#  Heavy Jet Mass 

 



Based on JHEP 1008:058,2010([arXiv:1005.1644](http://arxiv.org/abs/arXiv:0709.2709))Yang-Ting Chein and Matthew D. Schwartz

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Heavy jet mass is an event shape similar to [thrust](http://jets.physics.harvard.edu/thrust). It can also be computing to high precision in the threshold region using Soft-Collinear Effective Theory.

Comparing the fits for heavy jet mass and thrust, we find that thrust is a much better fit.

The values of alpha\_s consequently have somewhat larger uncertainty than from thrust

The average value of alpha\_s from ALEPH data using NNLO + NNNLL accuracty, without power corrections, is alpha\_s = 0.1220 +/- 0.0031.

Work is in progress to understand power corrections. Some interesting preliminary observations are about a sensitivity to the profile functions and the scheme used for boundary conditions at the kinematically limiting value of thrust.

[Profile dependence](http://jets.physics.harvard.edu/HJM/profbound.pdf)