Fit Run8 p+p NPE results (data points provided by Wei and Jin Fu) with Power-law D0 decays.

The fit results are below:

==================== Fit TOF Only ===================

<pt> = 1.04  +/- 0.07 +/- 0.10 (GeV/c)

n = 18.5 +/- 5.0 +/- 10.5

xsec = 1.05 +/- 0.07 +/- 0.28 (mb)

chi²/ndf = 22.98/19 (stat.), 3.77/19 (stat. + sys.)

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========= Fit TOF+EMC with uncorrelated error ============

<pt> = 0.92  +/- 0.05 +/- 0.14 (GeV/c)

n = 11.5 +/- 2.0 +/- 5.5

xsec = 1.06 +/- 0.10 +/- 0.36 (mb)

chi²/ndf = 40.18/28 (stat.), 2.33/28 (stat. + sys.)

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========== Fit TOF+EMC with correlated error ==============

<pt> = 0.92  +/- 0.05 +/- 0.08 (GeV/c)

n = 11.5 +/- 2.0 +/- 3.0

xsec = 1.07 +/- 0.10 +/- 0.30 (mb)

chi²/ndf = 40.18/28 (stat.), 8.53/28 (stat. + sys.)

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========== Fit latest TOF+EMC with correlated error ==============

TOF data: http://portal.nersc.gov/project/star/jfazj/NPE/YIFEI_NPE_XS/NPE_XS_YIFEI.txt

EMC data: combined latest results of Run5 (Gang) and Run8 (Wei)

<pt> = 0.90  +/- 0.04 +/- 0.10 (GeV/c)

n = 10.5 +/- 1.0 +/- 2.0

xsec = 1.08 +/- 0.05 +/- 0.32 (mb)

chi²/ndf = 52.13/28 (stat.), 5.06/28 (stat. + sys.)

see Fig. 7 and 8

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Fit plots and cross section vs Nbin are below:

                            Fig. 1 Fit TOF NPE only with Power-law D0 decay.

 

               Fig. 2 Combined fit to TOF and EMC NPE with Power-law D0 decay.

 

 

                   Fig. 3 Charm cross section as a function of Nbin.

            p+p data point is from the combined fit to TOF and EMC NPE in Run8.

 

                 Fig. 4 pT spectra compared with FONLL calculation.

 

                                        Fig. 5 Ratio to FONLL （Log Scale).

 

                                    Fig. 5 Ratio to FONLL （Linear Scale).

 

                            Fig. 6 Ratio to FONLL （Compare with Run 3).

 

 

            Fig. 7 Combined fit to latest TOF and EMC NPE with Power-law D0 decay.

 

                 Fig. 8 Charm cross section as a function of Nbin.

            p+p data point is from the combined fit to TOF and EMC NPE in Run8+5.

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Summary:  The cross section constrained by low pT TOF data points.

The fit results with TOF only and with TOF+EMC are consistent.

high pT EMC data points constrain the spectrum shape (<pt>, n).

The systematic error in the cross section includes the bin-by-bin

stat. + sys. errors from spectrum and the overall normalization errors

(latest correlated sys. error: TOF 14%, EMC 4%).

The final result is consistent with previous measurements.

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