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arXiv · 1802.08109

A Grand-Unified Nelson-Barr Model

Jakob Schwichtenberg·Paul Tremper·Robert Ziegler
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Abstract

We argue that the Nelson-Barr solution to the Strong CP Problem can be naturally realized in an E$_6$ Grand-Unified Theory. The chiral SM fermions reside in three generations of E$_6$ fundamentals together with heavy vectorlike down quarks, leptons doublets and right-handed neutrinos. CP is imposed on the Lagrangian and broken only spontaneously at high scales, leading to a mixing between chiral and vectorlike fields that allows to solve the Strong CP Problem through the Nelson-Barr mechanism. The main benefit of the E$_6$ GUT structure is the predictivity in the SM fermion sector, and a perfect fit to all SM observables can be obtained despite being over-constrained. Definite predictions are made for the neutrino sector, with a Dirac CP phase that is correlated to the CKM phase, allowing to test this model in the near future.

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Jakob Schwichtenberg, Paul Tremper, Robert Ziegler. 2018-02-22. A Grand-Unified Nelson-Barr Model. https://doi.org/10.1140/epjc%2Fs10052-018-6388-6

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