Chang Chao-hsi

Instantaneous Bethe–Salpeter Equation and Its Exact Solution

We present an approach to solve Bethe-Salpeter (BS) equations exactly without any approximation if the kernel of the BS equations exactly is instantaneous, and take positronium as an example to illustrate the general features of the exact solutions. The key step for the approach is from the BS equations to derive a set of coupled and well-determined integration equations in linear eigenvalue for the components of the BS wave functions equivalenity which may be solvable numerically under a controlled accuracy, even though there is no analytic solution. For positronium, the exact solutions precisely present corrections to those of the corresponding Schrodinger equation in order upsilon(1) (v is the relative velocity) for eigenfunctions, in order upsilon(2) for eigenvalues, and the mixing between S and D components in J(PC) = 1(--) states etc., quantitatively. Moreover, we also point out that there is a questionable step in some existent derivations for the instantaneous BS equations if one is pursuing the exact solutions. Finally, we emphasize that one should take the O(upsilon) corrections emerging in the exact solutions into account accordingly if one is interested in the relativistic corrections for relevant problems to the bound states.

Calculation of four-quark condensate beyond vacuum saturation approximation

Based on a modification of the global color symmetry model, we have calculated the four-quark condensate [: (q) over bar gamma mu lambdaC degrees /2 q(q) over bar gamma mu lambdaC degrees /2 q :] beyond vacuum saturation approximation by including the contribution of pi and sigma masons. The numerical results show that there is a sizeable correction of the four-quark condensate in comparison with its factorized value using the vacuum saturation approximation.

Bilinear R-Parity Violation and Mixing Production in e+e- Colliders*

A R-parity breaking SUSY model characterized by an effective bilinear violation with only

Factorization of SUC(3) at Hypercolor Scale ΛH and Induced Goldstone Bosons in Composite Models

\tau

On (πμ) atoms produced in K0L decay

-lepton number breaking in the superpotential is outlined. The CP-odd Higgs boson masses and those of charged Higgs bosons are discussed. In the model, several interesting mass mixings else such as the mixing between

Non-spectator Contributions to Lifetime of Λb*

\tau

Nonperturbative aspects of axial vector vertex

lepton and charginos etc in the model are discussed too. Being one of example, we have computed the mixing production

QCD sum rule external field approach and vacuum susceptibilities

e^{+} e^{-} \to \tau^{\mp} \tilde{\kappa}^{\pm}_{i} (i=1,2)

A New Type of Accessible Environmental Influences on Neutrino Oscillation

in e^+ e^- colliders, where

Vacuum Condensates from the Modification of Global Color Symmetry Model

\tau^{\mp}, \tilde{\kappa}^{\pm}_{i}(i=1,2)