-- WouterHulsbergen - 14 Mar 2006

14 Mar 2006. This is still a big mess, because I started too late. More next week


  • The Supersymmetry Parameter Analysis homepage has links to all (?) available tools:
    • spectrum calculators
    • calculations of other observables (decays, cross sections, low-energy observables ...)
    • event generators
    • fitters
    • 'RGE programs' (isn't this part of what the spectrum calculators are supposed to do?)

  • With respect to event generation, there seem to be a few programs that can do everything.
    • Herwig. interface to Isajet spectrum calculator via Isawig. there was something like a Herwig++ project, but it is not clear where that went. does it have a different name now? Isajet (home page) uses a numerical solution to the RGEs.

    • Pythia (description home page implements various BSM models, among which susy. Pythia uses a analytic approximation to solve the RGE. (I got this wisdom from Frank Paige's note.) Is this the reason that the SUSY spectrum differs from that from Isajet?

According to remarks in the SUSY meeting, pythia does not calculate the spectrum correctly: at least it solves the RG equations different from herwig, and as a result you get a different spectrum, especially for decays into 3rd generation quarks: those are unreliable in spythia.

it was once agreed upon to use isawig (==isasusy) to compute the spectrum and then feed to low energy spectrum directly to pythia.

The SUSY extensions of ISAJET, PYHTIA and HERWIG all us mSugra. ISAJET has a few more parameters that allow to deviate from mSUGRA. It has for example GMSB parameters.

What do we have in atlas?

  • What is the 'generator chain' for susy events in atlas? a flowchart would be helpful ...

  • What is Jimmy? --> generator for multi-parton scattering

More documentation

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Topic revision: r2 - 2006-04-04 - unknown
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