In addition to his physics publications, Rajaraman has written widely on topics including fissile material production in India and Pakistan and the radiological effects of nuclear weapon accidents.
In 1962-63, as part of his PhD thesis, Rajaraman demonstrated that the prevalent calculations of the energy of nuclear matter in powers of the Brueckner reaction matrix would not yield a convergent result.
[6] These developments, summarized in the 1967 review article by Rajaraman with Bethe,[7] eventually led to the Coupled Cluster method in Many Body theory.
[13] With Finkelstein, he analysed Exchange Degeneracy in inclusive reactions involving the triple-Reggeon vertex[14][15] With S. Rai Choudhary and G. Rajasekaran, he obtained several results on deep inelastic electron scattering data being then generated at SLAC.
[21] In 1982, Rajaraman and the theorist John Bell, examined the curious phenomenon of quantum states with fractional fermion number, discovered theoretically by Jackiw and Rebbi and experimentally observed in Polyacetylene.
Rajaraman and Bell clarified this puzzle, in a pair of papers, one addressing the problem in the continuum Dirac theory, and the other in a lattice model of polyacetylene.
The criteria derived by Dashen and RR, when applied to the neutron star equation of state, showed that treating the Δ(3-3 ) as an independent elementary particle was a reasonable approximation.
Separately Rajaraman studied, with Dashen and Ma, the finite temperature behaviour of the Gross and Neveu model which spontaneously breaks chiral symmetry.
A.H. MacDonald and T. Jungwirth and Rajaraman constructed their phase diagram at filling factor of two as a function of the Zeeman coupling, the layer bias and interlayer tunneling.
[38] Rajaraman and PhD student Sankalpa Ghosh studied topologically non trivial "meron" and bi-meron excitations in layer-spin for bilayer Hall systems taking into account differences in interlayer and intra-layer coulomb energy.
In this he was greatly helped by repeated visits to Princeton University’s Program on Science and Global Security, led by Frank von Hippel, a leader on nuclear arms control.
Since then, through articles, television appearances and lectures at think tanks and universities in India and abroad, Rajaraman has tried to bring clarity to nuclear issues in South Asia and at the global level.
[44][45][46][47] He has championed nuclear de-alert agreements and other confidence building measures at track II meetings with Pakistani and Chinese colleagues.
The same holds for the numerous mini-courses he has given at summer and winter schools in India and abroad, explaining new advances in theoretical physics research.
[19] It explained in simple and coherent manner these developments as well as associated techniques of path integrals, instanton induced vacuum tunnelling, Grassman fields, and multiple gauge vacua.
Since these methods have found applications in nuclear, particle and condensed matter physics, this book has been widely used around the world by a generation of theoretical physicists.