Steve has produced trees for a large fraction of the ppTransverse run. In this update, I show asymmetry figures for 388 runs. Please, refer to my previous update for a bit of background discussion. Again, note, the asymmetries are not corrected for polarization. Also, errors are purely statistical and potentially azimuthally dependent backgrounds are not corrected.

Figure 1

In Fig. 1 we see various plots for di-photons. There is obviously quite a bit of background under the pion peak which will need to be removed. The x_F vs. p_T kinematic distribution shows almost no events above x_F = 0.5.

Figure 2

pT	xF

The top row shows the extracted asymmetry while the bottom row shows the constant of the fit. Asymmetries for x_F > 0 are in blue circles, while asymmetries for x_F < 0 are in red triangles. In the p_T plots I have shifted the blue points by 0.25 to attempt to make the figures easier to read. Again, I emphasize the asymmetries are not corrected for polarization. There do not appear to be large effects in either blue beam, yellow beam, or in the p₀'s. However, it does seem like the x_F asymmetries are systematically above the horizontal. It will be important to examine, again, the individual fits to make sure they are sensible.

Figure 3

Fitted Asymmetries as a Function of pT (xF > 0)

One other interesting check is to look at the p_T dependence, if any, of the asymmetry. One would expect an effect driven by pQCD to fall off as ∼1/p_T. In Fig. 3, on the left, I plot a p₀/p_T fit to the x_F > 0 asymmetries; and on the right I fit with a function of the form p₀+p₁/p_T. There is a 2σ dependence with a not-so-crazy χ². Again, I would caution against any conclusions until we check not only individual fits but also systematics and background corrections.

Figure 4: Fit Results for p_T Bins

0 < pT < 4 GeV/c
4 < pT < 5 GeV/c
5 < pT < 6 GeV/c
6 < pT < 7 GeV/c
7 < pT < 8 GeV/c
8 < pT < 9 GeV/c
9 < pT < 10 GeV/c
10 < pT < 12 GeV/c
12 < pT < 16 GeV/c

In Fig. 4 I show the fits for the individual p_T bins as well as the instrumental and luminosity asymmetries. Instrumental asymmetries seem to be below 30% and typically below 10%. Luminosity asymmetries also appear to be fairly unremarkable.

Figure 5: Fit Results for x_F Bins

0 < xF < 0.1
0.1 < xF < 0.2
0.2 < xF < 0.3
0.3 < xF < 0.5

One thing to note about the x_F asymmetries is that the χ² values appear to be way too good. It seems as though I could fit each of them with a constant and do just as well. Most points are statistically consistent with zero.