Based on Phys.Rev.D77:014026,2008 (arXiv:0709.2709) by Matthew D. Schwartz and JHEP 0807 (2008) 034 ( arXiv:0803.0342) byThomas Becher and Matthew D. Schwartz


Some of the best measured and theoretically cleanest observbales at colliders are event shapes. Thrust is perhaps the most studied and the best measured of all the event shapes. Event shapes can be computed at fixed order in pertubation theory, or including resummation. In arXiv:0803.0342 the resummation was performed at next-to-next-to-next-to-leading logarithmic order. When combined with the next-to-next-to-leading order calculation, the result is the world's best calculation of thrust

The thrust distribution before and after resummation with SCET

Before -- previous work in fixed order pertubation theory

After with resummation using SCET

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thrust can be used to measure the strong coupling constant.

Here is the extraction from ALEPH data at LEP at different energies

The average value of the strong coupling constant extracted from ALEPH and OPAL data using this method was 0.1174 +/- 0.002, which is competitive with the world average.

Follow up work by Abbate et al, arXiv:1006.3080, added power corrections to this. Work is in progress to combine with Heavy Jet Mass, including power corrections.