[R] Latex symbols in R (\perp and \parallel)

[Lorenzo Isella]

Dear All,
I am sure this is a one-liner, but I cannot find the R command to
generate the LaTex symbols \perp and \parallel. Consider for instance
the figure
(one can use any kind of data for the plot)

pdf("friction_linear_chain_perpendicular.pdf")

par( mar = c(4.5,5, 2, 1) + 0.1)

plot(data[ ,1], data[
,4],col="blue",lwd=1.5,lty=1,pch=5,ylab=expression(""*beta[n]^{perpendicular}/beta[1]*""),
xlab=expression(""*n*"")
     ,cex.axis=1.4,cex.lab=1.6)
lines(x,beta_perp(as.list(coef(nls.out)), x), col="black", lwd=2)
dev.off()

Greek letters are understood on the spot, but this is not the case for
the perpendicular symbol in LaTex.
Does anyone know where I can find a list of LaTex symbols translated for R?
Many thanks

Lorenzo