Hyun Min Lee

TeV scale 5D SU(3)W unification and the fixed point anomaly cancellation with chiral split multiplets

A possibility of 5D gauge unification of SU(2)L × U(1)Y in SU(3)W is examined. The orbifold compactification allows fixed points where SU(2)L × U(1)Y representations can be assigned. We present a few possibilities which give long proton lifetime, top-bottom mass hierarchy from geometry, and reasonable neutrino masses. In general, these chiral models can lead to fixed point anomalies. We can show easily, due to the simplicity of the model, that these anomalies are cancelled by the relevant Chern-Simons terms for all the models we consider. It is also shown that the fixed point U(1)-graviton-graviton anomaly cancels without the help from the Chern-Simons term. Hence, we conjecture that the fixed point anomalies can be cancelled if the effective 4D theory is made anomaly free by locating chiral fermions at the fixed points.

Various modified solutions of the Randall–Sundrum model with the Gauss–Bonnet interaction

Abstract The Gauss–Bonnet interaction is the only consistent quadratic interaction below the Planck scale in the Randall–Sundrum compactification. We study various static and inflationary solutions including this Gauss–Bonnet interaction.

Effective Gauss-Bonnet interaction in Randall-Sundrum compactification

The effective gravitational interaction below the Planck scale in the Randall-Sundrum world is shown to be the Gauss-Bonnet term. In this theory we find that there exists another static solution with a positive bulk cosmological constant. Also, there exist solutions for a positive visible sector cosmological constant, which is needed for a later Friedmann-Robertson-Walker universe.

Randall-Sundrum Model for Self-Tuning the Cosmological Constant

The vanishing cosmological constant in the four-dimensional space-time is obtained in a 5D Randall-Sundrum model with a brane (B1) located at y = 0. The matter fields can be located at the brane. For settling any vacuum energy generated at the brane to zero, we need a three-index antisymmetric tensor field A(MNP) with a specific form for the Lagrangian. For the self-tuning mechanism, the bulk cosmological constant should be negative.

Localized gravity and mass hierarchy in D = 6 with Gauss-Bonnet term

We obtain the localized gravity on the intersection of two orthogonal non-solitonic or solitonic 4-branes in D=6 in the presence of the Gauss-Bonnet term. The tension of the intersection is allowed to exist unlike the case without the Gauss-Bonnet term. We show that gravity could be confined to the solitonic 4-branes for a particular choice of the Gauss-Bonnet coupling. If the extra dimensions are compactified with the

Self-tuning solution of the cosmological constant problem with antisymmetric tensor field

T^2/(Z_2\times Z_2)

Gravity in the Einstein-Gauss-Bonnet theory with the Randall-Sundrum background

orbifold symmetry, the mass hierarchy between the Planck scale and the weak scale can be explained by putting our universe at the TeV intersection of positive tension located at the orbifold fixed point.

More self-tuning solutions with HMNPQ

We obtain the self-tuning solution of the cosmological constant problem in the Randall-Sundrum model with introducing a three-index antisymmetric tensor field of a specific form in the Lagrangian. We also consider the dual description of the self-tuning solution.

Erratum to: “Gravity in the Einstein–Gauss–Bonnet theory with the Randall–Sundrum background”: [Nucl. Phys. B 602 (2001) 346–366]

Abstract We obtain the full 5D graviton propagator in the Randall–Sundrum model with the Gauss–Bonnet interaction. From the decomposition of the graviton propagator on the brane, we show that localization of gravity arises in the presence of the Gauss–Bonnet term. We also obtain the metric perturbation for observers on the brane with considering the brane bending and compute the amplitude of one massless graviton exchange. For the positive definite amplitude or no ghost states, the sign of the Gauss–Bonnet term should be negative in our convention, which is compatible with string amplitude computations. In that case, the ghost-free condition is sufficient for obtaining the Newtonian gravity. For a vanishing Gauss–Bonnet coefficient, the brane bending allows us to reproduce the correct graviton polarizations for the effective 4D Einstein gravity.

Wave function of the radion in the brane background with a massless scalar field and a self-tuning problem

We find more self-tuning solutions by introducing a general form for Lagrangian of a 3-index antisymmetric tensor field