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.
101
questions
-1
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0
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39
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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\...
0
votes
0
answers
33
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 ...
- 29
0
votes
1
answer
57
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 ...
- 19
1
vote
0
answers
108
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 ...
- 285
0
votes
1
answer
67
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 ...
- 21
1
vote
0
answers
73
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 ...
1
vote
0
answers
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 ...
0
votes
0
answers
55
views
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 ...
- 29
0
votes
0
answers
91
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 $k^2$, ...
- 1
0
votes
1
answer
57
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 ...
- 1
0
votes
0
answers
72
views
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 <...
1
vote
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:...
- 1,357
1
vote
0
answers
108
views
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 ...
- 331
1
vote
0
answers
73
views
Feynman Rules in FeynCalc
I am trying to find the feynman rules with FeynCalc Package. K1 and K2 are the mésons $K^+$ and $K^-$
...
- 163
0
votes
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 ...
- 55
0
votes
1
answer
117
views
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:
...
2
votes
1
answer
124
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;
...
2
votes
0
answers
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/...
- 165
0
votes
1
answer
240
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 ...
- 21
1
vote
0
answers
81
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 ...
- 31
1
vote
0
answers
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) ...
- 11
0
votes
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 ...
- 31
0
votes
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 ...
- 23
0
votes
0
answers
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 ...
- 395
1
vote
0
answers
72
views
Apply Formula automatically in Feyncalc
I want to apply the function Tdec in Feyncalc automatically. Here is an example what the input is:
...
- 235
0
votes
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:
...
- 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 ...
- 23
0
votes
0
answers
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 ...
- 237
0
votes
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:
...
- 395
1
vote
0
answers
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 ...
- 113
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)...
- 11
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}
...
- 11
0
votes
0
answers
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 ...
- 691
1
vote
0
answers
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 ...
- 113
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
...
- 11
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
...
- 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 ...
- 53
1
vote
0
answers
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 ...
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 ...
- 11
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 ...
- 11
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, ...
- 1,357
0
votes
0
answers
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 ...
0
votes
0
answers
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/...
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:
...
- 185
1
vote
0
answers
182
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 ...
- 11
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 ...
- 11
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 ...
- 21
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, ...
- 133
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 $x=B(u,v)$....
- 19
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_{...
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