Discrimination of converted photons and neutral pions at high energies

XIAO Hong; CHEN Guo-Ming; TAO Jun-Quan; BIAN Jian-Guo; FAN Jia-Wei; LIANG Song; MENG Xiang-Wei; SHEN Yu-Qiao; TANG Zhi-Cheng; WANG Jian; WANG Xian-You; WANG Zheng; XU Ming; XU Wei-Wei; YANG Min; YAN Qi

doi:10.1088/1674-1137/36/10/011

Chinese Physics C> 2012, Vol. 36> Issue(10) : 979-984 DOI: 10.1088/1674-1137/36/10/011

Discrimination of converted photons and neutral pions at high energies

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In the LHC experiment, the H→γγ channel provides a clean nal state with an effective mass peak that is reconstructed with great precision, despite the small branching ratio. As a consequence, the H→γγ channel is one of the most promising channels for the Higgs discovery in the very low mass region. In order to increase the sensitivity of the Higgs search, background rejection rate is very important, so γ/π⁰ discrimination is one of the key points in the analysis. At least 40% of photons will convert with the experience of ATLAS and CMS. We constructed electromagnetic calorimeter (ECAL) in GEANT4 simulation, using 6 variables which have different shapes between converted γ and π⁰, with the TMVA (Toolkit for Multivariate Data Analysis) to do the separation. With this method we can get 30% to 60% π⁰ rejection efficiency when keeping 90% converted γ efficiency, in the region of transverse momentum 15 GeV to 75 GeV, not only in MC sumulation but also in real data.

References

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XIAO Hong, CHEN Guo-Ming, TAO Jun-Quan, BIAN Jian-Guo, FAN Jia-Wei, LIANG Song, MENG Xiang-Wei, SHEN Yu-Qiao, TANG Zhi-Cheng, WANG Jian, WANG Xian-You, WANG Zheng, XU Ming, XU Wei-Wei, YANG Min and YAN Qi. Discrimination of converted photons and neutral pions at high energies[J]. Chinese Physics C, 2012, 36(10): 979-984. doi: 10.1088/1674-1137/36/10/011

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Received: 2012-01-18
Revised: 2012-03-15

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通讯作者: 陈斌, bchen63@163.com

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沈阳化工大学材料科学与工程学院沈阳 110142

Discrimination of converted photons and neutral pions at high energies

Corresponding author: XIAO Hong,

Received Date: 2012-01-18

Accepted Date: 2012-03-15

Available Online: 2012-10-05

Abstract: In the LHC experiment, the H→γγ channel provides a clean nal state with an effective mass peak that is reconstructed with great precision, despite the small branching ratio. As a consequence, the H→γγ channel is one of the most promising channels for the Higgs discovery in the very low mass region. In order to increase the sensitivity of the Higgs search, background rejection rate is very important, so γ/π⁰ discrimination is one of the key points in the analysis. At least 40% of photons will convert with the experience of ATLAS and CMS. We constructed electromagnetic calorimeter (ECAL) in GEANT4 simulation, using 6 variables which have different shapes between converted γ and π⁰, with the TMVA (Toolkit for Multivariate Data Analysis) to do the separation. With this method we can get 30% to 60% π⁰ rejection efficiency when keeping 90% converted γ efficiency, in the region of transverse momentum 15 GeV to 75 GeV, not only in MC sumulation but also in real data.

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Discrimination of converted photons and neutral pions at high energies

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