Light Higgs bosons in three-generation Calabi-Yau superstring theory.

Abstract

An analysis of the Higgs sector is given in three-generation superstring models which arise via Calabi-Yau compactifications where the flux breaking at the compactification scale reduces the ${\mathrm{E}}_{6}$ grand unified group to ${[\mathrm{S}\mathrm{U}(3)]}^{3}$ and a further spontaneous breaking at an intermediate scale ${M}_{I}$ reduces this symmetry down to the standard-model gauge group symmetry $\mathrm{SU}{(3)}_{C}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}{(1)}_{Y}$. The analysis is carried out within the framework of matter parity invariance which is needed for proton stability and the assumption that spontaneous breaking at the intermediate scale is triggered by supersymmetry breaking. Conditions for the existence of a pair of light Higgs doublets needed for the further breaking of the $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}{(1)}_{Y}$ electroweak symmetry are obtained. These conditions act as constraints on the moduli space of the theory in order that the ${(27)}^{3}$ interactions accommodate light Higgs bosons below the intermediate mass scale.