Rotation-invariant observables as Density Matrix invariants

Abstract

It is shown that general dilepton angular distribution (with parity violating terms taking into account) in vector particle decays can be described through a set of five SO(3) rotational-invariant observables. These observables are derived as invariants of the spacial part of the hadronic tensor (density matrix) expressed in terms of angular coefficients. The restrictions on the invariants following from the positivity of the hadronic tensor are obtained. Special cases of SO(2) rotations are considered. Calculation of invariants for available data on Z and J/ψ decays is performed.

11 pages, 5 figures

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Cited by in corpus (7)

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• Chiral vortical effect for vector fields
• Polarization and cross section of midrapidity J/$\psi$ production in proton-proton collisions at $\sqrt{s}=510$ GeV
• Lepton angular distribution of $W$ boson productions
• Velocity-like maximum polarization: irreversibility and quantum measurements
• First polarisation measurement of coherently photoproduced J/$\psi$ in ultra-peripheral Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• Glauber gluons in pion-induced Drell-Yan processes revisited