Electroweak symmetry breaking of standard model in SU(2) doublet extension

The long-awaited Higgs particle with mass around 125 GeV has been observed at the LHC. Considering it as the standard model Higgs boson and if there is no new physics between electroweak scale and Planck scale, then we don’t have a stable vacuum. Here, we give a brief review of the Standard Model vacuum stability and some other theoretical issues in the standard model. Possible ways to enhance the vacuum stability are also discussed. The Standrd Model (SM) is a guage theory which explains all the interactions nicely but leaves the particles massless. Higgs mechanism gives mass to all the particles in Standard Model except neutrinos, photon and gluons through Spontaneous symmetry breaking. Motivations from different sectors: such as baryon asymmetry, dark matter, supersymmetry and many more lead to extension of SM Higgs sector. We discuss theoretical and phenomenological aspects of Two Higgs Doublet Model. This extension has flavor changing neutral currents which are strongly constrained by experiment. Various strategies are discussed to eliminate these flavor changing neutral currents by imposing a discrete Z2 symmetry. In particular, scenarios with natural flavor conservation are investigated, including the so-called type I and type II models as well as leptonspecific and flipped models.