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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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How to simplify the results of squared amplitude calculations in FeynCalc?

I want to calculate the squared amplitude of the Feynman diagram of double-pion photoproduction using FeynCalc package. Here is the code I created: ...
Albert Copperfield's user avatar
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49 views

Feyncalc computations using parallel computing (multicore computing)?

I'm doing very long computations with FeynCalc (they're dimensional regularizations of diagrams with a lot of D-dimensional metric and D-dimensional momentum contractions like Contract[ MTD[$\alpha,\...
adlc's user avatar
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FeynCalc TID PaVeLimitTo4 option leads to divergence

I'm trying to compute the Higgs to gluon pair decay at 1-loop using Feyncalc and FeynHelper (to connect with Package-X). I first define variables and loop part as: ...
Isaac Wang's user avatar
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36 views

The mcc command generated program segfaults

I am trying to get FormCalc to work with FeynArts, the only problem is that the ReadForm program that is required for FormCalc to work compiles fine but segfaults... I am using Mathematica 14, should ...
user15032639's user avatar
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In Feyncalc what is the purpose of DiracChainEvalSign and why does FCFAconvert fail if it is present?

I have run into this issue and I am not sure how to proceed, I cannot find where DiracChainEvalSign enters into diracObjectsEval which triggers the error in the library source code (see here). Any ...
user15032639's user avatar
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50 views

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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1 answer
81 views

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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161 views

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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2 answers
135 views

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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94 views

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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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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131 views

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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1 answer
65 views

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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1 answer
137 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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1 vote
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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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2 votes
0 answers
80 views

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
2 votes
2 answers
2k 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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1 answer
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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
2 votes
1 answer
148 views

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
0 answers
118 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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1 answer
266 views

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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87 views

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
1 vote
0 answers
374 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
534 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
0 votes
1 answer
805 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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0 answers
395 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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1 vote
0 answers
82 views

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
  • 285
0 votes
1 answer
364 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
  • 405
2 votes
1 answer
219 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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0 answers
160 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
223 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
  • 405
1 vote
0 answers
130 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
863 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
82 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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0 answers
73 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
0 answers
400 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
125 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
256 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
7 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
0 answers
186 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
145 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
518 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
148 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
0 answers
129 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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0 answers
263 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
587 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
0 answers
196 views

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
52 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
184 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
241 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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