论文标题
在$ρ$ -Meson发行幅度的第二个Gegenbauer时刻
On the second Gegenbauer moment of $ρ$-meson distribution amplitude
论文作者
论文摘要
使用软胎定理，交叉和两个Pion分布幅度的分散关系（$2π$ da），我们认为第二个Gegenbauer时刻$ρ$ -Meson da（$ a_2^{（ρ）} $）很可能很可能为负。该结果与$ a_2^{（ρ）} $的大多数模型计算有所不同。 使用QCD真空的插入理论，我们在低归一位点计算$ a_2^{（ρ）} $，并获得比率$ a_2^{（ρ）}/m_3^{（π）} $ {\ us a_2^^{（π）; -1] $。值范围对应于激体真空参数的宽敞变化。 Pion DA的第二个Gegenbauer矩的值在整个范围内为正，并且与其最先进的晶格测量兼容。 QCD真空（Instantons）中拓扑上的非平凡场配置似乎会导致样前的质量不同和$ρ$ -Meson DAS。
Using the soft pion theorem, crossing, and the dispersion relations for the two pion distribution amplitude ($2π$DA) we argue that the second Gegenbauer moment the $ρ$-meson DA ($a_2^{(ρ)}$) most probably is negative. This result is at variance with the majority of the model calculations for $a_2^{(ρ)}$. Using the instanton theory of the QCD vacuum, we computed $a_2^{(ρ)}$ at a low normalisation point and obtain for the ratio $ a_2^{(ρ)}/M_3^{(π)}$ {\it definitely negative value} in the range of $a_2^{(ρ)}/M_3^{(π)}\in [-2, -1]$. The range of values corresponds to a generous variation of the parameters of the instanton vacuum. The value of the second Gegenbauer moment of pion DA is positive in the whole range and is compatible with its the most advanced lattice measurement. It seems that the topologically non-trivial field configurations in the QCD vacuum (instantons) lead to qualitatively different shapes of the pion and the $ρ$-meson DAs.
