Upsilon (Upper) in LaTeX (\Upsilon)

Where it is used

Uppercase Greek Upsilon, best known for the Upsilon meson in particle physics.

\Upsilon denotes the bottomonium meson family, \Upsilon(1S), \Upsilon(2S), in particle physics. In mathematics it is rare, occasionally naming a function or a set when other letters are taken. Unlike capital alpha or beta, capital upsilon has a distinct shape in Computer Modern with curled arms, so it is not just a Latin Y and has its own command. Like other capital Greek letters it is upright; \varUpsilon gives the italic form. Watch its readability on slides, where it can look like a Y.

Minimal compilable example

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

\documentclass{article}
\begin{document}
Upsilon (Upper): $\Upsilon$

\[ \Upsilon(1S) \to \mu^+ \mu^- \]
\end{document}

Related symbols

• Phi\phi
• Upsilon\upsilon
• Phi (Upper)\Phi
• Tau\tau
• Chi\chi
• Sigma (Upper)\Sigma

Frequently asked questions

How do I write Upsilon (Upper) in LaTeX?

Type \Upsilon in math mode, for example $\Upsilon(1S) \to \mu^+ \mu^-$. It works in plain LaTeX without loading any package.

Which package do I need for \Upsilon?

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

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

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