You can vary the mean free path for pions and nucleons. This should have a similar effect (adding an FSI-free formation zone is equivalent with having a longer mean free path).
As Torben says, in the current implementation, the actual formation zone parameter is relevant only for DIS events, not resonance events. The argument for this is rather simplistic, as is the formation zone effect itself.
On 14 Feb 2014, at 17:57, "Xinchun Tian" <[log in to unmask]<mailto:[log in to unmask]>> wrote:
I want to understand the FSI in Res by varying the Formation Zone parameter. For example, by changing this ct0 to different numbers, and compare the kinematics of final state particles to data.
From: Torben Ferber <[log in to unmask]<mailto:[log in to unmask]>>
Reply-To: Torben Ferber <[log in to unmask]<mailto:[log in to unmask]>>
Date: Friday, February 14, 2014 at 1:32 AM
To: "[log in to unmask]<mailto:[log in to unmask]>" <[log in to unmask]<mailto:[log in to unmask]>>
Subject: Re: Formation zone parameter - ct0
the formation zone is a concept that is only used for generating DIS events. reweighting (which works for DIS) or regenerating RES or QEL with changed parameter ct0 in your UserPhysicsOptions will not effect your RES or QEL events.
what do you want to achieve by tweaking the formation zone for RES/QEL?
On February 14, 2014 3:41:31 AM CET, Xinchun Tian <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Dear GENIE experts,
As there is no way to using the re-weight technique on formation zone parameter for QE and Res, but I still want to have different samples by varying the ct0 parameters.
Is there a way to work around this problem? Can I change UserPhysicsOptions.xml “<param type="double" name="FZONE-ct0"> 0.342 </param> “, for example, to <param type="double" name="FZONE-ct0"> 0.513 </param> and regenerate the splines, then do the event generation?
Dr. Torben Ferber
Belle & Belle II
Deutsches Elektronen Synchrotron (DESY)
Notkestraße 85, Bld. 1d, O2/412
phone: +49 (0)40-8998-3982
fax: +49 (0)40-8994-3982
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