[QUE/QFT-06003] QFT-PROBLEM

 $\newcommand{\matrixelement}[3]{\langle#1|#2|#3\rangle}\newcommand{\dd}[2][]{\frac{d#1}{d#2}}${}$\newcommand{\pp}[2][]{\frac{\partial #1}{\partial #2}}${}$\newcommand{\ket}[1]{|#1\rangle}$ {} $\newcommand{\bra}[1]{\langle #1|}$
Compute the matrix element \[ \matrixelement{s,\vec{q}}{J_\mu(x)}{r,\vec{p}}\] % where \(J_\mu(x)\) is the current for a Dirac particle and \( \ket{s,\vec{q}}\) and \(\ket{r,\vec{p}} \) denote one particle states of spin half particle with spin and momenta as specified.