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.

Filter by
Sorted by
Tagged with
0 votes
0 answers
37 views

Kaon Photoproduction Reaction for FeynArts

I'm trying insert this kaon photoproduction into FeynArts (photon and proton to kaon+ and hyperon lambda): any idea how to build this feynman diagram?
0 votes
0 answers
34 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 ...
1 vote
0 answers
308 views

How long does it take to load FormCalc package?

I've installed the package (FeynArts, LoopTools, and FormCalc) via FeynInstall. Then, I load the package by <<FeynArts` <<FormCalc` I get message <...
0 votes
0 answers
23 views

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 ...
0 votes
2 answers
106 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 ...
0 votes
0 answers
42 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 ...
0 votes
1 answer
71 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 ...
0 votes
1 answer
61 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 vote
0 answers
136 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 ...
1 vote
0 answers
85 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
111 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 ...
1 vote
1 answer
490 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 ...
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 ...
1 vote
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 ...
1 vote
0 answers
507 views

Is there a method in FeynCalc for collecting like powers of four vectors?

If I have a polynomial in some momentum $l^{\mu}$ such as $(q_1+l)^{\mu_1}(q_2+l)^{\mu_2}(q_3+l)^{\mu_3}...(q_n+l)^{\mu_n}$ in the numerator of an integral with measure $d^Dl$, is it possible to ...
1 vote
0 answers
84 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 ...
0 votes
0 answers
108 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 vote
3 answers
2k views

Can I specify the components of FourVector in FeynCalc?

I'm using FeynCalc to calculate Compton's scattering. I need to use specific values for the components of the photon polarization four-vector. How can I do that?
1 vote
1 answer
235 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 ...
1 vote
1 answer
121 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 vote
0 answers
132 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 ...
1 vote
0 answers
76 views

Feynman Rules in FeynCalc

I am trying to find the feynman rules with FeynCalc Package. K1 and K2 are the mésons $K^+$ and $K^-$ ...
0 votes
1 answer
133 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
138 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
113 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/...
0 votes
1 answer
495 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 ...
0 votes
1 answer
251 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 ...
1 vote
3 answers
721 views

Replace on FeynCalc

I can do replacements easily using /. p = {1, 2, 3}; //in input = 4 Overscript[p, _]^2 /. {Overscript[x_, _]^2 -> x.x} //in 56 //Out However, using the same ...
1 vote
0 answers
345 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) ...
0 votes
1 answer
722 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 ...
0 votes
0 answers
365 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 ...
1 vote
0 answers
79 views

Apply Formula automatically in Feyncalc

I want to apply the function Tdec in Feyncalc automatically. Here is an example what the input is: ...
0 votes
1 answer
315 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: ...
1 vote
1 answer
663 views

FeynCalc does not simplify Spinor relations

Is there a reason why sometimes FeynCalc does not simplify expressions that looks very simple like $$\bar{u}^s(p,m).u^s(p,m). $$ This does not happen all the time, eg. if I simply input ...
2 votes
1 answer
204 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 ...
0 votes
1 answer
478 views

How to set gauge in FeynCalc?

I want to set gauge in all of my calculation with FeynArts and FeynCalc to $\xi$ gauge. I use $Gauge=ξ but it does not work. How to change gauge in these packages?...
0 votes
0 answers
147 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 ...
1 vote
1 answer
144 views

Unexpected result when evaluating DiracGamma[5]

ComplexConjugate[DiracGamma[5]] // StandardForm returns -DiracGamma[5] Instead of simply ...
0 votes
1 answer
207 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: ...
1 vote
0 answers
129 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 ...
1 vote
1 answer
836 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)...
0 votes
2 answers
855 views

Implementing four-fermions operators on FeynRules and FeynArts

I am trying to implement operators of the form $$ \bar{q}_L \gamma^\mu T^A q_L \bar{q}_L \gamma_\mu T^A q_L $$ where T^A are the SU(3) generators and $q_L$ is the Electroweak SU(2) doublet. I use ...
1 vote
0 answers
78 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} ...
0 votes
0 answers
70 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 ...
1 vote
0 answers
387 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 ...
1 vote
0 answers
116 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 ...
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 ...
1 vote
0 answers
181 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
138 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 ...
1 vote
0 answers
136 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, ...