Physics Colloquium

Starts: November 6, 2009 at 4:00 PM
Location: William Small Physical Laboratory, Rm 109

Summary

Peter Bosted, Jefferson Lab, Title of talk: " Probing the internal structure of the proton and neutron at Jefferson Lab using electrons and pions"

Full Description

Peter Bosted,  Jefferson Lab

" Probing the internal structure of the proton and neutron
 at Jefferson Lab using electrons and pions"

 Abstract: Understanding the internal structure of nucleons (protons and neutrons), which make up most of the  mass of our solar system, is of fundamental interest for many reasons. It is the frontier in the quest to "peel back the onion" at ever smaller distance scales, and new discoveries continue to challenge simple assumptions about the motion of spinning quarks inside the nucleon. It is also of practical importance, for example in the quest to find new particles in high energy proton colliders, such as the Large Hadron Collider.
     In this talk I will discuss the experimental technique of exploring nucleon internal structure in which a pion is produced in the scattering of a high energy electron off of one of the quarks inside a nucleon (dubbed "semi-inclusive deep inelastic scattering, or SIDIS). In particular, I will discuss two experiments which may be pointing the path to answering the questions: what are the momentum distributions of up and down quarks in a nucleon, and do they differ?; and do the average momenta of quarks differ if their spin is aligned or opposite with that of the nucleon itself?  While definite answers are not yet possible, recent data from Jefferson Lab can provide a first glimpse, which will be sharpened when the accelerator is upgraded to higher energies in the near future.

**Everyone is invited**