A brief procedure:
1. Determin the Kinematics. Match QCD to SCET + NRQCD, basically by writing down the gauge-invariant operators (color singlet or octect) and doing the non-relativistic expansion for quark spinors and etc. in QCD case then matching the results ,to get the hard coefficient at hard-scale. A tree level work(but NOT easy at all).
2. Calculate the scattering amplitude at that (hard) scale : factorize, optical theorem. So a loop integral may be needed for singlet case.
3. Use Renormalizatoin Group to run the coefficent to some other scale, by calculating the “vertex” corrections. Also need to take operator-mixing into consideration at this step, but it may seem small in my case. Bunch of integrals here, damned hard piece!!!
4. Interpolating: combine the end-point-result with result away from that. Maybe some structure functions are needed. No one knows whether these functions are physically correct or not. So maybe, two minus mak e a plus….
October 23, 2006 at 11:19 am |
[...] 4. Interpolating: combine the end-point-result with result away from that. Maybe some structure functions are needed. No one knows whether these functions are physically correct or not. So maybe, two minus mak e a plus…. Posted by xil41Nice postLink to original article [...]