9-14 September 2018
University of Ferrara
Europe/Rome timezone
23RD INTERNATIONAL SPIN SYMPOSIUM

On the spin correlations of muons and tau leptons produced in the high-energy annihilation processes $e^+ e^- \rightarrow \mu^+ \mu^-, \tau^+ \tau^-$

11 Sep 2018, 17:55
25m
A8 (Polo degli Adelardi - Via Adelardi, 33)

A8

Polo degli Adelardi - Via Adelardi, 33

Via Adelardi, 33
Parallel Sessions Spin Physics in Nuclear Reactions and Nuclei Spin physics in Nuclear Reactions and Nuclei

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)

Presentation Materials