Realistic Flipped SU(5) from Orbifold SO(10)

We propose a realistic flipped SU(5) model derived from a five-dimensional orbifold SO(10) model. The Standard Model (SM) fermion masses and mixings are explained by combining the traditional Froggatt-Nielsen mechanism with the five-dimensional wave function profiles of the SM fermions. Employing tree-level spontaneous R-symmetry breaking in the hidden sector and extra(ordinary) gauge mediation, we obtain realistic supersymmetry breaking soft mass terms with non-vanishing gaugino masses. Including the messenger fields at the intermediate scale and Kaluza-Klein states at the compactification scale, we study gauge coupling unification. We show that the SO(10) unified gauge coupling is very strong and the unification scale can be much higher than the compactification scale. We briefly discuss proton decay as well.Comment: 25 pages, 1 fi

Flavor Structures Of Quarks and Leptons From Flipped SU(5) GUT with A4A_4 Modular Flavor Symmetry

We propose to generate the flavor structures of the Standard Model plus neutrinos from flipped SU(5) GUT with $A_4$ modular flavor symmetry. Possible way to assign different moduli values for quarks and leptons in modular GUT scheme is discussed. We propose to reduce the multiple modular symmetries to a single modular symmetry in the low energy effective theory with proper boundary conditions. We classify all possible scenarios in this scheme according to the assignments of the modular $A_4$ representations for matter superfields and give the expressions of the quark and lepton mass matrices predicted by our scheme at the GUT scale. After properly selecting the modular weights for various superfields that can lead to better fitting, we can obtain the best-fit points with the corresponding $\chi^2$ values for the sample subscenarios. We find that the flavor structures of the Standard Model plus neutrinos can be fitted perfectly in such a $A_4$ modular flavor GUT scheme with single or two modulus fields. Especially, the $\chi^2_{total}$ of our fitting can be as low as $1.558$ for sample ${\bf IX^\prime}$ of scenario ${\bf III}$ even if only a single common modulus field for both quark and lepton sectors is adopted. The most predictive scenario ${\bf III}$, in which all superfields transform as triplets of $A_4$, can be fitted much better with two independent moduli fields $\tau_q,\tau_l$ for quark sector and lepton sector ( $\chi^2_{total}\approx 95$) than that with the single modulus case ($\chi^2_{total}\approx 282.4$).Comment: 45 pages, 8 table

Deconfinement Phase Transition Heating and Thermal Evolution of Neutron Stars

The deconfinement phase transition will lead to the release of latent heat during spins down of neutron stars if the transition is the first-order one.We have investigated the thermal evolution of neutron stars undergoing such deconfinement phase transition. The results show that neutron stars may be heated to higher temperature.This feature could be particularly interesting for high temperature of low-magnetic field millisecond pulsar at late stage.Comment: 4 pages, to be published by American Institute of Physics, ed. D.Lai, X.D.Li and Y.F.Yuan, as the Proceedings of the conference Astrophysics of Compact Object