Magnetic moment of the pentaquark state ${\mathrm{\Theta }}^{+}(1540)$

In this article, we study the magnetic moment of the pentaquark ${\mathrm{\Theta }}^{+}(1540)$ as (scalar)diquark-(pseudoscalar)diquark-antiquark state with the QCD sum rules approach in the external electromagnetic field. Due to the special structure of the interpolating current, only the electromagnetic interactions of the $s$ quark with the external field have contributions to the magnetic moment with tensor structure ${\sigma_{\mu\nu} {\hat p} +{\hat p}\sigma_{\mu\nu}}$. The numerical results indicate the magnetic moment of the pentaquark state ${\mathrm{\Theta }}^{+}(1540)$ is about ${\mu }_{{\mathrm{\Theta }}^{+}}=(0.16\pm 0.03){\mu }_N$.