Questions tagged [feyncalc]

Questions about Mathematica packages for High Energy Physics and Quantum Field Theory, e.g. FeynCalc, FeynArts, FormCalc, FeynRules, HEPMath, Package-X, LoopTools, Tracer etc.

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Out put of FeynCalc is not symbolic

When I run, for example: LC[$\alpha$, $\beta$, $\mu$, $\nu$] MT[$\mu$, $\nu$] the out put is LC[$\alpha$, $\beta$, $\mu$, $\nu$] MT[$\mu$, $\nu$] rather than $\varepsilon_{\alpha \beta \mu \nu}g_{\mu\...
João Paulo Melo's user avatar
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How to convert xAct output to FeynCalc input?

For the packages xAct and Feyncalc, is there a way to convert xAct output into Feyncalc input? I have an expression of one rank and four rank tensors as an output from xAct. The number of terms is ...
NovoGrav's user avatar
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How to change FeynArts Paint style settings?

I'm a Mathematica stylesheet enthusiast. I love using beautiful stylesheet instead of the default one, such as Dracular. I'm also a physics researcher on scattering amplitudes, which forces me to use ...
Handger's user avatar
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How to output TeX with FeynArts?

I've recently installed FeynArts since I can use mathematica to generate topologies and it comes with a set of commands to make diagrams in LaTeX. However, nowhere in the manual can I find a command ...
Guy's user avatar
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FeynCalc Phi4 example error with FeynRules

I'm starting on FeynCalc and was trying to run through a few examples coming with the package. For the ones of which the models are generated by FeynRules, it doesn't work out well. (When the model is ...
khaki's user avatar
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FeynCalc error: FeynCalc`ComplexConjugate`Private`diracChainCC?

I am trying to evaluate an amplitude. It is an electron-positron annihilation into $W^{-}W^{+}$ bosons. I am only considering the channel for a photon mediator, that is, $e^{-}e^{+} \rightarrow \gamma ...
Jacinto Paulo's user avatar
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92 views

Problems in generating example models of FeynCalc

I'm getting started with FeynCalc and FeynArts, so I tried to run some of the examples they give you. Everything works fine, except for the ones which require to generate a model using the scripts in ...
Andrea Filippo Beretta's user avatar
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LiteRed Package for Feynman Integral

<< LiteRed`(Loading the package) SetDirectory[NotebookDirectory[]] SetDim[d]; These commands I am using to load the package 1.83 LiteRed. Though, it is prompting as cannot open LiteRed. Any ...
NovoGrav's user avatar
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Simplification of Momentums in FeynCalc

I have a little problem involving the following contraction in FeynCalc: $$\frac{k^{\delta}k^{\sigma}}{k^2}$$ By hand one would lower $\sigma$ and contract with the other momentum to cancel $k^2$, ...
bocchi's user avatar
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FeynCalc Kronecker delta contraction

I want to simplify some expressions like a[i]*b[i]*KD[i,j]. After contraction, it should be a[j]*b[j], but it seems that FeynCalc cannot handle more than 3 of the same CartesianIndices. I know for ...
Mirai's user avatar
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Working with Vertex Functions in FeynArts

FeynArts supports in its current version 3.11 the use of vertex functions in Feynman diagrams. As described in the manual, one can create topologies with generic vertex functions using the function <...
maximumphysics's user avatar
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1 answer
106 views

How can I use FeynCalc in ParallelTable or ParallelSum?

I want to speed up a FeynCalc calculation. However I found out that it doesn't seem to work in ParallelSum or ParallelTable. MWE:...
infinitezero's user avatar
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Hermitian Adjoint of Gamma matrices in FeynCalc

I expected the following code: GA[0] . ConjugateTranspose[GA[μ]] . GA[0] to return GA[μ], since it's a fundamental property of ...
SciJewel's user avatar
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Feynman Rules in FeynCalc

I am trying to find the feynman rules with FeynCalc Package. K1 and K2 are the mésons $K^+$ and $K^-$ ...
Andre Luiz MB's user avatar
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2 answers
1k views

Package-X has been terminated. FeynCalc and FeynHelpers not working

I want to compute the finite parts of 1-loop integrals using FeynCalc. One of the most important package used for this is FeynHelpers (which in it uses Package-X). But, since July 1, 2022, Package-X ...
jar-'s user avatar
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How do I NOT reduce loop integrals to one-point in FeynCalc?

So I am doing a box integral, the amplitudes look like this: I do the loop integration of it using the following code: ...
avocado_love's user avatar
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1 answer
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What does the command '$FAVerbose = 0' do in FeynCalc

I have seen this right below the "<<FeynCalc`" command that loads FeynCalc. $LoadAddOns={"FeynArts"}; <<FeynCalc; ...
chicago.physicist's user avatar
2 votes
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103 views

Field derivatives in FeynCalc

I am using the latest version of both Mathematica and FeynCalc. I'm trying to obtain the Feynman rules for a theory with derivative interactions. Following https://www.feyncalc.org/FeynCalcBook/...
johnny's user avatar
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FeynCalc Commutator of Matrices

I am trying to learn how to use FeynCalc to handle commutators in Mathematica, but I can't seem to figure out how to take the commutator of two matrices with entries made up of products non-commuting ...
John Smith's user avatar
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Can FeynCalc be used for Heavy quark effective field?

I start to learn FeynCalc. I want to use it for Heavy quark field theory. For example, extract the vertices from Eq.(34) from paper 1901.10339. Since I am not good at FeynCalc, so I want to know ...
zephyrus's user avatar
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307 views

Exclusion of particular vertices in FeynArts

I am trying to generate diagrams for H -> ZZ process at one loop level. I only want these 5 diagrams in the final output given by (T1 P1 N1), (T1 P2 N2), (T8 P1 N12), (T9 P1 N14), (T10 P1 N16) ...
mandeep kaur's user avatar
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1 answer
459 views

Feynrules + FeynArts - Calculating amplitudes

I am working on a model which is an extended model of the standard model (SM + Complex Scalar Field). I am using FeynCalc (9.0.3) patched with FeynArts (3.11). I run ...
João Viana's user avatar
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1 answer
633 views

How to Contract Indices Using Feyncalc

I am slowly learning how to use Feyncalc, and I have a quick question. I have a third rank tensor B[mu,nu,tao] and I also have a four-vector FV[W,mu]. I would like to contract the first two indices ...
Andrew Hyman's user avatar
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321 views

Easiest way to export amplitude from FeynArts to FeynCalc

I am having trouble calculating some unpolarized squared amplitudes with FeynArts+FormCalc and want to use FeynCalc to manually handle the amplitudes calculated by FeynArts. What is the easiest way to ...
GaloisFan's user avatar
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Apply Formula automatically in Feyncalc

I want to apply the function Tdec in Feyncalc automatically. Here is an example what the input is: ...
NeAr's user avatar
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1 answer
272 views

FermionSpinSum in FeynCalc

I have to evaluate the spin chains as described in the following PSE question. To that end, in FeynCalc, I have done the following: ...
GaloisFan's user avatar
  • 395
2 votes
1 answer
195 views

Tensor Algebra Problem

I am just getting started with tensor algebra using Mathematica. I could use some help with a simple problem I am starting with at my website: http://www.tifis.org/mathematicaproblem.pdf An ...
Andrew Hyman's user avatar
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139 views

Feyncalc Chain re-ordering problem

I am encountering a similar problem with much more complex terms than the ones shown in the figures below. Basically, I wrote the chain for a process(in this case, a simple 2 particle scattering in ...
Lelouch's user avatar
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1 answer
193 views

Visual (apparently) bug with ComplexConjugate in FeynCalc

When I use ComplexConjugate in Feyncalc, if there are repeated indices in its argument, a visual bug occurs. The most minimal example would be: ...
GaloisFan's user avatar
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127 views

Dirac Operator in de Sitter background

I am attempting to write the Dirac operator in a curved background, and eventually solve the equation as a second order PDE, since I am attempting to bring it into Klein-Gordon form. Essentially what ...
lastgunslinger's user avatar
1 vote
1 answer
790 views

How much can we trust NIntegrate when NIntegrate::eincr is shown?

I have been dealing with a high oscillation integration using NIntegrate. The warning of eincr shows that no matter how large (X)...
ParlorPink's user avatar
1 vote
0 answers
77 views

How solve integral with three moment and delta function [closed]

I am trying solve this integral in mathematica: \begin{equation} \int \dfrac{d^3 p_3}{(2\pi)^3 2 E_3} \dfrac{d^3 p_4}{(2\pi)^3 2 E_4}(p_1 p_2)(p_3 p_4) \delta (p_3 + p_4 - p_1 - p_2). \end{equation} ...
V.Oliveira's user avatar
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69 views

How to properly evaluate a Green's equation in FeynCalc (or any other package)?

In 4D, the Green's function of the box operator with respect to $p$ is $1/p^2$,i.e. $$\partial_p^2 \frac{1}{p^2} = -(2\pi)^2 \delta^{(4)}(p). \tag{1}$$ I use the package FeynCalc, in which the ...
Pxx's user avatar
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1 vote
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377 views

Calculating Amplitudes with FeynArts

I'm following a lecture on how to use FeynCalc, FeynArts, I have done exactly what they say to me to do. Everything was going ok until that point. FeynArts is not calculating amplitudes, error message ...
IamZack's user avatar
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1 vote
0 answers
107 views

Feyncalc : problem with diracreduce/diracsimplify. BUG?

I am new to Feyncalc and I am facing the following problem. I am doing the following: I set q3=-q2-q1; Then I write ...
gekatsia's user avatar
1 vote
1 answer
227 views

How to evaluate an expression with FeynCalc?

How can I evaluate specific expressions in FeynCalc? For example, if there is a $\delta^i_j$, how can I set $i$ to 1 and $j$ to 2 and make it evaluate to zero? I've tried ...
ersbygre1's user avatar
  • 225
5 votes
1 answer
2k views

Distinguish FeynRules, FeynCalc, FeynArts, FormCalc and LoopTools

I am totally confused: I can't distinguish the packages FeynRules, FeynCalc, FeynArts, FormCalc, LoopTools properly. Once I installed FeynRules I think. It seems to include the packages FeynCalc and ...
Kathi's user avatar
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1 vote
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168 views

FeynArts is not plotting Propagator labels/fields

I am trying to use FeynArts to generate two feynman diagrams (one for electron scattering, and one for higgs->bb w/ VGF). On the first I can't seem to figure out how to get labels or arrows, not get ...
Silas K Grossberndt's user avatar
1 vote
0 answers
128 views

Need to use FeynArts to determine Feynman diagrams of a process with initial particles having no masses

so i'm facing this problem in using FeynArts, i need to find the feynman diagrams of a process with intial particles not having masses, but i can't find the command to use to declare particles as ...
user65351's user avatar
1 vote
1 answer
466 views

Cannot Install FormCalc on Linux

so i tried to install FormCalc on linux and when i run the compile command i get "cannot determine mathematica's system ID using_/usr/local/bin/math" Has anyone encountered such error and is there a ...
user65263's user avatar
1 vote
0 answers
123 views

Simplify GA[a].GA[b]+GA[b].GA[a] to 2 MT[a,b]

Does a FeynCalc command exist, that simplifies the expression GA[a].GA[b]+GA[b].GA[a] to 2 MT[a,b] I've tried Calc, ...
infinitezero's user avatar
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0 votes
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113 views

Why does Null appear in Contract and Pair commands of FeynCalc?

I started now to use FeynCalc on Mathematica 10. The installation looks like okay, but every time I use Contract or Pair commands the output is something with "Null". Even in this simple case, for a ...
Dyana Duarte's user avatar
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245 views

FeynCalc example — muon decay — integration issue

I'm just starting out using Mathematica and I'm trying to work through one of the examples given for FeynCalc, specifically the muon decay: https://github.com/FeynCalc/feyncalc/blob/master/FeynCalc/...
N Solomons's user avatar
2 votes
1 answer
526 views

FeynCalc: FermionSpinSum problems with interference of diagrams

I encountered a problem in FeynCalc, where i wanted to calculate the $\sum_\text{spins}|\mathcal{M}|^2$ of a process and therefore need the function FermionSpinSum[ ] of FeynCalc. I run: ...
DomDoe's user avatar
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1 vote
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Abstract derivatives in Feyncalc

I have encountered several problems regarding the application of formal derivative operators in FeynCalc, using the built-in function FCPartialD, Left/RightPartialD Schematic description of my ...
TheDude's user avatar
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1 vote
0 answers
51 views

How to represent Dirac matrices in general $n$ dimensions in mathematica? [duplicate]

I want to represent Dirac matrices in $N$ dimensions in Mathematica like we have for the Pauli matrices, i.e. PauliMatrix[i], {i,1,3} I guess there must be some ...
Weicheng Ye's user avatar
2 votes
0 answers
171 views

Antiparticles in Feynrules Lagrangian

I am trying to implement a simple extension of the SM to Feynrules, generating the Lagrangian in a Mathematica notebook file. I am wondering about the following: Is there a way to explicitly use the ...
UFO.newbie's user avatar
1 vote
0 answers
228 views

Summation over gamma matrices in a spin connection with FeynCalc

I need to construct the following object $\Gamma_{\mu} = \frac{1}{8} \omega_{\mu}^{ab}[\gamma_{a},\gamma_{b}]$ where $\omega_{\mu}^{ab}$ is object with space-time index $\mu$ and vierbeins index $a, ...
Kamog's user avatar
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1 vote
1 answer
970 views

Solving the Dirac equation in an arbitrary metric [closed]

I want to solve Dirac equation in a metric like $ds^2=g(u,v)\,du\,dv$. The relations of $u$ and $v$ with Minkowski coordinates $t$ and $x$ are given by functions $A$ and $B$, $t=A(u,v)$ and $x=B(u,v)$....
aber's user avatar
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1 vote
1 answer
1k views

Working with Dirac Gamma Matrices using FeynCalc - A simple problem

I need to obtain this using package FeynCalc: $$ \begin{align} [\gamma_{0},\gamma_{i}]=& 2 \gamma_{0}\gamma_{i}, \\ [\gamma_{i},\gamma_{0}]=& 2 \gamma_{i}\gamma_{0} , \\ [\gamma_{0},\gamma_{...
Kamog's user avatar
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