arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.06270hep-phhep-exhep-lat
收藏

关于$ρ$介子分布振幅的第二Gegenbauer矩

On the second Gegenbauer moment of $ρ$-meson distribution amplitude

Maxim V. Polyakov, Hyeon-Dong Son

摘要:

利用软π介子定理、交叉和双π介子分布振幅($2π$ DA)的色散关系,我们论证了$ρ$介子DA($a_2^{(ρ)}$)的第二Gegenbauer矩很可能是负的.该结果与$a_2^{(ρ)}$的大多数模型计算结果不同。利用QCD真空的瞬子理论,我们计算了低归一化点的$a_2^{(ρ)}$,得到了在$a_2^{(ρ)}/M_3^{(π)}\in [-2, -1]$范围内的$ a_2^{(ρ)}/M_3^{(π)}$比{ \it肯定为负值}.值的范围对应于瞬子真空的参数的慷慨的变化。π DA的二阶Gegenbauer矩的值在整个范围内都是正的,并且与它的最先进的晶格测量相一致。看来,在QCD真空(瞬子)的拓扑非平凡的场配置导致性质不同的形状的π介子和$ρ$ -介子DA。

英文摘要:

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.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑