Seminar Room #512, APCTP HQ (Hogil Kim Memorial Bldg., POSTECH)
* ABSTRACT
Some of the basic properties of geometric phase（Berry phase）and chiral anomaly are discussed. An exactly solvable example of the spin motion inside a time dependent magnetic field is used to illustrate the topologically trivial property of Berry phase, namely, the monopole-type singularity in this example is an artifact of the adiabatic approximation. This property is shown to be valid for the general level crossing problem in quantum mechanics. To illustrate the difference between chiral anomaly and the Berry phase associated with the level crossing problem, a simple quantum mechanical model of M. Stone, which was originally introduced to show the equivalence of the Wess-Zumino term (chiral anomaly) and Berry phase, is analyzed in some detail. Those explicit examples show that chiral anomaly, which is intrinsically a field theoretical notion and exact, and Berry phase are quite different. Possible implications of our analysis on the study of the Weyl semimetal are briefly mentioned.
