[Jlab-seminars] Theory Center Seminar

[Mary Fox]

Theory Center Seminar
Friday, Feb. 5, 2016
10:00 a.m. (coffee at 9:45 a.m.)
TED Bldg., Room 2561 A&B

Phiala Shanahan
MIT

*Strange and Charge Symmetry Violating Electromagnetic Form Factors of 
the Nucleon from Lattice QCD*

Since strange quark contributions to nucleon observables must arise 
entirely through interactions with the vacuum, their sign and magnitude 
provide key information regarding the nonperturbative structure of the 
nucleon. Understanding this structure is a grand challenge for nuclear 
physics and a central focus of research at Jefferson Lab. At the present 
time, the dominant uncertainty in the experimental numbers for the 
strange proton form factors arises from the assumption of good charge 
symmetry which informs their extraction. In fact, with theoretical 
predictions of the size of charge symmetry violation (CSV) varying 
through several orders of magnitude, this uncertainty (along with the 
remarkable experimental challenges) has halted certain aspects of 
experimental parity-violating electron scattering programs. In this 
seminar I will describe the use of dynamical 2 + 1-flavor lattice QCD 
simulation results for the electromagnetic form factors of the octet 
baryons, together with effective field theory methods, to determine both 
the strange and CSV form factors of the nucleon to an unprecedented 
level of precision. In addition, I will present my vision for my 
research program which will center around the role of hidden flavors and 
gluons in both hadron and nuclear structure, as well as the 3D spatial 
and momentum tomography of the nucleon, from lattice QCD. The 
calculation of gluon observables in the deuteron will make contact with 
experiments proposed in a JLab letter of intent, while studies of hidden 
flavor in nuclei will tie in with the ATHENNA experiment. There has 
recently been significant technical progress which makes the lattice 
calculation of GPDs and TMDs, which are a focus of the JLab 12GeV 
research program, an achievable goal.
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