[Rivet] [Fwd: Re: Using S0 + Prof LEP FS tune]

[Andy Buckley]

FYI, information from Peter about setting up the current "Skands + Prof"
best tune for pT-ordered Py6. This is what is needed for testing Rivet
in Athena with the best Py6 tune. I'll send the detailed params in the
next email, but this one is also interesting for documenting what's
coming in Py6420.

If we're lucky, we might have the Professor full tune of
pT-ordered/interleaved Pythia6 ready for 6420, too: I'm not sure what
Peter's planned schedule is.

Andy


-------- Original Message --------
Subject: Re: Using S0 + Prof LEP FS tune
Date: Wed, 19 Nov 2008 17:21:29 -0600
From: Peter Skands <skands at fnal.gov>
To: Andy Buckley <andy.buckley at durham.ac.uk>
References: <49249C29.2070307 at durham.ac.uk>

Hi Andy,

D0 and CDF have started using the "S0" tune. You can activate it
either by calling PYTUNE(300) before initialization, or by setting
MSTP(5)=300. Using MSTP(5) is just a shorthand, it will make PYINIT
call PYTUNE, and is sometimes easier for experimental setups, but the
two ways do exactly the same thing.

What will come with 6420 are
* A tune identical to S0, except for the fact it uses the professor
LEP parameters. I am tentatively calling that tune S0-Pro, to
distinguish it from the amateur S0, and am planning to give it number
310. That way, by comparing 300 and 310, people can see explicitly
what the change of the fragmentation parameters does.
* In fact, all the pT-ordered tunes will receive "Pro" variants,
obtained by adding 10 to their tune number, so there will also be APT-
Pro (211), NOCR-Pro (314), etc. But that's a minor thing, just
intended if someone wants to check what the effect is for a particular
tune.
* In addition to these "revamped" tunes with professor parameters, I
have also improved S0 itself, so that it now scales better to 630 GeV
and describes, e.g., <pT>(Nch) better. That tune I am calling
Perugia-0, and it will have number 320. It will include the professor
parameters from the start (another reason why its name starts with
"P"). In combination with that tune, I have attempted to make a "+"
and a "-" tune, for systematic variations. These will also be included
in 6420 and will get numbers 321 and 322.

For the time being, what you can do is:
1) Run Tune S0 as it is. That is what the experiments have so far been
looking at.
2) Run Tune S0, with the professor fragmentation parameters slapped
onto it. That should simply be a LEP-improved variant of S0, which I
already showed in Perugia, and which will be available with number 310
from 6420 on. You should do this by calling PYTUNE(300) and *then* set
the fragmentation parameters, since Lambda_FSR may otherwise be
overwritten. The newest "Perugia" tunes I am still in the process of
finalizing, so let me hold on to them a little while longer.

Cheers,
PEter



On Nov 19, 2008, at 5:07 PM, Andy Buckley wrote:

> Hi Peter,
>
> Can you remind me what is the status of the Pythia 6 pT-ordered  
> shower /
> interleaved UE tune that we were going to call "PRO1" (or similar)? Is
> this a standard tune now in Pythia, or will that come with 6420?
>
> For now, so I can show D0 how some of their distributions are  
> described
> by the "best available" Pythia tunes, how can I activate this tune?  
> And
> what PDF set was used in making the ISR/UE part?
>
> Thanks!
> Andy


-- 
Dr Andy Buckley
Institute for Particle Physics Phenomenology
Durham University
0191 3343798 | 0191 3732613 | www.insectnation.org