Posts Tagged ‘ParticlePhysics’

Quarks and Antiquarks in the Nucleon

5 January 2019

My earliest research in physics was in a particle physics collaboration at FermiLab.  The idea of the experiment I worked on from 1994 to 1997 (FermiLab E866) was to study the nucleon sea—a tiny but turbulent region bubbling with quantum activity inside a proton or neutron, where quark-antiquark pairs can appear for an instant before annihilating each other.

In particular, we made a precise measurement of how often pairs of “up” quarks are produced, relative to how often “down” quarks are produced in the nucleon sea, and showed that there was a statistically significant difference which particle physics theory could not account for.


While I went on to more mathematical and theoretical work, I have colleagues who continued research along these lines, and it’s still nice to look in and see what’s going on in the area I started out in.

Fortunately for me, there’s a nice new review article on the subject of quark-antiquark pairs in the nucleon, written by two of my senior colleagues from E866, Don Geesaman and Paul Reimer:

D. F. Geesaman and P. E. Reimer, The Sea of Quarks and Antiquarks in the Nucleon: a Review,

It’s nicely written, and explains the state of the art in sea quark physics from both the experimental and theoretical sides.