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arXiv · 1307.5017

Complete Electroweak Chiral Lagrangian with a Light Higgs at NLO

Gerhard Buchalla·Oscar Cata·Claudius Krause
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Abstract

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, ${\cal O}(v^2/Λ^2)$. 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.

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Gerhard Buchalla, Oscar Cata, Claudius Krause. 2015-12-07. Complete Electroweak Chiral Lagrangian with a Light Higgs at NLO. https://doi.org/10.1016/j.nuclphysb.2014.01.018

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