Upsilon (Υ υ) in LaTeX
Upsilon is the twentieth letter of the Greek alphabet. In LaTeX maths mode it is written \upsilon for the lowercase form (upsilon glyph) and \Upsilon for the uppercase form, both built into core LaTeX with no extra package required.
LaTeX command
\UpsilonNot the symbol you meant? Draw it to find the command →
Upsilon is one of the least used Greek letters in everyday mathematics, but it turns up as a variable name when a document has already used most of the alphabet, and in specific technical contexts such as differential geometry and control theory. It is genuinely rare compared with letters like alpha, theta or sigma.
Its best known appearance is in particle physics, where the upsilon meson, a bound state of a bottom quark and its antiquark, is written \Upsilon, often with a state label such as \Upsilon(1S). String theory and some areas of statistics also borrow upsilon occasionally as a free variable name.
Because \upsilon and \Upsilon are core LaTeX primitives, they work in plain LaTeX, amsmath documents and KaTeX with no package loaded. The main practical issue is legibility: lowercase upsilon can look close to \nu or a slanted v in some fonts, so pick a variable name that will not be confused with its neighbours.
Other forms
\upsilonlowercase upsilon\Upsilonuppercase upsilon (Υ)Examples
$\upsilon$lowercase upsilon inline
$\Upsilon$uppercase upsilon
$\Upsilon(1S)$the ground-state upsilon meson in particle physics
$\upsilon \in [0,1]$upsilon used as an ordinary bound variable
Tips and common mistakes
\upsilonand\Upsilonneed no package, they are defined in core LaTeX.- Lowercase upsilon can be visually close to
\nuor an italic v in some fonts, so avoid using both in the same document if you can. - Uppercase Upsilon closely resembles a Latin Y, make sure the surrounding context makes clear which one you mean.
- There is no curly
\varupsilonvariant, unlike phi, theta or sigma.
Working from handwritten notes?
LatexNotes turns a photo or PDF of handwritten mathematics into clean, compilable LaTeX - graphs and all. Free to try, no sign-up.
Convert your maths to LaTeX →FAQ
How do I type upsilon in LaTeX?
Use \upsilon for lowercase or \Upsilon for uppercase inside maths mode, for example . No package is needed.
Is there a variant form of upsilon like \varphi for phi?
No. Unlike phi, theta, sigma, rho, kappa and pi, upsilon has no \var- variant in standard LaTeX.
What is the upsilon meson?
A subatomic particle made of a bottom quark and antiquark, written \Upsilon in physics notation, often with a state label like \Upsilon(1S).
Why does upsilon look like a Latin Y or v?
The glyphs are historically related; Upsilon is one of the Greek letters that gave rise to the Latin alphabet's Y, U and V, which is why the shapes overlap.