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Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18356&th=4654#msg_18356
during my investigation of cascade reconstruction with PandaRoot, I found that after the four-constraint fitter my mass resolution got worse. You can see the difference in the plot I attached. Shown are the invariant mass distributions after applying a cut on the probability (>0.01) of the four-constraint fit, once with the pre-fit values (blue) and once with the values after the fit (green).
My decay is p̅p → Ξ̅Ξ → Λ̅π⁺ & ΛK⁻ with Λ → π⁻p and Λ̅ → π⁺p̅. So in my reconstruction I'm dealing with neutral particles (Λ). I asked a bit around here in the institute and it seems, others see a similar effect when having a mixture of neutral and charged candidates as input to the 4C fitter.
I'm running with trunk r27694 but it has been seen from others here with scrut14 as well. More details like a minimal running example will follow as soon as I have concluded my thesis, which is due in the next days. In the meantime: did anyone else see something like this? If so, is there an explanation to that?
Best,
-André
PS: The mass values are taken from the PndRhoTupleQA method qaCand().
]]>André Zambanini2015-07-08T07:37:40-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18357&th=4654#msg_18357
StefanoSpataro2015-07-08T08:03:01-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18358&th=4654#msg_18358
What the covariance matrix is concerned I don't know. I didn't store this information and I'll probably don't get to it before the 20th. ]]>André Zambanini2015-07-08T08:10:48-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18359&th=4654#msg_18359
StefanoSpataro2015-07-08T08:18:37-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18360&th=4654#msg_18360
]]>André Zambanini2015-07-08T08:29:13-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18365&th=4654#msg_18365
StefanoSpataro2015-07-08T09:26:53-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18366&th=4654#msg_18366
My original intention was to ask around first if anybody else saw this in the past. The hunt for the source of this feature I wanted to postpone, otherwise I fear my deadline is endangered.]]>André Zambanini2015-07-08T09:33:07-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18367&th=4654#msg_18367
StefanoSpataro2015-07-08T09:38:17-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18368&th=4654#msg_18368
André Zambanini2015-07-08T09:41:56-00:00Re: Invariant Mass Distribution Widening after 4C Fit
https://forum.gsi.de/index.phpindex.php?t=rview&goto=18372&th=4654#msg_18372
StefanoSpataro2015-07-09T13:50:39-00:00