# First Look at Single-spin Asymmetries

Updated on Thu, 2007-10-18 12:53. Originally created by kocolosk on 2007-10-18 12:30.

**This is a study of 2005 data conducted in March 2006. Ported to Drupal from MIT Athena in October 2007**

eL_asymmetries.pdf

phi_asymmetries.pdf

Single-spin asymmetries for blue and yellow beams are calculated for each fill and sorted by particle charge and trigger ID. Each plot includes a legend that lists the value I calculate for the asymmetry when I integrate over pt bins. I fit each plot with a straight line and include the values of the fit parameters. The first page of the PDF is integrated over all data, and then fill-by-fill plots are available on subsequent pages. The basic structure of the PDF is as follows: each page contains all the plots for a given fill. Trigger IDs are constant for each column (mb,ht1,ht2,jp1,jp2). The top two rows are yellow and blue beam asymmetries for positively charged hadrons; the bottom two rows are the same plots for q=-1. This gives a total of twenty single-spin asymmetries for each fill.

I also increment 20 separate histograms with (asymmetry/error) for each fill and then fit the resulting distribution with a Gaussian. Ideally the mean of this Gaussian should be centered at zero and the width should be exactly 1. The results are in asymSummaryPlot.pdf

Finally, a summary of single-spin asymmetries integrated over all data. 2-sigma effects are highlighted in **bold**:

+ | MB | HT1 | HT2 | JP1 | JP2 |

Y | 0.0691 +/- 0.0775 | 0.0069 +/- 0.0092 | -0.0038 +/- 0.0126 | 0.0086 +/- 0.0104 | 0.0116 +/- 0.0069 |

B | -0.0809 +/- 0.0777 | -0.0019 +/- 0.0092 | -0.0218 +/- 0.0126 | 0.0067 +/- 0.0104 | -0.0076 +/- 0.0069 |

- | MB | HT1 | HT2 | JP1 | JP2 |

Y | -0.0206 +/- 0.0767 | -0.0193 +/- 0.0092 |
-0.0158 +/- 0.0130 | -0.0035 +/- 0.0101 | 0.0061 +/- 0.0070 |

B | 0.0034 +/- 0.0769 | -0.0021 +/- 0.0092 | 0.0006 +/- 0.0130 | -0.0164 +/-0.0101 | -0.0147 +/- 0.0070 |

**: The jet group sees significant nonzero single-spin asymmetries in Yellow JP2 (2.5 sigma) and Blue JP1 (4 sigma). I do not see these effects in my analysis. I do see a handful of 1 sigma effects and two asymmetries for negatively charged hadrons that just break 2 sigma, but in general these numbers are consistent with zero. I also do not see any significant dependence on track phi.**

Conclusions

Conclusions

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