Roh-Suan Tung: the Origin of the Immirzi Parameter

[marcus]

Roh-Suan Tung used to be at University of Chicago, and at Uni Lancaster in the UK and at Taiwan Central University. Now he is at University of Shanghai.

He has co-authored with Ted Jacobson.

Eventually Loop Quantum Gravity could get securely established in Chinese People's Republic. It might look like this.

http://www.arxiv.org/abs/gr-qc/0509028
Origin of the Immirzi Parameter
Chung-Hsien Chou, Roh-Suan Tung, Hoi-Lai Yu

"Using quadratic spinor techniques we demonstrate that the Immirzi parameter can be expressed as ratio between scalar and pseudo-scalar contributions in the theory and can be interpreted as a measure of how Einstein gravity differs from a generally constructed covariant theory for gravity. This interpretation is independent of how gravity is quantized. One of the important advantage of deriving the Immirzi parameter using the quadratic spinor techniques is to allow the introduction of renormalization scale associated with the Immirzi parameter through the expectation value of the spinor field upon quantization."

Tung et al cite two very interesting papers, one by Freidel et al and one by Perez and Rovelli

[7] A. Perez and C. Rovelli, “Physical effects of the Immirzi parameter”, http://arxiv.org/gr-qc/0505081 [Broken].

[8] L. Freidel, D. Minic and T. Takeuchi, “Quantum gravity, torsion, parity violation and all that" http://arxiv.org/hep-th/0507253 [Broken].

If I was trying to be funny I would say something about outsourcing. like "outsourcing the immirzi parameter". Incredible as it sounds, there is now even a service in Shanghai where american high school kids can log on and get help with their physics and math homework. A lot of the brainwork is being shipped out these days. But anyway this is not funny. References [7] and [8] are two very recent and (in my humble) very smart papers to follow up on. And these people have followed up on the Freidel within two months.

Next time I visit the Loops 05 website I will see if Roh-Suan is planning to attend.

 

[marcus]

Nope, the only people listed as coming from China are these four from Beijing U.

You Ding
Yong-ge Ma
Li Qin
Hua Zhang

here is an example of their recent work:
http://arxiv.org/abs/gr-qc/0503024
Hamiltonian analysis of n-dimensional Palatini gravity with matter
Muxin Han, Yongge Ma, You Ding, Li Qin
7 pages
Mod.Phys.Lett. A20 (2005) 725-732

"We consider the Palatini formalism of gravity with cosmological constant Lambda coupled to a scalar field phi in n-dimensions. The n-dimensional Einstein equations with Lambda can be derived by the variation of the coupled Palatini action provided n is greater than 2. The Hamiltonian analysis of the coupled action is carried out by a 1+(n-1) decomposition of the spacetime. It turns out that both Palatini action and Hilbert action lead to the same geometric dynamics in the presence of Lambda and phi. While, the n-dimensional Palatini action could not give a connection dynamics formalism directly."

 

[marcus]

Yongge Ma is giving a presentation that relates to Thomas Thiemann Master Constraint program in LQG

Speaker: Prof. Yongge Ma
Title: On the Master Constraint Operator for Loop Quantum Gravity
Abstract: A Master Constraint Operator $\hat{\mathbf{M}}$ can be densely defined in the diffeomorphism invariant Hilbert space in loop quantum gravity. The corresponding quadratic form coincides with the one proposed by Thiemann in the master constraint programme. It is shown that $\hat{\mathbf{M}}$ is positive and symmetric, and hence has its Friedrichs self-adjoint extension. So the master constraint programme for loop quantum gravity can be carried out in principle by employing $\hat{\mathbf{M}}$.