Achasov, M.N
Proton-Proton Scattering
POL
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First measurement of A(N) at s**(1/2) = 200-GeV in polarized proton proton elastic scattering at RHIC.

Bultmann, S. ; Chiang, I.H. ; Chrien, R.E. ; et al.
Phys.Lett.B 632 (2006) 167-172, 2006.
Inspire Record 688172 DOI 10.17182/hepdata.31570

We report on the first measurement of the single spin analyzing power (A_N) at sqrt(s)=200GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). Data points were measured in the four momentum transfer t range 0.01 < |t| < 0.03 (GeV/c)^2. Our result, averaged over the whole t-interval is about one standard deviation above the calculation, which uses interference between electromagnetic spin-flip amplitude and hadronic non-flip amplitude, the source of A_N. The difference could be explained by an additional contribution of a hadronic spin-flip amplitude to A_N.

1 data table
Table 1

The single spin analyzing power for 3 T intervals.


Lambda0 polarization in 800-GeV/c p p --> p(f) (Lambda0 K+).

The E690 collaboration Felix, J. ; Berisso, M.C. ; Christian, D.C. ; et al.
Phys.Rev.Lett. 88 (2002) 061801, 2002.
Inspire Record 560899 DOI 10.17182/hepdata.42919

We report results from a study of Λ0 polarization in the exclusive reaction pp→pf(Λ0K+) at 800−GeV/c. We observe a dependence of the polarization on the Λ0K+ invariant mass with large (+71%) positive polarization at small mass (1.63−GeV/c2) and large (−43%) negative polarization at large mass (2.75−GeV/c2). This observation confirms the result of the CERN ISR R608 experiment and extends the range over which the effect is observed. The strong dependence of the polarization on the Λ0K+ invariant mass suggests that the origin of the polarization is closely related to the production dynamics of the diffractively produced Λ0K+ system.

2 data tables
Table 1

The measured LAMBDA polarisation as a function of the (LAMBDA K+) invariantmass.

Table 2

The measured LAMBDA polarisation as functions of the LAMBDA transverse momentum and Feynman X.


Study of Lambda0 polarization in four different exclusive p p reactions at 27.5-GeV/c

Felix, J. ; Avilez, C. ; Christian, D.C. ; et al.
Phys.Rev.Lett. 82 (1999) 5213-5216, 1999.
Inspire Record 457464 DOI 10.17182/hepdata.19473

We have measured the xF and PT dependence of the polarization of Λ0 hyperons produced in exclusive final states pp→pΛ0K+π+π−, pp→pΛ0K+π+π−π+π−, pp→pΛ0K+π+π−π+π−π+π−, and pp→pΛ0K+π+π−π+π−π+π−π+π− at 27.5 GeV/ c. We present an empirical parametrization for Λ0 polarization as a function of xF and PT: P=(−0.443±0.037)xFPT for −1≤xF≤1 and 0≤PT≤1.8GeV/c. This parametrization is independent of the final state and provides a good description of the data. We note that the mechanism responsible for Λ0 polarization appears to be independent of the production mechanism.

1 data table
Table 1

Result of a linear fit to all the data in the XL and PT region.