Magnetic moment of the pentaquark ${\Theta }^{+}(1540)$ as diquark-diquark-antiquark state with QCD sum rules

Abstract

In this article, we study the magnetic moment of the pentaquark state ${\Theta }^{+}(1540)$ as diquark-diquark-antiquark ($[ud][ud]\bar{s}$) state with the QCD sum rules in the external weak electromagnetic field (EFSR) and the light-cone QCD sum rules (LCSR) respectively. The numerical results indicate the magnetic moment is about ${\mu }_{{\Theta }^{+}}=-(0.11\pm 0.02){\mu }_N$ for the EFSR and ${\mu }_{{\Theta }^{+}}\approx -(0.1-0.5){\mu }_N$ for the LCSR. As the values obtained from the EFSR are more stable than the corresponding ones from the LCSR, ${\mu }_{{\Theta }^{+}}=-(0.11\pm 0.02){\mu }_N$ is more reliable.

Comments: 17 pages, 4 figures, unifing hep-ph/0503007 with hep-ph/0503073 into one article, input parameters changed slightly, add more discussions