This report summarises the activities of the working group on ‘Physics beyond the Standard Model’. The results of investigations in incorporatingR-parity in grand unification, the possibility of a light charged Higgs boson in extension of MSSM and radiative generation of neutral vector boson self-couplings within the MSSM are described. Also given is an account of activities in neutrino physics, namely a proposal for a study of the atmospheric muon anomaly in deep underground mines, a field theoretic study of neutrino oscillations and a mechanism to generate appropriate masses of three active plus one sterile neutrino species.

A review of chiral perturbation theory and recent developments on the comparison of its predictions with experiment is presented. Some interesting topics with scope for further elaboration are touched upon.

This is a summary of the projects undertaken by the working group I on high energy and collider physics.

At the international linear collider large beam polarization of both the electron and positron beams will enhance the signature of physics due to interactions that are beyond the standard model. Here we review our recently obtained results on a general model-independent method of determining for an arbitary one-particle inclusive state the space-time structure of such new physics through the beam polarization dependence and angular distribution of the final state particle.

The $K \phi$ form factors are investigated at low energies by the method of unitarity bounds adapted so as to include information on the phase and modulus along the elastic region of the unitarity cut. Using as input the values of the form factors at $t = 0$, and at the Callan–Treiman point in the scalar case, stringent constraints are obtained on the slope and curvature parameters of the Taylor expansion at the origin.

The top polarization at the International Linear Collider (ILC) with transverse beam polarization is utilized in the $e^{+} e^{-} \rightarrow t\bar{t}$ process to probe interactions of the scalar and tensor type beyond the Standard Model and to disentangle their individual contributions. Confidence level limits of 90% are presented on the interactions with realistic integrated luminosity and are found to improve by an order of magnitude compared to the case when the spin of the top quark is not measured. Sensitivities of the order of a few times $10^{−3}$ TeV^-2 for real and imaginary parts of both scalar and tensor couplings at $\sqrt{s} = 500$ and 800 GeV with an integrated luminosity of 500 fb^-1 and completely polarized beams are shown to be possible.

Analyticity and unitarity techniques are employed to estimate Taylor coefficients of the pion electromagnetic form factor at $t = 0$ by exploiting the recently evaluated two-pion contribution to the muon $(g − 2)$ and the phase of the pion electromagnetic form factor in the elastic region, known from $\pi \pi$ scattering by Fermi–Watson theorem and the values of the form factor at several points in the space-like region. Regions in the complex 𝑡-plane are isolated where the form factor cannot have zeros.