Missing (up) Mass, Accidental Anomalous Symmetries, and the Strong CP Problem
نویسنده
چکیده
We reconsider the massless up quark solution of the strong CP problem. We show that an anomaly free horizontal symmetry can naturally lead to a massless up quark and to a corresponding accidental anomalous symmetry. Reviewing the controversy about the phenomenological viability of m u = 0 we conclude that this possiblity is still open and can solve the strong CP problem.
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