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arXiv 1507.01607hep-phhep-exnucl-th
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自旋翻转项在$Υ(4S)$强子跃迁中的作用

The role of spin-flipping terms in hadronic transitions of $Υ(4S)$

Jorge Segovia, Francisco Fernandez, David R. Entem

摘要:

最近关于$Υ(4S)\toΥ(1S)η$和$Υ(4S)\to h_{b}(1P)η$过程的实验数据似乎与带有自旋翻转项的强子跃迁应该相对于没有自旋翻转项的强子跃迁被抑制的天真期望相矛盾。我们使用QCD多极展开(QCDME)的方法和组成夸克模型的框架内,已成功地应用于重夸克部门在过去几年中分析这些转变。QCDME的形式主义要求的混合中间态的计算已进行了自然的,无参数的扩展我们的组分夸克模型的基础上夸克禁闭弦(QCS)计划。我们表明,i)的M1-M1的贡献在$Υ(4S)\toΥ(1S)η$的衰变率是重要的,它的抑制,直到现在是不合理的; ii)的$L=0$混合状态,这在计算的M1-M1的贡献,解释了$Υ(4S)\toΥ(1S)η$的衰变率的增强所发挥的作用;和iii)的异常大的衰变率的$Υ(4S)\to h_{b}(1P)η$过程具有相同的物理起源。

英文摘要:

Recent experimental data on the $Υ(4S)\toΥ(1S)η$ and $Υ(4S)\to h_{b}(1P)η$ processes seem to contradict the naive expectation that hadronic transitions with spin-flipping terms should be suppressed with respect those without spin-flip. We analyze these transitions using the QCD Multipole Expansion (QCDME) approach and within a constituent quark model framework that has been applied successfully to the heavy-quark sectors during the last years. The QCDME formalism requires the computation of hybrid intermediate states which has been performed in a natural, parameter-free extension of our constituent quark model based on the Quark Confining String (QCS) scheme. We show that i) the M1-M1 contribution in the decay rate of the $Υ(4S)\toΥ(1S)η$ is important and its supression until now is not justified; ii) the role played by the $L=0$ hybrid states, which enter in the calculation of the M1-M1 contribution, explains the enhancement in the $Υ(4S)\toΥ(1S)η$ decay rate; and iii) the anomalously large decay rate of the $Υ(4S)\to h_{b}(1P)η$ process has the same physical origin.

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