[R] Display Conditional Probabilities on y-label

[Brian Phillip Weaver]

Hello,

I am trying to display a conditional probability for the y-label on a beta
distribution plot. Here is the code I have been using:

z = expression("f(x|")
g = paste(z,expression(alpha),",",expression(beta),")")
plot(x,y,ylim=c(0,3),xlab="x",ylab=g,lwd=3,type="l",cex.lab=1.3)

The output on the plot is as follows:
f(x|alpha,beta)

This is what I want except have the greek letters for alpha and beta
instead of the words.  I have consulted plotmath and other options with no
luck.  I appreciate any help and thank you ahead of time.

best,
Brian