Inkscape - Feynman Diagrams

Question

So, in the field of particle physics there are a kind of diagrams called Feynman diagrams. Please search "Feynman diagrams" in google to see how they are if you don't know them.

I am interested in drawing Feynman diagrams in inkscape, which will require, for general purposes, a set of basic "patterned curves". My present question has two purposes:

1. There are some "patterned curves" that I really do not know how to create in inkscape; these are presented and indicated below.
2. I am hoping this question will serve as a reference for any one else interested in drawing Feynman diagrams with Inkcape.

The following is a list of the curves (and respective "names") used when creating Feynman diagrams, with a description of how I create it. Please feel free to modify any instruction you consider confusing (I have very few background on Inkscape), or you think there is a better way to do it:

1.- Straight lines:

• Fermionic line:

Select "Bezier Curve". Holding down "ctrl", then "right-click" and trace a horizontal solid line. In order to add arrow in the middle, select the line and then the option "Edit paths by nodes"; double click in the middle of the line in order to add a node just there. Then go to "Object" and select "Fill and Stroke...". In the "Stroke style" tab, select a middle arrow in "Markers"

• Scalar line:

Create a fermionic line. Then in the "Stroke style" tab, select a dashed pattern in the "Dashes" option.

• Gluon line:

This line I build according to the method provided by the user "Beenwu" (here) on YouTube. Go to "Extensions", then "Render", then "Parametric Curves...". Enter the following values:

• Start t-value: -1,0
• End t-value: 6,0
• Multiply t-range by 2*pi: No
• X-value of rectangle's left: -1,0
• X-value of rectangle's right: 1,0
• Y-value of rectangle's bottom: -1,0
• Y-value of rectangle's top: 1,0
• Samples: 80
• Isotropic scaling: No
• X-funtion: t*pi+cos(3*pi*t)
• Y-funtion: sin(3*pi*t)
• Remove rectangles: Yes
• Draw Axes: No
• Live preview: No

With the tool "Create rectangles and squares" create a rectangle, and then click on "Apply".

• Vector line:

Analogous to the gluon case, only this time you have to enter the following parameters:

• Start t-value: 0,0
• End t-value: 1,0
• Multiply t-range by 2*pi: Yes
• X-value of rectangle's left: -1,0
• X-value of rectangle's right: 1,0
• Y-value of rectangle's bottom: -1,0
• Y-value of rectangle's top: 1,0
• Samples: 40
• Isotropic scaling: No
• X-funtion: t
• Y-funtion: sin(15*t)
• Remove rectangles: Yes
• Draw Axes: No
• Live preview: No

2.- Curved lines

I would like to draw also the four above lines but "curved"; for instance, something like this:

I can use the tool "Bezier curve" to draw fermionic and scalar curved lines, but I do not know how to do it for gluon and vector curved lines.

3.- Loops: the same four above lines but in the form of a loop, i.e.

I draw the fermionic and scalar loops with the tool "Create circles, ellipses and arcs", but not shure how to add those two arrows like in the above image.

and

I do not know how to draw those gluon and vector loops.

Answer 1

You can copy to the clipboard any of those lines. Then you can draw with the pen a curve. Set from the info panel shape mode "Bend from clipboard" => your curve is a bended version of what's in the clipboard:

Arrowed loops:

Draw a circle. Convert it to a path (Path > Object to Path). Select proper stroke thickness, color and dashing.

With the node tool select holding shift at the sane time two opposite nodes. With double clicking you can create new nodes in other places if needed.. In the following image at left nodes clock 9 and 3 are selected:

Click in the info panel option break path at selected nodes. The parts can be selected individually and moved apart (if needed) after applying Path > Break apart. They can be moved easily together if you have snap to nodes ON. The parts are separated in the middle to show, what I mean.

In the right both parts are together again and both have got an arrowhead in the beginning. Group the parts to keep them together. Rotate the shape, if the arrows are not in good places (Object > Transform > Rotate)

I think your best bet is to draw the arrowheads with the pen (remove Bend from Cipboard). No complex splits are needed and the placement is exactly wanted - only have snaps ON. Learn the snap options properly or you will not get anything useful. An example (drawn arrowheads, free hand rotation done):

Group the result.

Warning: Grouping isnt't watertight. Double clicking selects still only one part and the group can be trashed by partial edits. Learn to use the Objects panel for selections. From there you can easily select the wanted part and see what is selected.

For shaped stroke circles there's no need to draw a circle with the pen. Convert normal circle to path, add path function "Pattern along path". Have your parametric curve or other shape in the clipboard. Select pattern source option Link to Path On Clipboard.

NOTE: If you want to have grouped or colored shapes placed along a path, use Extension Generate from Path > Pattern along Path. See Inkscape manual for details. They differ from the same named path function.

Answer 2

Since nobody mentioned it yet, for that looping circle, you can use Extensions > Render > Spirograph

And for the wavy circle, the polygon/star tool