Skip to Main content Skip to Navigation
Journal articles

Spin observables and spin structure functions: inequalities and dynamics

X. Artru 1 M. Elchikh J.-M. Richard 2 J. Soffer O.V. Teryaev 
1 Théorie
IP2I Lyon - Institut de Physique des 2 Infinis de Lyon
Abstract : Model-independent identities and inequalities relating the various spin observables of a reaction are reviewed in a unified formalism, together with their implications for dynamical models, their physical interpretation, and the quantum aspects of the information carried by spins, in particular entanglement. These constraints between observables can be obtained from the explicit expression of the observables in terms of a set of amplitudes, a non-trivial algebraic exercise which can be preceded by numerical simulation with randomly chosen amplitudes, from anticommutation relations, or from the requirement that any polarisation vector is less than unity. The most powerful tool is the positivity of the density matrices describing the reaction or its crossed channels, with a projection to single out correlations between two or three observables. For the exclusive reactions, the cases of the strangeness-exchange proton-antiproton scattering and the photoproduction of pseudoscalar mesons are treated in some detail: all triples of observables are constrained, and new results are presented for the allowed domains. The positivity constraints for total cross-sections and single-particle inclusive reactions are reviewed, with application to spin-dependent structure functions and parton distributions. The corresponding inequalities are shown to be preserved by the evolution equations of QCD.
Document type :
Journal articles
Complete list of metadata
Contributor : Sylvie Flores Connect in order to contact the contributor
Submitted on : Monday, February 4, 2008 - 2:52:01 PM
Last modification on : Monday, June 28, 2021 - 3:56:02 PM

Links full text




X. Artru, M. Elchikh, J.-M. Richard, J. Soffer, O.V. Teryaev. Spin observables and spin structure functions: inequalities and dynamics. Physics Reports, Elsevier, 2009, 470, pp.1-92. ⟨10.1016/j.physrep.2008.09.004⟩. ⟨in2p3-00238395⟩



Record views