Chia-Hung Vincent Chang

       

Address Information

Physics Department
National Taiwan Normal University, Taipei, Taiwan
Telephone (02)2933-1075 ext. 158

e-mail: chchang@phy.ntnu.edu.tw

 

Associate Professor of the Physics Department

I am an associate professor in the Physics Department of the National Taiwan Normal University. My research specialty is the theoretical physics of elementary particles and quantum fields, especially the phenomenology of the standard model, extra dimension physics and other beyond standard models.

My talk at NTU Nov 2008

 

The Courses I teach

General Physics (Chemistry Department) 

Particle Physics

The following is my current interest and ongoing projects:

1.    Extra Dimension Physics
It has been a long held belief that the gravitational force is too feeble to have an impact on particle physics at the weak scale. But why is it so weak? The idea is to assume the existence of n compact extra dimension plus 4 noncompact spacetime. All the matters are to live in a three dimensional membrane, called brane, but the gravitational force line can escape into the n extra dimension. Assume that either n is large or the size of the extra dimension is large compared to particle size. For example n=2 and the size is about 0.1mm or n=3 and the size is 10-7 cm. Anyway, the gravity field lines are too spread out that the gravitational force between matters becomes extremely weak, as we observed.

  1. Perturbative Quantum Chromodynamics (PQCD) and Non-leptonic Heavy Quark Decays
    QCD poses one of the most interesting challenge to theorist's attempt to understand nature. Asymptotic freedom gives it the rich and changeable characteristics of being both weak and strong. Due to this property, we also get a handle to understand it by going to higher energy or heavier mass. Due to the high energy and large mass involved, highly sophisticated schemes, such as perturbative QCD (PQCD) and heavy quark effective theory, can be devised to describe the strong interaction perturbatively. I am currently applying the technique of perturbative QCD to describe the non-leptonic B meson decays, which never has a solid theoretical description.
  2. Supersymmetry (SUSY) and Low Energy Phenomenology
    Supersymmetry is a beautiful idea that not only cures the "naturalness" problem of the Higgs mechanism in Standard Model and also unifies the physics of bosons and fermions. The latter property render huge predictive power which is only recently discovered. By holomorticity, non-perturbative property of SUSY gauge field theory can be calculated. This could have strong impact on our understanding of symmetry and symmetry breaking property of quantum field thery. Currently we are concentrating on how this predictive power can be used in the discreet symmetry, like CP, in a SUSY gauge field theory. On the other hand, one of the most urgent problems facing SUSY is how to break it as it has to be. Attention has turned to the dynamical symmetry breaking mechanism lately. However the models built so far are still too clumsy to be true. I plan to study the phenomenological implication of SUSY dynamical symmetry breaking and also try to improve on the models realizing this idea.
  3. Optical Property of $\pi$ Conjugated Polymer
    Recently $\pi$ conjugated polymer has generated great scientific interest after the demonstration of electroluminescence in poly($p$-phenylenevinylene) (PPV). Last year it was even shown that a lasing process is availble for this material and thus opened the possibility of optoelectronic devices. To understand lasing better, it call for a detailed theoretical investigation of the electronic property of PPV, especially the absorption and emission spectrum in the presence of phonon interaction. A whole series of study will be needed to clarify the issue.
  4. Effective Field Theory of Fractional Quantum Hall States
    Condensed matter physics has provided a wide range of interesting phenomena, which serve as a testing ground for ideas in quantum field theory. Especially Fractional Quantum Hall Effects is a beautiful example, which realizes very interesting properties of low dimensionquantum field theory not seen in particle physics. Effectively it could be described by a Chern-Simons gauge field theory. I'll study the topological stability of this theory.

My Education:

  1. 1983-1987 NATIONAL TAIWAN UNIVERSITY, Taipei, Taiwan, Bachelor of Science degree in Physics, June 1987.
  2. 1989-1995 HARVARD UNIVERSITY Cambridge, Massachusetts, Ph.D. degree in Physics, June 1995. Doctoral thesis adviser: Howard Georgi.

My Experience:

  1. 1995-1997 POSTDOCTORAL RESEARCH in the Physics Department of National Tsing Hua University, Taiwan.
  2. 1997-1998 POSTDOCTORAL RESEARCH in the Physics Division of NSC Center for Theoretical Sciences, Taiwan.

A full Curriculum Vitae in postscript format is available.

Recent Papers

I maintain an archive for research papers. You have the choice of browsing the abstracts, or downloading LaTeX, or Postscript versions of the papers.

Family Information

Chia-Hung is married to Shan-Shan Guo, who is a manager for public relation at Taiwan Semiconductor Manufacturing Company (TSMC). They have a 10 year old daughter, Connie.

Address Information

Physics Department
National Taiwan Normal University
Taipei, Taiwan
R.O.C.

Telephone (02)2933-1075 ext. 158