Noncyclic geometric phase in counting statistics and its role as an excess contribution

We propose an application of fiber bundles to counting statistics. The framework of the fiber bundles gives a splitting of a cumulant generating function for a current in a stochastic process, i.e., contributions from the dynamical phase and the geometric phase. We will show that the introduced noncyclic geometric phase is related to kinds of excess contributions, which have been investigated a lot in nonequilibrium physics. Using a specific nonequilibrium model, the characteristics of the noncyclic geometric phase are discussed; in particular, we reveal differences between a geometric contribution for the entropy production and the 'excess entropy production' which has been used to discuss the second law of steady-state thermodynamics. (paper)