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| 3 | === Questions and Answers === |

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| 5 | * ''Is there a simple way to get a histogram of of the center of mass energy, sqrt(\hat s) ?... Roni'' |

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| 7 | Hi Roni, I assume you are speaking about the true center of mass energy at the partonic level in hadronic collision (otherwise it is of course a fixed quantity). By default ExRootAnalysis is not set up to produce such an histogram automatically so there is no an "easy" way to get it (i.e. by only modifying the plot_card). Nevertheless this quantity can be trivially extracted from the parton level rootfile which is produced during generation. Of course you need to know a little bit about ROOT to do so. You can write directly to our ROOT expert and author of ERA, Pavel (pavel.deminATfynu.ucl.ac.be), if you need more support for this. ''Michel'' |

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| 10 | -- Main.MichelHerquet - 06 Apr 2007 |