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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.

103 questions
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Using ModelMaker.m in FeynArts

I want to write a model file in FeynArts and I came across ModelMaker which takes in the Lagrangian as Input and then generates the .mod file. I am trying to make a model file for $\phi^4$ theory as a start. I have a couple of questions as I cannot…
Abhishek Pal
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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: TESTM = SpinorUBar[l,…
DomDoe
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FeynCalc capability in Beyond Standard Model

Few days ago I started to learn FeynCalc, but it seemed to me that it has not capability of handling new models, thus I quit. It seemed that it just loads some predefined Lagrangians. My questions are: Can I define an arbitrary Lagrangian with…
javad
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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: FCClearScalarProducts[]; SP[k1, k1] = 0; SP[k2, k2] = 0; SP[q, q] = mH^2; SP[k1, q] =…
Isaac Wang
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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 FeynRules. They all give me the following error…
Andrea Filippo Beretta
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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 whether it can be used to Heavy quark field theory. If…
zephyrus
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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) given in the following FeynArts diagrams output. Can…
mandeep kaur
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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: (GAD[x].FVD[k, x] + \[Omega]* GAD[x].FVD[v, x]).(GAD[y].FVD[k, y] + \[Omega]* GAD[y].FVD[v, y]) // ExpandScalarProduct //…
NeAr
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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 says I did not pass a FeynAmpList object, but…
IamZack
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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 Pair[LorentzIndex[k], Momentum[q3]] - (-Pair[LorentzIndex[k], Momentum[q2]] - Pair[LorentzIndex[k], Momentum[q1]])) //…
gekatsia
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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 TR[GA[µ,v]] /. {µ -> 1, v -> 2} but that does not work, it just yields…
ersbygre1
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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 being massless. Is there such a command for the…
user65351
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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 way to fix it ?
user65263
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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, DiracSimplify and DiracTrick to no avail. If not, how can I do it with vanilla Mathematica? edit for clarification…
infinitezero
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V particle appearing in FeynArts/FeynCalc

I have the following problem. I am using Feynarts. I am running the following code: I am using QEDOnly. topologies2 = CreateTopologies[0, 2 -> 2, Adjacencies -> {3}, ExcludeTopologies -> {Tadpoles}]; AA3 = InsertFields[ topologies2, {F[2, {1}],…
David Espinoza
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