This report summarises the work done in the ‘Beyond the Standard Model’ working group of the Sixth Workshop on High Energy Physics Phenomenology (WHEPP-6) held at the Institute of Mathematical Sciences, Chennai, Jan 3–15, 2000. The participants in this working group were: R Adhikari, B Ananthanarayan, K P S Balaji, Gour Bhattacharya, Gautam Bhattacharyya, Chao-Hsi Chang (Zhang). D Choudhury, Amitava Datta, Anindya Datta, Asesh K Datta, A Dighe, N Gaur, D Ghosh, A Goyal, K Kar, S F King, Anirban Kundu, U Mahanta, R N Mohapatra, B Mukhopadhyaya, S Pakvasa, P N Pandita, M K Parida, P Poulose, G Raffelt, G Rajasekaran, S Rakshit, Asim K Ray, A Raychaudhuri, S Raychaudhuri, D P Roy, P Roy, S Roy, K Sridhar and S Vempati.

This report summarises the work done during WHEPP-6 (Institute of Mathematical Sciences, Chennai, India, Jan 3–15, 2000) in Working group on ‘B and collider physics’.

We consider the UED scenario and study the detectability of the first KK electron-positron pair at the ILC. A few hundred GeV KK electron decays into a nearly degenerate KK photon, which carries away missing energy, and the standard electron. The mass splitting between the KK electron and KK photon is controlled by the bulk- and brane-induced radiative corrections. We look for the signal event $e^{+} e^{-} +$ large missingenergy for $\sqrt{s} = 1$ TeV and observe that with a few hundred fb^-1 luminosity the signal can be deciphered from the standard model background. We briefly outline how the UED signals may be distinguished from the supersymmetric signals.

In this talk, I shall first discuss the Standard Model Higgs mechanism and then highlight some of its deficiencies making a case for the need to go beyond the Standard Model (BSM). The BSM tour will be guided by symmetry arguments. I shall pick up four specific BSM scenarios, namely, supersymmetry, little Higgs, gauge-Higgs unification, and the Higgsless approach. The discussion will be confined mainly on their electroweak symmetry breaking aspects.

In this paper, two key issues related to electroweak symmetry breaking are addressed. First, how fine-tuned different models are that trigger this phenomenon? Second, even if a light Higgs boson exists, does it have to be necessarily elementary? After a brief introduction, the fine-tuning aspects of the MSSM, NMSSM, generalized NMSSM and GMSB scenarios shall be reviewed, then the little Higgs, composite Higgs and the Higgsless models shall be compared. Finally, a broad overview will be given on where we stand at the end of 2011.

One of the attractive properties of the NMSSM is that it can accommodate a light pseudoscalar of order 10 GeV. However, such scenarios are constrained by several experimental results, especially those related to the fermionic decays of the pseudoscalar. In this work, extending the NMSSM field content by two gauge singlets, with lepton number +1 and $−1$, we generate neutrino masses via the inverse see-saw mechanism at one hand and on the other hand a very light pseudoscalar becomes experimentally viable by having dominant invisible decay channels which help it to evade the existing bounds.

The ‘hierarchy problem’ plagues the Standard Model of particle physics. The source of this problem is our inability to answer the following question: Why is the Higgs mass so much below the GUT or Planck scale? A brief description about how ‘supersymmetry’ and ‘composite Higgs’ address this problem is given here.