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arXiv 2210.01993hep-phnucl-th
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Nambu Jona-Lasinio模型中轻标量介子的逆质量序

Inverse mass ordering of light scalar mesons in the Nambu Jona-Lasinio model

Takahiro Saionji, Daisuke Jido, Masayasu Harada

摘要:

在三味Nambu Jona-Lasinio(NJL)模型中,将标量介子看作一个夸克和一个反夸克的复合体,研究了低位标量介子的质量.众所周知,一个简单的$\bar qq$图像不能再现标量介子的所谓逆质量排序。最近,在线性西格玛模型中,通过引入U(1)轴反常引起的味对称破缺,提出了一种再现标量介子质量谱的新机制.出于这一建议,我们研究这种新的机制是否也适用于NJL模型。通过对标量介子质量的计算,我们发现NJL模型在新项具有足够强度的情况下再现了所观察到的质量有序。在这种机制下,如果逆质量序被再现,组成奇异夸克的质量将退化为上夸克和下夸克的质量。我们还讨论了标量双夸克质量,以检验组分夸克质量简并度与轻重子质量的一致性。

英文摘要:

The masses of the low-lying scalar mesons are investigated in the three-flavor Nambu Jona-Lasinio (NJL) model by treating the scalar mesons as composite objects of a quark and an antiquark. It is known that a simple $\bar qq$ picture fails to reproduce so-called inverse mass ordering for the scalar mesons. Recently a new mechanism to reproduce the observed mass spectrum of the scalar mesons was proposed in a linear sigma model by introducing flavor symmetry breaking induced by the U(1) axial anomaly. Motivated by this proposal, we examine whether this new mechanism works also in the NJL model. By calculating the scalar meson masses, we find that the NJL model reproduces the observed mass ordering with sufficient strength of the new term. With this mechanism, it turns out that the constituent strange quark mass gets degenerate to that of the up and down quark if the inverse mass ordering is reproduced. We also discuss the scalar diquark masses to check the consistency of the degeneracy of the constituent quark masses with the light baryon masses.

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