Understand
We describe a Python-based computer program, DEFT, for manipulating operators in effective field theories (EFTs).
- In its current incarnation, DEFT can be applied to 4-dimensional, Poincar\'{e} invariant theories with gauge group $SU(3)\times SU(2) \times U(1)$, such as the Standard Model (SM), but a variety of extensions (e.g.
- to lower dimensions or to an arbitrary product of unitary gauge groups) are conceptually straightforward.
- Amongst other features, the program is able to: (i) check whether an input list of Lagrangian operators (of a given dimension in the EFT expansion) is a basis for the space of operators contributing to S-matrix elements, once redundancies (such as Fierz-Pauli identities, integration by parts, and equations of motion) are taken into account; (ii) generate such a basis (where possible) from an input algorithm; (iii) carry out a change of basis.