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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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/...
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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 ...
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Quits Kernel during evaluation of CreateTopologies

I am using Feynarts 3.9 and FeynCalc 9.0.1 with Mathematica 10. Every time I load FeynArts with FeynCalc and execute t = CreateTopologies[1, 1 -> 2]; ...
Heerak Banerjee's user avatar
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Trace of gamma matrices using FeynCalc

I am using FeynCalc package in Mathematica to evaluate some complicated Dirac Traces, but as you know the default convention for the anticommutator of two Gamma matrices in this package is $$\{\gamma^...
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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 ...
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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 ...
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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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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 ...
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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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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 ...
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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) ...
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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: ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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, ...
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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 ...
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FeynArts: how to generate all the Feynman graphs for a given order of perturbation theory?

I am totally new to FeynArts Mathematica package and I am wondering if there is an opportunity to generate all (connected) Feynman graphs for a given order of perturbation theory? What I really want ...
Margarita's user avatar
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Inserting Lorentz vectors in Lagrangian in FeynRules

I am writing the model file for an effective theory. The lagrangian of the theory has an external physical lorentz vector (say velocity in Heavy Quark Effective Theory where the Kinetic part is $\bar\...
Abhishek Pal's user avatar
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309 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 <...
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Now why LoopTools do not make calculation

In deed I still in calculating the self energy diagram I started in this post Why FormCalc gives zero amplitude for this process Here is the code I use after the last answer ...
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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?
Albert Copperfield's user avatar
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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 ...
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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 ...
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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 ...
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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 ...
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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 $k^2$, ...
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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 ...
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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 ...
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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 ...
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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 ...
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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/...
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FeynCalc Notebook does not run

I've been trying to run an example of Chiral perturbation theory calculation. The notebook is from the site here. Every time I run the notebook, the InsertFields command throws up an error the says <...
Shastry's user avatar
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Question for FeynRules: How to implement velocity dependent coupling

I am working with an extension of Standard Model which includes a fermionic field for the magnetic monopole. The photon-monopole coupling is velocity (beta = sqrt{1 - 4*monopoleMass^2/(s^2)} where ...
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Selecting few arrays from a list and displaying their content

I am using FeynHiggs package on Mathematica 11 to calculate fermion masses in MSSM. Function FHGetPara[] returns a list that ...
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How to use Neglect function in FormCalc?

I am trying to calculate amplitude from Feynman diagram with FormCalc package and I want to set mass of external particle to be zero which I found that I have to use "Neglect". However, I can't find ...
NaC's user avatar
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Expressing the output product using dot

I have an expression of the form Hbar.H where H and Hbar are vectors. How can I get the ...
Abhishek Pal's user avatar
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1 answer
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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 ...
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