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تسجيل مستخدم جديدPoincare recurrence theorem and the strong CP-problem
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The existence in the physical QCD vacuum of nonzero gluon condensates, such as $<g^2F^2>$, requires dominance of gluon fields with finite mean action density. This naturally allows any real number value for the unit ``topological charge $q$ characterising the fields approximating the gluon configurations which should dominate the QCD partition function. If $q$ is an irrational number then the critical values of the $theta$ parameter for which CP is spontaneously broken are dense in $mathbb{R}$, which provides for a mechanism of resolving the strong CP problem simultaneously with a correct implementation of $U_{rm A}(1)$ symmetry. We present an explicit realisation of this mechanism within a QCD motivated domain model. Some model independent arguments are given that suggest the relevance of this mechanism also to genuine QCD.
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