A variant form of the capital Lambda symbol commonly used as a parameter or operator in mathematical physics and algebra.
Examples
Eigenvalue notation in linear algebra
\text{The eigenvalues are } \varLambda_1, \varLambda_2, \ldots, \varLambda_n
Lambda calculus expression
\varLambda x.\, x^2 + 2x
Energy scale in particle physics
E > \varLambda_{\text{QCD}} \approx 200 \text{ MeV}