Kyungpook National University, Taegu.
Phys Rev Lett. 2010 Aug 27;105(9):091801. doi: 10.1103/PhysRevLett.105.091801. Epub 2010 Aug 25.
We search for dimuon decays of a low mass particle in the decays B0→K0 X and B0→ρ0 X using a data sample of 657×10(6)BB events collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We find no evidence for such a particle in the mass range from 212 MeV/c2 to 300 MeV/c2 for lifetimes below 10(-12) s, and set upper limits on its branching fractions. In particular, we search for a particle with a mass of 214.3 MeV/c2 reported by the HyperCP experiment, and obtain upper limits on the products B(B0→K0 X)×B(X→μ+ μ- )<2.26(2.27)×10(-8) and B(B0→ρ0 X)×B(X→μ+ μ-)<1.73(1.73)×10(-8) at 90% C.L. for a scalar (vector) X particle.
我们使用 Belle 探测器在 KEKB 对撞机上收集的 657×10(6)BB 事件数据样本，搜索 B0→K0 X 和 B0→ρ0 X 衰变中低质量粒子的介子衰变。我们在寿命低于 10(-12) s 的 212 MeV/c2 到 300 MeV/c2 质量范围内没有发现这样的粒子的证据，并对其分支比设置了上限。特别是，我们搜索了 HyperCP 实验报告的质量为 214.3 MeV/c2 的粒子，并获得了 B(B0→K0 X)×B(X→μ+ μ- )<2.26(2.27)×10(-8) 和 B(B0→ρ0 X)×B(X→μ+ μ-)<1.73(1.73)×10(-8) 的 90%置信水平上限，对于标量（矢量）X 粒子。
