Electromagnetic Structure of Spin-$\frac12$ Doubly Charmed Baryons in Lattice QCD

We compute the electromagnetic properties of spin-$\frac12$ doubly charmed baryons on 2+1 flavor lattices that have a pion mass of $\sim$ 156 MeV. The Tsukuba action is employed for the charm quark in addition to the standard isotropic Clover action to quantify the $\mathcal{O}(m_q a)$ effects. We calculate the electric and magnetic Sachs form factors and extract the magnetic moments and electric and magnetic charge radii. We also investigate the individual quark sector contributions to the charge radii and the magnetic moments. The results provide vital information to understand the size and shape of the doubly charmed baryons. We find that the two heavy charm quarks drive the charge radii and the magnetic moments to smaller values than that of light baryons. The central values of the observables that are obtained using the relativistic action for the charm quark are $5$ to $10\%$ larger than those obtained using the Clover action. Utilizing the available lattice data, we reexamine the quark mass dependence of the observables.