The electroweak symmetry breaking riddle

Abstract

I present a concise review of the Higgs problem which plays a central role in particle physics today. The Higgs of the minimal Standard Model is so far just a conjecture that needs to be verified or discarded at the LHC. Probably the reality is more complicated. I will summarize the motivation for New Physics that should accompany or even replace the Higgs discovery and a number of its possible forms that could be revealed by the LHC.Copyright line will be provided by the publisher The programme of LHC physicsFinally in November '09 the first collisions were observed at the LHC and the physics run at 3.5 TeV per beam will soon start. The particle physics community eagerly waits for the answers that one expects from the LHC to a number of big questions. The main physics issues at the LHC, addressed by the ATLAS and CMS collaborations, will be: 1) the experimental clarification of the Higgs sector of the electroweak (EW) theory, 2) the search for new physics at the weak scale that, on conceptual grounds, one predicts should be in the LHC discovery range, and, hopefully, 3) the identification of the particle(s) that make the Dark Matter in the Universe, in particular if those are WIMPs (Weakly Interacting Massive Particles). In addition the LHCb detector will be devoted to the study of precision B physics, with the aim of going deeper into the physics of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and of CP violation. The LHC will also devote a number of runs to accelerate heavy ions and the ALICE collaboration will study their collisions for an experimental exploration of the QCD phase diagram.