Abstract:
We study the CP conserving and violating contributions to the decay of $\knng$ in the standard model. In our analysis, we use the form factors for $K\to\gamma$ transitions calculated directly in the entire physical range of momentum transfer within the light front model. We find that the branching ratios for the CP conserving and violating parts are about $1.0\times 10^{-13}$ and $1.5\times 10^{-15}$, respectively.

Abstract:
We study the T violating transverse muon polarization in the decay of $K^+\to \mu^+\nu\gamma$ due to CP violation in theories beyond the standard model. We find that the polarization asymmetry could be large in some CP violation models and it may be detectable at the ongoing KEK experiment of E246 as well as the proposed BNL experiment.

Abstract:
Within the light front framework, we calculate the form factors for $B\to\gamma$ transitions directly in the entire physical range of momentum transfer. Using these form factors, we study the radiative decays of $B\to l\nu_l\gamma$ and $B_{s(d)}\to\nu\bar{\nu}\gamma$. We show that the decay rates of $B\to l\nu_l\gamma (l=e,\mu)$ and $B\to\nu\bar{\nu}\gamma$ are larger than that of the corresponding purely leptonic modes. Explicitly, in the standard model, we find that the branching ratios of $B\to \mu\nu_{\mu}\gamma$ and $B_s\to\nu\bar{\nu}\gamma$ are $3.7\times 10^{-6}$ and $5.0\times 10^{-8}$, in contrast with $3\times 10^{-7}$ and 0 for $B\to\mu\nu_{\mu}$ and $B\to\nu\bar{\nu}$, respectively.

Abstract:
We study the lepton polarization asymmetries in the radiative leptonic B decays of $B^+\to l^+\nu_{l}\gamma$ and $B^+_{c}\to l^+\nu_{l}\gamma$. We concentrate on the transverse component of the $\tau$ lepton asymmetries in the tau decay modes due to CP violation in theories beyond the standard model to search T violating effect.

Abstract:
We study the decays of $B_{s,d} \to l^+ l^- \gamma (l=e, \mu,\tau)$ within the light-front model. We calculate the tensor type form factors and use these form factors to evaluate the decay branching ratios. We find that, in the standard model, the branching ratios of $B_{s(d)} \to \l^+ \l^- \gamma$ ($\l=e, \mu,\tau$) are $7.1\times 10^{-9}$ ($1.5\times 10^{-10}$), $8.3\times 10^{-9}$ ($1.8\times 10^{-10}$), $1.6\times 10^{-8}$ ($6.2\times 10^{-10}$), respectively.

Abstract:
We study the radiative leptonic $D$ meson decays of $D^+_{(s)}\to \l^+\nu_{\l}\gamma$ ($\l=e,\mu,\tau$), $D^0\to \nu\bar{\nu}\gamma$ and $D^0\to \l^+\l^-\gamma$ ($l=e,\mu$) within the light front quark model. In the standard model, we find that the decay branching ratios of $D^+_{(s)}\to e^+\nu_e\gamma$, $D^+_{(s)}\to\mu^+\nu_{\mu}\gamma$ and $D^+_{(s)}\to\tau^+\nu_{\tau}\gamma$ are $6.9\times 10^{-6}$ ($7.7\times 10^{-5}$), $2.5\times 10^{-5}$ ($2.6\times 10^{-4}$), and $6.0\times 10^{-6}$ ($3.2\times 10^{-4}$), and that of $D^0\to\l^+\l^-\gamma$ ($\l=e,\mu$) and $D^0\to\nu\bar{\nu}\gamma$ are $6.3\times 10^{-11}$ and $2.7\times 10^{-16}$, respectively.

Abstract:
We study the semileptonic decays of $B^-\to f_0(1710\,,1500\,,1370) e^-\bar \nu_e$, in which the three $f_0$ states mix with glueball, $\bar s s$ and $(\bar u u+\bar d d)/\sqrt 2$ states, respectively. By averaging the mixings fitted in the literature, we find that the branching ratios of $B^-\to f_0 e^-\bar \nu_e$ are $O(10^{-6})$, $O(10^{-6})$ and $O(10^{-5})$, respectively, which can be simultaneously observed in experiments at $B$ factories. The large predicted branching rate for $B^-\to f_0(1370) e^-\bar \nu_e$ would provide a clean mode to directly observe the $f_0(1370)$ state.

Abstract:
We study the ground state properties of an ABA-stacked trilayer graphene. The low energy band structure can be described by a combination of both a linear and a quadratic particle-hole symmetric dispersions, reminiscent of monolayer- and bilayer-graphene, respectively. The multi-band structure offers more channels for instability towards ferromagnetism when the Coulomb interaction is taken into account. Indeed, if one associates a pseudo-spin 1/2 degree of freedom to the bands (parabolic/linear), it is possible to realize also a band-ferromagnetic state, where there is a shift in the energy bands, since they fill up differently. By using a variational procedure, we compute the exchange energies for all possible variational ground states and identify the parameter space for the occurrence of spin- and band-ferromagnetic instabilities as a function of doping and interaction strength.

Abstract:
We show that the dynamics of cold bosonic atoms in a two-dimensional square optical lattice produced by a bichromatic light-shift potential is described by a Bose-Hubbard model with an additional effective staggered magnetic field. In addition to the known uniform superfluid and Mott insulating phases, the zero-temperature phase diagram exhibits a novel kind of finite-momentum superfluid phase, characterized by a quantized staggered rotational flux. An extension for fermionic atoms leads to an anisotropic Dirac spectrum, which is relevant to graphene and high-$T_c$ superconductors.

Abstract:
The internal Josephson oscillations between an atomic Bose-Einstein condensate (BEC) and a molecular one are studied for atoms in a square optical lattice subjected to a staggered gauge field. The system is described by a Bose-Hubbard model with complex and anisotropic hopping parameters that are different for each species, i.e., atoms and molecules. When the flux per plaquette for each species is small, the system oscillates between two conventional zero-momentum condensates. However, there is a regime of parameters in which Josephson oscillations between a vortex-carrying atomic condensate (finite momentum BEC) and a conventional zero-momentum molecular condensate may be realized. The experimental observation of the oscillations between these qualitatively distinct BEC's is possible with state-of-the-art Ramsey interference techniques.