= '''Effective Theories for a light Axion-Light-Particle (ALP)''' =

== Authors ==

I. Brivio^a,b)^, M.B. Gavela^a)^, L. Merlo^a)^, K. Mimasu^c,d)^, J.M. No^c,e)^, R. del Rey^a)^, V. Sanz^c)^

''
a) Departamento de Física Teórica and Instituto de Física Teórica, Universidad Autónoma de Madrid, Spain[[BR]]
b) NBIA and Discovery Center, Niels Bohr Institute, University of Copenhagen, Denmark[[BR]]
c) Department of Physics and Astronomy, University of Sussex, UK[[BR]]
d) Centre for Cosmology, Particle Physics and Phenomenology (CP3), Université catholique de Louvain, Belgium[[BR]]
e) Department of Physics, King’s College London, UK''

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== The model description ==

The Standard Model (SM) is extended with the inclusion of a generic CP-odd scalar field, that is a singlet under the SM gauge symmetries. 
This new field is assumed to be an Axion-Like-Particle, i.e. the (pseudo) Nambu-Goldstone boson of an unspecified spontaneously broken U(1) symmetry, associated with a heavy scale f,,,a,,,.
As such, the ALP field respects an approximate shift symmetry that requires its couplings to the SM to be purely derivative and weighted by inverse powers of f,,a,,. Moreover, its mass must be much lighter than f,,a,,.
In these models the benchmark values f,,a,,= 1 TeV, m,,a,, = 1 MeV are assumed.


Two major frameworks for the electroweak sector are considered: a linear realization of electroweak symmetry breaking (EWSB), typical of weakly coupled new physics, and a non-linear one, such as those in constructions involving new strongly interacting physics.







The Feynrules models supplied contain only the definition of the ALP particle and of its interactions, and should therefore be loaded alongside the SM Lagrangian.


Please report bugs or questions to:  ilaria.brivio@nbi.ku.dk

== References ==


* I. Brivio, M.B. Gavela, L. Merlo, K. Mimasu, J.M. No, R. del Rey, V. Sanz, ''ALPs Effective Field Theory and Collider Signatures'', [https://arxiv.org/abs/1701.05379/ arXiv:1701.05379] 


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== Files ==

'''FeynRules sources'''

* [attachment:"ALP_chiral_Feynrules.tar.gz"] The Feynrules model file for the chiral EFT.
* [attachment:"ALP_linear_Feynrules.tar.gz"] The Feynrules model file for the linear EFT.

'''Mathematica notebook'''

* [attachment:"ALPs_EFT.nb"] Demo notebook

'''Pre-exported UFO models'''

* [attachment:"ALP_chiral_UFO.tar.gz"] The UFO model file for the chiral EFT.
* [attachment:"ALP_linear_UFO.tar.gz"] The UFO model file for the linear EFT.