Xi

fourteenth letter of the Greek alphabet

Xi (uppercase/lowercase Ξ ξ) is the 14th letter of the Greek alphabet. It is used to represent the "x" sound in Ancient and Modern Greek. In the system of Greek numerals, it has a value of 60. The Roman letter X and Cyrillic letter Ѯ came from Xi.

In mathematics, both uppercase Ξ and lowercase ξ are used to refer to variants of Riemann Xi function (itself a variant of Riemann zeta function).[1] In physics, the uppercase Ξ is used to represent the cascade particle and xi baryon.[2]

References

  1. "Greek/Hebrew/Latin-based Symbols in Mathematics". Math Vault. 2020-03-20. Retrieved 2020-10-06.
  2. "Xi Symbol in Greek Alphabet". www.greeksymbols.net. Retrieved 2020-10-06.