Implementing chiral EFTs in FeynCalc

[AlexLong152]

Hello, I am interested in implementing diagrams such as the one below which shows pion scattering off of two nucleons.
Are there any examples that implement something like this? Any recommendations on how to do this, and other similar diagrams?

[vsht]

Hi,

well, you certainly could use QGRAF to implement your model and generate your diagrams

https://feyncalc.github.io/FeynHelpersBookDev/Extra/QGRAFUsageExamples.html

Whether the output can be conveniently calculated using FeynCalc is of course a totally different question.
Apart from that, I have no recommendations or pointers to similar projects.

[AlexLong152]

Thank you for pointing out QGRAF to me, I didn't know that existed.

I am attempting to calculate Pion-Pion scattering in chiral perturbation theory. The Feynman rules for this theory can be found in appendix A of this pdf: https://arxiv.org/abs/hep-ph/9501384v1.

Do you have any recommendations on how to proceed with this? The learning curve seems rather steep.

[vsht]

> > Do you have any recommendations on how to proceed with this? The > learning curve seems rather steep. >

QGRAF is pretty much the only way to get the generation of such nonstandard diagrams automated, so learning how to use is a valuable investment that will pay off in many ways. BTW, it's also the standard tool for almost all multiloop calculations. The model itself should be pretty easy to implement since you don't need to specify any Feynman rules at that point. Inserting Feynman rules and visualizing the diagrams is something that requires custom codes built around QGRAF. FeynHelpers offers one way of doing that, but there are other options like Alibrary, tapir, Feamngen.jl, HepLib etc. There's no shortcut to get your diagrams generated without understanding how the underlying machinery works. So if it's important to get those calculations automated, you'll have to spend some time dealing with the codes. If it's just a gimmick that has no real importance, I'd rather write down the amplitudes by hand, which should be much faster. Am 26.02.24 um 19:10 schrieb Alex Long:

…

Thank you for pointing out QGRAF to me, I didn't know that existed. I am attempting to calculate Pion-Pion scattering in chiral perturbation theory. The Feynman rules for this theory can be found in appendix A of this pdf: https://arxiv.org/abs/hep-ph/9501384v1 <https://arxiv.org/abs/hep-ph/9501384v1>. Do you have any recommendations on how to proceed with this? The learning curve seems rather steep. — Reply to this email directly, view it on GitHub <#244 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABXSD5ABG7FEHS4XBTWFXJ3YVTFYVAVCNFSM6AAAAABCPWYR4OVHI2DSMVQWIX3LMV43SRDJONRXK43TNFXW4Q3PNVWWK3TUHM4DKOJWGEYDC>. You are receiving this because you commented.Message ID: ***@***.***>