We study the enhanced Kerr-nonlinear coefficient in a three-level A-type atomic system for various coupling-beam powers. The Kerr-nonlinear coefficient behaves very differently in the strong and the weak coupling power regions and changes sign when the coupling or probe frequency detuning changes sign. Comparisons of Kerr-nonlinear coefficients as functions of probe frequency detuning, coupling...

The general theory of a massless fermion coupled to a massive vector meson in two dimensions is formulated and solved to obtain the complete set of Green's functions. Both vector and axial vector couplings are included. In addition to the boson mass and the two coupling constants, a coefficient which denotes a particular current definition is required for a unique specification of the model. Th...

We calculate the O(αs) gluonic operator matrix elements for the twist–2 operators, which contribute to the heavy flavor Wilson coefficients in unpolarized deeply inelastic scattering in the region Q2 ≫ m2, up to the linear terms in the dimensional parameter ε, (D = 4+ε). These quantities are required for the description of parton distribution functions in the variable flavor number scheme (VFNS...

We calculate the density dependence of the ρ-meson mass and coupling constant(gρNN ) for ρ-nucleon-nucleon vertex at one loop using the lagrangian where the ρ-meson is included as a dynamical gauge boson of a hidden local symmetry. From the condition that thermodynamic potential should not depend on the arbitrary energy scale, renormalization scale, one can construct a renormalization group equ...

We consider solutions of the one-dimensional equation −u+(Q+ λV )u = 0 where Q : R → R is locally integrable, V : R → R is integrable with supp(V ) ⊂ [0, 1], and λ ∈ R is a coupling constant. Given a family of solutions {uλ}λ∈R which satisfy uλ(x) = u0(x) for all x < 0, we prove that the zeros of b(λ) := W [u0, uλ], the Wronskian of u0 and uλ, form a discrete set unless V ≡ 0. Setting Q(x) := −...

By applying the perturbation method, we show in a general way how to determine the coupling coefficient of a waveguide cavity coupling system and as a special example we derive the analytical expressions of the coupling coefficient for a waveguide cavity coupling system as shown in Fig. 1. The term “cavity” in this paper stands for the cavity in both standing wave and travelling wave structures.

We propose a silicon ring-based optical modulation method to perform chirp-free optical modulations. In this scheme, we locate the light to be modulated at the resonance of the ring and tune the coupling coefficient between the ring and the straight waveguide by using a push-pull coupling structure. The chirp-free phase modulation can be achieved by varying the coupling coefficient in a large r...

Piezoelectric micromachined ultrasonic transducers (pMUTs) are an example of the application of MEMS technology to ultrasound generation and detection, which is expected to offer many advantages over conventional transducers. In this work, we investigate pMUTs through novel design and fabrication methods. A finite element (FE) model, with original tools to measure device performance, was develo...