2013/07/31 by Gerhard Buchalla, Oscar Cata, Claudius Krause · 1 citation
Physics and Astronomy · #hep-ph
paper · pdf · doi:10.1016/j.nuclphysb.2014.01.018
25 pages, no figures; v2: references added, matches published version; v3: corrected matching of Higgs-portal example to chiral Lagrangian in sec. 7.2
arxiv created 2015/12/07 · arxiv updated 2015/12/08
We consider the Standard Model, including a light scalar boson h, as an effective theory at the weak scale v=246 \rm GeV of some unknown dynamics of electroweak symmetry breaking. This dynamics may be strong, with h emerging as a pseudo-Goldstone boson. The symmetry breaking scale Λ is taken to be at 4πv or above. We review the leading-order Lagrangian within this framework, which is nonrenormalizable in general. A chiral Lagrangian can then be constructed based on a loop expansion. A systematic power counting is derived and used to identify the classes of counterterms that appear at one loop order. With this result the complete Lagrangian is constructed at next-to-leading order, \cal O(v2/Λ2). This Lagrangian is the most general effective description of the Standard Model containing a light scalar boson, in general with strong dynamics of electroweak symmetry breaking. Scenarios such as the SILH ansatz or the dimension-6 Lagrangian of a linearly realized Higgs sector can be recovered as special cases.