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研究生：	林舒芳 Victoria Louise Quilatan
論文名稱：	Search for a Higgs boson decay into γ*γ→µµγ in pp collisions at √s = 13 TeV
指導教授：	郭家銘 Chia-Ming Kuo
口試委員:
學位類別：	碩士 Master
系所名稱：	理學院 - 物理學系 Department of Physics
論文出版年：	2018
畢業學年度：	106
語文別：	英文
論文頁數：	130
中文關鍵詞：	希格斯玻色子、渺子、緊湊渺子線圈、大強子對撞機
外文關鍵詞：	Dalitz, 13 TeV
相關次數：	點閱：18 下載：0
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本篇論文研究希格斯玻色子衰變為一個光子和一個虛光子，其中虛光子再衰變為正負渺子對。此分析使用從質子-質子對撞，質心能量於13兆電子伏特，且於大強子對撞機之緊湊渺子線圈偵測器所記錄的數據，使用數據量則對應於綜合亮度35.9fb-1。研究結果顯示，在重建希格斯粒子的質量範圍120到130十億電子伏特區間內，沒有超出背景預期的訊號產生。在雙渺子重建質量低於50十億電子伏特的條件，及95％的信心水平下，希格斯玻色子生產橫截面的實際觀察（預測）訊號強度上限為標準模型預測值的1.44（2.15）和4.04（2.26）倍之間。

A search for a Higgs boson decay into a real and a virtual photon, where the virtual photon internally converts into muons, H → γ∗γ → µµγ, is described. The analysis uses data collected from proton-proton collisions with a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9fb−1. No excess above background has been found for the three-body invariant mass range 120 < mµµγ < 130. Limits have been derived for the Higgs Boson production cross section, where the dilepton invariant mass is below 50 GeV. The observed(expected) exclusion limits at 95% confidence level (CL) are between 1.44(2.15) and 4.04(2.26) times the standard model value.

Introduction 1
1 Standard model and Higgs mechanism . . . . . . . . . . . . . . . . . 1
2 Higgs boson production at the LHC . . . . . . . . . . . . . . . . . . . 2
2.1 Background processes . . . . . . . . . . . . . . . . . . . . . . . 2
3 Higgs decays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4 Higgs to `+`−γ final state . . . . . . . . . . . . . . . . . . . . . . . . 3
5 Higgs to `+`−γ analysis at √
s = 8TeV . . . . . . . . . . . . . . . . . 5
The LHC and CMS detector 13
1 The Large Hadron Collider . . . . . . . . . . . . . . . . . . . . . . . . 13
2 The Compact Muon Solenoid detector . . . . . . . . . . . . . . . . . 14
Physics Analysis 17
1 Simulated samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.1 Background estimation . . . . . . . . . . . . . . . . . . . . . . 18
1.2 Data samples . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2 Event reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3 Event selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.1 Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Analysis objects . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3 Kinematic selection . . . . . . . . . . . . . . . . . . . . . . . . 37
4 Statistical methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5 Background and signal fits . . . . . . . . . . . . . . . . . . . . . . . . 43
ix
5.1 F-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.2 Background fit bias study . . . . . . . . . . . . . . . . . . . . 50
5.3 Bias studies in VBF category . . . . . . . . . . . . . . . . . . 53
6 Systematic uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.1 Underlying event and parton shower uncertainty . . . . . . . . 57
6.2 Pileup reweighting uncertainty . . . . . . . . . . . . . . . . . . 57
6.3 Trigger scale factor uncertainty . . . . . . . . . . . . . . . . . 58
6.4 Muon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.5 Photon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
6.6 Jet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Results 61
1 Results for 2016 data . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2 Combination with 8 TeV results . . . . . . . . . . . . . . . . . . . . . 62
Bibliography 67
A Background MC 71
B ttH process 75
C Data-MC comparison 77
D Cut optimization 83
E Parameter Interpolation 91
                                

[1] de Florian, D., Grojean, C., Maltoni, F., Mariotti, C., Nikitenko, A., Pieri, M., Savard, P., Schumacher, M., Tanaka, R., & Aggleton, R. (2016). Handbook of LHC
Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector. Technical Report FERMILAB-FN-1025-T. https://cds.cern.ch/record/2227475.
[2] DJOUADI, A. (2012). Higgs physics: Theory. Pramana, 79 (4), 513–539. doi:10.1007/s12043-012-0361-y, https://doi.org/10.1007/s12043-012-0361-y.
[3] Abbasabadi, A., Bowser-Chao, D., Dicus, D. A., & Repko, W. W. (1997). Radiative Higgs boson decays H → ff γ. Phys. Rev. D, 55, 5647. doi: 10.1103/PhysRevD.55.5647.
[4] Sun, Y., Chang, H., & Gao, D. (2013). Higgs decays to γ`+`− in the standard model. JHEP, 05, 061. doi: 10.1007/JHEP05(2013)061.
[5] Chen, L. B., Qiao, C. F., & Zhu, R. L. (2013). Reconstructing the 125 GeV SM Higgs boson through `
¯`γ. Phys. Lett. B, 726, 306. doi: 10.1016/j.physletb.2013.08.050.
[6] Passarino, G. (2013). Higgs boson production and decay: Dalitz sector. Phys. Lett. B, 727, 424. doi: 10.1016/j.physletb.2013.10.052.
[7] Korchin, A. & Kovalchuk, V. (2014). Angular distribution and forward-backward asymmetry of the higgs-boson decay to photon and lepton pair. Eur. Phys. J. C,
74. doi: 10.1140/epjc/s10052-014-3141-7.
[8] Bauer, M., Neubert, M., & Thamm, A. (2017). LHC as an Axion Factory: Probing an Axion Explanation for (g−2)µ with Exotic Higgs Decays. Phys. Rev. Lett., 119.
doi: 10.1103/PhysRevLett.119.031802.
[9] Khachatryan, V., Sirunyan, A., Tumasyan, A., Adam, W., Asilar, E., & Bergauer, T. (2016). Search for a Higgs boson decaying into γ ∗ γ → llγ with low dilepton mass in pp collisions at √s = 8 TeV. Physics Letters B,
753, 341 – 362. doi: http://dx.doi.org/10.1016/j.physletb.2015.12.039, http:
//www.sciencedirect.com/science/article/pii/S0370269315009879.
[10] Sun, Y., Chang, H.-R., & Gao, D.-N. (2013). Higgs decays to γl + l in the standard model. Journal of High Energy Physics, 2013 (5), 61. doi:
10.1007/JHEP05(2013)061, https://doi.org/10.1007/JHEP05(2013)061.
[11] Abbasabadi, A., Bowser-Chao, D., A. Dicus, D., & Repko, W. (1997). Radiative higgs boson decays h–¿ff. 55, 5647–5656.
[12] de Florian, D. et al. (2016). Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector. doi: 10.23731/CYRM-2017-002.
[13] Campbell, J. M. & Ellis, R. (2010). MCFM for the Tevatron and the LHC. Nucl. Phys. Proc. Suppl., 205-206, 10. doi: 10.1016/j.nuclphysbps.2010.08.011.
[14] Dicus, D. A. & Repko, W. W. (2013). Calculation of the decay H → eeγ¯ . Phys. Rev. D, 87, 077301. doi: 10.1103/PhysRevD.87.077301.
[15] Dicus, D. A. & Repko, W. W. (2014). Dalitz decay H → f¯f γ as a background for H → γγ. Phys. Rev. D, 89, 093013. doi: 10.1103/PhysRevD.89.093013.
[16] Firan, A. & Stroynowski, R. (2007). Internal conversions in Higgs decays to two photons. Phys. Rev. D, 76, 057301. doi: 10.1103/PhysRevD.76.057301.
[17] Aad, G. et al. (2014). Search for Higgs boson decays to a photon and a Z boson in pp collisions at √s = 7 and 8 TeV with the ATLAS detector. Phys. Lett. B,
732, 8. doi: 10.1016/j.physletb.2014.03.015.
[18] Chatrchyan, S. et al. (2013). Search for a Higgs boson decaying into a Z and a photon in pp collisions at √s = 7 and 8 TeV. Phys. Lett. B, 726, 587. doi:
10.1016/j.physletb.2013.09.057.
[19] Brning, O., Burkhardt, H., & Myers, S. (2012). The Large Hadron Collider. Prog. Part. Nucl. Phys., 67 (CERN-ATS-2012-064), 705–734. mult. p. https://
cds.cern.ch/record/1443022. Published in Progress in Particle and Nuclear Physics (2012), 10.1016/j.ppnp.2012.03.001.
[20] Khachatryan, V. et al. (2017). The CMS trigger system. JINST, 12, P01020.
doi: 10.1088/1748-0221/12/01/P01020.
[21] Chatrchyan, S. et al. (2014). Description and performance of track and primary vertex reconstruction with the CMS tracker. JINST, 9, P10009. doi: 10.1088/1748-
0221/9/10/P10009.
[22] Chatrchyan, S. et al. (2012). Performance of CMS muon reconstruction in pp collision events at √s = 7 TeV. JINST, 7, P10002. doi: 10.1088/1748-0221/7/10/P10002.
[23] Khachatryan, V. et al. (2015). Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at √s = 8 TeV. JINST,
10, P08010. doi: 10.1088/1748-0221/10/08/P08010.
[24] Alwall, J., Frederix, R., Frixione, S., Hirschi, V., Maltoni, F., Mattelaer, O., Shao, H.-S., Stelzer, T., Torrielli, P., & Zaro, M. (2014). The automated computation
of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations. Journal of High Energy Physics, 2014 (7),
79. doi: 10.1007/JHEP07(2014)079, http://dx.doi.org/10.1007/JHEP07(2014)
079.
[25] Artoisenet, P. et al. (2013). A framework for Higgs characterisation. JHEP, 11, 043. doi: 10.1007/JHEP11(2013)043.
[26] Sjstrand, T., Mrenna, S., & Skands, P. (2008). A brief introduction to {PYTHIA} 8.1. Computer Physics Communications, 178 (11), 852 – 867. doi: http://dx.doi.org/10.1016/j.cpc.2008.01.036, http://www.sciencedirect.
com/science/article/pii/S0010465508000441.
[27] Campbell, J. M. & Ellis, R. K. (2010). MCFM for the Tevatron and the LHC.Nucl. Phys. Proc. Suppl., 205-206, 10–15. doi: 10.1016/j.nuclphysbps.2010.08.011.
[28] SM Higgs production cross sections at √s = 13T eV . https://twiki.cern.ch/twiki/bin/view/LHCPhysics/CERNYellowReportPageAt13TeV.
[29] Sirunyan, A. M. et al. (2017). Particle-flow reconstruction and global event description with the cms detector. JINST, 12, P10003. doi: 10.1088/1748-0221/12/10/P10003.
[30] Ahmad, M., Amapane, N., Bachtis, M., Bellan, R., Bhattacharya, R., Charlot, C., & Cheng, T. (2016). Measurement of the properties of the higgs boson in the
four-lepton nal state at √s = 13T eV . CMS Analysis Note CMS AN-15-277.
[31] Cacciari, M., Salam, G. P., & Soyez, G. (2008). The anti-kt jet clustering algorithm.
JHEP, 04, 063. doi: 10.1088/1126-6708/2008/04/063.
[32] Cacciari, M., Salam, G. P., & Soyez, G. (2012). FastJet user manual. Eur. Phys. J. C, 72, 1896. doi: 10.1140/epjc/s10052-012-1896-2.
[33] CMS Collaboration (2015). Technical proposal for the phase-ii upgrade of the compact muon solenoid. CMS Technical proposal CERN-LHCC-2015-010, CMSTDR-15-02, CERN. http://cds.cern.ch/record/2020886.
[34] Adam, N., Berryhill, J., Halyo, V., Hunt, A., & Mishra, K. (2009). Generic tag and probe tool for measuring efficiency at cms with early data. CMS Analysis Note CMS-AN-2009/111.
[35] Baseline muon selections for run-2. https://twiki.cern.ch/twiki/bin/view/
CMS/SWGuideMuonIdRun2.
[36] Bodek, A., van Dyne, A., Han, J. Y., Sakumoto, W., & Strelnikov, A. (2012). Extracting muon momentum scale corrections for hadron collider experiments. The
European Physical Journal C, 72 (10), 2194. doi: 10.1140/epjc/s10052-012-2194-8,
http://dx.doi.org/10.1140/epjc/s10052-012-2194-8.
[37] The CMS collaboration (2015). Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at √s = 8T eV .
Journal of Instrumentation, 10 (08), P08010. http://stacks.iop.org/1748-
0221/10/i=08/a=P08010.
[38] Chatrchyan, S. et al. (2011). Measurement of the inclusive W and Z production cross sections in pp collisions at √
s = 7 TeV with the CMS experiment. JHEP, 10, 132.
[39] Jet identification for the 13 TeV data run2016. https://twiki.cern.ch/twiki/bin/viewauth/CMS/JetID13TeVRun2016.
[40] Instructions for applying electron and photon ID. https://twiki.cern.ch/twiki/bin/viewauth/CMS/EgammaIDRecipesRun2.
[41] The CMS collaboration (2012). Performance of CMS muon reconstruction in pp collision events at s = 7 TeV. Journal of Instrumentation, 7 (10), P10002.
http://stacks.iop.org/1748-0221/7/i=10/a=P10002.
[42] Chatrchyan, S., Khachatryan, V., Sirunyan, A., Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Er, J., Fabjan, C., & Friedl, M. (2013). Search for a Higgs boson decaying into a Z and a photon in pp collisions at √s = 7and8 TeV. Physics Letters B, 726 (45), 587– 609. doi: http://dx.doi.org/10.1016/j.physletb.2013.09.057, http://www.
sciencedirect.com/science/article/pii/S0370269313007880.
[43] (2011). Procedure for the LHC Higgs boson search combination in Summer 2011. Technical Report CMS-NOTE-2011-005. ATL-PHYS-PUB-2011-11, CERN, Geneva. https://cds.cern.ch/record/1379837.
[44] Cowan, G., Cranmer, K., Gross, E., & Vitells, O. (2011). Asymptotic formulae for likelihood-based tests of new physics. The European Physical Journal C, 71 (2), 1554. doi: 10.1140/epjc/s10052-011-1554-0, https://doi.org/10.1140/
epjc/s10052-011-1554-0.
[45] Rochester correction. https://twiki.cern.ch/twiki/bin/viewauth/CMS/
RochcorMuon.
[46] Energy smearing and scale correction 80x. https://twiki.cern.ch/twiki/
bin/view/CMS/EGMSmearer.

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