[Jlab-seminars] Theory Center Seminar

[Mary Fox]

Theory Center Seminar
Wed., Dec. 11, 2013
1:00 p.m. (coffee at 12:45 p.m.)
CEBAF Center, Room L102


Emanuele Mereghetti
Lawrence Berkeley National Laboratory

*Heavy Quark Production in Soft Collinear Effective Theory *

Heavy quarks play an important role in collider experiments. Due to the 
large scale set by the quark mass, heavy flavor production provides a 
valuable test of perturbative QCD. In addition, heavy flavor production 
processes are the background to many electroweak and new physics 
processes, and a great number of new physics searches rely on the 
efficient tagging of b jets. It is therefore very important to have a 
clear theoretical understanding of the production of heavy flavor and 
heavy flavored jets . Many theoretical tools are currently available, 
which allow to obtain a successful description of heavy flavor 
production in fully inclusive observable, or at moderate energies Q, 
close the scale of the quark mass mQ. However, if Q >> mQ, large 
logarithms of the ratio mQ/Q appear, threatening the convergence of the 
perturbative series, and introducing large theoretical uncertainties. 
The hierarchy of scales Q >> mQ can be exploited to establish an 
effective field theory treatment of heavy quark production. Using Soft 
Collinear Effective Theory (SCET), I will show how the dynamics at the 
different scales that enter heavy flavor production processes can be 
factorized, and large logarithms be resumed through renormalization 
group equations. I will first discuss the definition of heavy quark 
fragmentation function in the SCET, and its extraction from e+ e- 
annihilation data. I will then move on to hadronic collision, and 
discuss how SCET allows to achieve the resummation of large logarithms 
for more exclusive observables than in standard perturbative QCD.
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