R注释中的下标ell

Question

我试图在我的情节中使用ell作为下标，但我仍然得到l而不是ell。这是代码：

library(ggplot2)
ggplot(data.frame(x = c(-7, 21)), aes(x)) +
 stat_function(fun = dnorm, args = list(mean = 5, sd = 3))+
 stat_function(fun = dnorm, args = list(mean = 9, sd = 3)) + 
 theme_void() + theme(legend.position="none") +
 annotate("text", x = 5, y = 0.15,size = 5, label = 
  as.character(expression(paste("f(E | X"["\u2113"], ")" ))) , parse = T) +
 annotate("text", x = 9, y = 0.15,size = 5, label = 
  as.character(expression(paste("f(E | X"[h], ")" ))) , parse = T)