References - Bogoliubov Laboratory of Theoretical Physics - JINR

(1.205 ± 0.0012) GeV/c, 10 10 p/s, 75% respectively. It was shown that the neutron longitudinal
polarization reaches about 40% at the kinetic energies T ≥ 450 MeV. This beam
was extensively used to fulfill the complete set of the np-elastic scattering experiments.
Spin Transfer tensor in
Inclusive Λ
Figure 1: Depolarization DNN data as a function of pT .
0 Production by
Transversely Polarized Protons
at 200 GeV/c
This is the first and only example
of non-zero Spin Transfer
Mechanism, experimentally established
at 200 GeV/c [5]. The
depolarization tensor DNN =
KN0;N0 (Wolfstein’s parameter)
in the reaction p ↑ +p =Λ0 ↑
+X has been measured with
the transversely polarized protons
at 200 GeV/c over a wide
xF range and a moderate pT .
DNN reaches positive values of
about 30% at high xF and pT ∼
1.0 GeV/c (see Fig 2). This result proves the existence of the essential spin transfer mech-
anism at sufficiently high energy.
Figure 2: Longitudinal spin transfer of Λ and
Λinμp collisions
Longitudinal s pin transfer of Λ
and Λ in DIS at COMPASS The Fig. 3
presents the results of longitudinal spin
transfer of Λ and ΛinDISatCOMPASS
[6]. We would like to emphasize two features
of these datas: 1) The spin transfer
tensor DLL is not zero for Λ. This is in contrast
to the generally accepted statement
that the spin transfer is absent in the case
when the final and initial baryons do not
have any common quark. It means that
there is another channel of transferring the
polarization. As an example we may refer
to professor H.Artru, who indicated us that
the polarized proton may emit the polarized
gluon which fragments into polarized
quark-antiquark pair. The polarized anti-
quark may fragment into polarized antibaryon. Obviously the spin transfer in this chain
should be small as it is seen from this slide. 2) It is surprizing that the spin transfer in
the case of Λ- hyperon is zero. This is also in variance with the above general statement,
since lambda and initial proton have common quarks. On the basis of these data we may
expect that the spin transfer from the polarized proton to the final antiproton may be
not zero also.
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