ABSTRACT (original article): We derive a saturation theorem for general Effective Field Theories (EFTs) constructed using spurion analysis. Let
S
be a set of spurion fields introduced to organize the breaking of a global symmetry
G
f
, and
H
S
be the subgroup of
G
f
that remains unbroken under a generic vacuum expectation value
〈S〉
; we show that the EFT Lagrangian constructed from the spurion analysis saturates the EFT Lagrangian without the spurions but restricted to
H
S
invariance, provided that arbitrary powers of the spurion fields are allowed. As examples, we study several implementations of the Minimal Lepton Flavor Violation (MLFV) principle, corresponding to various origins of the neutrino masses. In each scenario, we compute the Hilbert series to obtain the numbers of independent lepton flavor covariants that appear in the corresponding EFT at mass dimension 6. These numbers agree with the number of
H
S
invariants in the EFT without the spurions, demonstrating the saturation theorem. Motivated by phenomenological connections, we provide linearly independent spurion polynomials for selected lepton flavor covariants. An ancillary file is supplied at this https URL , which is a Mathematica notebook that provides functions for computing general Hilbert series of invariants and covariants of compact classical groups. It presents examples demonstrating the use of the code, including the Hilbert series for our MLFV scenarios. CITATION (original article): Benjamín Grinstein, Xiaochuan Lu, Carlos Miró, Pablo Quílez (2024), Most general EFTs from spurion analysis: Hilbert series and Minimal Lepton Flavor Violation, arXiv:2412.16285. https://doi.org/10.48550/arXiv.2412.16285 GitHub: https://github.com/HilbertSeries/Group_Invariants_and_Covariants
In this ancillary Mathematica notebook we provide detailed instructions on how to use our optimized code for the computation of single-graded and multi-graded Hilbert series (HS), focusing, in particular, in the classical Lie groups SU(n), SO(n), Sp(n=2r), and U(1) abelian factors. In Section 1, we introduce the three pieces that make up the integrand in the Molien-Weyl formula, that is, the Haar measures, the Weyl characters, and the graded characters of polynomial rings from the building block fields. Section 2 contains our main functions for the computation of the Hilbert series. A simple application demo is presented in Section 3 to clearly illustrate the call of the previous functions, the structure of their input arguments, and the expected output. Finally, in Section 4 we address a phenomenologically motivated scenario, namely, the Minimal Lepton Flavor Violation (MLFV) principle, in the context of a spurion analysis for different neutrino mass generation mechanisms. Within each scenario, we collect both single-graded and (some) multi-graded HS for the lepton flavor group covariants of interest. In any case, this ancillary file is intended to serve the interested reader as a package for computing their own HS.
1. Constructing the integrand: Haar measures, Weyl characters, and graded polynomial ring characters
Haar measures and reduced Haar measures (based on arXiv: 1706.08520)
Weyl characters They refer to the character function restricted to the Cartan subgroup ── see arXiv: 1706.08520 for details. A Weyl character depends on the group and the irreducible representation (irrep). Syntax for computing Weyl characters WeylChGroup[gp, chvars, irrephwt]: Weyl character for an irrep “irrephwt” of a group “gp”, using parametrization variables in the list “chvars”. WeylChProductGroup[gplist, chvarsGps, irrephwtGps]: Weyl character for an irrep “irrephwtGps” (which is a list of “irrephwt”) of the product group “gplist”. Highest weight vector of irreducible representations (irreps) We use the highest weight vector to label irreps ── “irrephwt”, which is a list with
r
components, where r is the rank of the group. Taking SU(3) for example, we have fundamental irrep: irrephwt = {1,0} anti-fundamental irrep: irrephwt = {1,1} adjoint irrep: irrephwt = {2,1} For SU(n=r+1) groups, we embed the weight lattice in the (r + 1)-dimensional space, such that the components of the weight vectors are all integers. The (r + 1)-th component of a highest weight vector is zero, and we can view it as a vector with r components, as in the above SU(3) examples. With this convention, for a given SU(n=r+1) irrep, there is a convenient map between its highest weight vector and its Young diagram ── the k-th component of “irrephwt” gives the number of boxes in the k-th row of the Young diagram. “irrephwtGps” is a list of “irrephwt”: irrephwtGps = {
irrephwt
1
,
irrephwt
2
, ... }, where each “
irrephwt
k
” specifies the irrep of the k-th factor in the product group “gplist”. Together, “irrephwtGps” specifies an irrep of the product group. Dynkin labels of irreps A frequently used alternative convention is to label irreps by the Dynkin labels ── “dynkinlabels” is a list of r non-negative integers. We provide functions to translate between the highest weight vector and the Dynkin labels: DynkinLabelsFromIrrephwt[gp, irrephwt]: gives the Dynkin labels of an irrep from the highest weight vector “irrephwt”. IrrephwtFromDynkinLabels[gp, dynkinlabels]: gives the highest weight vector “irrephwt” of an irrep from the Dynkin labels. Dimension of irreps We also provide a function to compute the dimension of an irrep from the highest weight vector “irrephwt”: DimIrrephwt[gp, irrephwt]: gives the dimension of an irrep “irrephwt” of the group “gp”. Summary table of irreps We also provide a function to generate a quick summary table: IrrepTableGroup[gp, maxdynkinlabel]: generates a summary table of the Dynkin labels, dimensions, and the highest weight vectors for irreps of the group “gp”. “maxdynkinlabel” is a non-negative integer that sets the maximum value for each component of the Dynkin labels.
DynkinLabelsandIrrepDimensions
U(1)
SU(n)
SO(n)
Sp(n=2r)
General
Graded (Weyl) characters of the polynomial ring from the building block fields
Graded characters of polynomial rings from the building blocks fields Each building block field contributes to the integrand with a determinant factor that corresponds to the graded Weyl character of their polynomial ring. Syntax for computing graded characters of polynomial rings GradedRingChGroup[gp, chvars, BBFlist]: Graded character of the polynomial ring in a set of building block fields “BBFlist” for a group “gp”. GradedRingChProductGroup[gplist, chvarsGps, BBFlist]: Graded character of the polynomial ring in a set of building block fields “BBFlist” for a product group “gplist”. Building blocks fields Each building block field, “BBF”, is a list that contains three components: BBF 〚1〛 = the grading variable BBF 〚2〛 = 0 (Grassmann even) or 1 (Grassmann odd) BBF 〚3〛 = “irrephwtGps”, which is a list of highest weight vectors. irrephwtGps = {
irrephwt
1
,
irrephwt
2
, ...}, where each “
irrephwt
k
” specifies the irrep of the k-th factor in the product group. For example, when there is a single group SU(3), we have a bosonic field ϕ1 that is a fundamental irrep: BBF = { ϕ1, 0, { {1,0} } } a bosonic field ϕ2 that is an adjoint irrep: BBF = { ϕ2, 0, { {2,1} } } a fermionic field ψ that is a symmetric two-index irrep: BBF = { ψ, 1, { {2,0} } } For a product group SU(3)×SU(3), we have a bosonic field ϕ that is (fundamental, adjoint) irrep: BBF = { ϕ, 0, { {1,0}, {2,1} } } Note that, in the examples above, we are using the same symbol to denote the fields and their grading variables in a slight abuse of notation. A “BBFlist” is a list of “BBF”: BBFlist =
{
BBF
1
,
BBF
2
, ... }.
Compute the list of eigenvalues from a character ch
Hilbert series Hilbert series encodes the group invariants and covariants that are made out of polynomials in a set of building block fields. Syntax for computing Hilbert series ── Main Functions HilbertSeriesBBFGRCh[gplist, chvarsGps, irrephwtGps, BBFgrch]: Hilbert series for an irrep “irrephwtGps” of a product group “gplist” from a set of building block fields. It takes the graded character of the polynomial ring “BBFgrch” as an input. HilbertSeriesBBFlist[gplist, chvarsGps, irrephwtGps, BBFlist]: Hilbert series for an irrep “irrephwtGps” of a product group “gplist” from a set of building block fields. It takes the list of building block fields “BBFlist” as an input. There are a variety of explicit examples provided in Section 3 below.
Main Hilbert series function for a product group that takes the graded polynomial ring character from the building block fields as input
[1] For the Hilbert series for covariants: Benjamín Grinstein, Xiaochuan Lu, Luca Merlo, Pablo Quílez (2023), Hilbert series for covariants and their applications to Minimal Flavor Violation, arXiv:2312.13349. https://doi.org/10.48550/arXiv.2312.13349
[2] For the Haar measures and the Weyl characters: arXiv: Henning, B., Lu, X., Melia, T. et al. Operator bases, S-matrices, and their partition functions. J. High Energ. Phys. 2017, 199 (2017). https://doi.org/10.1007/JHEP10(2017)199