MathematicalPhysicist said:
Are there any statistics on PHD doctorants whose thesis was on beyond the standard model, I mean how many percentage of them got to keep working in this field after they got their PHD?
You may get a different perspective from others, here's my impression. I've seen some statistics specifically about string theory (where the numbers are large enough to have statistics about.) I don't have links but I remember seeing figures about number of PhDs per year, number of first-time faculty hires, average number of years spent post-doc before faculty job, and so on. So the answer there would be yes, there are relevant statistics.
The picture is quite different in non-string quantum gravity.
You can get an idea of post-PhD prospects simply by eyeballing three websites:
Rovelli, Ashtekar, Loll.
With Rovelli, let's take a recent sample: PhDs completed since 2000.
I see 10, most of whom continue to work in QG---I see their papers on arxiv and their talks listed at conferences.
1. Alejandro Perez (University of Cordoba)
Completed May 2001
“Finiteness of Spin Foam models”
Alejandro Perez has obtained an Assistant Professor postion at the Penn State University,
in State College, USA. He has then obtained the position of Maitre de Conference at the
Université de la Méditerranée, in Marseille, France.
2. Marcus Gaul (Munich University)
Completed 2001
“Hamiltonian constraint in LQG”
3. Richard Livine (Université de la Méditerranée).
Completed 2002
“Modèles de mousse de spin” (Prix de Thèse 2003 de l’Université de la Méditerranée)
Richard Livine has a permanent CR2 (Chargé de Recherche) position at the Ecole National
Superieure de Lyon, France.
4. Daniele Colosi (Université de la Méditerranée et Università di Roma)
Completed Mars 2005
“Dynamique quantique covariante”
Daniele Colosi has obtained a postdoctoral position at the University of Morelia, Mexico.
5. Luisa Doplicher (Università di Roma)
Completed February 2005
“Teoria dei campi quantistica covariante”
Luisa Doplicher has obtained a postdoctoral position at the Sissa, Trieste, Italy.
6. Florian Conrady (Berlin University)
Completed September 2005
“The classical limit of spin foam models”
Florian Conrady has obtained a postdoctoral position at Penn State University, State College,
USA.
7. Simone Speziale (Università di Roma)
Completed January 2006
“2d Quantum Gravity”
Simone Speziale has obtained a postdoctoral position at the Perimeter Institute, Toronto.
8. Winston Fairbairn (Universitée de la Méditerranée)
“Separability in LQG” (Prix de Thèse 2007 de l’Université de la Méditerranée)
Winston Fairbairn has obtained a postdoctoral position in Nottingham, UK.
9. Mauricio Mondragon Lopez (Universitée de la Méditerranée)
Completed March 2008
“Probability in relativistic quantum mechanics”
10. Emanuele Alesci (Università di Roma III)
Completed January 2008
“Scattering amplitudes in LQG”
Here's Rovelli's CV, scroll down for the list of PhDs.
http://www.cpt.univ-mrs.fr/~rovelli/vita.pdf
Loll has the same kind of list, but the numbers are smaller (before 2004 her approach was not very visible, it began getting attention and attracting students in 2004 when there was a landmark result).
http://www.phys.uu.nl/~loll/Web/group/group.html
She lists 3 students who completed PhD with her. One was jointly supervised by Loll and 't Hooft and is in a different field, so doesn't count for our purposes. Both quantum gravity students that completed their PhDs with Loll are now postdocs continuing to work in QG. So far it looks good but too early to tell.
I'll try to find something similar for Ashtekar.