How to input parameters in Whizard by using a .dat file

Asked by David Wang on 2020-08-24

Hi Whizard team,

In Madgraph, we can input a .dat file which contains all the parameters as a parameter card and run the process based on that specific set of parameters. I am wondering if we have equivalent command/function in Whizard which can take input parameters from a file.

I have tried to set parameter explicitly in the .sin script. This is convienient when I only have a few parameters to change. But, if I want to change more parameters, it is more convenient to use the parameter card generated with the UFO file(by FeynmanRule) directly. I am wondering if we can do so.

Thanks.

Question information

Language:
English Edit question
Status:
Solved
For:
WHIZARD Edit question
Assignee:
Juergen Reuter Edit question
Solved by:
Juergen Reuter
Solved:
2020-09-07
Last query:
2020-09-07
Last reply:
2020-08-28
Best Juergen Reuter (j.r.reuter) said : #1

Hi David,
yes, this option exists. It is assumed that there is a SLHA-like file, <your_param_file>.slha, that is then read in with the SINDARIN
command
read_slha ("<your_param_file>.slha")
This has the follow the usual BLOCK structure specified in the (S)LHA standard.
This part has not yet been added to the WHIZARD manual.
Best,
    JRR

David Wang (david-mhw) said : #2

Thank you!

Is QNUMBERS extension also supported in this SLHA-like file?

For instance, I have the following error when I use the QNUMBERS extension. Here is what I have in the slha file.
###################################
## INFORMATION FOR QNUMBERS 35
###################################
BLOCK QNUMBERS 35 # h2
      1 0 # 3 times electric charge
      2 1 # number of spin states (2s+1)
      3 1 # colour rep (1: singlet, 3: triplet, 8: octet)
      4 0 # particle/antiparticle distinction (0=own anti)

The error is :
BLOCK QNUMBERS 35 $
               ^-^
| Expected syntax: SEQUENCE <block_def> = BLOCK <block_spec> '$' <block_line>*
| Found token: NUMERIC: '35'

Juergen Reuter (j.r.reuter) said : #3

QNUMBERS is an extension beyond the usual (S)LHA standard. It is not needed inside WHIZARD to define new BSM particles. Of course, we could hack in order for the parser to ignore these blocks, but I think the safer option is not to generate them in the first place.

Wolfgang Kilian (whkilian) said : #5

I should add that according to the original SLHA standard, this block syntax is a violation of the standard, hence the parser issues an error. I know that this "standard" has been developing over the years, so the parser might be too pedantic in that case.

Otherwise, Juergen's comment applies: the program should run fine if this block is deleted from the input file.

David Wang (david-mhw) said : #6

Thank you!

David Wang (david-mhw) said : #7

Thanks Juergen Reuter, that solved my question.

Juergen Reuter (j.r.reuter) said : #8

As an add-on: we were not aware (this information was missing to us) that there is a tool that ships with a UFO model that creates this BSM SLHA file. We were vetoing an SLHA block of the form
Block QNUMBERS <signed_integer>
because it is not part of the original SLHA standard. However, from tonight on (2020, Sep 25) our development version will accept this (and only this) additional structure, but as I said we do not use this information internally. This will be included in v3.0.0 of WHIZARD.