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  2. Form factor (quantum field theory) - Wikipedia

    en.wikipedia.org/wiki/Form_factor_(quantum_field...

    In elementary particle physics and mathematical physics, in particular in effective field theory, a form factor is a function that encapsulates the properties of a certain particle interaction without including all of the underlying physics, but instead, providing the momentum dependence of suitable matrix elements.

  3. Bispherical coordinates - Wikipedia

    en.wikipedia.org/wiki/Bispherical_coordinates

    Illustration of bispherical coordinates, which are obtained by rotating a two-dimensional bipolar coordinate system about the axis joining its two foci. The foci are located at distance 1 from the vertical z-axis. The red self-intersecting torus is the σ=45° isosurface, the blue sphere is the τ=0.5 isosurface, and the yellow half-plane is ...

  4. Oblate spheroidal coordinates - Wikipedia

    en.wikipedia.org/wiki/Oblate_spheroidal_coordinates

    Oblate spheroidal coordinates are a three-dimensional orthogonal coordinate system that results from rotating the two-dimensional elliptic coordinate system about the non-focal axis of the ellipse, i.e., the symmetry axis that separates the foci. Thus, the two foci are transformed into a ring of radius in the x-y plane.

  5. Bipolar coordinates - Wikipedia

    en.wikipedia.org/wiki/Bipolar_coordinates

    The equations for x and y can be combined to give + = ⁡ (+) [2] [3] or + = ⁡ (). This equation shows that σ and τ are the real and imaginary parts of an analytic function of x+iy (with logarithmic branch points at the foci), which in turn proves (by appeal to the general theory of conformal mapping) (the Cauchy-Riemann equations) that these particular curves of σ and τ intersect at ...

  6. Structure function - Wikipedia

    en.wikipedia.org/wiki/Structure_function

    It is somewhat analogous to the structure factor in solid-state physics, and the form factor (quantum field theory). The nucleon (proton and neutron) electromagnetic form factors describe the spatial distributions of electric charge and current inside the nucleon and thus are intimately related to its internal structure; these form factors are ...

  7. Toroidal coordinates - Wikipedia

    en.wikipedia.org/wiki/Toroidal_coordinates

    The angle is formed by the two foci in this plane and P, whereas is the logarithm of the ratio of distances to the foci. The corresponding circles of constant σ {\displaystyle \sigma } and τ {\displaystyle \tau } are shown in red and blue, respectively, and meet at right angles (magenta box); they are orthogonal.

  8. Wigner's theorem - Wikipedia

    en.wikipedia.org/wiki/Wigner's_theorem

    The physical states in a quantum theory are represented by unit vectors in Hilbert space up to a phase factor, i.e. by the complex line or ray the vector spans. In addition, by the Born rule the absolute value of the unit vector's inner product with a unit eigenvector , or equivalently the cosine squared of the angle between the lines the ...

  9. Elliptic cylindrical coordinates - Wikipedia

    en.wikipedia.org/wiki/Elliptic_cylindrical...

    The foci of the ellipse and hyperbola lie at x = ±2.0. Elliptic cylindrical coordinates are a three-dimensional orthogonal coordinate system that results from projecting the two-dimensional elliptic coordinate system in the perpendicular -direction. Hence, the coordinate surfaces are prisms of confocal ellipses and hyperbolae.