Coupling constants meeting at one point

Michel Deby

For short reference, here is a description of the content of the Nobel
Prize 2004 granted to Gross, Politzer and Wilczek for their work on QCD
: http://nobelprize.org/physics/laurea...04/public.html.

At the end of this document is a graphic showing roughly the meeting
point of the three coupling constant.

It seems to be around 27 ou 28.

Has it been calculated more precisely?

I guess yes.

Could someone give a short explanation on the calculation and a more
precise value?

Michel Deby