Task: Text Categorization
Input (English): When multiplied by charge, the difference between this quantity and the momentum three-vector is in turn multiplied by a vector whose components are matrices, symbolized sigma, on the left side of the bra-ket in the Pauli equation. This quantity is sometimes given as a function equaling q beta over r minus beta-dot-r, where beta is velocity divided by the speed of light, in a relativistically corrected model named for Lienard and Wiechert. When this is nonzero, its path integral is proportional to phase shifts in the wavefunctions of electrons moving past solenoids, according to a phenomenon first predicted by Ehrenberg and Siday in the absence of external fields; that phenomenon is the Aharaonov-Bohm effect. Setting the Laplacian of this quantity equal to the negative of permeability times current density makes the divergence of this quantity equal zero, which is called the Coulomb gauge. For 10 points, name this field symbolized A whose curl gives the magnetic field.
Output (English): Science