Motivated by a desire to attempt a unified description of some recently observed phenomena such as the unusual events in the deep underground experiments at Kolar, the dilepton events initlated by high energy laboratory neutrino beams, the possible production of a new heavy lepton ine⁺e⁻ annihilation along with the conventional weak interaction processes, a U₃ gauge theory of weak and electromagnetic interactions is proposed. The theory makes use of six flavours of quarks (Charm, Taste and Grace plus the three old SU₃ flavours), each in three colours, and correspondingly six lepton-types. The introduction of the corresponding fermions, and their assignment to representations of the proposed U₃ group, is dictated by the stringent requirements of attaining an anomaly free renormalizable gauge theory and of ensuring that the neutral currents turn out strangeness-preserving. A spontaneous gauge symmetry breaking mechanism is employed to generate the mechanical masses of the vector gauge-bosons of the theory (other than the photon) and of the quarks and the leptons. Diagonalisation of the quark mass matrix so generated enables a natural introduction of mixing angles including the Cabibbo-angle.

Using Glauber’s theory of eikonal approximation, an algebraic representation of the broken Zweig rule in the constituent quark model is obtained. Null plane language is then elaborated. It is pointed out that the exotic current associated with the disconnected quark diagrams, which break the Zweig rule, can have canonical dimension.

From the transverse cuts off of the electron positron annihilation in the SPEAR II regime, we obtain positivity domains of bare quark masses.

An exact differential equation is given to evaluate the energy average of the scattering function. The advantage of the differential equation as compared to the earlier methods based on series expansion is that one has to evaluate only single sums over the complex poles of the S-matrix. Using Wigner’s semicircle law for the distribution of the real parts of the poles of the scattering matrix, the earlier expression for the energy average of the scattering function is rederived.

Nuclear demagnetisation as a means of refrigeration has been proposed and achieved long ago. In this paper an attempt has been made to show that PrBe₁₃, a Van-Vleck paramagnet, can be used to produce a lattice temperature of 10µK. or lower. Such a calculation can be used for a computer simulation of the process.

TheA²Π_ustate of O₂⁺ was earlier established as an inverted state contrary to previous assumptions. The rotational analysis of a few more bands of theA-X system of O₂⁺ has now been completed. These studies show that the spin-orbit coupling constantA in theA²Π_ustate gradually varies with the vibrational quantum numberν and is found to be positive forν⩾6. It has also been observed that the spia-rotation interaction is not negligible in theA²Π_ustate. The spin splitting constantγ is reported for various vibrational levels of this electronic state.

Gravitational recoil of a gigantic black hole (M∼10^8–9 M_⊙) formed in the nonspherical collapse of the nuclear part of a typical galaxy can take place with an appreciable speed as a consequence of the anisotropic emission of gravitational radiation. Accretion of gaseous matter during its flight through the galaxy results in the formation of a glowing shock front. The accompanying stellar captures can lead to the formation of an accretion disk-star system about the hole. Consequently, the hole can become “luminous” enough to be observable after it emerges out of the galaxy. The phenomenon seems to have an importance in relation to the observations of quasar-galaxy association in a number of cases.

It is shown that in the framework of a conformally invariant gravitation theory, the singularity which is present in some anisotropic universes in general relativity is due to a wrong choice of conformal frame. Frames exist in which these models can be made singularity free.

An experiment to measure energetic neutrons and gamma rays in space was launched in the first Indian scientific satellite,Aryobhata, on April 19, 1975. From this experiment, the first measurements in space of the Earth’s albedo fiux of neutrons of energy between 20 and 500 MeV have been made; the values obtained for two mean geomagnetic vertical cut-off rigidities of 5.6 and 17.0 GV are (6.3±0.4)×10⁻² and (1.4±0.3)×10⁻² neutrons cm⁻² sec⁻¹ respectively. These measurements confirm that protons arising from cosmic ray albedo neutron decay, can adequately account for the protons in the inner radiation belt. Observations on gamma rays of energy between 0.2 and 24 MeV have enabled the determination of the total background gamma ray flux in space as a function of latitude. This in turn has permitted useful information on the diffuse cosmic gamma rays. We have also observed four events that showed sudden increases in the gamma ray counting rates between 0.2 and 4.0 MeV. Observational details of these events are given.