<div dir="ltr"><div><div><div>Hi MK,<br></div> 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>
<br><a href="http://hadron.physics.fsu.edu/~skpark/document/ROOT/jdhaas_RooFit.pdf">http://hadron.physics.fsu.edu/~skpark/document/ROOT/jdhaas_RooFit.pdf</a><br><br></div><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>
<br><a href="http://root.cern.ch/phpBB3/viewtopic.php?t=6196">http://root.cern.ch/phpBB3/viewtopic.php?t=6196</a><br><br></div>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>
<br></div><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. <br>
<br></div><div>Good luck!<br><br>--cb<br></div><div><br><br></div><div><br></div></div>