Alekseev, I.G.
POL.POL
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Measurement of the Longitudinal Spin Transfer to Lambda and Anti-Lambda Hyperons in Polarised Muon DIS

The COMPASS collaboration Alekseev, M. ; Alexakhin, V.Yu. ; Alexandrov, Yu. ; et al.
Eur.Phys.J.C 64 (2009) 171-179, 2009.
Inspire Record 824774 DOI 10.17182/hepdata.52400

The longitudinal polarisation transfer from muons to lambda and anti-lambda hyperons, D_LL, has been studied in deep inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN. The spin transfers to lambda and anti-lambda produced in the current fragmentation region exhibit different behaviours as a function of x and xF . The measured x and xF dependences of D^lambda_LL are compatible with zero, while D^anti-lambda_LL tends to increase with xF, reaching values of 0.4 - 0.5. The resulting average values are D^lambda_LL = -0.012 +- 0.047 +- 0.024 and D^anti-lambda_LL = 0.249 +- 0.056 +- 0.049. These results are discussed in the frame of recent model calculations.

5 data tables
Table 1

The weighted average of the spin transfers for the 2003 and 2004 data.

Table 2

The XL dependence of the spin transfer from muons to the LAMBDA hyperon.

Table 3

The X dependence of the spin transfer from muons to the LAMBDA hyperon.

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Double Spin Asymmetries A_NN and A_SS at sqrt{s}=200 GeV in Polarized Proton-Proton Elastic Scattering at RHIC

The pp2pp collaboration Bultmann, S. ; Chiang, I.H. ; Chrien, R.E. ; et al.
Phys.Lett.B 647 (2007) 98-103, 2007.
Inspire Record 729168 DOI 10.17182/hepdata.31499

We present the first measurements of the double spin asymmetries A_NN and A_SS at sqrt{s}=200 GeV, obtained by the pp2pp experiment using polarized proton beams at the Relativistic Heavy Ion Collider (RHIC). The data were collected in the four momentum transfer t range 0.01<|t|<0.03 (GeV/c)^2. The measured asymmetries, which are consistent with zero, allow us to estimate upper limits on the double helicity-flip amplitudes phi_2 and phi_4 at small t as well as on the difference Delta(sigma_T) between the total cross sections for transversely polarized protons with antiparallel or parallel spin orientations.

3 data tables
Table 1

Double spin asymmetries.

Table 2

Double spin asymmetries.

Table 3

T dependence of the double spin asymmetry ASS3 with statistical errors only.


An investigation of the spin structure of the proton in deep inelastic scattering of polarized muons on polarized protons.

The European Muon collaboration Ashman, J. ; Badelek, B. ; Baum, Guenter ; et al.
Nucl.Phys.B 328 (1989) 1, 1989.
Inspire Record 280143 DOI 10.17182/hepdata.49587

The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured in the range 0.01<×<0.7. The spin dependent structure function g 1 ( x ) for the proton has been determined and, combining the data with earlier SLAC measurements, its integral over x found to be 0.126±0.010(stat.)±0.015(syst.), in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Biorken sum rule, this result implies a significant negative value for the integral of g 1 for the neutron. These integrals lead to the conclusion, in the naïve quark parton model, that the total quark spin constitutes a rather small fraction of the spin of the nucleon. Results are also presented on the asymmetries in inclusive hadron production which are consistent with the above picture.

7 data tables
Table 1

THE MEAN Q**2 FOR EACH OF THE 10 VALUES OF X BELOW ARE 3.5,4.5,6.0, 8.010.3,12.9,15.2,18.0,22.5,29.5.

Table 2

No description provided.

Table 3

No description provided.

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