Electromagnetic form factors of ${\mathrm{\Lambda }}_b$ in the Bethe-Salpeter equation approach

The heavy baryon ${\mathrm{\Lambda }}_b$ is regarded as composed of a heavy quark and a scalar diquark which has good spin and isospin quantum numbers. In this picture, we calculate the electromagnetic (EM) form factors of ${\mathrm{\Lambda }}_b$ in the Bethe-Salpeter equation approach. We find that the shapes of the EM form factors of ${\mathrm{\Lambda }}_b$ are similar to those of $\mathrm{\Lambda }$, which have a peak at about $\omega =1$, but the amplitudes are much smaller than those of $\mathrm{\Lambda }$.