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Too small chi2 in CMS_TTBAR_8TEV_2L_DIF_MTTBAR-YT-NORM

Open jacoterh opened this issue 5 months ago • 1 comments

The new commentata implementation of dataset CMS_TTBAR_8TEV_2L_DIF_MTTBAR-YT-NORM seems to overestimate experimental uncertainties in the new commondata implementation resulting in a super low chi2=0.0274 per datapoint (ndat = 15). The old commondata implementation did a much better job, giving chi2=1.28 per datapoint. Both chi2 are computed with the fully NNLO TTBAR FK tables from MATRIX.

In these comparisons, current fit refers to the NNLO TTBAR FK tables, while the reference fit refers to theory 708, i.e. NLO + K-factors.

jacoterh avatar Aug 14 '25 12:08 jacoterh

@kamillaurent please have a look at the implementation of the dataset (check that all correlations are ok / bin widths taken into account, etc)

scarlehoff avatar Oct 21 '25 12:10 scarlehoff