Trustees 

DR. J. K. BAJAJ


Work in Theoretical Physics (1973-1981)


After completing M.Sc.(Hons.) from the Department of Physics, Punjab University, Chandigarh, in 1973, began research work towards a Ph.D. degree in the same Department. The research work, a major part of which was carried out at the Indian Institute of Technology, Kanpur, involved studying the possibility of generating a hadronic vertex in a chiral symmetric gauge-invariant model of mesons. The model was then successfully used in explaining the data on non-leptonic decays of K-mesons and parity violating decays of baryons. The gauge-invariant theories represented the frontiers of elementary particle theory at that stage; these theories later evolved into the standard unified gauge theory which could explain the weak, electromagnetic and strong forces of nature within a single formalism. The work was published in a detailed article in Phys. Rev. D 16 2226(1977).

In addition to the above, research work for the Ph.D. degree included an extensive analysis of the phenomenology of non-leptonic decays of baryons in various conventional schemes of symmetry breaking in weak interactions. This work was published in Phys. Rev. D 10 3076(1974), Phys. Rev. D 18 2526(1978) and Phys. Rev. D 18 3442(1978).

After obtaining the Ph.D. degree in 1978, joined the Department of Theoretical Physics, Chennai University, as a UGC Research Associate. Besides teaching Particle Physics for M. Sc. classes, engaged in intensive research, in collaboration with Prof. G. Rajasekaran, in neutral-current phenomenology and the structure of grand-unified models, which were to soon become the standard theory of all physical interactions.

While studying low-energy weak neutral current data, we were able to pin down the unique left-right symmetric model that fit all available data. The analysis, published in Pramana 12 397(1979) and Phys. Letters 93B 461(1980), formed a complete study of the low-energy weak neutral current effects in left-right symmetric gauge models; it was generally recognized to be so in the reviews of the period, and probably made some contribution in the evolution of the final consensus on the standard Weinberg-Salam model.

A related direction of work consisted in analyzing the then fast evolving grand-unification schemes with a view to isolate the essential features that determined their experimentally testable predictions and to emphasize the various assumptions involved in obtaining low-energy results from these theories. The work, published in Pramana 14 395(1980) and Pramana 14 411(1980), not only offered a simple way of determining the unification results for any low-energy theory of strong and electro-weak interactions, but also provided a deeper insight into the unification programme. In fact, the analysis led to the important conclusion that the simple unification programme was sustainable only for the standard theory.

The importance and timeliness of this work was generally recognized by the theoretical physics community in India; which was reflected in the invitation to present a review talk on Unified Gauge Theories at the V High Energy Physics Symposium at Cochin (1980) and to present a series of lectures on Unified Gauge Theories at the S. N. Bose Institute of Physical Sciences at Calcutta (1980).