Phillial Oh

Notes on supersymmetry enhancement of ABJM theory

We study the supersymmetry enhancement of ABJM theory. Starting from a = 2 supersymmetric Chern-Simons matter theory with gauge group U(2) × U(2) which is a truncated version of the ABJM theory, we find by using the monopole operator that there is additional = 2 supersymmetry related to the gauge group. We show this additional supersymmetry can combine with = 6 supersymmetry of the original ABJM theory to an enhanced = 8 SUSY with gauge group U(2) × U(2) in the case k = 1,2. We also discuss the supersymmetry enhancement of the ABJM theory with U(N) × U(N) gauge group and find a condition which should be satisfied by the monopole operator.

String pair creations in D-brane systems

We investigate the criterion, on the Born-Infeld background fields, for the open string pair creation to occur in Dp-(anti-)Dp-brane systems. Although the pair creation occurs generically in both Dp-Dp and Dp-anti-Dp systems for the cases which meet the criterion, it is more drastic in Dp-anti-Dp-brane systems by some exponential factor depending on the background fields. Various configurations exhibiting pair creations are obtained via duality transformations. These include the spacelike scissors and two D-strings (slanted at different angles) passing through each other. We raise the scissors paradox and suggest a resolution based on the triple junction in IIB setup.

Conformal Invariance in Einstein-Cartan-Weyl space

We consider conformally invariant form of the actions in Einstein, Weyl, Einstein–Cartan and Einstein–Cartan–Weyl space in general dimensions (> 2) and investigate the relations among them. In Weyl space, the observational consistency condition for the vector field determining non-metricity of the connection can be obtained from the equation of motion. In Einstein–Cartan space a similar role is played by the vector part of the torsion tensor. We consider the case where the trace part of the torsion is the Kalb–Ramond type of field. In this case, we express conformally invariant action in terms of two scalar fields of conformal weight -1, which can be cast into some interesting form. We discuss some applications of the result.

More on generalized Heisenberg ferromagnet models

Abstract We generalize the integrable Heisenberg ferromagnet model according to each Hermitian symmetric spaces and address various new aspects of the generalized model. Using the first order formalism of generalized spins which are defined on the coadjoint orbits of arbitrary groups, we construct a Lagrangian of the generalized model from which we obtain the Hamiltonian structure explicitly in the case of CP ( N − 1) orbit. The gauge equivalence between the generalized Heisenberg ferromagnet and the nonlinear Schrodinger models is given. Using the equivalence, we find infinitely many conserved integrals of both models.

Anisotropic Weyl symmetry and cosmology

We construct an anisotropic Weyl invariant theory in the ADM formalism and discuss its cosmological consequences. It extends the original anisotropic Weyl invariance of Ho?ava-Lifshitz gravity using an extra scalar field. The action is invariant under the anisotropic transformations of the space and time metric components with an arbitrary value of the critical exponent z. One of the interesting features is that the cosmological constant term maintains the anisotropic symmetry for z = ?3. We also include the cosmological fluid and show that it can preserve the anisotropic Weyl invariance if the equation of state satisfies P = z?/3. Then, we study cosmology of the Einstein-Hilbert-anisotropic Weyl (EHaW) action including the cosmological fluid, both with or without anisotropic Weyl invariance. The correlation of the critical exponent z and the equation of state parameter provides a new perspective of the cosmology. It is also shown that the EHaW action admits a late time accelerating universe for an arbitrary value of z when the anisotropic conformal invariance is broken, and the anisotropic conformal scalar field is interpreted as a possible source of dark energy.

Massive Photon and Dark Energy

We investigate cosmology of massive electrodynamics and explore the possibility whether massive photon could provide an explanation of the dark energy. The action is given by the scalar-vector-tensor theory of gravity which is obtained by non-minimal coupling of the massive Stueckelberg QED with gravity and its cosmological consequences are studied by paying a particular attention to the role of photon mass. We find that the theory allows cosmological evolution where the radiation- and matter-dominated epochs are followed by a long period of virtually constant dark energy that closely mimics

Dark spinor model with torsion and cosmology

\Lambda

Conformally-coupled dark spinor and FRW universe

CDM model and the main source of the current acceleration is provided by the nonvanishing photon mass governed by the relation

Supersymmetric monopole quantum mechanics on a sphere

\Lambda\sim m^2

Coherent state quantization of SU(N) non-Abelian Chern-Simons particles

. A detailed numerical analysis shows that the nonvanishing photon mass of the order of