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Einstein notation is used throughout this article. This article uses the "analyst's" sign convention for Laplacians, except when noted otherwise. This article uses the "analyst's" sign convention for Laplacians, except when noted otherwise.
In mathematics, especially the usage of linear algebra in mathematical physics and differential geometry, Einstein notation (also known as the Einstein summation convention or Einstein summation notation) is a notational convention that implies summation over a set of indexed terms in a formula, thus achieving brevity.
The Einstein–Infeld–Hoffmann equations of motion, jointly derived by Albert Einstein, Leopold Infeld and Banesh Hoffmann, are the differential equations describing the approximate dynamics of a system of point-like masses due to their mutual gravitational interactions, including general relativistic effects.
The equation for the mass shell is also often written in terms of the four-momentum; in Einstein notation with metric signature (+,−,−,−) and units where the speed of light =, as =. In the literature, one may also encounter p μ p μ = − m 0 2 {\displaystyle p^{\mu }p_{\mu }=-m_{0}^{2}} if the metric signature used is (−,+,+,+).
This section uses Einstein notation, including Einstein summation convention. See also Ricci calculus for a summary of tensor index notations, and raising and lowering indices for definition of superscript and subscript indices, and how to switch between them. The Minkowski metric tensor η here has metric signature (+ − − −).
From Wikipedia, the free encyclopedia. Redirect page
The Casimir invariants of the Poincaré group are = , (Einstein notation) where P is the 4-momentum operator, and = , where W is the Pauli–Lubanski pseudovector. The eigenvalues of these operators serve to label the representations.
The text here uses Einstein notation in which summation over repeated indices is assumed. Two types of derivatives are used: Partial derivatives are denoted either by the operator ∂ i {\displaystyle \partial _{i}} or by subscripts preceded by a comma.