Mitra has made several original research contributions in the field of nuclear and particle physics. His prominent contributions include: (i) exact solution of the nuclear 3-body problem with separable potentials which offered a new insight into the structure of the 3-body wave function leading to "few-nucleon studies" as a new branch of physics (ii) a node in the proton electro magnetic form factor unless fermion quarks have an extra d.o.f. a forerunner for the discovery of "color" and (iii) the "quark-recoil effect" (in association with Marc Ross), for the understanding of enhanced heavy meson modes of decay. He has developed a comprehensive dynamical framework leading to an integrated view of the dynamics of 2- and 3- body systems at successively deeper levels of compositeness, from nuclear to sub-hadronic with a formulational style designed to bridge the traditional gap between theoretical sophistication and empirical fits to data.