Xi (Upper) in LaTeX (\Xi)

Where it is used

Uppercase Greek Xi, a three-bar letter used for the Xi baryon and some special functions.

\Xi is comparatively rare in mathematics. Particle physicists use it for the Xi baryons, written \Xi^0 and \Xi^-, and it sometimes names Riemann's xi function \Xi(t) in analytic number theory. Statistical mechanics occasionally writes the grand canonical partition function as \Xi. Like other capital Greek letters in LaTeX, it is upright; \varXi gives the italic form. Do not confuse it with the equivalence sign \equiv, which has three bars of equal length and relation spacing.

Minimal compilable example

Paste this into an empty .tex file and compile it with pdfLaTeX, XeLaTeX or LuaLaTeX.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
Xi (Upper): $\Xi$

\[ \Xi(t) = \xi\!\left(\tfrac{1}{2} + it\right) \]
\end{document}

Related symbols

• Pi\pi
• Xi\xi
• Pi (Upper)\Pi
• Nu\nu
• Rho\rho
• Mu\mu

Frequently asked questions

How do I write Xi (Upper) in LaTeX?

Type \Xi in math mode, for example $\Xi(t) = \xi\!\left(\tfrac{1}{2} + it\right)$. It works in plain LaTeX without loading any package.

Which package do I need for \Xi?

None. \Xi is part of standard LaTeX, so it compiles with nothing in the preamble but the document class.

Can I use \Xi in text mode, or only in math mode?

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\Xi$ in running text. If you only need the glyph in text, paste the Unicode character Ξ instead (with XeLaTeX or LuaLaTeX and a font that has it).