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<div class="moz-cite-prefix">... and in RooFit you also find the Novosibirsk function I mentioned. Not that I am an expert but maybe it is similar.<br>
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<a href="http://root.cern.ch/root/html/RooNovosibirsk.html">http://root.cern.ch/root/html/RooNovosibirsk.html</a><br>
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<pre class="moz-signature" cols="72">Susan Schadmand
<a href="http://www.fz-juelich.de/ikp">www.fz-juelich.de/ikp</a></pre>
On 10.12.2013 20:53, Craig Bookwalter wrote:<br>
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<div>Hi MK,<br>
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My intuition is not well-developed in this arena, but in your binned fits of the pi0 yield, it seems to me that a reverse Crystal Ball function would better suit your data, given the tails that stick out on the high side. This shape is included with RooFit
(which I have never used myself but seems to be heavily used in HEP) as RooCBShape. I found a tutorial online for RooFit that includes a CB lineshape (written by a guy I went to grad school with, actually):<br>
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<a href="http://hadron.physics.fsu.edu/%7Eskpark/document/ROOT/jdhaas_RooFit.pdf">http://hadron.physics.fsu.edu/~skpark/document/ROOT/jdhaas_RooFit.pdf</a><br>
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<div>However he uses a regular CB, whereas I think you need a reverse CB. From the following link, I think you can get a reverse CB from requiring the parameter "n" to be negative:<br>
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<a href="http://root.cern.ch/phpBB3/viewtopic.php?t=6196">http://root.cern.ch/phpBB3/viewtopic.php?t=6196</a><br>
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There is also a Wikipedia article about it:<br>
<a href="http://en.wikipedia.org/wiki/Crystal_Ball_function">http://en.wikipedia.org/wiki/Crystal_Ball_function</a><br>
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<div>I am sorry that I don't have any direct experience with which to help you, but perhaps this can get you started. Also, I checked my flights, and I'll be able to come to the first 20 minutes of next week's meeting.
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<div>Good luck!<br>
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--cb<br>
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