Imports
/- Copyright (c) 2026 Joseph Tooby-Smith. All rights reserved. Released under Apache 2.0 license as described in the file LICENSE. Authors: Joseph Tooby-Smith -/ module public import Physlib.Particles.BeyondTheStandardModel.TwoHDM.GramMatrix public import PhyslibAlpha.Particles.BeyondTheStandardModel.TwoHDM.Module public import Mathlib.RingTheory.MvPolynomial.Tower

The effective potential of the two Higgs doublet model

i. Overview

An effective potential of the two Higgs doublet model is a real-valued function V : TwoHiggsDoublet → ℝ of the field configuration. This file introduces the two physical properties of such a potential used when expressing it through the gauge-invariant bilinears:

    IsInvariant V — invariance under the global gauge group, and

    HasMaxMassDimLE V n — being a polynomial in the field components of mass dimension ≤ n.

ii. Key results

    EffectivePotential — the type of effective potentials.

    IsInvariant — gauge invariance of a potential.

    HasMaxMassDimLE — being a bounded-degree polynomial in the field components.

    HasMaxMassDimLE.exists_comp_linear_poly — a polynomial potential, restricted along any real-linear parametrisation of configurations, is a polynomial in the parameters.

iii. Table of contents

    A. The effective potential and its gauge invariance

    B. Maximum mass dimension

@[expose] public section

A general potential of the Higgs field.

abbrev EffectivePotential : Type := TwoHiggsDoublet

A. The effective potential and its gauge invariance

The proposition that the general potential is invariant under the global action of the gauge group.

def IsInvariant (V : EffectivePotential) : Prop := (g : GaugeGroupI), (φ : TwoHiggsDoublet), V (g φ) = V φ

B. Maximum mass dimension

The proposition that the potential V has a maximum mass dimension less then or equal to n - also implying it is a polynomial.

def HasMaxMassDimLE (V : EffectivePotential) (n : ) : Prop := p : MvPolynomial (Module.Dual TwoHiggsDoublet) , ( φ : TwoHiggsDoublet, V φ = p.eval (fun i => i φ) ) p.totalDegree n

A polynomial potential, restricted along any real-linear parametrisation L of field configurations, is a genuine polynomial in the parameters. This is the bookkeeping that lets the potential be evaluated on the field components of a gauge slice.

V:EffectivePotentialn:ι:Type u_1inst✝¹:Fintype ιinst✝:DecidableEq ιL:(ι ) →ₗ[] TwoHiggsDoubletp:MvPolynomial (Module.Dual TwoHiggsDoublet) hp: (φ : TwoHiggsDoublet), V φ = (MvPolynomial.eval fun i => i φ) pa:ι key:(fun i => i (L a)) = fun i => (MvPolynomial.eval a) (∑ k, MvPolynomial.C (i (L (Pi.single k 1))) * MvPolynomial.X k)(MvPolynomial.eval fun i => (MvPolynomial.eval a) (∑ k, MvPolynomial.C (i (L (Pi.single k 1))) * MvPolynomial.X k)) p = (MvPolynomial.eval ((MvPolynomial.eval a) fun i => k, MvPolynomial.C (i (L (Pi.single k 1))) * MvPolynomial.X k)) p All goals completed! 🐙