Physics
Maple provides a state-of-the-art environment for algebraic computations in Physics, with emphasis on ensuring that the computational experience is as natural as possible. The theme of the Physics project for Maple 2022 has been the consolidation of the functionality introduced in previous releases, including a significant speed-up across the package and significant enhancements in the areas of Particle Physics, Functional Differentiation in general relativity, and Integral Vector Calculus.
As part of its commitment to providing the best possible computational environment in Physics, Maplesoft launched a Maple Physics: Research and Development website in 2014, which enabled users to download research versions of the package, ask questions, and provide feedback. The results from this accelerated exchange have been incorporated into the Physics package in Maple 2022. The presentation below illustrates both the novelties and the kind of mathematical formulations that can now be performed.
The StandardModel package
Feynman Diagrams
FeynmanIntegral module with 9 new commands
Integral Vector Calculus and Parametrization of curves, surfaces and volumes
Functional Differentiation in General Relativity
CompactDisplay and Typesetting:-Suppress unified
Documentation advanced examples
See Also
StandardModel is a Physics's package that implements computational representations for the mathematical objects formulating the Standard Model in particle physics. The package includes field representations for the leptons and quarks of the model, as well as for Weinberg's angle, the Higgs boson, and the fields and field strengths after breaking symmetries and most of the fields before that. Loading the package sets things to proceed computing with the model.
withPhysics:withStandardModel
⁢_______________________________________________________
Setting lowercaselatin_is letters to represent Dirac spinor indices
Setting lowercaselatin_ah letters to represent SU(3) adjoint representation, (1..8) indices
Setting uppercaselatin_ah letters to represent SU(3) fundamental representation, (1..3) indices
Setting uppercaselatin_is letters to represent SU(2) adjoint representation, (1..3) indices
Setting uppercasegreek letters to represent SU(2) fundamental representation, (1..2) indices
Defined as the electron, muon and tau leptons and corresponding neutrinos: ej , μj , τj , ElectronNeutrinoj , MuonNeutrinoj , TauonNeutrinoj
Defined as the up, charm, top, down, strange and bottom quarks: uA,j , cA,j , tA,j , dA,j , sA,j , bA,j
Defined as gauge tensors: Bμ , 𝔹μ,ν , Aμ , 𝔽μ,ν , Wμ,J , 𝕎μ,ν,J , WPlusFieldμ , WPlusFieldStrengthμ,ν , WMinusFieldμ , WMinusFieldStrengthμ,ν , Zμ , ℤμ,ν , Gμ,a , 𝔾μ,ν,a
Defined as Gell-Mann (Glambda), Pauli (Psigma) and Dirac (Dgamma) matrices: λa , σJ , γμ
Defined as the electric, weak and strong coupling constants: g__e , g__w , g__s
Defined as the charge in units of |g__e| for 1) the electron, muon and tauon, 2) the up, charm and top, and 3) the down, strange and bottom: %q__e = −1, %q__u = 23, %q__d = −13
Defined as the weak isospin for 1) the electron, muon and tauon, 2) the up, charm and top, 3) the down, strange and bottom, and 4) all the neutrinos: %I__e = −12, %I__u = 12, %I__d = −12, %I__n = 12
You can use the active form without the % prefix, or the 'value' command to give the corresponding value to any of the inert representations %q__e , %q__u , %q__d , %I__e , %I__u , %I__d , %I__n
⁢Default differentiation variables for d_, D_ and dAlembertian are:⁢X=x,y,z,t
Minkowski spacetime with signatre - - - +
%I__d,%I__e,%I__n,%I__u,%q__d,%q__e,%q__u,BField,BFieldStrength,Bottom,CKM,Charm,Down,ElectromagneticField,ElectromagneticFieldStrength,Electron,ElectronNeutrino,FSU3,Glambda,GluonField,GluonFieldStrength,HiggsBoson,Lagrangian,Muon,MuonNeutrino,Strange,Tauon,TauonNeutrino,Top,Up,WField,WFieldStrength,WMinusField,WMinusFieldStrength,WPlusField,WPlusFieldStrength,WeinbergAngle,ZField,ZFieldStrength,g__e,g__s,g__w
The Leptons, Quarks, Gauge Fields and structure constants of the model
The massless fields of the model are the electromagnetic field A, the gluons G and neutrinos MuonNeutrino,TauonNeutrinoand ElectronNeutrino
Setupmassless
* Partial match of 'massless' against keyword 'masslessfields'
_______________________________________________________
masslessfields=G,MuonNeutrino,TauonNeutrino,A,ElectronNeutrino
The Leptons and Quarks of the model are
StandardModel:-Leptons
e,μ,τ,ElectronNeutrino,MuonNeutrino,TauonNeutrino
StandardModel:-Quarks
u,c,t,d,s,b
The Gauge fields
StandardModel:-GaugeFields
A,𝔽,B,𝔹,W,𝕎,G,𝔾,WMinusField,WMinusFieldStrength,WPlusField,WPlusFieldStrength,Z,ℤ
For readability, omit the functionality of all these fields from the display of formulas that follows (see CompactDisplay) and use the lowercase i instead of the uppercase I to represent the imaginary unit
CompactDisplayStandardModel:-LeptonsX,StandardModel:-QuarksX,StandardModel:-GaugeFieldsX, HiggsBosonX,quiet
interfaceimaginaryunit = i:
The definitions of the gauge fields can be seen as with any other tensor of the Physics package using the keyword definition
ElectromagneticFielddefinition
Aμ=sin⁡WeinbergAngle⁢Wμ3μ3+cos⁡WeinbergAngle⁢Bμ
mapu → udefinition,StandardModel:-GaugeFields
ElectromagneticFieldμ=sin⁡WeinbergAngle⁢WFieldμ,~3+cos⁡WeinbergAngle⁢BFieldμ,ElectromagneticFieldStrengthμ,ν=d_μ⁡ElectromagneticFieldν⁡X,X−d_ν⁡ElectromagneticFieldμ⁡X,X,BFieldμ=BField1BField2BField3BField4,BFieldStrengthμ,ν=d_μ⁡BFieldν⁡X,X−d_ν⁡BFieldμ⁡X,X,WFieldμ,J=WField1,1WField1,2WField1,3WField2,1WField2,2WField2,3WField3,1WField3,2WField3,3WField4,1WField4,2WField4,3,WFieldStrengthμ,ν,J=d_μ⁡WFieldν,J⁡X,X−d_ν⁡WFieldμ,J⁡X,X+g__w⁢LeviCivitaJ,K,L⁢`*`⁡WFieldμ,K⁡X,WFieldν,L⁡X,GluonFieldμ,a=GluonField1,1GluonField1,2GluonField1,3GluonField1,4GluonField1,5GluonField1,6GluonField1,7GluonField1,8GluonField2,1GluonField2,2GluonField2,3GluonField2,4GluonField2,5GluonField2,6GluonField2,7GluonField2,8GluonField3,1GluonField3,2GluonField3,3GluonField3,4GluonField3,5GluonField3,6GluonField3,7GluonField3,8GluonField4,1GluonField4,2GluonField4,3GluonField4,4GluonField4,5GluonField4,6GluonField4,7GluonField4,8,GluonFieldStrengthμ,ν,a=d_μ⁡GluonFieldν,a⁡X,X−d_ν⁡GluonFieldμ,a⁡X,X+g__s⁢FSU3a,b,c⁢`*`⁡GluonFieldμ,b⁡X,GluonFieldν,c⁡X,WMinusFieldμ=12⁢WFieldμ,~1+ⅈ⁢WFieldμ,~2⁢2,WMinusFieldStrengthμ,ν=d_μ⁡WMinusFieldν⁡X,X−d_ν⁡WMinusFieldμ⁡X,X,WPlusFieldμ=12⁢WFieldμ,~1−ⅈ⁢WFieldμ,~2⁢2,WPlusFieldStrengthμ,ν=d_μ⁡WPlusFieldν⁡X,X−d_ν⁡WPlusFieldμ⁡X,X,ZFieldμ=cos⁡WeinbergAngle⁢WFieldμ,~3−sin⁡WeinbergAngle⁢BFieldμ,ZFieldStrengthμ,ν=d_μ⁡ZFieldν⁡X,X−d_ν⁡ZFieldμ⁡X,X
Note that the conventions used in the definitions of covariant derivatives (not shown above) and field strength tensors, follow Peskin, S. "An Introduction to Quantum Field Theory", also the Wikipedia, and are not uniform in the literature: the gauge term involving the gluon in the covariant derivative of the quarks, e.g. the Top, uj,A , has a minus sign and the third term in the gluon field strength definition (shown above) has a plus sign:
D_muUpA,jX: % = expand%
D_μ⁡UpA,j⁡X,X=d_μ⁡UpA,j⁡X,X−12⁢ⅈ⁢g__s⁢`*`⁡GlambdaaA,B,UpB,j⁡X,GluonFieldμ,a⁡X
GluonFieldStrengthdefinition
GluonFieldStrengthμ,ν,a=d_μ⁡GluonFieldν,a⁡X,X−d_ν⁡GluonFieldμ,a⁡X,X+g__s⁢FSU3a,b,c⁢`*`⁡GluonFieldμ,b⁡X,GluonFieldν,c⁡X
The convention for the signs in the definitions of Aμ and Zμin (7) also follow Peskin's book and the presentation of the Standard Model in Wikipedia.
The Gell-Mann matrices, that enter gauge terms in the interaction Lagrangian of the StandardModel are represented by Glambda, implemented as a tensor with an SU(3) adjoint representation index, all of whose components are matrices
Glambda
Glambdaa=Glambda1Glambda2Glambda3Glambda4Glambda5Glambda6Glambda7Glambda8
seqGlambdaa,matrix, a=1..8
λ1=010100000,λ2=0−ⅈ0ⅈ00000,λ3=1000−10000,λ4=001000100,λ5=00−ⅈ000ⅈ00,λ6=000001010,λ7=00000−ⅈ0ⅈ0,λ8=3300033000−2⁢33
These matrices satisfy a SU(3) algebra
Library:-DefaultAlgebraRulesGlambda
%Commutator⁡Glambdab,Glambdac=2⁢ⅈ⁢FSU3a,b,c⁢Glambdaa
The structure constants FSU3a,b,c entering (12) and interaction Lagrangian terms of the StandardModel form a three-dimensional array of 8 x 8 matrices represented by the command FSU3. implemented as a tensor with three SU(3) adjoint representation indices. As with any other tensor of the Physics package, to see its components you can use the keyword matrix, e.g.
FSU31,b,c,matrix
FSU31,b,c=00000000001000000−100000000000012000000−1200000012000000−12000000000000
or, for a more general exploration of the components of FSU3a,b,cyou can use the command TensorArray with the option explore
TensorArrayFSU3a,b,c,explore
⁢FSU3a,b,c ordering of free indices=a,b,c
Index 1
abc
Value of Index 1
The tensorial equation for the Gell-Mann matrices
is computable for each value of its tensor indices, e.g.
SumOverRepeatedIndices
%Commutator⁡Glambdab,Glambdac=2⁢ⅈ⁢FSU31,b,c⁢Glambda1+FSU32,b,c⁢Glambda2+FSU33,b,c⁢Glambda3+FSU34,b,c⁢Glambda4+FSU35,b,c⁢Glambda5+FSU36,b,c⁢Glambda6+FSU37,b,c⁢Glambda7+FSU38,b,c⁢Glambda8
eval,b=4,c=5
%Commutator⁡Glambda4,Glambda5=2⁢ⅈ⁢12⁢Glambda3+12⁢3⁢Glambda8
Activating the left-hand side,
value
2⁢ⅈ⁢FSU34,5,a⁢λa=2⁢ⅈ⁢λ32+3⁢λ82
expandSumOverRepeatedIndices
ⅈ⁢λ3+ⅈ⁢3⁢λ8=ⅈ⁢λ3+ⅈ⁢3⁢λ8
To see all the components of (12) ≡ %Commutator⁡Glambdab,Glambdac=2⁢I⁢FSU3a,b,c⁢λa at once you can use TensorArray
TensorArray
%Commutator⁡Glambda1,Glambda1=0%Commutator⁡Glambda1,Glambda2=2⁢I⁢Glambda3%Commutator⁡Glambda1,Glambda3=−2⁢I⁢Glambda2%Commutator⁡Glambda1,Glambda4=I⁢Glambda7%Commutator⁡Glambda1,Glambda5=−I⁢Glambda6%Commutator⁡Glambda1,Glambda6=I⁢Glambda5%Commutator⁡Glambda1,Glambda7=−I⁢Glambda4%Commutator⁡Glambda1,Glambda8=0%Commutator⁡Glambda2,Glambda1=−2⁢I⁢Glambda3%Commutator⁡Glambda2,Glambda2=0%Commutator⁡Glambda2,Glambda3=2⁢I⁢Glambda1%Commutator⁡Glambda2,Glambda4=I⁢Glambda6%Commutator⁡Glambda2,Glambda5=I⁢Glambda7%Commutator⁡Glambda2,Glambda6=−I⁢Glambda4%Commutator⁡Glambda2,Glambda7=−I⁢Glambda5%Commutator⁡Glambda2,Glambda8=0%Commutator⁡Glambda3,Glambda1=2⁢I⁢Glambda2%Commutator⁡Glambda3,Glambda2=−2⁢I⁢Glambda1%Commutator⁡Glambda3,Glambda3=0%Commutator⁡Glambda3,Glambda4=I⁢Glambda5%Commutator⁡Glambda3,Glambda5=−I⁢Glambda4%Commutator⁡Glambda3,Glambda6=−I⁢Glambda7%Commutator⁡Glambda3,Glambda7=I⁢Glambda6%Commutator⁡Glambda3,Glambda8=0%Commutator⁡Glambda4,Glambda1=−I⁢Glambda7%Commutator⁡Glambda4,Glambda2=−I⁢Glambda6%Commutator⁡Glambda4,Glambda3=−I⁢Glambda5%Commutator⁡Glambda4,Glambda4=0%Commutator⁡Glambda4,Glambda5=I⁢3⁢Glambda8+Glambda3%Commutator⁡Glambda4,Glambda6=I⁢Glambda2%Commutator⁡Glambda4,Glambda7=I⁢Glambda1%Commutator⁡Glambda4,Glambda8=−I⁢3⁢Glambda5%Commutator⁡Glambda5,Glambda1=I⁢Glambda6%Commutator⁡Glambda5,Glambda2=−I⁢Glambda7%Commutator⁡Glambda5,Glambda3=I⁢Glambda4%Commutator⁡Glambda5,Glambda4=−I⁢3⁢Glambda8+Glambda3%Commutator⁡Glambda5,Glambda5=0%Commutator⁡Glambda5,Glambda6=−I⁢Glambda1%Commutator⁡Glambda5,Glambda7=I⁢Glambda2%Commutator⁡Glambda5,Glambda8=I⁢3⁢Glambda4%Commutator⁡Glambda6,Glambda1=−I⁢Glambda5%Commutator⁡Glambda6,Glambda2=I⁢Glambda4%Commutator⁡Glambda6,Glambda3=I⁢Glambda7%Commutator⁡Glambda6,Glambda4=−I⁢Glambda2%Commutator⁡Glambda6,Glambda5=I⁢Glambda1%Commutator⁡Glambda6,Glambda6=0%Commutator⁡Glambda6,Glambda7=I⁢−Glambda3+3⁢Glambda8%Commutator⁡Glambda6,Glambda8=−I⁢3⁢Glambda7%Commutator⁡Glambda7,Glambda1=I⁢Glambda4%Commutator⁡Glambda7,Glambda2=I⁢Glambda5%Commutator⁡Glambda7,Glambda3=−I⁢Glambda6%Commutator⁡Glambda7,Glambda4=−I⁢Glambda1%Commutator⁡Glambda7,Glambda5=−I⁢Glambda2%Commutator⁡Glambda7,Glambda6=−I⁢−Glambda3+3⁢Glambda8%Commutator⁡Glambda7,Glambda7=0%Commutator⁡Glambda7,Glambda8=I⁢3⁢Glambda6%Commutator⁡Glambda8,Glambda1=0%Commutator⁡Glambda8,Glambda2=0%Commutator⁡Glambda8,Glambda3=0%Commutator⁡Glambda8,Glambda4=I⁢3⁢Glambda5%Commutator⁡Glambda8,Glambda5=−I⁢3⁢Glambda4%Commutator⁡Glambda8,Glambda6=I⁢3⁢Glambda7%Commutator⁡Glambda8,Glambda7=−I⁢3⁢Glambda6%Commutator⁡Glambda8,Glambda8=0
To represent, in what follows, the interaction Lagrangians for QCD and the Electro-Weak sector as sums over leptons and quarks, all of them fermions, it is useful to introduce two anticommutative prefixes to be used as summation indices
Setupanticommutativeprefix = f__L,f__Q
anticommutativeprefix=f__L,f__Q
CompactDisplayf__L,f__QX
f__L⁡x,y,z,t⁢will now be displayed as⁢f__L
f__Q⁡x,y,z,t⁢will now be displayed as⁢f__Q
The Quantum Chromodynamics (QCD) sector of the Standard Model and its interaction Lagrangian
QCD is about the interaction between quarks and gluons and the self-interaction of the latter. Quarks are implemented as tensors with one spinor and one SU(3) fundamental representation (1..3) indices. Unless set otherwise, according to the starting message these indices are represented by lowercaselatin_is and uppercaselatin_ah letters. Gluons are tensors with one spacetime and one SU(3) adjoint representation index (1..8), respectively represented by greek and lowercaselatin_ah letters, and g__s is the QCD coupling constant.
The interaction Lagrangian for the QCD can then be introduced as the sum of two terms
L__QCD ≔ L__QG+L__GG
L__QCD≔L__QG+L__GG
where L__QG represents the part involving the interaction between quarks and gluons, and L__GG the part related to the self-interaction between gluons. L__QG is given by
L__QG ≔ g__s2⋅Dgammamuk, j⋅GluonFieldmu, aX⋅GlambdaaA, B ⋅%addconjugatef__QA,kX⋅f__QB,jX,f__Q=StandardModel:-Quarks
12⁢g__s⁢`*`⁡%add⁡`*`⁡conjugate⁡f__QA,k⁡X,f__QB,j⁡X,f__Q=Up,Charm,Top,Down,Strange,Bottom,GluonFieldμ,a⁡X,GlambdaaA,B⁢Dgamma~muk,j
The self-interactions of the gluons L__GG can be written using the structure constants FSU3d,a,b and the Gell-Mann matrices λa
L__GG ≔ −g__s ⋅FSU3a, b, c⋅d_muGluonFieldnu, aX, X⋅ GluonField~mu, bX⋅ GluonField~nu, cX + g__s4⋅FSU3e, d, c⋅GluonFieldmu, aX⋅ GluonFieldlambda, bX⋅GluonField~mu, eX⋅GluonField~lambda, dX
−g__s⁢FSU3a,b,c⁢`*`⁡d_μ⁡GluonFieldν,a⁡X,X,GluonField~mu,b⁡X,GluonField~nu,c⁡X−14⁢g__s⁢FSU3c,d,e⁢`*`⁡GluonFieldμ,a⁡X,GluonFieldλ,b⁡X,GluonField~mu,e⁡X,GluonField~lambda,d⁡X
From where
L__QCD
12⁢g__s⁢`*`⁡%add⁡`*`⁡conjugate⁡f__QA,k⁡X,f__QB,j⁡X,f__Q=Up,Charm,Top,Down,Strange,Bottom,GluonFieldμ,a⁡X,GlambdaaA,B⁢Dgamma~muk,j−g__s⁢FSU3a,b,c⁢`*`⁡d_μ⁡GluonFieldν,a⁡X,X,GluonField~mu,b⁡X,GluonField~nu,c⁡X−14⁢g__s⁢FSU3c,d,e⁢`*`⁡GluonFieldμ,a⁡X,GluonFieldλ,b⁡X,GluonField~mu,e⁡X,GluonField~lambda,d⁡X
L__QCD ≔ valueL__QCD
12⁢g__s⁢`*`⁡`*`⁡conjugate⁡UpA,k⁡X,UpB,j⁡X+`*`⁡conjugate⁡CharmA,k⁡X,CharmB,j⁡X+`*`⁡conjugate⁡TopA,k⁡X,TopB,j⁡X+`*`⁡conjugate⁡DownA,k⁡X,DownB,j⁡X+`*`⁡conjugate⁡StrangeA,k⁡X,StrangeB,j⁡X+`*`⁡conjugate⁡BottomA,k⁡X,BottomB,j⁡X,GluonFieldμ,a⁡X,GlambdaaA,B⁢Dgamma~muk,j−g__s⁢FSU3a,b,c⁢`*`⁡d_μ⁡GluonFieldν,a⁡X,X,GluonField~mu,b⁡X,GluonField~nu,c⁡X−14⁢g__s⁢FSU3c,d,e⁢`*`⁡GluonFieldμ,a⁡X,GluonFieldλ,b⁡X,GluonField~mu,e⁡X,GluonField~lambda,d⁡X
Each of these terms has different contributions to a scattering amplitude. For example, take the first term with the interaction between Up quarks and gluons and last one with the self-interaction between four gluons.
L__uG ≔ op1, expandvalueL__QCD
12⁢g__s⁢Dgamma~muk,j⁢`*`⁡conjugate⁡UpA,k⁡X,UpB,j⁡X,GluonFieldμ,a⁡X,GlambdaaA,B
The amplitude for the process with two incoming and two outgoing Up quarks (particle and antiparticle)
FeynmanDiagramsL__uG, incomingparticles = Up, conjugateUp, outgoingparticles = Up, conjugateUp, numberofloops = 0, diagrams
−ⅈ⁢uuC,l⁡P__1_⁢vuE,m⁡P__2_&conjugate0;⁢uuF,n⁡P__3_&conjugate0;⁢vuG,p⁡P__4_⁢g__s2⁢γ⁢α⁢αn,p⁢γ⁢ν⁢νm,l⁢gα,ν⁢δb,c⁢δ⁡−P__3~beta−P__4~beta+P__1~beta+P__2~beta⁢λcF,G⁢λbE,C16⁢π2⁢P__1κ+P__2κ⁢P__1~kappa+P__2~kappa+ⅈ⁢ε+ⅈ⁢uuC,l⁡P__1_⁢vuE,m⁡P__2_&conjugate0;⁢uuF,n⁡P__3_&conjugate0;⁢vuG,p⁡P__4_⁢g__s2⁢γ⁢α⁢αm,p⁢γ⁢ν⁢νn,l⁢gα,ν⁢δb,c⁢δ⁡−P__3~beta−P__4~beta+P__1~beta+P__2~beta⁢λcE,G⁢λbF,C16⁢π2⁢P__1~kappa−P__3~kappa⁢P__1κ−P__3κ+ⅈ⁢ε
L__GGGG ≔ op−1, expandL__QCD
14⁢g__s2⁢FSU3a,b,c⁢FSU3c,d,e⁢`*`⁡GluonFieldλ,b⁡X,GluonFieldμ,a⁡X,GluonField~lambda,d⁡X,GluonField~mu,e⁡X
The amplitude for the process with two incoming and two outgoing gluons
FeynmanDiagramsL__GGGG,incomingparticles=GluonField, GluonField,outgoingparticles=GluonField,GluonField,numberofloops=0,diagrams
ⅈ16⁢g__s2⁢δ⁡−P__3~sigma−P__4~sigma+P__1~sigma+P__2~sigma⁢ϵGν,f⁡P__1_⁢ϵGα,g⁡P__2_⁢ϵGβ,h⁡P__3_&conjugate0;⁢ϵGκ,a1⁡P__4_&conjugate0;⁢FSU3c,g,h⁢FSU3a1,c,f−FSU3a1,c,h⁢FSU3c,f,g⁢g⁢β,ν⁢β,ν⁢g⁢α,κ⁢α,κ+g⁢κ,ν⁢κ,ν⁢FSU3c,f,h⁢FSU3a1,c,g+FSU3a1,c,h⁢FSU3c,f,g⁢g⁢α,β⁢α,β+−FSU3c,g,h⁢FSU3a1,c,f−FSU3c,f,h⁢FSU3a1,c,g⁢g⁢α,ν⁢α,ν⁢g⁢β,κ⁢β,κπ2⁢E__1⁢E__2⁢E__3⁢E__4
The Electroweak sector of the Standard Model and its interaction Lagrangian
The computation of scattering amplitudes is performed with the model after symmetry breaking. The electro-weak interaction before symmetry breaking, from where the formulation after symmetry breaking is derived, can be expressed as a sum of four terms mentioned in the Wikipedia page for the weak interaction
L__EW ≔ L__g+L__f+L__h+L__y
L__EW≔L__g+L__f+L__h+L__y
Out of these four, in the Maple 2022.0 implementation of StandardModel it is possible to represent the first term, L__g, the kinetic term for the Wμ,J and Bμ vector bosons
L__g ≔ −14⋅WFieldStrengthμ,ν,J2+BFieldStrengthμ,ν2
L__g≔−𝕎μ,ν,J⁢𝕎⁢μ,νJ⁢μ,νJ4−𝔹μ,ν⁢𝔹⁢μ,ν⁢μ,ν4
Introducing the definitions of these tensors we have
BFieldStrengthdefinition,WFieldStrengthdefinition
𝔹μ,ν=∂μ⁡BFieldν⁡X−∂ν⁡BFieldμ⁡X,𝕎μ,ν,J=∂μ⁡WFieldν,J⁡X−∂ν⁡WFieldμ,J⁡X+g__w⁢εJ,K,L⁢WFieldμ,K⁡X⁢WFieldν,L⁡X
L__g ≔ SubstituteTensor,L__g
−14⁢`*`⁡d_μ⁡WFieldν,J⁡X,X−d_ν⁡WFieldμ,J⁡X,X+g__w⁢LeviCivitaJ,K,L⁢`*`⁡WFieldμ,K⁡X,WFieldν,L⁡X,d_~mu⁡WField~nu,J⁡X,X−d_~nu⁡WField~mu,J⁡X,X+g__w⁢LeviCivitaJ,M,N⁢`*`⁡WField~mu,M⁡X,WField~nu,N⁡X−14⁢`*`⁡d_μ⁡BFieldν⁡X,X−d_ν⁡BFieldμ⁡X,X,d_~mu⁡BField~nu⁡X,X−d_~nu⁡BField~mu⁡X,X
The L__f term is the kinetic term for the fermions of the model before symmetry breaking, and their interaction with the gauge bosons Wμ,K and Bμis through the covariant derivative. Note that the electron field ej, as well as all the leptons are Dirac spinors that result after symmetry breaking. The quarks are also particles that appear through the symmetry breaking mechanism. So the terms you get expanding the covariant derivatives of the leptons and quarks, e.g.
D_muElectronjX:% = expand%
D_μ⁡Electronj⁡X,X=d_μ⁡Electronj⁡X,X+ⅈ⁢g__e⁢`*`⁡Electronj⁡X,ElectromagneticFieldμ⁡X
D_muUpA,jX:% = expand%
are of no use for constructing the Lagrangian before symmetry breaking. The L__h term involves the Higgs boson before symmetry breaking (here too, the HiggsBoson field implemented in the StandardModel in Maple 2022 is the Higgs after symmetry breaking) and the L__y formulates the Yukawa interaction with the fermions.
After symmetry breaking
For the purpose of computing scattering amplitudes, the formulation of the interaction Lagrangian after symmetry breaking is more relevant; this one is given by
L__EW ≔ L__K+L__N+L__C+L__H+L__HV+L__WWV+L__WWVV+L__Y;
L__EW≔L__K+L__N+L__C+L__H+L__HV+L__WWV+L__WWVV+L__Y;
where we use the notation shown in the Wikipedia page for the weak interaction. As illustration, we compute here the L__K and L__N terms, respectively containing the kinetic terms corresponding to the free fields and the interaction terms between the fermions - leptons and quarks - and the gauge bosons Aμand Zμ.
Following the Wikipedia page mentioned, the kinetic term L__K is given by
L__K ≔ −14ElectromagneticFieldStrengthmu,nu2 − 12WPlusFieldStrengthmu,nu⋅WMinusFieldStrengthmu,nu+12⋅mWField2⋅WPlusFieldmu⋅WMinusFieldmu −14ZFieldStrengthmu,nu2+12mZField2⋅ZFieldmu2+12d_muHiggsBosonX2−mHiggsBoson22⋅HiggsBosonX2 +%addconjugatef__LjX⋅Dgammamu j,k⋅i⋅d_muf__LkX − mf__L⋅f__LjX, f__L = StandardModel:-Leptons1..3 +%addconjugatef__LjX⋅Dgammamu j,k⋅i⋅d_muf__LkX , f__L = StandardModel:-Leptons4..6 +%addconjugatef__QA,jX⋅Dgammamuj,k⋅i⋅d_muf__QA,kX − mf__Q⋅f__QA,jX, f__Q = StandardModel:-Quarks
−14⁢`*`⁡ElectromagneticFieldStrengthμ,ν,ElectromagneticFieldStrength~mu,~nu−12⁢`*`⁡WPlusFieldStrengthμ,ν,WMinusFieldStrength~mu,~nu+12⁢mWField2⁢`*`⁡WPlusFieldμ,WMinusField~mu−14⁢`*`⁡ZFieldStrengthμ,ν,ZFieldStrength~mu,~nu+12⁢mZField2⁢`*`⁡ZFieldμ,ZField~mu+12⁢`*`⁡d_μ⁡HiggsBoson⁡X,X,d_~mu⁡HiggsBoson⁡X,X−12⁢mHiggsBoson2⁢`^`⁡HiggsBoson⁡X,2+%add⁡`*`⁡conjugate⁡f__Lj⁡X,ⅈ⁢d_μ⁡f__Lk⁡X,X⁢Dgamma~muj,k−mf__L⁢f__Lj⁡X,f__L=Electron,Muon,Tauon+%add⁡ⅈ⁢`*`⁡conjugate⁡f__Lj⁡X,d_μ⁡f__Lk⁡X,X⁢Dgamma~muj,k,f__L=ElectronNeutrino,MuonNeutrino,TauonNeutrino+%add⁡`*`⁡conjugate⁡f__QA,j⁡X,ⅈ⁢d_μ⁡f__QA,k⁡X,X⁢Dgamma~muj,k−mf__Q⁢f__QA,j⁡X,f__Q=Up,Charm,Top,Down,Strange,Bottom
The inert sums over the leptons and quarks can be activated using value
−14⁢`*`⁡ElectromagneticFieldStrengthμ,ν,ElectromagneticFieldStrength~mu,~nu−12⁢`*`⁡WPlusFieldStrengthμ,ν,WMinusFieldStrength~mu,~nu+12⁢mWField2⁢`*`⁡WPlusFieldμ,WMinusField~mu−14⁢`*`⁡ZFieldStrengthμ,ν,ZFieldStrength~mu,~nu+12⁢mZField2⁢`*`⁡ZFieldμ,ZField~mu+12⁢`*`⁡d_μ⁡HiggsBoson⁡X,X,d_~mu⁡HiggsBoson⁡X,X−12⁢mHiggsBoson2⁢`^`⁡HiggsBoson⁡X,2+`*`⁡conjugate⁡Electronj⁡X,ⅈ⁢d_μ⁡Electronk⁡X,X⁢Dgamma~muj,k−mElectron⁢Electronj⁡X+`*`⁡conjugate⁡Muonj⁡X,ⅈ⁢d_μ⁡Muonk⁡X,X⁢Dgamma~muj,k−mMuon⁢Muonj⁡X+`*`⁡conjugate⁡Tauonj⁡X,ⅈ⁢d_μ⁡Tauonk⁡X,X⁢Dgamma~muj,k−mTauon⁢Tauonj⁡X+ⅈ⁢`*`⁡conjugate⁡ElectronNeutrinoj⁡X,d_μ⁡ElectronNeutrinok⁡X,X⁢Dgamma~muj,k+ⅈ⁢`*`⁡conjugate⁡MuonNeutrinoj⁡X,d_μ⁡MuonNeutrinok⁡X,X⁢Dgamma~muj,k+ⅈ⁢`*`⁡conjugate⁡TauonNeutrinoj⁡X,d_μ⁡TauonNeutrinok⁡X,X⁢Dgamma~muj,k+`*`⁡conjugate⁡UpA,j⁡X,ⅈ⁢d_μ⁡UpA,k⁡X,X⁢Dgamma~muj,k−mUp⁢UpA,j⁡X+`*`⁡conjugate⁡CharmA,j⁡X,ⅈ⁢d_μ⁡CharmA,k⁡X,X⁢Dgamma~muj,k−mCharm⁢CharmA,j⁡X+`*`⁡conjugate⁡TopA,j⁡X,ⅈ⁢d_μ⁡TopA,k⁡X,X⁢Dgamma~muj,k−mTop⁢TopA,j⁡X+`*`⁡conjugate⁡DownA,j⁡X,ⅈ⁢d_μ⁡DownA,k⁡X,X⁢Dgamma~muj,k−mDown⁢DownA,j⁡X+`*`⁡conjugate⁡StrangeA,j⁡X,ⅈ⁢d_μ⁡StrangeA,k⁡X,X⁢Dgamma~muj,k−mStrange⁢StrangeA,j⁡X+`*`⁡conjugate⁡BottomA,j⁡X,ⅈ⁢d_μ⁡BottomA,k⁡X,X⁢Dgamma~muj,k−mBottom⁢BottomA,j⁡X
Introducing the definition of the field strengths 𝔽μ,ν, WPlusFieldStrengthμ,ν, WMinusFieldStrengthμ,ν and ℤμ,ν
ElectromagneticFieldStrengthdefinition
ElectromagneticFieldStrengthμ,ν=d_μ⁡ElectromagneticFieldν⁡X,X−d_ν⁡ElectromagneticFieldμ⁡X,X
WPlusFieldStrengthdefinition
WPlusFieldStrengthμ,ν=d_μ⁡WPlusFieldν⁡X,X−d_ν⁡WPlusFieldμ⁡X,X
WMinusFieldStrengthdefinition
WMinusFieldStrengthμ,ν=d_μ⁡WMinusFieldν⁡X,X−d_ν⁡WMinusFieldμ⁡X,X
ZFieldStrengthdefinition
ZFieldStrengthμ,ν=d_μ⁡ZFieldν⁡X,X−d_ν⁡ZFieldμ⁡X,X
L__K ≔ SubstituteTensor,,,,
−14⁢`*`⁡d_μ⁡ElectromagneticFieldν⁡X,X−d_ν⁡ElectromagneticFieldμ⁡X,X,d_~mu⁡ElectromagneticField~nu⁡X,X−d_~nu⁡ElectromagneticField~mu⁡X,X−12⁢`*`⁡d_μ⁡WPlusFieldν⁡X,X−d_ν⁡WPlusFieldμ⁡X,X,d_~mu⁡WMinusField~nu⁡X,X−d_~nu⁡WMinusField~mu⁡X,X+12⁢mWField2⁢`*`⁡WPlusFieldμ,WMinusField~mu−14⁢`*`⁡d_μ⁡ZFieldν⁡X,X−d_ν⁡ZFieldμ⁡X,X,d_~mu⁡ZField~nu⁡X,X−d_~nu⁡ZField~mu⁡X,X+12⁢mZField2⁢`*`⁡ZFieldμ,ZField~mu+12⁢`*`⁡d_μ⁡HiggsBoson⁡X,X,d_~mu⁡HiggsBoson⁡X,X−12⁢mHiggsBoson2⁢`^`⁡HiggsBoson⁡X,2+`*`⁡conjugate⁡Electronj⁡X,ⅈ⁢d_μ⁡Electronk⁡X,X⁢Dgamma~muj,k−mElectron⁢Electronj⁡X+`*`⁡conjugate⁡Muonj⁡X,ⅈ⁢d_μ⁡Muonk⁡X,X⁢Dgamma~muj,k−mMuon⁢Muonj⁡X+`*`⁡conjugate⁡Tauonj⁡X,ⅈ⁢d_μ⁡Tauonk⁡X,X⁢Dgamma~muj,k−mTauon⁢Tauonj⁡X+ⅈ⁢`*`⁡conjugate⁡ElectronNeutrinoj⁡X,d_μ⁡ElectronNeutrinok⁡X,X⁢Dgamma~muj,k+ⅈ⁢`*`⁡conjugate⁡MuonNeutrinoj⁡X,d_μ⁡MuonNeutrinok⁡X,X⁢Dgamma~muj,k+ⅈ⁢`*`⁡conjugate⁡TauonNeutrinoj⁡X,d_μ⁡TauonNeutrinok⁡X,X⁢Dgamma~muj,k+`*`⁡conjugate⁡UpA,j⁡X,ⅈ⁢d_μ⁡UpA,k⁡X,X⁢Dgamma~muj,k−mUp⁢UpA,j⁡X+`*`⁡conjugate⁡CharmA,j⁡X,ⅈ⁢d_μ⁡CharmA,k⁡X,X⁢Dgamma~muj,k−mCharm⁢CharmA,j⁡X+`*`⁡conjugate⁡TopA,j⁡X,ⅈ⁢d_μ⁡TopA,k⁡X,X⁢Dgamma~muj,k−mTop⁢TopA,j⁡X+`*`⁡conjugate⁡DownA,j⁡X,ⅈ⁢d_μ⁡DownA,k⁡X,X⁢Dgamma~muj,k−mDown⁢DownA,j⁡X+`*`⁡conjugate⁡StrangeA,j⁡X,ⅈ⁢d_μ⁡StrangeA,k⁡X,X⁢Dgamma~muj,k−mStrange⁢StrangeA,j⁡X+`*`⁡conjugate⁡BottomA,j⁡X,ⅈ⁢d_μ⁡BottomA,k⁡X,X⁢Dgamma~muj,k−mBottom⁢BottomA,j⁡X
The neutral current Lagrangian containing the interactions between fermions and the gauge bosons Aμand Zμ is expressed in terms of the electromagnetic and weak currents J__E, μ and J__W,μ as
L__N ≔g__e⋅ JE, μ⋅ElectromagneticFieldμX + g__wcosWeinbergAngle⋅JW,mu − sinWeinbergAngle2⋅JE,mu⋅ZFieldmuX
g__e⁢JE,μ⁢ElectromagneticFieldμ⁡X+g__w⁢JW,μ−sin⁡WeinbergAngle2⁢JE,μ⁢ZFieldμ⁡Xcos⁡WeinbergAngle
In turn, these currents are expressed as
JE,μ ≔ %q__e⋅Dgammamuk, j⋅%addconjugatef__LkX⋅f__LjX,f__L=Electron, Muon, Tauon +%q__u⋅Dgammamuk, j⋅%addconjugatef__QA,kX⋅f__QA,jX,f__Q=Up,Charm,Top +%q__d⋅Dgammamuk, j⋅%addconjugatef__QA,kX⋅f__QA,jX,f__Q=Down,Strange,Bottom
%q__e⁢Dgammaμk,j⁢%add⁡`*`⁡conjugate⁡f__Lk⁡X,f__Lj⁡X,f__L=Electron,Muon,Tauon+%q__u⁢Dgammaμk,j⁢%add⁡`*`⁡conjugate⁡f__QA,k⁡X,f__QA,j⁡X,f__Q=Up,Charm,Top+%q__d⁢Dgammaμk,j⁢%add⁡`*`⁡conjugate⁡f__QA,k⁡X,f__QA,j⁡X,f__Q=Down,Strange,Bottom
To activate only the sum over the different kinds of fermions,
JE,mu ≔eval,%add = add
%q__e⁢Dgammaμk,j⁢`*`⁡conjugate⁡Electronk⁡X,Electronj⁡X+`*`⁡conjugate⁡Muonk⁡X,Muonj⁡X+`*`⁡conjugate⁡Tauonk⁡X,Tauonj⁡X+%q__u⁢Dgammaμk,j⁢`*`⁡conjugate⁡UpA,k⁡X,UpA,j⁡X+`*`⁡conjugate⁡CharmA,k⁡X,CharmA,j⁡X+`*`⁡conjugate⁡TopA,k⁡X,TopA,j⁡X+%q__d⁢Dgammaμk,j⁢`*`⁡conjugate⁡DownA,k⁡X,DownA,j⁡X+`*`⁡conjugate⁡StrangeA,k⁡X,StrangeA,j⁡X+`*`⁡conjugate⁡BottomA,k⁡X,BottomA,j⁡X
To activate the sums and also the inert representations of the different charges you can use the value command
JE,mu ≔ value
−Dgammaμk,j⁢`*`⁡conjugate⁡Electronk⁡X,Electronj⁡X+`*`⁡conjugate⁡Muonk⁡X,Muonj⁡X+`*`⁡conjugate⁡Tauonk⁡X,Tauonj⁡X+23⁢Dgammaμk,j⁢`*`⁡conjugate⁡UpA,k⁡X,UpA,j⁡X+`*`⁡conjugate⁡CharmA,k⁡X,CharmA,j⁡X+`*`⁡conjugate⁡TopA,k⁡X,TopA,j⁡X−13⁢Dgammaμk,j⁢`*`⁡conjugate⁡DownA,k⁡X,DownA,j⁡X+`*`⁡conjugate⁡StrangeA,k⁡X,StrangeA,j⁡X+`*`⁡conjugate⁡BottomA,k⁡X,BottomA,j⁡X
For the weak current, from the Wikipedia reference mentioned,
JW,μ ≔ Dgammamuk, j⋅KroneckerDeltaj,l−Dgamma5j,l⋅%I__e⋅%addconjugatef__LkX⋅f__LlX,f__L=StandardModel:-Leptons1..3 +%I__n⋅%addconjugatef__LkX⋅f__LlX,f__L=StandardModel:-Leptons4..6 +%I__u⋅%addconjugatef__QA,kX⋅f__QA,lX,f__Q=StandardModel:-Quarks1..3 +%I__d⋅%addconjugatef__QA,kX⋅f__QA,lX,f__Q=StandardModel:-Quarks4..6
Dgammaμk,j⁢KroneckerDeltaj,l−Dgamma5j,l⁢%I__e⁢%add⁡`*`⁡conjugate⁡f__Lk⁡X,f__Ll⁡X,f__L=Electron,Muon,Tauon+%I__n⁢%add⁡`*`⁡conjugate⁡f__Lk⁡X,f__Ll⁡X,f__L=ElectronNeutrino,MuonNeutrino,TauonNeutrino+%I__u⁢%add⁡`*`⁡conjugate⁡f__QA,k⁡X,f__QA,l⁡X,f__Q=Up,Charm,Top+%I__d⁢%add⁡`*`⁡conjugate⁡f__QA,k⁡X,f__QA,l⁡X,f__Q=Down,Strange,Bottom
To activate only the sums,
JW,μ ≔ eval,%add = add
Dgammaμk,j⁢KroneckerDeltaj,l−Dgamma5j,l⁢%I__e⁢`*`⁡conjugate⁡Electronk⁡X,Electronl⁡X+`*`⁡conjugate⁡Muonk⁡X,Muonl⁡X+`*`⁡conjugate⁡Tauonk⁡X,Tauonl⁡X+%I__n⁢`*`⁡conjugate⁡ElectronNeutrinok⁡X,ElectronNeutrinol⁡X+`*`⁡conjugate⁡MuonNeutrinok⁡X,MuonNeutrinol⁡X+`*`⁡conjugate⁡TauonNeutrinok⁡X,TauonNeutrinol⁡X+%I__u⁢`*`⁡conjugate⁡UpA,k⁡X,UpA,l⁡X+`*`⁡conjugate⁡CharmA,k⁡X,CharmA,l⁡X+`*`⁡conjugate⁡TopA,k⁡X,TopA,l⁡X