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icon5.gif  question concerning pbar p->pi0 pi0 [message #5549] Mon, 03 December 2007 21:06 Go to next message
Johan Messchendorp is currently offline  Johan Messchendorp
Messages: 693
Registered: April 2007
Location: University of Groningen
first-grade participant

From: *xs4all.nl
Dear all,

Please find below an email from Michael Dueren who asks whether there exists a parameterization of the pbar p -> pi0 pi0 cross section. Can anyone help him out here?

Johan.

----------- original email --------------

Irina Brodski in our group is simulating the ppbar -> gamma gamma and to gamma pi-zero processes.

In addition she needs the background p pbar -> pizero pizero, but she does not know where to get the cross section for this reaction. Do you know if in the pandaroot there is already a generator for p pbar -> pizero pizero that has the right energy dependence of the cross section? If not: do you know if there is a parameterization of a database with this cross section somewhere accessible?

Best regards,
Michael.

-------------------------------------


Johan Messchendorp
University of Groningen/KVI
Zernikelaan 25
NL-9747 AA Groningen
The Netherlands
tel. +31-503633558
fax +31-503634003
Re: question concerning pbar p->pi0 pi0 [message #5550 is a reply to message #5549] Tue, 04 December 2007 07:02 Go to previous message
Jens Sören Lange is currently offline  Jens Sören Lange
Messages: 193
Registered: June 2005
first-grade participant
From: *kek.jp
Dear all,

no parametrization, but at least a few cross section numbers
in the 2-4 GeV region: (but one can see an energy dependance)

http://durpdg.dur.ac.uk/cgi-bin/hepdata/testreac/10738/FULL/q
http://durpdg.dur.ac.uk/cgi-bin/hepdata/testreac/7414/FULL/q
http://durpdg.dur.ac.uk/cgi-bin/hepdata/testreac/3008/FULL/q

Please note that Irina is using EvtGen which fixes the initial
state to J=1 (so the J=0,2,3,4,... are missing in her simulation,
but are in the above cross section numbers). But currently there
is no way to avoid this (and nobody knows the exact angular
momentum mixture in the initial state anyway before Panda
starts running).

Furthermore, her EvtGen does (right now) not take into account
intermediate resonances, such as the f0(980)
(which we know must be there in pi0 pi0).

Soeren
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