[Blackmax] Interesting eta distributions from BlackMax

[Eram Rizvi]

Hi Chris,

Sorry for the delay in getting back to you regarding this problem. We
have now found and fixed a bug in BlackMax which was causing this -
so, thank you for bringing it to our attention.

There are a few minor changes we are making to BlackMax and once those
are complete we will release a new version, probably within the next
month. If you are happy to wait till then you will receive an email
when the new version is released as long as your signed up to our
mailing list. If you'd like a test version sooner to check, then
perhaps we can send you a private patched version of the code.
However, this would only be for testing and I'd ask you to switch to
the new release as soon as it is announced.

Thanks again,
Eram

On 23 July 2010 09:38, Chris Pollard <chris.pollard at duke.edu> wrote:
> Hello BlackMax authors,
> A few of my colleagues at Duke and I have been using with your generator off
> and on for a year now, and we've recently found some puzzling eta
> distributions coming out of it.
> For instance, I've attached graph that comes from proton-proton collisions
> at 7 TeV with the two particle final state setting on.  This is for the
> top+graviton channel.  We can't think of why the eta distributions for the
> tops and gravitons would be asymmetric at a proton-proton collider,
> We see similar asymmetries for the top+bottom and top+strange final state
> eta distributions, while top+charm and top+up final states are symmetric, as
> expected.
> One other thing we've noticed is that for whatever reason, the generator
> output is always "sorted" based on some parameter when the asymmetry arises.
>  For instance, when the final state is top+charm, the top can be either the
> first or second particle listed in the output, each about half the time.
>  But in the top+graviton final state, the top is always listed second, and
> in the tob+bottom final state, always first.
> This seems strange to us, but perhaps we are overlooking something?
> I've also attached my parameter.txt file if that helps.  Maybe I have an
> error there.
> Thanks for your time!
> Chris Pollard
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