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2017:groups:tools:susylha [2017/06/20 16:22] stefan.liebler |
2017:groups:tools:susylha [2017/06/22 18:20] olivier.mattelaer [The details] |
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- | Extension to the SLHA for cross sections | + | ====== Extension to the SLHA for cross sections ====== |
Interested people: Olivier Mattelaer, Sezen, Benjamin, Stefan ... ADD YOUR NAME | 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: | + | Work started in LH 2013. Already quite complete. Needs to be polished and written up. Need to get agreement for the SUSY code developers. |
- | Details in 2013 twiki: | + | |
- | https://phystev.cnrs.fr/wiki/2013:groups:tools:slha | + | ==== The details ==== |
+ | |||
+ | 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 | ||
+ | <code> | ||
+ | XSECTION SQRTS PDG_CODE1 PDG_CODE2 NF PDG_CODE3 .... | ||
+ | </code> | ||
+ | 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 | ||
+ | <code> | ||
+ | SCALE_SCHEME QCD_ORDER EW_ORDER KAPPA_F KAPPA_R PDF_ID1 PDF_ID2 VALUE VALUEUP VALUEDOWN DUMMY | ||
+ | </code> | ||
+ | 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... | ||
+ | |||
+ | Stefan comments: | ||
+ | - 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. | ||
+ | - | ||
+ | - 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. | ||
+ | - | ||
+ | - Some codes also give a scale uncertainty in the same run. Can this be added? |