Wei J-T, Chang P, Adachi I, Aihara H, Aulchenko V, Aushev T, Bakich A M, Balagura V, Barberio E, Bondar A, Bozek A, Bracko M, Browder T E, Chang Y-W, Chao Y, Chen A, Chen K-F, Cheon B G, Chiang C-C, Cho I-S, Choi Y, Dalseno J, Drutskoy A, Dungel W, Eidelman S, Gabyshev N, Goldenzweig P, Golob B, Ha H, Han B-Y, Hayasaka K, Hayashii H, Hazumi M, Horii Y, Hoshi Y, Hou W-S, Hyun H J, Iijima T, Inami K, Itoh R, Iwasaki M, Iwasaki Y, Kah D H, Kaji H, Kang J H, Kapusta P, Katayama N, Kawasaki T, Kichimi H, Kim H J, Kim H O, Kim S K, Kim Y I, Kim Y J, Kinoshita K, Ko B R, Korpar S, Krizan P, Krokovny P, Kuzmin A, Kwon Y-J, Kyeong S-H, Lange J S, Lee M J, Lee S E, Lesiak T, Li J, Limosani A, Liu C, Liventsev D, Louvot R, Mandl F, Matyja A, McOnie S, Medvedeva T, Miyabayashi K, Miyata H, Miyazaki Y, Mizuk R, Nakano E, Nakao M, Nakazawa H, Natkaniec Z, Nishida S, Nishimura K, Nitoh O, Nozaki T, Ogawa S, Ohshima T, Okuno S, Ozaki H, Pakhlova G, Park C W, Park H, Park H K, Park K S, Piilonen L E, Rozanska M, Sahoo H, Sakai K, Sakai Y, Schneider O, Schwanda C, Schwartz A J, Seidl R, Sekiya A, Senyo K, Sevior M E, Shapkin M, Shen C P, Shiu J-G, Shwartz B, Stanic S, Staric M, Sumiyoshi T, Suzuki S, Tanaka M, Taylor G N, Teramoto Y, Trabelsi K, Uehara S, Uglov T, Unno Y, Uno S, Urquijo P, Usov Y, Varner G, Varvell K E, Vervink K, Wang C C, Wang C H, Wang M-Z, Wang P, Wang X L, Watanabe Y, Wedd R, Wicht J, Won E, Yabsley B D, Yamashita Y, Yamauchi M, Yuan C Z, Zhang Z P, Zivko T, Zupanc A, Zyukova O
Department of Physics, National Taiwan University, Taipei.
Phys Rev Lett. 2009 Oct 23;103(17):171801. doi: 10.1103/PhysRevLett.103.171801. Epub 2009 Oct 20.
We study B --> K()l+l- decays (l = e, mu) based on a data sample of 657 x 10(6) BB pairs collected with the Belle detector at the KEKB e+e- collider. We report the differential branching fraction, isospin asymmetry, K polarization, and the forward-backward asymmetry (A(FB)) as functions of q2 = M(ll)(2)c2. The fitted A(FB) spectrum exceeds the standard model expectation by 2.7 standard deviations. The measured branching fractions are B(B --> Kl+l-) = (10.7(-1.0)(+1.1) +/- 0.9) x 10(-7) and B(B --> Kl+l-) = (4.8(-0.4)(+0.5) +/- 0.3) x 10(-7), where the first errors are statistical and the second are systematic, with the muon to electron ratios R(K) = 0.83 +/- 0.17 +/- 0.08 and R(K) = 1.03 +/- 0.19 +/- 0.06.
我们基于在KEKB正负电子对撞机上使用Belle探测器收集的657×10⁶个BB对的数据样本，研究B→K（）l⁺l⁻衰变（l = e，μ）。我们报告了作为q² = M（ll）²c²函数的微分分支比、同位旋不对称性、K极化以及前后不对称性（A（FB））。拟合得到的A（FB）谱超出标准模型预期2.7个标准差。测量得到的分支比为B（B→Kl⁺l⁻） = （10.7（-1.0）（+1.1）±0.9）×10⁻⁷和B（B→Kl⁺l⁻） = （4.8（-0.4）（+0.5）±0.3）×10⁻⁷，其中第一个误差是统计误差，第二个是系统误差，μ子与电子的比率R（K） = 0.83±0.17±0.08以及R（K） = 1.03±0.19±0.06。
