Speaker
Dr
Valery Lyuboshitz
(Joint Institute for Nuclear Research ( Dubna ))
Description
The electromagnetic processes of annihilation of $(e^+ e^-)$ pairs --
which may be generated, in particular, in relativistic nucleus-nucleus and hadron-nucleus collisions -- into heavy flavor lepton pairs are
theoretically studied in the one-photon approximation, using the
technique of helicity amplitudes . For the process $e^+ e^- \rightarrow
\mu^+\mu^-$, it is shown that -- in the case of the unpolarized
electron and positron -- the final muons are also unpolarized but their spins prove to be strongly correlated. For the final $(\mu^+ \mu^-)$ system, the structure of triplet states is analyzed and explicit expressions for the components of the spin density
matrix and correlation tensor are derived; besides, the formula for
the angular correlation at the decays of the final $\mu^+$ and $\mu^-$ is obtained .
It is demonstrated that the spin correlations of muons in the
process $e^+ e^- \rightarrow \mu^+ \mu^-$, have the purely quantum character, since one of the Bell-type incoherence inequalities for
the diagonal components of correlation tensor is always violated
( i.e., there is always one case when the modulus of sum of two
diagonal components exceeds unity ) . In doing so, it is also established that, when involving the additional contribution of
the weak interaction of lepton neutral currents through the virtual $Z^0$ boson, the qualitative character of the muon spin correlations does not change.
Analogous consideration can be wholly applied as well to the annihilation process $e^+ e^- \rightarrow \tau^+ \tau^-$,
which becomes possible at much higher energies.
Primary author
Dr
Valery Lyuboshitz
(Joint Institute for Nuclear Research ( Dubna ))
Co-author
Dr
Vladimir Lyuboshitz
(JINR, Dubna)
