Preparation (physics) experienced in quantum mechanics. Preparation (physics) Generally, measuring instruments are meant to get the (pre-)existent value of a physical quantity of a system with as little change of, or interaction with the system as possible. — If a measuring instrument fixes a physical quantity of a physical system for further use (post-existent), then the measurement process is called preparation. For example, a graduated cylinder filled to a definite mark prepares a certain volume of the liquid for further use. Though preparation measures a physical quantity — at least by fixing it — it often destroys previous states of the physical
Yukawa interaction explained by the fact that the Yukawa particle has spin zero and even spin always results in an attractive potential. The negative sign of the exponential gives the interaction an effectively finite range, so that particles at great distances will hardly interact any longer (interaction forces drop off exponentially with increasing separation). Now suppose that the potential formula_7 has a minimum not at formula_18 but at some non-zero value formula_19. This can happen, for example, with a potential form such as formula_20 with formula_9 set to an imaginary value. In this case, the Lagrangian exhibits spontaneous symmetry breaking. This is