[Jlab-seminars] Today's Physics Seminar: Gerald A. Miller; “The Electron is Not Round: Electron Shape, Size and GPDs in QED”

[Stephanie Tysor]

*Physics Seminar*

*Gerald A. Miller*

*University of Washington*

/“//The Electron is Not Round: Electron Shape, Size and GPDs in QED//”///

*Abstract*

**

The shape of the electron is studied using lowest-order perturbation 
theory. Quantities used to probe the structure of the proton: form 
factors, generalized parton distributions, transverse densities, Wigner 
distributions and the angular momentum content are computed for the 
electron-photon component of the electron wave function. We find that 
the size of the electron (as defined by the slope of its Dirac form 
factor) bound in a hydrogen atom is found to be about four times larger 
than when the electron is scattered by a target. The shape of the 
electron, as determined from the transverse density and generalized 
parton distributions is shown to not be round, and the scattered 
electron is shown to be far less round than the bound electron. An 
electron distribution function (analogous to the quark distribution 
function) is defined, and that of the bound electron is shown to be 
suppressed compared to that of the free electron. If the relative 
transverse momentum of the virtual electron and photon is large compared 
with the electron mass, the virtual electron and photon each carry 
nearly the total angular momentum of the physical electron (1/2), with 
the orbital angular momentum being nearly (-1/2). Furthermore we find 
that  end-point contributions to form factors are suppressed. 
Implications for proton structure and color transparency are discussed.

*Friday, February 20, 2015*

*11:00 am*

*CEBAF Auditorium*

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