Low energy behaviour of standard model extensions

TL;DR

This paper explores how integrating out heavy scalar fields in extended Standard Model scenarios affects low-energy behavior, revealing complexities in decoupling limits and operator structures.

Contribution

It systematically analyzes the low-energy effects of heavy scalars in BSM models, including non-decoupling scenarios with mixed operators and extended scalar representations.

Findings

Decoupling limit cannot be achieved by a single large scale without additional assumptions.

Derived systematic low-energy expansions for non-decoupling cases.

Identified a larger set of local operators than previously reported.

Abstract

The integration of heavy scalar fields is discussed in a class of BSM models, containing more that one representation for scalars and with mixing. The interplay between integrating out heavy scalars and the Standard Model decoupling limit is examined. In general, the latter cannot be obtained in terms of only one large scale and can only be achieved by imposing further assumptions on the couplings. Systematic low-energy expansions are derived in the more general, non-decoupling scenario, including mixed tree-loop and mixed heavy-light generated operators. The number of local operators is larger than the one usually reported in the literature.