ABSTRACT:   The Standard Model describes our current understanding of nearly all the interactions of the fundamental particles.  This theory is often broken into several supposedly distinct sectors.  The familiar photon and electron are placed in the electroweak sector and the quarks and gluons reside in the QCD sector.  The properties of something like the electron are usually only very slightly altered by the presence of quarks and gluons, so this distinction normally holds.  However, the accuracy of many Standard Model predictions is reaching the point at which this is no longer valid, and the effects of QCD must be accounted for even when describing a particle that does not directly feel the QCD interactions.

 

I will describe the methods that we are using to account for these effects nonperturbatively using lattice QCD and focusing on the magnetic moment of the muon as an example.  The Standard Model prediction for this quantity disagrees with the measured value by more than three standard deviations.  Clearly accounting for these effects of QCD is essential for potentially discovering new physics that lies beyond the Standard Model.