Forward Neutral Pion Transverse Single Spin Asymmetries in p+p Collisions at √s=200 GeV
B.I. Abelev et al, submitted to Phys. Rev. Lett. [arXiv:0801.2990]

Figure 1

(.png   eps )  Correlation between pion longitudinal momentum scaled by √s/2 (xF) and transverse momentum (pT) for all events. Bins in xF used in Figs. 2 and 4 are indicated by the vertical lines. There is a strong correlation between xF and pT at a single pseudorapidity (η).

Figure 2

(.png   eps )  Transverse single spin asymmetries in xF bins (see Fig. 1) at two different pseudorapidities (<η>). Statistical errors are indicated for each point. Systematic errors are given by the shaded band, excluding normalization uncertainty. The Sivers and twist-3 calculations are described in the text. The inset shows examples of the spin-sorted di-photon invariant mass distributions. The vertical lines mark the π0 mass.

AN(xF)


Ebin <η>=3.7 <η>=3.3
[GeV] <xF> <pT> AN δAN-stat δAN-syst <xF> <pT> AN δAN-stat δAN-syst
18-22




0.201 1.56 0.00087 0.00130 0.0019
22-25 0.237 1.19 0.00571 0.00579 0.0063 0.234 1.78 0.00213 0.00157 0.0006
25-30 0.283 1.34 0.00192 0.00122 0.0004 0.270 2.03 0.01021 0.00174 0.0009
30-35 0.322 1.53 0.00909 0.00093 0.0004 0.320 2.39 0.02726 0.00315 0.0011
35-40 0.371 1.79 0.02343 0.00144 0.0004 0.370 2.74 0.03917 0.00579 0.0019
40-47 0.427 2.04 0.03859 0.00228 0.0008 0.425 3.14 0.05333 0.01015 0.0004
47-56 0.501 2.36 0.06916 0.00478 0.0004 0.499 3.66 0.05989 0.02630 0.0073
56-80 0.598 2.78 0.10345 0.01369 0.0051






AN(-xF)


Ebin <η>=3.7 <η>=3.3
[GeV] <xF> AN δAN-stat δAN-syst <xF> AN δAN-stat δAN-syst
18-22



-0.201 -0.00039 0.00127 0.0020
22-25 -0.237 -0.00442
 0.00538 0.0067 -0.234 0.00032 0.00153 0.0005
25-30 -0.283 -0.00030
 0.00123 0.0013 -0.270 0.00229 0.00170 0.0011
30-35 -0.322 -0.00087
 0.00095 0.0004 -0.320 -0.00454 0.00307 0.0007
35-40 -0.371 0.00150 0.00147 0.0004 -0.370 0.00390 0.00566 0.0021
40-47 -0.427 0.00131 0.00233 0.0009 -0.425 -0.01457 0.00990 0.0027
47-56 -0.501 -0.00547
 0.00489 0.0014 -0.499 0.01008 0.02574 0.0122
56-80 -0.598 -0.00381
 0.01405 0.0068



Figure 3

(.png   eps )  Transverse single spin asymmetries versus π0 transverse momentum (pT) for events with scaled π0 longitudinal momentum |xF| > 0.4. Errors are as described for Fig. 2.

AN(pT) for |xF| > 0.4


pT |<xF>| xF > 0.4 xF < -0.4
[GeV/c]
AN δAN-stat δAN-syst AN δAN-stat δAN-syst
1.283 0.425 0.05070 0.01460 0.0056 -0.00751 0.01682 0.0028
1.500 0.441 0.03062 0.01249 0.0042 -0.01051 0.01403 0.0019
1.713 0.428 0.02595 0.00543 0.0009 0.00005 0.00561 0.0010
1.901 0.431 0.03816 0.00376 0.0010 0.00205 0.00386 0.0013
2.095 0.444 0.04785 0.00401 0.0008 0.00374 0.00411 0.0007
2.293 0.458 0.05675 0.00512 0.0004 -0.00417 0.00524 0.0024
2.531 0.472 0.06055 0.00599 0.0004 -0.00128 0.00612 0.0038
2.902 0.480 0.06240 0.00774 0.0012 -0.01195 0.00780 0.0021
3.528 0.482 0.05538 0.01231 0.0031 -0.01428 0.01213 0.0025

Figure 4

(.png   eps )  Transverse single spin asymmetries versus π0 transverse momentum (pT) in fixed xF bins (see Fig. 1). Errors are as described for Fig. 2. The Sivers and twist-3 calculations are described in the text.

AN(pT) in xF bins


pT 0.25 < xF < 0.30, <xF>=0.28
[GeV/c] AN δAN-stat δAN-syst
0.9551 0.00598 0.00445 0.0051
1.2645 0.00122 0.00145 0.0008
1.6118 0.00559 0.00184 0.0019
2.0959 0.00954 0.00216 0.0004
2.5249 0.02110 0.00738 0.0035
pT 0.30 < xF < 0.35, <xF>=0.32
[GeV/c] AN δAN-stat δAN-syst
1.0571 0.01380 0.00501 0.0004
1.4669 0.00826 0.00101 0.0004
1.8728 0.01229 0.00221 0.0004
2.4107 0.03089 0.00379 0.0004
2.8514 0.03401 0.00937 0.0016
pT 0.35 < xF < 0.40, <xF>=0.37
[GeV/c] AN δAN-stat δAN-syst
1.2912 0.00817 0.00441 0.0028
1.6959 0.02016 0.00174 0.0004
2.0779 0.03596 0.00290 0.0006
2.6443 0.03959 0.00582 0.0007
3.1814 0.03685 0.01383 0.0029
pT 0.40 < xF < 0.47, <xF>=0.43
[GeV/c] AN δAN-stat δAN-syst
1.5516 0.02623 0.00480 0.0004
1.9819 0.04036 0.00292 0.0011
2.4307 0.04523 0.00474 0.0010
3.2374 0.06155 0.01102 0.0020
pT 0.47 < xF < 0.56, <xF>=0.50
[GeV/c] AN δAN-stat δAN-syst
1.7029 0.07517 0.01347 0.0004
2.2041 0.06459 0.00640 0.0004
2.5861 0.07055 0.00854 0.0004
3.3166 0.08877 0.01598 0.0023
pT 0.56 < xF < 0.80, <xF>=0.60
[GeV/c] AN δAN-stat δAN-syst
2.2962 0.08020 0.01911 0.0056
2.8710 0.11799 0.02392 0.0036
3.5122 0.09162 0.03986 0.0114

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