Higgs decay $H \to \gamma \gamma$: New theoretical results and possible experimental implications

The contribution of one W loop to the decay of the Higgs particle into two gammas is recalculated. Since this matrix element is finite in the standard model, it should be calculated in a straightforward way without artifacts such as regularization or ghosts. The result of the present calculation differs from the previous one, giving a Higgs decay rate smaller by a factor of 2 in the mass range of physical interest. In view of the results from the ATLAS Collaboration and the CMS Collaboration, this leads to possible far-reaching experimental consequences.