  A complex order parameter is used for describing inhomogeneous quark
condensate and its phase is decomposed into a regular part and a singular part.
An emergent gauge symmetry is found to connect these two parts. The singular
part plays the role of an emergent gauge field while the regular part can be
considered as an axionic excitation, provided that the chromoelectric flux tube
is capable of inducing a vortex configuration in the quark condensate, with the
help of axial anomaly.
