Resonance production in FeynMF

How could I make the picture: using FeynMF?

• Welcome to TeX.SX! Please help us help you and add a minimal working example (MWE) that illustrates your problem. Reproducing the problem and finding out what the issue is will be much easier when we see compilable code, starting with \documentclass{...} and ending with \end{document}. – albert Aug 15 '18 at 13:58
• Take a look at this example: texample.net/tikz/examples/feynman-diagram – sporc Aug 15 '18 at 14:15
• Thanks for the answers. My figure was pretty crazy @albert, because of this I didn't show the code (next time I'll do it). – Marcos Aug 15 '18 at 14:59
• Always show your effort, people can always point you to the problematic part (and you and others can learn from the problems). – albert Aug 15 '18 at 16:01

You mention feynmf in the title but are tagging the question with almost everything... Here a feynmf working start point, to run with latex + mf + latex. (There is surely room for improvement.) It works the same way with feynmp and METAPOST, of course.

\documentclass{article}

\usepackage{feynmf}

\begin{document}

\begin{fmffile}{diagram}
\begin{fmfgraph*}(100,80)
\fmfstraight
\fmfleftn{i}{5}
\fmfrightn{o}{5}
\fmf{fermion}{i5,vt,o5}
\fmf{phantom}{i1,vb,o1}
\fmf{photon,label=$W$}{vt,vb}
\fmffreeze
\fmf{fermion}{i1,vb}
\fmf{fermion,label=$\Delta^{++}$}{vb,vr}
\fmf{fermion}{vr,o2}
\fmf{fermion}{vr,o1}
\fmflabel{$\nu_1$}{i5}
\fmflabel{p}{i1}
\fmflabel{p}{o1}
\fmflabel{$\mu^-$}{o5}
\fmflabel{$\pi^+$}{o2}
\end{fmfgraph*}
\end{fmffile}
\end{document} Very similar to campa's nice answer but with a scalar propagator for the pion. I only post the code of the Feynman diagram.

\begin{fmfgraph*}(50,40)
\fmfleft{i1,i2}
\fmfright{f1,f2}
\fmf{fermion,label={}}{i1,v1,f1}
\fmf{fermion,label={}}{i2,v2,f2}
\fmf{photon,label={$W$}}{v1,v2}
\fmffreeze
\fmf{phantom}{f1,f3,h1,h2,h3,f2}
\fmf{phantom}{v1,h4,h5,v3,f1}
\fmffreeze
\fmf{phantom}{h1,pi,f3}
\fmf{phantom,label=$\Delta^{++}$}{v1,v3}
\fmf{dashes}{v3,f3}
\fmflabel{$p$}{i1}
\fmflabel{$\nu_1$}{i2}
\fmflabel{$p$}{f1}
\fmflabel{$\pi^+$}{pi}
\fmflabel{$\mu^-$}{f2}
\end{fmfgraph*} • +1 Indeed, I did say in my answer "There is surely room for improvement ;-). – campa Aug 15 '18 at 14:52

Using \usepackage{feynman}, https://ctan.org/tex-archive/macros/latex209/contrib/feynman

\documentclass[a4paper,12pt]{article}

\usepackage{mathtools}
\usepackage{feynman}
\usetikzlibrary{patterns, arrows, decorations.pathreplacing, decorations.markings}
\begin{document}

\begin{feynman}
\fermion[]{6.20, 1.20}{7.20, 2.20}
\fermion[]{0.20, 5.20}{3.20, 4.20}
\electroweak[]{3.20, 2.20}{3.20, 4.20}
\fermion[]{3.20, 2.20}{6.20, 1.20}
\fermion[]{3.20, 4.20}{6.20, 5.20}
\fermion[lineWidth=2]{6.20, 1.20}{7.20, 2.20}
\fermion[]{0.20, 1.20}{3.20, 2.20}
\fermion[showArrow=true, flip=true]{7.20, 0.20}{6.20, 1.20}
\text{5.00,2.20}{\Delta^{++}}
\text{1.00,0.90}{p}
\text{5.60,4.60}{\mu^-}
\text{6.60,0.20}{p}
\text{0.90,4.50}{v_1}
\text{6.70,2.20}{\pi^+}
\end{feynman}

\end{document}

Here I have added feynman.sty (to save as .sty).

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{feynman}
[2015/02/01 v0.8 LaTeX package for drawing feynman diagrams with an interface similar to the one found at feynman.aivazis.com]

\RequirePackage{xcolor}
\RequirePackage{tikz}
\RequirePackage{xifthen}
\RequirePackage{kvoptions}
\RequirePackage{fp}

\usetikzlibrary{patterns, arrows, decorations.pathreplacing, decorations.markings}

% turn off the fp messages
\FPmessagesfalse

% treat @ like a normal letter
\makeatletter

%------------------------------------------------------------------------------
% configuration parameters
%------------------------------------------------------------------------------

% define the diagram configuration settings family
\SetupKeyvalOptions{family=diagram, prefix=diagram@}
\DeclareStringOption[in]{unit}
\DeclareStringOption[An Example Feynman Diagram]{title}

% define the propagator configuration settings family
\SetupKeyvalOptions{family=style, prefix=style@}
\DeclareStringOption{color}
\DeclareStringOption{lineWidth}
\DeclareBoolOption[true]{endcaps}
\DeclareStringOption[1/3]{gluonWidth}
\DeclareStringOption[center]{location}
\DeclareStringOption{label}
\DeclareStringOption[0.5]{labelDistance}
\DeclareStringOption[0.5]{labelLocation}
\DeclareBoolOption[true]{showArrow}
\DeclareBoolOption[false]{flip}

%------------------------------------------------------------------------------
% the feynman diagram environment
%------------------------------------------------------------------------------

% define an enviroment to encompass a single diagram
\newenvironment{feynman}[]
% before the content
{
% load the diagram configuration settings
\setkeys{diagram}{#1}
% start the tikz environment
\begin{tikzpicture}[x=1\diagram@unit, y=1\diagram@unit]
}
% after the content
{
% close the tikz environment
\end{tikzpicture}
}

%------------------------------------------------------------------------------
% utility macros
%------------------------------------------------------------------------------

% convert a particular length to the designated unit
% i.e. \convertto{mm}{1pt}
\newcommand*{\convertto}{\strip@pt\dimexpr #2*65536/\number\dimexpr 1#1}

% compute the length between two points
\def\calcLength(#1,#2)#3{
% compute the delta between two points
\pgfpointdiff{\pgfpointanchor{#1}{center}}
{\pgfpointanchor{#2}{center}}
\pgf@xa=\pgf@x
\pgf@ya=\pgf@y
% cast the deltas in the appropriate unit system
\FPeval\@temp@a{\pgfmath@tonumber{\pgf@xa}/72.27}
\FPeval\@temp@b{\pgfmath@tonumber{\pgf@ya}/72.27}

% store the sum of the squares
\FPeval\@temp@sum{(\@temp@a*\@temp@a+\@temp@b*\@temp@b)}
% take the square root of the result
\FProot{\FPMathLen}{\@temp@sum}{2}
% cut off at 5 decimal places
\FPround\FPMathLen\FPMathLen9\relax
% set the value of the macro we were given
\expandafter\edef\csname #3\endcsname{\FPMathLen}
}

% compute the angle between two points
\def\calcAngle(#1,#2)#3{
% compute the difference between the two points
\pgfpointdiff{\pgfpointanchor{#1}{center}}
{\pgfpointanchor{#2}{center}}
% extract the delta between the two points
\pgf@xa=\pgf@x
\pgf@ya=\pgf@y
% cast the deltas as numbers
\FPeval{\deltaX}{\pgfmath@tonumber{\pgf@xa}}
\FPeval{\deltaY}{\pgfmath@tonumber{\pgf@ya}}
% use pgf to compute atan2
\pgfmathparse{atan2(\deltaY, \deltaX)}
%  set the angle to the result
\FPeval{\angle}{round(\pgfmathresult , 5)}

% set the value of the macro we were given
\expandafter\edef\csname #3\endcsname{\angle}
}

% shortcut macro to print an expression to the console
\newcommand*{\print}{\typeout{#1}}

%------------------------------------------------------------------------------
% patterns and colors
%------------------------------------------------------------------------------

% declare the parameters for the pattern
\tikzset{
hatch distance/.store in=\hatchdistance,
hatch distance=10pt,
hatch thickness/.store in=\hatchthickness,
hatch thickness=1pt
}
% define the parton fill pattern
\pgfdeclarepatternformonly[\hatchdistance,\hatchthickness]{parton}
% declare the origin
{\pgfqpoint{0pt}{0pt}}
% define the variables in this coordinate system
{\pgfqpoint{\hatchdistance}{\hatchdistance}}
{\pgfpoint{\hatchdistance-1pt}{\hatchdistance-1pt}}
% set up the pattern
{
\pgfsetcolor{\tikz@pattern@color}
\pgfsetlinewidth{\hatchthickness}
\pgfpathmoveto{\pgfqpoint{0pt}{0pt}}
\pgfpathlineto{\pgfqpoint{\hatchdistance}{\hatchdistance}}
\pgfusepath{stroke}
}

% define the arrow style
\tikzset{
arrow/.style={
decoration={
markings,
mark=at position .5 with {
\arrow[#1, scale=1.5]{latex}
}
},
postaction={decorate},
}
}
\tikzset{
arrow flipped/.style={
decoration={
markings,
mark=at position .5 with {
\arrow[#1, scale=1.5]{latex reversed}
}
},
postaction={decorate},
}
}

% define a light gray to be used as a fill color for partons
\definecolor{light-gray}{gray}{.7}

%------------------------------------------------------------------------------
% text macros
%------------------------------------------------------------------------------

% overline with variable width (the second brace)
\newcommand*\anti[1.0]{
\overline{#2}
}

% overline with variable width (the second brace)
\newcommand*\txt{
\textrm{#1}
}

%------------------------------------------------------------------------------
% propagator styles
%------------------------------------------------------------------------------

% fermions
\newcommand*{\fermion}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}

% parse the color of the line
\definecolor{lineColor}{HTML}{\style@color}

% if they asked to draw the arrow
\ifstyle@showArrow
\ifstyle@flip
% draw the line with an arrow
\draw[color=lineColor, line width = \style@lineWidth, arrow flipped] (#2) -- (#3);
\else
% draw the line with an arrow
\draw[color=lineColor, line width = \style@lineWidth, arrow] (#2) -- (#3);
\fi
% otherwise they did not ask to draw the arrow
\else
% draw the line
\draw[color=lineColor, line width = \style@lineWidth] (#2) -- (#3);
\fi

% draw the label
\drawLabel{#2}{#3}
\endgroup
}

% dashed propagators
\newcommand*{\dashed}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}

% parse the color of the line
\definecolor{lineColor}{HTML}{\style@color}

% if they asked to draw the arrow
\ifstyle@showArrow
\ifstyle@flip
% draw the line with an arrow
\draw[dashed, color=lineColor, line width = \style@lineWidth, arrow flipped=lineColor] (#2) -- (#3);
\else
% draw the line with an arrow
\draw[dashed, color=lineColor, line width = \style@lineWidth, arrow=lineColor] (#2) -- (#3);
\fi
% otherwise they did not ask to draw the arrow
\else
% draw the line
\draw[dashed, color=lineColor, line width = \style@lineWidth] (#2) -- (#3);
\fi

% draw the label
\drawLabel{#2}{#3}
\endgroup
}

% gluons
\newcommand*{\gluon}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}

% create TikZ coordinates at the end points
\coordinate  (start) at (#2);
\coordinate  (finish) at (#3);
% store the distance between the two points
\calcLength(start,finish){length} % stores it in a macro called \length
% store the angle between the two points
\calcAngle(start,finish){angle} % stores it in a macro called \angle

% turn the start coordinate into a pgf point
\pgfpointanchor{start}{center}
\FPeval{\startX}{\pgfmath@tonumber{\pgf@x}}
\FPeval{\startY}{\pgfmath@tonumber{\pgf@y}}

\FPeval{\gluonWidth}{\style@gluonWidth}
% store a value for half of the gluonWidth
\FPeval{\halfWidth}{\gluonWidth/2}
% store the closest whole number of full periods
\FPeval{\nLoops}{round((\length / \gluonWidth ) - 1, 0)}
\FPeval{\totalLength}{(\nLoops+1) * \gluonWidth}
\FPeval{\scale}{\length / \totalLength}
% parse the color of the line
\definecolor{lineColor}{HTML}{\style@color}

% if we dont fit a whole loop between the two points
\ifthenelse{\equal{\nLoops}{0}}{
% use a fermion line instead
\fermion{#2}{#3}

% we fit at least one loop between the two points
}{

% if they want the end caps (to draw the right kind of line)
\ifstyle@endcaps
% if they asked to flip the loops
\ifstyle@flip
% set the maximum value to be positive
\FPeval{ymax}{\halfWidth}
\FPeval{ymin}{0-\halfWidth}
% otherwise draw the loops right side up
\else
% set the maximum value to be negative
\FPeval{ymax}{0-\halfWidth}
\FPeval{ymin}{\halfWidth}
\fi

% style the opening end cap
\draw[color=lineColor, line width = \style@lineWidth, yshift=\startY, xshift=\startX,
rotate=\angle, xscale=\scale, yscale=\scale]
% draw the opening end cap
(0,0) .. controls (\halfWidth, 0) and (0, \ymin) .. (\halfWidth, \ymin);
% for each loop that we have to draw
\foreach \loopNumber in {1,...,\nLoops}{
% compute the starting location of the loop
\FPeval{\x}{\loopNumber * \gluonWidth - \halfWidth}
% compute the half way point of the loop
\FPeval{\xMid}{\halfWidth + \x}
% compute the endpoint of the loop
\FPeval{\xFinal}{\gluonWidth + \x}

% style the first half of the loop
\draw[color=lineColor, line width = \style@lineWidth, yshift=\startY, xshift=\startX,
rotate=\angle, xscale=\scale, yscale=\scale]
% draw the first half of the loop
(\x, \ymin) .. controls (\xFinal, \ymin) and (\xFinal, \ymax) .. (\xMid, \ymax);
% style the second half of the loop
\draw[color=lineColor, line width = \style@lineWidth, yshift=\startY, xshift=\startX,
rotate=\angle, xscale=\scale, yscale=\scale]
% draw the second half of the loop
(\xMid, \ymax) .. controls (\x, \ymax) and (\x, \ymin) .. (\xFinal, \ymin);
}

% compute the locations for the closing end cap
\FPeval{\finalStart}{(\nLoops+1) * \gluonWidth - \halfWidth}
\FPeval{\finalHalf}{\finalStart + \halfWidth}
\FPeval{\finalStop}{\finalStart + \halfWidth}
% style the closing end cap
\draw[color=lineColor, line width = \style@lineWidth, yshift=\startY, xshift=\startX,
rotate=\angle, xscale=\scale, yscale=\scale]
% draw the closing end cap
(\finalStart, \ymin) .. controls (\finalStop, \ymin) and (\finalStart, 0) .. (\finalStop, 0);

% they did not want end caps
\else
% if they asked for the gluons to be flipped
\ifstyle@flip
% store a value for the height of the gluon loop
\FPeval{height}{0-\gluonWidth}
\else
% store a value for the height of the gluon loop
\FPeval{height}{\gluonWidth}
\fi

% for each loop that we have to draw
\foreach \loopNumber in {0,...,\nLoops}{
% compute the starting location of the loop
\FPeval{\x}{\loopNumber * \gluonWidth}
% compute the midpoint of the loop
\FPeval{\xMid}{\halfWidth + \x}
% compute the endpoint of the loop
\FPeval{\xFinal}{\gluonWidth + \x}
% style the first half of the loop
\draw[color=lineColor, line width = \style@lineWidth, yshift=\startY, xshift=\startX,
rotate=\angle, xscale=\scale, yscale=\scale]
% draw the first half of the loop
(\x,0) .. controls (\xFinal, 0) and  (\xFinal, \height) .. (\xMid, \height);
% style the second half of the loop
\draw[color=lineColor, line width = \style@lineWidth, yshift=\startY, xshift=\startX,
rotate=\angle, xscale=\scale, yscale=\scale]
% draw the second half of the loop
(\xMid,\height) .. controls (\x, \height) and  (\x, 0) .. (\xFinal, 0);
}
\fi
}
% draw the label
\drawLabel{#2}{#3}
\endgroup
}

% electroweak lines
\newcommand*{\electroweak}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}

% create TikZ coordinates at the end points
\coordinate  (start) at (#2);
\coordinate  (finish) at (#3);
% store the distance between the two points
\calcLength(start,finish){length} % stores it in a macro called \length
% store the angle between the two points
\calcAngle(start,finish){angle} % stores it in a macro called \angle

% turn the start coordinate into a pgf point
\pgfpointanchor{start}{center}
\FPeval{\startX}{\pgfmath@tonumber{\pgf@x}}
\FPeval{\startY}{\pgfmath@tonumber{\pgf@y}}

\FPeval{\period}{\style@gluonWidth}
% store a value for half of the gluonWidth
\FPeval{\halfPeriod}{\period/2}
% store the closest whole number of full periods
\FPeval{\nLoops}{round((\length / \period ) - 1, 0)}
\FPeval{\totalLength}{(\nLoops+1) * \period}
\FPeval{\scale}{\length / \totalLength}
% parse the color of the line
\definecolor{lineColor}{HTML}{\style@color}

% if we dont fit a whole loop between the two points
\ifthenelse{\equal{\nLoops}{0}}{
% use a fermion line instead
\fermion{#2}{#3}

% we fit at least one loop between the two points
}{
% store the amplitude of the curve
\FPeval{amplitude}{\period * 3 / 2}

% if they asked for the gluons to be flipped
\ifstyle@flip
% save the maximum height of the curve
\FPeval{ymax}{\amplitude}
% save the minimum value of the curve
\FPeval{ymin}{0-\amplitude}
\else
% save the maximum height of the curve
\FPeval{ymax}{0-\amplitude}
% save the minimum value of the curve
\FPeval{ymin}{\amplitude}
\fi

% store the minimum height
% for each period that we have to draw
\foreach \loopNumber in {0,...,\nLoops}{
% compute the starting location
\FPeval{\x}{\loopNumber * \period}
% compute the midpoint
\FPeval{\xMid}{\halfPeriod + \x}
% compute the endpoint
\FPeval{\xFinal}{\period + \x}
% style the period
\draw[color=lineColor, line width = \style@lineWidth, yshift=\startY, xshift=\startX,
rotate=\angle, xscale=\scale, yscale=\scale]
% place the period
(\x,0) .. controls (\xMid, \ymin) and  (\xMid, \ymax) .. (\xFinal, 0);
}
}
% draw the label
\drawLabel{#2}{#3}
\endgroup
}

% gluinos
\newcommand*{\gluino}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}
% enforce that endcaps is true
\setkeys{style}{endcaps=true}
% draw a fermion between the two points
\fermion{#2}{#3}
% draw a gluon between the two points
\gluon{#2}{#3}
% draw the label
\drawLabel{#2}{#3}
\endgroup
}

% sfermions
\newcommand*{\sfermion}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}
% enforce that endcaps is true
\setkeys{style}{endcaps=true}
% draw a fermion between the two points
\fermion{#2}{#3}
% draw a gluon between the two points
\electroweak{#2}{#3}
% draw the label
\drawLabel{#2}{#3}
\endgroup
}

%------------------------------------------------------------------------------
% other objects
%------------------------------------------------------------------------------

% circle centered at #2 with radius #3
\newcommand*{\parton}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}
% parse the color of the line
\definecolor{lineColor}{HTML}{\style@color}
% style the circle
\draw[color=lineColor, line width = \style@lineWidth, pattern=parton,
pattern color=light-gray]
% draw the circle
(#2) circle (#3 \diagram@unit);
\endgroup
}

% text a located at #2 with content #3
\newcommand*{\text}[]{
% scope the configuration options
\begingroup
% load the configuration parameters
\setkeys{style}{#1}
% parse the color of the line
\definecolor{color}{HTML}{\style@color}
% create a node at the location with the given contents
\draw[text=color, anchor=\style@location] (#2) node {\huge #3};
\endgroup
}

% draw a label using the coordinate system along the line joining #1 and #2
\newcommand*{\drawLabel}{

% if they provided a value for the label
\ifthenelse{\equal{\style@label}{}}{}{

% create TikZ coordinates at the end points
\coordinate  (start) at (#1);
\coordinate  (finish) at (#2);

% compute the difference between the two points
\pgfpointdiff{\pgfpointanchor{start}{center}}
{\pgfpointanchor{finish}{center}}
\pgf@xa=\pgf@x
\pgf@ya=\pgf@y
% cast the deltas in the appropriate unit system
\FPeval{dX}{\pgfmath@tonumber{\pgf@xa}/72.27}
\FPeval{dY}{\pgfmath@tonumber{\pgf@ya}/72.27}

% compute the location of the starting coordinate
\pgfpointanchor{start}{center}
\pgf@xa=\pgf@x
\pgf@ya=\pgf@y
\FPeval{startX}{round(\pgfmath@tonumber{\pgf@xa}/72.27, 5)}
\FPeval{startY}{round(\pgfmath@tonumber{\pgf@ya}/72.27, 5)}

% store local copies of the target position
\FPeval{labelLocation}{\style@labelLocation}
\FPeval{labelDistance}{0+\style@labelDistance}

% compute the location along the line where we belong
\FPeval{@temp@locX}{round(\startX + \labelLocation * {\dX}, 5)}
\FPeval{@temp@locY}{round(\startY + \labelLocation * \dY, 5)}

% if the change in y is zero (infinite slope)
\ifthenelse{\equal{\dY}{0}}{
\FPeval{labelX}{\@temp@locX}
\FPeval{labelY}{\@temp@locY+\labelDistance}
% otherwise we are safe to compute the slope
}{
% compute the slope of the perpendicular line
\FPeval{perpSlope}{0 - {\dX}/\dY}

% the points that are perpedicular to the line a distance r away satisfy
% y = mx
% x^2 + y^2 = r

% compute the x that satisfies this equation
% note: macro can start with \ because it can never be negative
\FPeval{\x2}{(0+\labelDistance) * (0+\labelDistance) / (1 + (\perpSlope * \perpSlope))}
\FProot{\x}{\x2}{2}
% compute the y that satisfies this equation
\FPeval{y}{\x * \perpSlope}

\newdimen \distance
\distance = \labelDistance pt
\newdimen \slope
\slope = \perpSlope pt

% if the perpendicular line has positive slope
\ifthenelse{\slope > 0 pt \OR \slope = 0 pt}{
% if they are a positive distance away
\ifthenelse{\distance > 0 pt}{
\FPeval{labelX}{@temp@locX + \x}
\FPeval{labelY}{@temp@locY + \y}
% otherwise they are a negative distance away
}{
\FPeval{labelX}{@temp@locX - \x}
\FPeval{labelY}{@temp@locY - \y}
}
% otherwise the perpendicular line as negative slope
}{
% if the label is a positive distance away
\ifthenelse{\distance > 0 pt}{
\FPeval{labelX}{\@temp@locX - \x}
% note: the y is negative so we subtract even though we want to add
\FPeval{labelY}{\@temp@locY - \y}
% otherwise the label is a negative distance from the line
}{
\FPeval{labelX}{\@temp@locX + \x}
% note: the y is negative so we add even though we want to subtract
\FPeval{labelY}{\@temp@locY + \y}
}
}
}

% place the label on the right of the coordinates
\def\loc{right}

% draw the label
\draw[\loc] (\labelX,\labelY) node {\huge \style@label};
}
}

%------------------------------------------------------------------------------
% cleanup
%------------------------------------------------------------------------------

% turn @ back into a special character
\makeatother

\endinput

% end of file