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W predictions at LHC using the H1-ZEUS combined fit. W e cross-sections at LHC calculated at NLO with MCFM. Goal : look at how the uncertainties are reduced with the DIS’08 combined fit, comparisons with Mandy. Cuts: P T,e > 25 GeV | e | < 3
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W predictions at LHC using the H1-ZEUS combined fit W e cross-sections at LHC calculated at NLO with MCFM. Goal : look at how the uncertainties are reduced with the DIS’08 combined fit, comparisons with Mandy. Cuts: PT,e > 25 GeV | e | < 3 R (j, e) > 0.7 if real emission Use the MCFM interface to LHAPDF to calculate the predictions with various fits : - CTEQ 6.1 - H1pdf2k - ZEUS 2002 ZM but some jobs crashed - H1ZEUS DIS’08 (I first put the fit results into a LHgrid file). 14 May 08
Differential cross-sections • H1ZEUS gives larger cross-section than CTEQ 6.1 • Note the much smaller uncertainty (see later) • Calculations with CTEQ 6.1 : differences between my xs and Mandy’s xs : • due to the R cut that I have in the MCFM calculations. • Without this cut, my total xsection is ~ 15% higher. 14 May 08
CTEQ 6.1, Mandy vs. mine : different shape at high eta. To be checked with MCFM without the R cut. 14 May 08
Relative uncertainties of W predictions My errors: sym. formula, i.e. (up – down) / 2. • Fit uncertainty : large reduction with H1ZEUS, compared with H1pdf2k. • Full uncertainty : yellow hist = mine - the 6 model variations. • black dashed = Mandy’s - vary Q20 (largely dominant) • Many and I get the same rel. uncertainty. • Much smaller than the error obtained from CTEQ 6.1 14 May 08
