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.

[4][5] In the eighties he developed a powerful Bethe-Salpeter approach for the relativistic quark models and studied successfully (in collaborations with others) the meson and baryon dynamics and spectrum.

Mitra has taken increasing interest in the structure of scientific ideas through articles of a general nature in Pramana, Current Science etc., as well as through invited talks.