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arXiv 0712.1644hep-phhep-ex
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弦结模型、集团假说、五夸克重子和四夸克介子

String Junction Model, Cluster Hypothesis, Penta-Quark Baryon and Tetra-Quark Meson

Masahiro Imachi, Fumihiko Toyoda, Shoichiro Otsuki

摘要:

三十年前我们提出了强子的弦结模型,研究了强子的结构和反应,包括奇异强子。奇异轻夸克强子的质量$m$大致由$m \sim N_J\cdot m_B$给出,其中$N_J$是结的总数,$m_B \sim 1$ GeV是普通轻重子的质量。本文将“团簇假说”引入复杂强子的质量由组成它的团簇质量之和给出的模型中,这一假说保证了同一弦结结构的强子的质量差异是由组成夸克的质量差异引起的这一既定图象。对Bell合作组最近报道的一个五夸克重子$Θ$(1530 MeV,$S=+1)$,包括一个奇异的反夸克${\sb}$)和一个四夸克介子$Z^+$(4430 MeV)的候选粒子进行了平行检验. $Θ$被认为有非奇异的伙伴,它们比奇异夸克和非奇异夸克之间的质量差$Δ_s$更轻。这种具有$N_J=3$的轻五夸克重子的质量预计约为3 GeV。几个参数的模型,如$m_J \sim O(10)$ MeV的结的质量进行了估计。虽然含$N_J=2$的轻四夸克介子的质量预计约为2 GeV,但含$(u,c,{\db},{\cb})$的$Z^+$(4430 MeV)给出了确定模型某些参数的线索,例如,结间串能量$m_{IJ}$。

英文摘要:

Thirty years ago we proposed string junction model of hadrons and examined structure and reaction of hadrons including exotic ones. Mass $m$ of exotic hadrons of light quarks is roughly given by $m \sim N_J\cdot m_B$, where $N_J$ is the total number of junctions and $m_B \sim 1$ GeV is the ordinary light baryon mass. In this paper we introduce "cluster hypothesis" into the model by which mass of a complex hadron is given by the sum of masses of clusters composing it. The hypothesis guarantees the established picture that mass differences of hadrons of the same string junction structure are due to those of the constituent quarks. A candidate for penta-quark baryon $Θ$(1530 MeV, $S=+1)$ including a strange anti-quark ${\sb}$ and that for tetra-quark meson $Z^+$(4430 MeV) recently reported by the Bell collaboration are examined in parallel. $Θ$ is considered to have non-strange partners, which are lighter by the mass difference $Δ_s$ between strange and non-strange quarks. Mass of such light penta-quark baryons with $N_J=3$ is expected to be about 3 GeV. Several parameters of the model are estimated such as mass of junction of $m_J \sim O(10)$ MeV. While mass of light tetra-quark meson with $N_J=2$ is expected to be about 2 GeV, $Z^+$(4430 MeV) containing $(u,c,{\db},{\cb})$ gives a clue to determine some parameters of the model, e.g., inter-junction string energy $m_{IJ}$.

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。

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