Sher A, Appel R, Atoyan G S, Bassalleck B, Bergman D R, Cheung N, Dhawan S, Do H, Egger J, Eilerts S, Fischer H, Herold W, Issakov V V, Kaspar H, Kraus D E, Lazarus D M, Lichard P, Lowe J, Lozano J, Ma H, Majid W, Pislak S, Poblaguev A A, Rehak P, Sher Aleksey, Thompson J A, Truöl P, Zeller M E
Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Phys Rev Lett. 2003 Dec 31;91(26 Pt 1):261802. doi: 10.1103/PhysRevLett.91.261802. Epub 2003 Dec 29.
E865 at the Brookhaven National Laboratory AGS collected about 70 000 K(+)(e3) events to measure the K(+)(e3) branching ratio relative to the observed K+-->pi(+)pi(0), K+-->pi(0)micro(+)nu, and K+-->pi(+)pi(0)pi(0) decays. The pi(0) in all the decays was detected using the e(+)e(-) pair from pi(0)-->e(+)e(-)gamma decay and no photons were required. Using the 2002 Particle Data Group branching ratios for the normalization decays, we obtain BR(K(+)(e3(gamma)))=(5.13+/-0.02(stat)+/-0.09(syst)+/-0.04(norm))%, where K(+)(e3(gamma)) includes the effect of virtual and real photons. This result is approximately 2.3sigma higher than the current Particle Data Group value. Implications for the V(us) element of the CKM matrix, and the matrix's unitarity are discussed.
布鲁克海文国家实验室交变梯度同步加速器（AGS）的E865实验收集了约70000个K⁺(e3)事件，以测量K⁺(e3)相对于观测到的K⁺→π⁺π⁰、K⁺→π⁰μ⁺ν和K⁺→π⁺π⁰π⁰衰变的分支比。所有衰变中的π⁰都是利用π⁰→e⁺e⁻γ衰变产生的e⁺e⁻对进行探测的，无需光子。利用2002年粒子数据组对归一化衰变的分支比，我们得到BR(K⁺(e3(γ)))=(5.13±0.02(统计)±0.09(系统)±0.04(归一化))%，其中K⁺(e3(γ))包括虚光子和实光子的效应。该结果比当前粒子数据组的值高约2.3个标准差。讨论了对CKM矩阵的V(us)元以及矩阵幺正性的影响。
