A D-brane inspired U(3)CxU(3)ₗxU(3)ᵣ model

الأصل · EN

Motivated by D-brane scenarios, we consider a non-supersymmetric model based on the gauge symmetry U(3)CxU(3)ₗxU(3)ᵣ which is equivalent to the SU(3)³ ``trinification'' model supplemented by three U(1)s. Two U(1) combinations are anomalous while the third U(1)Z' is anomaly free and contributes to the hypercharge generator. This hypercharge embedding correspods to sin²θW=6/19 in the case of full gauge coupling unification. The U(3)³ symmetry is broken down to the Standard Model by vev's of two (1,3,3)- scalar multiplets supplemented by two Higgs fields in (1,3,1) and (1,1,3) representations. The latter break U(1)Z' and provide heavy masses to the extra lepton doublets. Fermions belong to (3, 3,1)+(3,1,3)+ (1,3, 3) representations as in the trinification model. The model predicts a natural quark-lepton hierarchy, since quark masses are obtained from tree-level couplings, while charged leptons receive masses from fourth order Yukawa terms, as a consequence of the extra abelian symmetries. Light Majorana neutrino masses are obtained through a see-saw type mechanism operative at the SU(3)ᵣ breaking scale of the order Mᵣ≥ 10⁹ GeV.