Physlib.Particles.StandardModel.HiggsBoson.EffectivePotential
The effective potential of the Higgs field
We define a general effective potential for the Higgs field. For this we define two properties of the potential: invariance under the gauge group, and a maximum mass dimension.
Given these, we prove that the potential can be expressed as a polynomial in the norm of the Higgs field.
A. The invariance of the general potential under the gauge group
B. Maximum mass dimension
C. Terms of a given mass dimension
D. Potential in terms of the norm of the Higgs field
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Effective potential of the Higgs field
The type of general effective potentials for the Higgs field, defined as the set of real-valued functions , where is the 2-dimensional complex vector space .
Gauge invariance of the effective potential
The property `IsInvariant` defines the gauge symmetry of an effective potential . It states that for every element in the Standard Model gauge group and every Higgs field value , the potential remains unchanged under the gauge action: where the action is defined by the transformation with and .
A Gauge Invariant Higgs Potential Factors Through the Norm
Let be an effective potential of the Higgs field. If is gauge invariant (meaning for all elements of the Standard Model gauge group ), then there exists a function such that , or equivalently for all , where denotes the standard Euclidean norm on .
The Higgs potential has mass dimension
The effective potential is said to have a maximum mass dimension less than or equal to if there exists a real multivariate polynomial in four variables such that for every , the potential is equal to the evaluation of on the four real components of , and the total degree of is at most . Here, is the 2-dimensional complex vector space representing the Higgs doublet.
Multivariate polynomial associated with a Higgs potential of mass dimension
Given an effective potential that has a maximum mass dimension at most , where is the 2-dimensional complex vector space of the Higgs field, this definition provides the corresponding multivariate polynomial in four real variables. This polynomial represents the potential such that , and its total degree is at most .
The total degree of a Higgs potential with mass dimension is at most
Let be an effective potential for the Higgs field . If has a maximum mass dimension at most , then the total degree of its corresponding real multivariate polynomial satisfies .
Equals the Evaluation of its Associated Polynomial
Let be an effective potential of the Higgs field with maximum mass dimension at most , and let be its associated multivariate polynomial in four real variables. For any Higgs doublet , the value of the potential is equal to the evaluation of the polynomial on the four real components of , namely .
Mass dimension term of the Higgs potential
Given an effective potential with a maximum mass dimension at most , where is the space of the Higgs doublet, the function `termOfMassDim V h m` represents the part of the potential with exactly mass dimension . It is defined by taking the -th homogeneous component of the multivariate polynomial associated with and evaluating it on the four real components of the Higgs field .
The mass dimension term of the Higgs potential is for
Let be an effective potential of the Higgs field with maximum mass dimension at most , where . If is a natural number such that , then the term of mass dimension of the potential (denoted as `termOfMassDim V h m`) is zero for any Higgs doublet .
Homogeneity of the mass dimension term of the Higgs potential
Let be an effective potential of the Higgs field with maximum mass dimension at most . For any natural number , the term of mass dimension of the potential, denoted as , is homogeneous of degree . That is, for any Higgs field vector and real scalar ,
The Higgs potential equals the sum of its mass dimension terms up to its maximum dimension .
Let be an effective potential for the Higgs field, where is the 2-dimensional complex vector space of the Higgs doublet. If has a maximum mass dimension at most (i.e., it can be represented as a polynomial of degree at most in the real components of the field), then for any , the potential is equal to the sum of its terms of mass dimension for : where denotes the component of the potential with exactly mass dimension .
Expansion of the scaled Higgs potential into mass dimension terms
Let be an effective potential of the Higgs field with maximum mass dimension less than or equal to , where . For any Higgs field vector and any real scalar , the potential evaluated at the scaled field satisfies where denotes the -th mass dimension term of the potential .
Gauge Invariance of the Mass Dimension Term of the Higgs Potential
Suppose is an effective Higgs potential with a maximum mass dimension at most . If is gauge invariant, meaning for all elements of the gauge group and Higgs fields , then for any , the term of the potential with mass dimension is also gauge invariant.
The -th mass dimension term of a gauge-invariant Higgs potential satisfies
Let be an effective potential for the Higgs field with a maximum mass dimension at most . If is gauge invariant under the Standard Model gauge group, then for any , there exists a constant such that for every Higgs field value , the term of mass dimension in the potential, denoted , is given by where is the norm of the Higgs doublet in the 2-dimensional complex vector space .
Odd mass dimension terms of a gauge-invariant Higgs potential are zero
Let be an effective potential of the Higgs field that is gauge-invariant and has maximum mass dimension at most . For any odd natural number , the term of mass dimension in the potential vanishes for all , i.e.,
An Invariant Higgs Potential equals the Sum of its Even Mass Dimension Terms
Let be an effective Higgs potential. Suppose is invariant under the gauge group action (i.e., for all ) and has a maximum mass dimension less than or equal to (meaning is a polynomial in the real components of the Higgs field with total degree at most ). Then, for any , the potential is equal to the sum of its homogeneous components of even mass dimension : where denotes the part of the potential with exactly mass dimension .
Gauge Invariant Higgs Potential equals the Sum of its Even Mass Dimension Terms
Let be an effective potential for the Higgs field. Suppose is invariant under the gauge group action and has a maximum mass dimension at most . For any , the potential can be expressed as the sum of its terms with even mass dimension for : where denotes the part of the potential with exactly mass dimension .
An invariant Higgs potential with mass dimension is a sum of even powers of
Let be an effective potential for the Higgs field. Suppose is invariant under the gauge group action (i.e., for all ) and has a maximum mass dimension less than or equal to (meaning is a polynomial in the real components of the Higgs field with total degree at most ). Then, for any , there exist real coefficients for such that the potential can be expressed as a sum of even powers of the norm :
