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arXiv 2301.08199hep-phhep-exhep-lat
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来自NLO拉普拉斯求和规则的赝标量与矢量$T_{QQ\bar q\bar q'}$谱及其耦合

Pseudoscalar and Vector $T_{QQ\bar q\bar q'}$ Spectra and Couplings from LSR at NLO

R. Albuquerque, S. Narison, D. Rabetiarivony

AI总结:

本文利用NLO拉普拉斯求和规则系统研究了$T_{QQ\bar q\bar q'}$四夸克态的质量与耦合,区分出重类和轻类态,并揭示了约2 GeV的径向激发劈裂及检验四夸克凝聚真空饱和破坏的新途径。

摘要:

我们利用QCD拉普拉斯求和规则(LSR)及其比值R,在$\tau$和$t_c$稳定性判据下,并辅以(严格的)条件:$R_{P/C} \equiv$ {极点(共振)贡献与QCD连续谱贡献之比} $\geq 1$,对$(0^-)$和$(1^-)$的$T_{QQ\bar q\bar q'}$态($Q= c,b; q,q'= u,d,s$)的质量和耦合进行了系统性的改进估计。我们包含了NLO因子化微扰(PT)QCD修正,以便为所使用的跑动MS重夸克质量的选择提供依据,同时OPE在可控的$d=6$维凝聚项处截断。我们的结果汇总于表4、7、10、12中,并与一些已有的LO结果进行了比较。我们观察到,这些流导致两类态:H类(重)态,其质量在粲(分别为底)道中约为6(分别为13)GeV。L类(轻)态$T_{cc\bar q\bar q'}(3.8\sim 4.4)$,其中赝标量(分别为所有矢量态)位于开粲阈值以下,以及$T_{bb\bar q\bar q'}(\simeq 10.4)$,其中所有态均位于开底阈值以下。由SU3破缺引起的质量劈裂很小(< 50 MeV)。尽管在实验上更容易达到,L类态与流的耦合比H类态弱,可能难以观测。第一径向激发态与基态之间的质量劈裂约为2 GeV,这(几乎)与重味和流类型无关,而它们的耦合很大,表明这些奇特态具有新的动力学机制。基于经验观测讨论了质量和耦合对夸克质量的依赖行为。$T_{cc\bar u\bar d}$(6.3) $0^-$基态的最终发现可能不会被L类第一径向激发态所掩盖,这可以作为检验四夸克$d=6$凝聚项真空饱和破坏的另一种途径。

英文摘要:

We present systematic and improved estimates of the masses and couplings of the $(0^-)$ and $(1^-)$ $T_{QQ\bar q\bar q'}$ states ($Q= c,b;q,q'= u,d,s$) using QCD Laplace sum rules (LSR) and their ratios R within $τ$ and $t_c$-stabilities criteria complemented by the (rigorous) condition: $R_{P/C} \equiv$ { Pole (Resonance) over the QCD continuum contributions} $ \geq 1$. NLO factorized perturbative (PT) QCD corrections are included for giving a meaning on the choice of the used running MS heavy quark mass, while the OPE is truncated at the under-controlled $d=6$ dimension condensates. Our results are compiled in Tables 4,7,10,12 and compared with some LO existing ones. We observe that the icurrents lead to two classes : Class H (Heavy) states with masses around 6 (resp. 13) GeV for charm (resp. bottom) channels. Class L (Light) states $T_{cc\bar q\bar q'}(3.8\sim 4.4)$ where the pseudoscalar (resp. all vector states) are below the open charm thresholds and $T_{bb\bar q\bar q'}(\simeq 10.4)$ where all of them are below the open beauty thresholds. Mass-splittings due to SU3 breakings are tiny (< 50 MeV). Though more accessible experimentally, Class L states have weaker couplings to the currents than the Class H ones and may be difficult to observe. The mass-splittings between the 1st radial excitation and the ground state are about 2 GeV which are (almost) heavy flavour and current-type independent while their couplings are large signaling new dynamics of these exotic states. Quark masses behaviours of the masses and couplings based on empirical observation are discussed. The eventual findings of the $T_{cc\bar u\bar d}$(6.3) $0^-$ ground state which may not be obscured by the Class L 1st radial excitations can be an alternative way to test the vacuum saturation violation of the four-quark $d=6$ condensates.

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