Constructing Generic Effective Field Theory for All Masses and Spins

TL;DR

This paper introduces a comprehensive on-shell method for constructing operator bases in effective field theories for particles of any mass and spin, enabling systematic and efficient basis generation.

Contribution

It develops a novel systematic approach using Young tableaus and matrix projection to construct complete operator bases for all masses and spins in EFTs.

Findings

Constructed a complete set of four-vector operators up to dimension six.

Proposed a matrix projection method for massive amplitude bases with identical particles.

Enabled efficient computer-aided construction of operator bases in generic massive EFTs.

Abstract

We fully solve the long-standing problem of operator basis construction for fields with any masses and spins. Based on the on-shell method, we propose a novel method to systematically construct a complete set of lowest dimensional amplitude bases at any given dimension through semi-standard Young tableaus of Lorentz subgroup $SU(2)_r$ and global symmetry $U(N)$ ($N$ is the number of external legs), which can be directly mapped into physical operator bases. We first construct a complete set of monomial bases whose dimension is not the lowest and a redundant set of bases that always contains a complete set of amplitude bases with the lowest dimension. Then we decompose the bases of the redundant set into the monomial bases from low to high dimension and eliminate the linear correlation bases. Finally, the bases with the lowest dimension can be picked up. We also propose a matrix projection method to construct the massive amplitude bases involving identical particles. The operator bases of a generic massive effective field theory can be efficiently constructed by the computer programs. A complete set of four-vector operators at dimensions up to six is presented.