https://doi.org/10.1140/epja/i2006-10152-3
Regular Article - Nuclear Structure and Reactions
Polarisation observables in lepton-antilepton-to-proton-antiproton reactions including lepton mass
Trinity College, School of Mathematics, Dublin, Ireland
* e-mail: elise@maths.tcd.ie
Received:
20
July
2006
Accepted:
30
November
2006
Published online:
9
January
2007
General expressions, including the lepton mass, for the spin-averaged differential cross-section for the annihilation reaction lepton-antilepton to proton-antiproton are given, as well as general formulae for the single- and double-spin asymmetries in the centre-of-mass frame. In particular, we discuss the single-spin asymmetry, normal to the scattering plane, which measures the relative phase difference between nucleon electromagnetic form factors GE and GM. Recent experimental investigations of these form factors in the space- and time-like region are reviewed. It is thought that measurements of the phase of these form factors will provide fundamental information on the internal nucleon structure. The phases between GE and GM are accessible through polarisation observables measured in the antiproton-proton-to-lepton-antilepton reaction, or in its time-reversed process.
PACS: 13.40.Gp Electromagnetic form factors – / 13.75.Cs Nucleon-nucleon interactions (including antinucleons, deuterons, etc.) – / 13.66.Bc Hadron production in e - e + interactions – / 14.20.Dh Protons and neutrons –
© Società Italiana di Fisica and Springer-Verlag, 2007