Search results
Results from the WOW.Com Content Network
(sum over all bubble diagrams) (sum of all diagrams with no bubbles). The first term then cancels with the normalization factor in the denominator meaning that the n-point correlation function is the sum of all Feynman diagrams excluding vacuum bubbles
Bubble diagrams, which result in the RPA when summed up. Solid lines stand for interacting or non-interacting Green's functions , dashed lines for two-particle interactions. The random phase approximation ( RPA ) is an approximation method in condensed matter physics and nuclear physics .
Quantum foam (or spacetime foam, or spacetime bubble) is a theoretical quantum fluctuation of spacetime on very small scales due to quantum mechanics. The theory predicts that at this small scale, particles of matter and antimatter are constantly created and destroyed.
The Feynman diagram expansion may be obtained also from the Feynman path integral formulation. [3] The time-ordered vacuum expectation values of polynomials in φ, known as the n-particle Green's functions, are constructed by integrating over all possible fields, normalized by the vacuum expectation value with no external fields,
The geometry of space-time within the bubble is that of anti-de Sitter space, a space much like conventional de Sitter space except that its group of symmetries is O(3, 2) rather than O(4, 1). Although this space-time is free of singularities, it is unstable under small perturbations, and inevitably suffers gravitational collapse of the same ...
To produce simple poles on boson frequencies =, either of the following two types of Matsubara weighting functions can be chosen () = = = (+ ()),() = = (),depending on which half plane the convergence is to be controlled in. () controls the convergence in the left half plane (Re z < 0), while () controls the convergence in the right half plane (Re z > 0).
The need for exotic matter raises questions about whether one can distribute the matter in an initial spacetime that lacks a warp bubble in such a way that the bubble is created at a later time, although some physicists have proposed models of dynamical warp-drive spacetimes in which a warp bubble is formed in a previously flat space. [4]
Renormalization is a collection of techniques in quantum field theory, statistical field theory, and the theory of self-similar geometric structures, that are used to treat infinities arising in calculated quantities by altering values of these quantities to compensate for effects of their self-interactions.