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Spin and Orbital Angular Momentum of Quarks and Gluons in the Nucleon


Gian Maria Ziglio
+39 0461 314725
Monday, 25 August, 2014 - 09:00 to Friday, 29 August, 2014 - 17:30
ECT* Conference room

A major controversy has arisen in QCD as to how to split the total angular momentum of a nucleon into separate quark and gluon components; an issue of importance for understanding the internal structure of the nucleon. Deep questions have arisen as to how precisely to define these components and as to their measurability. Underlying this are issues about the role of gauge invariance and the validity of the age old textbook claim that it is impossible to separate the photon (gluon) angular momentum into a spin part and an orbital part in a gauge-invariant way. This is a matter of concern to the many experimentalists who believe they are measuring the polarization of the gluon in a polarized nucleon! There have been a host of papers on this subject in the last few years.
Controversial arguments have been given as to whether a physically measurable quantity really needs to correspond to a gauge-invariant operator. New sum rules have been derived and novel suggestions have been made for measuring some of the terms in them, either experimentally or on a lattice. And it has turned out that orbital angular momentum is now recognized as a key concept in hadron structure and in the theory of high momentum transfer polarized reactions. We believe it would be very fruitful to have a high level discussion of
these issues at this point.

Registration period: 
16 Jun 2014 to 10 Aug 2014
Eventbrite registration: 
Registration closed 11/08/2014.


Mauro Anselmino University of Turin (I)
E. Leader Imperial College
C. Lorcé IPN Orsay & Univ. Liège


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