Interested people: Olivier Mattelaer, Sezen, Benjamin, Stefan … ADD YOUR NAME

Work started in LH 2013. Already quite complete. Needs to be polished and written up. Need to get agreement for the SUSY code developers.

The plans is to add new blocks to a supersymmetric spectrum with information on production cross section of particles included in the spectrum of interest. We propose to add one new block for each process under consideration.

The block starts with

XSECTION SQRTS PDG_CODE1 PDG_CODE2 NF PDG_CODE3 ....

where

• SQRTS: a floating number representing the center-of-mass energy, to be given in GeV.
• PDG_CODE1 and PDG_CODE2: two integer numbers, representing the pdg codes of the initial state particles
• NF: an integer number, representing the number of final state particles
• PDG_CODE3, PDG_CODE4, …: NF integer numbers, representing the pdg codes of the final state particles

This general information line is then followed by the cross section themselves, given as a series of line under the form

  SCALE_SCHEME QCD_ORDER EW_ORDER KAPPA_F KAPPA_R PDF_ID1 PDF_ID2 VALUE VALUEUP VALUEDOWN DUMMY 

where

• SCALE_SCHEME: an integer number, related to the way the central scales are chosen. So far, the choices are
  • 0: the central scale is the average mass of the produced particles
  • 1: fixed scales
  • 2: the scale is set to the invariant mass of the final state particles at the LO
  • 3: the scale is set to the transverse mass of the final state particles at the LO
  • 4: some other definition to be described as a comment
• QCD_ORDER: an integer number, which contains information on the order in alpha_s included in the computation. This is codified as
  • 0: Born cross section
  • 1: NLO cross section
  • 2: NLO+NLL cross section
• EW_ORDER: same as above but with respect to electroweak corrections
• KAPPA_F: a floating point number, related to the variation of the factorization scale with respect to the central scale. For SCALE_SCHEME set to 1, the scale itself has to be provided.
• KAPPA_R: same as above, for the renormalization scale
• PDF_ID: the lhapdf code of the employed parton densities
• VALUE: a floating point number, representing the value of the cross section in pb.
• DUMMY: integer number to tag possible different options to be described in the comments
• CODE: as a COMMENT string representing the name of the program which has computed the cross section
• VERSION: as a COMMENT string, the version number of the proram employed
• REFERENCE: Citation
• FIX the meaning of DEFAULT values…

Olivier Questions:

1. Do we really want to have 1 line for each PDF replica? Would not be better to quote the theoretical uncertainty in % ?
2. What about non LHC collision (fix target/ DIS/…)? This requires 2 PDF id.
3. other scheme are often used like HT/2 and (CKKW ones) are not even analytic.
4. What about NNLO or NNLL?
5. using some xml tag in a non xml like file is weird (or I do not understand where you plan to write such information).
6. Missing the information of the statistical uncertainty

Stefan comments:

1. PREFERRED OPTION: In order to deal with resummation I suggest to add a second digit to QCD_ORDER, i.e. 0=LO, 1=NLO, 2=NNLO, etc. 11=NLO+NLL, 21=NNLO+NLL, 22=NNLO+NNLL, etc.. Only LO+LL=00 is then not well defined. And this approach is not specific to what is actually resummed (p_T, threshold,…). TYPE of resummation as a COMMENT.
3. OPTIONAL: For EW corrections it would be helpful to somehow encode if full factorization is assumed or not. ⇒ Implement as a comment what scheme is used to combine QCD and EW corrections.
5. Some codes also give a scale uncertainty in the same run. Can this be added?