Xi

Greek alphabet
Α α Alpha	Β β Beta
Γ γ Gamma	Δ δ Delta
Ε ε Epsilon	Ζ ζ Zeta
Η η Eta	Θ θ Theta
Ι ι Iota	Κ κ Kappa
Λ λ Lambda	Μ μ Mu
Ν ν Nu	Ξ ξ Xi
Ο ο Omicron	Π π Pi
Ρ ρ Rho	Σ σ Sigma
Τ τ Tau	Υ υ Upsilon
Φ φ Phi	Χ χ Chi
Ψ ψ Psi	Ω ω Omega
obsolete letters
Ϝ ϝ Digamma	Ϻ ϻ San
Ϙ ϙ Qoppa	Ϡ ϡ Sampi

Xi (upper case Ξ, lower case ξ) is the 14th letter of the Greek alphabet. In the system of Greek numerals it has a value of 60.

The lower-case letter ξ is used as a symbol for:

• Random Variables
• Extent of Reaction (a topic found most often in chemical engineering kinetics)

The upper-case letter Ξ is used as symbol for:

• The 'cascade particles' in particle physics.

See also: Xi, Alpha (letter), Baryon, Beta (letter), Chemical engineering, Chi (Greek letter), Delta (letter), Digamma