[G12] crystal ball function

[Susan Schadmand]

... and in RooFit you also find the Novosibirsk function I mentioned. Not that I am an expert but maybe it is similar.

http://root.cern.ch/root/html/RooNovosibirsk.html


Susan Schadmand
www.fz-juelich.de/ikp<http://www.fz-juelich.de/ikp>

On 10.12.2013 20:53, Craig Bookwalter wrote:
Hi MK,
  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):

http://hadron.physics.fsu.edu/~skpark/document/ROOT/jdhaas_RooFit.pdf<http://hadron.physics.fsu.edu/%7Eskpark/document/ROOT/jdhaas_RooFit.pdf>

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:

http://root.cern.ch/phpBB3/viewtopic.php?t=6196

There is also a Wikipedia article about it:
http://en.wikipedia.org/wiki/Crystal_Ball_function

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.

Good luck!

--cb






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