pm0.15_{\mathrm{stat}}\pm 0.14_{\mathrm{sys}})\times10^{-2},\\[3pt]\mathrm{Frac_{\mathrm{INT}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\[3pt]\quad =(-2.35\pm 0.35_{\mathrm{stat}}\pm0.39_{\mathrm{sys}})\times10^{-2}\end{array}$$范围内测量，其中是介子静止坐标系中带电介子的动能。这是第一次观察到干涉项inK±→π±π0γ衰减，从而允许测量归一化的电和磁振幅，得到xe =(−24±6)GeV−4,xm =(254±9)GeV−4。此外，该通道的k +和k−分支比的CP违反不对称性的极限已确定为小于1.5×10−3at 90% confidence level.
We report on the measurement of the direct emission (DE) and interference (INT) terms of theK±→π±π0γdecay by the NA48/2 experiment at the CERN SPS. From the data collected during 2003 and 2004 about 600k such decay candidates have been selected. The relative amounts of DE and INT with respect to the internal bremsstrahlung (IB) contribution have been measured in the rangeMeV: $$\begin{array}{l}\mathrm{Frac_{\mathrm{DE}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\[3pt]\quad =(3.32\pm0.15_{\mathrm{stat}}\pm 0.14_{\mathrm{sys}})\times10^{-2},\\[3pt]\mathrm{Frac_{\mathrm{INT}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\[3pt]\quad =(-2.35\pm 0.35_{\mathrm{stat}}\pm0.39_{\mathrm{sys}})\times10^{-2}\end{array}$$ whereis the kinetic energy of the charged pion in the kaon rest frame. This is the first observation of an interference term inK±→π±π0γdecays, thus allowing the normalised electric and magnetic amplitudes to be measured, givingXE=(−24±6) GeV−4, andXM=(254±9) GeV−4.In addition, a limit on the CP violating asymmetry in theK+andK−branching ratios for this channel has been determined to be less than 1.5×10−3at 90% confidence level.