Patterns of deviation from the standard model Original Research Article

Effective lagrangians can be used to parametrize the effects of physics beyond the Standard Model. Assuming the complete theory is a gauge theory, we determine which effective operators may be generated at tree level, and which are only generated at loop level. The latter are suppressed by factors of 116π2 and will therefore be quite difficult to detect. In particular, all operators changing the Standard-Model structure of the triplegauge-vector couplings fall into this category. We also point out that in certain cases, dimension-eight operators may be more important than dimension-six operators. We discuss both the linear and non-linear representation of the Higgs sector.