Speaker: Adam Lichtl (RIKEN BNL Research Center)

Title: 
Excited Baryon Analysis Using the Lattice

Abstract:
The tools of lattice QCD allow, in principal, the ab initio calculation of the 
hadron spectrum.  Such a determination of the pattern of QCD resonances would 
be an essential component of the broader experimental and theoretical efforts 
to understand the physics of excited hadronic resonances.  

After a brief review of the lattice formalism, we present lattice QCD's progress 
towards the goal of calculating the excited nucleon spectrum.  We show
that realistic operators are essential for interpolating for the states of 
interest and describe how such operators are designed.  We outline how a variant 
of the variational method combined with a systematic fitting approach can be used 
to extract finite-volume spectra, and illustrate the efficacy of the approach by 
showing preliminary results using two-flavors of dynamical fermions.  We discuss 
the connection between the finite-volume spectra obtained from the lattice and the 
continuum resonance states measured in experiment, and conclude with a description 
of current limitations and ongoing improvements.