Study of the subleading twist GTMD $E_{21}$ for proton in light-front quark-diquark model

In this work, we study the generalized transverse momentum dependent distribution (GTMD) $E_{21}$ for proton using light-front quark-diquark model. We construct the expression of $E_{21}$ GTMD using the overlap equation in light-front wave functions obtained from the GTMD correlator with Dirac matrix structure $\mathrm{\Gamma }=1$, in both situations of scalar and vector diquark. The $3$-dimensional plots of GTMD $E_{21}$ have been analyzed with respect to its variables by taking two variables at a time while holding others constant.