implementation of CMS_WCHARM_7TEV in the new format

[achiefa]

Comments

This dataset delivers two different observables:

• Total x-sec
• Ratio of x-secs

The variant sys_10 accounts for the 3pt prescription and thus it should be deprecated in the new format.

$(x,Q^2)$-map and data-theory comparison

Legacy: [default]

[achiefa]

This PR is still WIP. Here you can find a report of the new implementation, which is preliminary: report
I have some comments:

• The RATIO xsec in HepData provides statistical and systematic uncertainties. However, the legacy version implemented only the statistical uncertainty (I'm not considering the two additional sys uncertainties for the scale variations). Is there something here that I don't understand?
• For the TOT xsec, I can't reconstruct the covmat. Note that, for this observable, we have the correlation matrix.