General
In quantum field theory, the operator product expansion (OPE) is a convergent expansion of the product of two fields at different points as a sum (possibly infinite) of local fields.
More precisely, if x and y are two different points, and A and B are operator-valued fields, then there is an open neighborhood of y, O such that for all x in O/{y}
where the sum is over finitely or countably many terms, Ci are operator-valued fields, ci are analytic functions over O/{y} and the sum is convergent in the operator topology within O/{y}.
OPEs are most often used in conformal field theory.
The notation is often used to denote that the difference G(x,y)-F(x,y) remains analytic at the points x=y. This is an equivalence relation.
Read more about this topic: Operator Product Expansion
Famous quotes containing the word general:
“In communist society, where nobody has one exclusive sphere of activity but each can become accomplished in any branch he wishes, society regulates the general production and thus makes it possible for me to do one thing today and another tomorrow, to hunt in the morning, fish in the afternoon, rear cattle in the evening, criticize after dinner, just as I have a mind, without ever becoming hunter, fisherman, shepherd or critic.”
—Karl Marx (1818–1883)
“The general interest of the masses might take the place of the insight of genius if it were allowed freedom of action.”
—Denis Diderot (1713–1784)
“Towards him they bend
With awful reverence prone; and as a God
Extoll him equal to the highest in Heav’n:
Nor fail’d they to express how much they prais’d,
That for the general safety he despis’d
His own: for neither do the Spirits damn’d
Loose all thir vertue; lest bad men should boast
Thir specious deeds on earth, which glory excites,
Or close ambition varnisht o’er with zeal.”
—John Milton (1608–1674)