Particle Physics in the LHC Era and beyond

Abstract

This concluding talk is not meant to be a summary of the Symposium. Rather it is a very concise overview (as implied by the severe page limit) of the status of particle physics at the start of the LHC time [1], as reflected at this Conference, together with a collection of personal thoughts stimulated by the excellent talks that I followed in their totality. In a few words the general map of particle physics is as follows. The Standard Model (SM) is a low energy effective theory (nobody can believe it is the ultimate theory). It happens to be renormalizable, hence highly predictive and is extremely well supported by the data. However, one expects corrections from higher energies, in particular already from the TeV scale (LHC!), and also from the GUT/Planck scales and possibly from some additional intermediate scales. But even as a low energy effective theory the SM is not satisfactory. In fact while QCD and the gauge part of the EW theory are well established, the Higgs sector is so far just a conjecture. Not only it needs an experimental verification but it introduces serious theoretical problems, like the hierarchy problem, that demand some form of new physics at the electroweak scale. The most important goals of the experiments at the LHC [2, 3] are the clarification of the electroweak symmetry breaking mechanism, the search for signals of new physics at the TeV scale and, possibly, the identification of the unknown particles that make the dark matter in the Universe. The future of particle physics very much depends on the outcome of the LHC. The LHC with the luminosity upgrade [4] will last for 15-20 years. Still the LHC cannot be all. A worldwide effort in neutrino physics is under way (T2K, DChooz, RENO, Daya Bay, NOνA......) [5], [6], [7]. The continuation of experiments on the CKM mixing and CP violation [8], [9] will take place at CERN with LHCb [10] and NA62..... [11] and at new improved B-factories [12]. ”Small” experiments of capital importance will produce their results like those on τ and charm decays [13], neutrino mass (e.g. KATRIN) and neutrinoless double beta decay [14], EDM’s [15] and the laboratory experiments on dark matter search [16]. A special mention deserves MEG, the on going search for the μ → eγ decay at PSI [15], with a goal of improving the present