26 | | In the latter scenario, instead, two independent fields are introduced for the EW Goldstone bosons and for the physical Higgs, and one constructs a "chiral" EFT (sometimes also called non-linear or HEFT), in which the effective operators are ordered according to a more complex counting that, for the Goldstone bosons sector, reduces to a derivative one. |
| 26 | In the latter scenario, instead, two independent fields are introduced for the EW Goldstone bosons and for the physical Higgs, and one constructs a "chiral" EFT (sometimes also called non-linear EFT or HEFT), in which the effective operators are ordered according to a more complex counting that, for the Goldstone bosons sector, reduces to a derivative expansion. |
28 | | The models presented here implement complete sets of operators for ALP interactions with the bosonic sector of the SM, up to next-to-leading terms in the effective expansion. |
29 | | This corresponds to 4 operators of dimension 6 for the linear EFT and to 18 invariants with up to 4 derivatives for the chiral EFT. The operators are defined with an NDA normalization, according to the notation used in [https://arxiv.org/abs/1701.05379/ arXiv:1701.05379]. |
| 28 | The models presented here implement complete sets of CP-even operators for ALP interactions with the bosonic sector of the SM, up to next-to-leading terms in the effective expansions. |
| 29 | These amount to 4 operators of dimension 5 for the linear EFT and to 18 operators with up to 4 derivatives for the chiral EFT. |
| 30 | The chiral operators are defined with an NDA normalization, according to the notation used in [https://arxiv.org/abs/1701.05379/ arXiv:1701.05379]. |