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| CMS-PAS-HIG-23-004 | ||
| Search for the production of a Higgs boson pair in association with two top quarks in final states with photons | ||
| CMS Collaboration | ||
| 22 April 2025 | ||
| Abstract: A search for Higgs boson pair production in association with a pair of top quarks ($ \mathrm{t}\overline{\mathrm{t}}\mathrm{HH} $) targeting final states containing two photons and multiple jets or leptons is presented. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$ ^{-1} $. An upper limit is set on the $ \mathrm{t}\overline{\mathrm{t}}\mathrm{HH} $ production cross section. The observed (expected) 95% confidence level (CL) upper limit is found to be 119.4 (85.9) times the Standard Model (SM) prediction. The results are interpreted in the context of Higgs Effective Field Theory. Assuming all other couplings of the Higgs boson have SM values, the observed (expected) constraints on the contact interaction involving two Higgs bosons and two top quarks, $ c_2 $, is found to be $ -$8.0 $ < c_2 < $ 7.5 ($ -$7.4 $ < c_2 < $ 6.9) at 95% CL. A search for resonant $ \mathrm{t}\overline{\mathrm{t}}\mathrm{HH} $ production is performed in the context of two scenarios beyond the SM, a Type-II two-Higgs-doublet-model (2HDM) and a vector-like top quark partner (VLQ). No excess above the expectation is observed, and upper limits on the cross-section of the resonances is set at 95% CL. For the 2HDM in the alignment limit, the observed (expected) limits at 95% CL on the mass of the heavy CP-even Higgs boson are determined to be 265 GeV (280 GeV). The VLQ limits at 95% CL for the $ \mathrm{T'} $ masses are larger than 1100 GeV (1150 GeV). | ||
| Links: CDS record (PDF) ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Feynman diagrams contributing to $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ production, involving the contact interactions between one Higgs boson and two top quarks ($ \kappa_{\mathrm{t}} $) (left), the Higgs boson self-interaction ($ \kappa_{\lambda} $) (middle), and two Higgs bosons and two top quarks ($ c_2 $) (right), which only appears at LO in the HEFT framework [28]. |
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Figure 1-a:
Feynman diagrams contributing to $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ production, involving the contact interactions between one Higgs boson and two top quarks ($ \kappa_{\mathrm{t}} $) (left), the Higgs boson self-interaction ($ \kappa_{\lambda} $) (middle), and two Higgs bosons and two top quarks ($ c_2 $) (right), which only appears at LO in the HEFT framework [28]. |
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Figure 1-b:
Feynman diagrams contributing to $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ production, involving the contact interactions between one Higgs boson and two top quarks ($ \kappa_{\mathrm{t}} $) (left), the Higgs boson self-interaction ($ \kappa_{\lambda} $) (middle), and two Higgs bosons and two top quarks ($ c_2 $) (right), which only appears at LO in the HEFT framework [28]. |
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Figure 1-c:
Feynman diagrams contributing to $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ production, involving the contact interactions between one Higgs boson and two top quarks ($ \kappa_{\mathrm{t}} $) (left), the Higgs boson self-interaction ($ \kappa_{\lambda} $) (middle), and two Higgs bosons and two top quarks ($ c_2 $) (right), which only appears at LO in the HEFT framework [28]. |
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Figure 2:
Distribution of the BDT score used for the non-resonant analysis event categorization. Data (black points) and predictions from simulation (colored histograms) are shown. Only the selected signal regions derived from the SM are shown. The ``Single H'' component includes $ \mathrm{g}\mathrm{g}\mathrm{H} $, $ \mathrm{VBF} $, WH, and ZH. The ``$ \mathrm{t}\overline{\mathrm{t}}+\mathrm{X} $'' component includes $ {\mathrm{t}\overline{\mathrm{t}}} + \gamma\gamma $, $ {\mathrm{t}\overline{\mathrm{t}}} + \gamma $, and $ {\mathrm{t}\overline{\mathrm{t}}} + \text{jets}$. The ratio of the data to the sum of the non-resonant background predictions is shown in the lower panel. |
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Figure 3:
Parametric models of the signal process $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} \to \gamma\gamma\mathrm{b}\overline{\mathrm{b}} $ in SR$ _1 $. |
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Figure 4:
Signal, resonant, and non-resonant background model and uncertainty for SR 1 (left) and SR 2 (right). |
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Figure 4-a:
Signal, resonant, and non-resonant background model and uncertainty for SR 1 (left) and SR 2 (right). |
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Figure 4-b:
Signal, resonant, and non-resonant background model and uncertainty for SR 1 (left) and SR 2 (right). |
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Figure 5:
Observed upper limits for different values of $ c_2 $. The yellow (blue) bands display the one (two) standard deviation uncertainties in the expected limit. The dashed black line shows the median expected upper limit, while the solid black line shows the observed one. The red line shows the theoretical prediction for the $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ cross section. |
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Figure 6:
68% and 95% CL contours in the ($ c_2 $, $ \kappa_{\mathrm{t}} $) plane, obtained varying simultaneously the $ c_2 $ and $ \kappa_{\mathrm{t}} $ parameters. The solid (dashed) lines display the one (two) standard deviation contours. The black cross showcase the observed best fit value, while the red diamond depicts the SM expected values for $ c_2 $ and $ \kappa_{\mathrm{t}} $ parameters. |
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Figure 7:
95% CL upper limits on the $ \mathrm{p}\mathrm{p} \to {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}_2 \to {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ cross section for $ m_{\mathrm{H}_2} = 250- $ 350 GeV. The dashed black line shows the expected limit, while the yellow (blue) bands display the one (two) standard deviation uncertainties. The solid black line shows the observed limits. The red line shows the theory prediction on the production cross section times the branching ratio. |
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Figure 8:
95% CL upper limits on the $ \mathrm{p}\mathrm{p} \to \mathrm{T'}\overline{\mathrm{T'}} \to {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ cross section for $ m_{\mathrm{T'}} = $ 500-1500 GeV The dashed black line shows the expected limit, while the yellow (blue) bands display the one (two) standard deviation uncertainties. The solid black line shows the observed limits. The red line shows the theory prediction on the production cross section times the branching ratio. |
| Tables | |
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Table 1:
Additional photon requirements for barrel and endcap photons at different ranges of $ R_\mathrm{9} $, intended to mimic the HLT requirements. For photons with high $ R_\mathrm{9} $, the other cuts are dropped |
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Table 2:
Expected signal sensitivity, given in multiples of the SM cross section |
| Summary |
| A search for Higgs boson pair production in association with a pair of top quarks ($ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $) targeting final states containing two photons and multiple jets or leptons is presented. The search uses data from proton-proton collisions collected by the CMS experiment at the LHC in 2016--2018 at a center-of-mass energy of 13 TeV, corresponding to 138 fb$ ^{-1} $ of integrated luminosity. Three different interpretations are provided. The search for SM $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ production, where no significant deviation from the background-only hypothesis is observed. Upper limits at the 95% CL on the $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ production cross section are extracted for production in the SM and the observed upper limit for the SM production is found to be 92.5 fb, corresponding to 119.4 times the SM prediction, whilst the expected upper limit is 66.6 fb, corresponding to 85.9 times the SM prediction. The results are also interpreted to place constraints on the HEFT parameters. Limits are derived as a function of the $ {\mathrm{t}\overline{\mathrm{t}}} \mathrm{H}\mathrm{H} $ contact interaction coupling, $ c_2 $, assuming all other Higgs boson couplings are as predicted in the SM. The coupling modifier, $ c_2 $, is constrained within the range $ -$8.0 $ < c_2 < $ 7.5 ($ -$7.4 $ < c_2 < $ 6.9) at the 95 $ % \text{CL} $. In addition, this note also targets the resonant production of a CP-even heavy neutral scalar ($ \mathrm{H}_2 $) in the context of type-II 2HDM model and heavy VLQ $ \mathrm{T'} $ pair production in the $ \mathrm{T'} \to\mathrm{t}\mathrm{H} $ final state. No significant deviation from the background-only hypothesis is observed for either model and observed (expected) limits for the 2HDM in the alignment limit, for $ \tan \beta = $ 0.8, are placed at $ m_{\mathrm{H}_2} > $ 265 (280) GeV. The VLQ limits at 95% on the mass of the $ \mathrm{T'} $ are set at $ m_{\mathrm{T'}} > $ 1100 (1150) GeV. |
| References | ||||
| 1 | ATLAS Collaboration | Observation of a new particle in the search for the standard model Higgs boson with the detector at the LHC | PLB 716 (2012) 1 | 1207.7214 |
| 2 | CMS Collaboration | Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC | PLB 716 (2012) 30 | CMS-HIG-12-028 1207.7235 |
| 3 | CMS Collaboration | Observation of a new boson with mass near 125 GeV in pp collisions at $ \sqrt{s} $ = 7 and 8 TeV | JHEP 06 (2013) 081 | CMS-HIG-12-036 1303.4571 |
| 4 | CMS Collaboration | A portrait of the Higgs boson by the CMS experiment ten years after the discovery | Nature 607 (2022) 60 | CMS-HIG-22-001 2207.00043 |
| 5 | ATLAS Collaboration | A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery | Nature 607 (2022) 52 | 2207.00092 |
| 6 | B. D. Micco, M. Gouzevitch, J. Mazzitelli, and C. Vernieri | Higgs boson potential at colliders: Status and perspectives | Reviews in Physics 5 (2020) 100045 | 1910.00012 |
| 7 | S. Dawson, S. Dittmaier, and M. Spira | Neutral higgs-boson pair production at hadron colliders: QCD corrections | PRD 58 (1998) | hep-ph/9805244 |
| 8 | S. Borowka et al. | Higgs boson pair production in gluon fusion at next-to-leading order with full top-quark mass dependence | PRL 117 (2016) | 1604.06447 |
| 9 | J. Baglio et al. | Gluon fusion into Higgs pairs at NLO QCD and the top mass scheme | EPJC 79 (2019) 459 | 1811.05692 |
| 10 | D. de Florian and J. Mazzitelli | Higgs pair production at next-to-next-to-leading logarithmic accuracy at the LHC | JHEP 09 (2015) 053 | 1505.07122 |
| 11 | M. Grazzini et al. | Higgs boson pair production at NNLO with top quark mass effects | JHEP 2018 (2018) | 1803.02463 |
| 12 | J. Baglio et al. | $ gg\rightarrow{HH} $: Combined uncertainties | PRD 103 (2021) 056002 | 2008.11626 |
| 13 | D. de Florian and J. Mazzitelli | Higgs boson pair production at next-to-next-to-leading order in qcd | PRL 111 (2013) | 1309.6594 |
| 14 | D. Y. Shao, C. S. Li, H. T. Li, and J. Wang | Threshold resummation effects in higgs boson pair production at the LHC | JHEP 2013 (2013) | 1301.1245 |
| 15 | ATLAS Collaboration | Combination of searches for non-resonant and resonant Higgs boson pair production in the $ b\bar{b}\gamma\gamma $, $ b\bar{b}\tau^{+}\tau^{-} $ and $ b\bar{b}b\bar{b} $ decay channels using $ pp $ collisions at $ \sqrt{s} $ = 13 TeV with the ATLAS detector | technical report, CERN | |
| 16 | CMS Collaboration | Combination of searches for non-resonant Higgs boson pair production in proton-proton collisions at $ \sqrt{s} = $ 13 TeV | technical report, CERN, 2024 CDS |
|
| 17 | J. Baglio et al. | The measurement of the Higgs self-coupling at the LHC: theoretical status | JHEP 2013 (2013) | 1212.5581 |
| 18 | R. Frederix et al. | Higgs pair production at the LHC with NLO and parton-shower effects | PLB 732 (2014) 142 | 1401.7340 |
| 19 | L.-S. Ling et al. | NNLO QCD corrections to Higgs pair production via vector boson fusion at hadron colliders | PRD 89 (2014) | |
| 20 | F. A. Dreyer and A. Karlberg | Fully differential vector-boson fusion higgs pair production at next-to-next-to-leading order | PRD 99 (2019) | 1811.07918 |
| 21 | F. A. Dreyer and A. Karlberg | Vector-boson fusion higgs pair production at N$ ^3 $LO | PRD 98 (2018) 114016 | 1811.07906 |
| 22 | F. A. Dreyer, A. Karlberg, J.-N. Lang, and M. Pellen | Precise predictions for double-higgs production via vector-boson fusion | EPJC 80 (2020) | 2005.13341 |
| 23 | "ATLAS" Collaboration | Erratum to: Search for the HH $ \rightarrow b\bar{b}b\bar{b} $ process via vector-boson fusion production using proton-proton collisions at $ \sqrt{s} = $ 13 TeV with the ATLAS detector | JHEP 2021 (2021) | 2001.05178 |
| 24 | "CMS" Collaboration | Search for Higgs boson pair production in the four b-quark final state in proton-proton collisions at $ \sqrt{s} = $ 13 TeV | PRL 129 (2022) | 2205.02745 |
| 25 | G. Aad et al. | Search for Higgs boson pair production in association with a vector boson in pp collisions at $ \sqrt{s}=13\,\text {TeV} $ with the ATLAS detector | EPJC 83 (2023) | 2210.05415 |
| 26 | CMS Collaboration | Search for Higgs boson pair production with one associated vector boson in proton-proton collisions at $ \sqrt{s}=13\,\text {TeV} $ | JHEP 2024 (2024) | CMS-HIG-22-006 2404.08462 |
| 27 | D. de Florian and others" | Handbook of LHC Higgs cross sections: 4. Deciphering the nature of the Higgs sector | CERN Report CERN-2017-002-M, 2016 link |
1610.07922 |
| 28 | F. "Goertz, A. Papaefstathiou, L. L. Yang, and J. Zurita | Higgs boson pair production in the D=6 extension of the SM | JHEP 04 (2015) 167 | 1410.3471 |
| 29 | ATLAS Collaboration | Combination of searches for Higgs boson pair production in $ pp $ collisions at $ \sqrt{s}=13\text{ }\text{ }\mathrm{TeV} $ with the ATLAS detector | PRL 133 (2024) 101801 | |
| 30 | G. C. Branco et al. | Theory and phenomenology of Two-Higgs-Doublet Models | Physics Reports 516 (2012) | 1106.0034 |
| 31 | L. Li, Y.-Y. Li, and T. Liu | Anatomy of ttHH physics at the HL-LHC | PRD 101 (2020) | 1905.03772 |
| 32 | ATLAS Collaboration | Combination of searches for resonant higgs boson pair production using pp collisions at $ \sqrt{s} = $ 13 tev with the ATLAS detector | PRL 132 (2024) | |
| 33 | CMS Collaboration | Searches for higgs boson production through decays of heavy resonances | Physics Reports 111 (2025) 5 | 2403.16926 |
| 34 | M. Buchkremer, G. Cacciapaglia, A. Deandrea, and L. Panizzi | Model-independent framework for searches of top partners | Nuclear Physics B 876 (2013) | 1305.4172 |
| 35 | ATLAS Collaboration | Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector | JHEP 2018 (2018) | 1803.09678 |
| 36 | ATLAS Collaboration | Search for pair-production of vector-like quarks in lepton+jets final states containing at least one b-tagged jet using the run 2 data from the ATLAS experiment | PLB 854 (2024) 138743 | 2401.17165 |
| 37 | CMS Collaboration | Search for pair production of vector-like quarks in leptonic final states in proton-proton collisions at $ \sqrt{s} $ = 13 TeV | JHEP 2023 (2023) | 2209.07327 |
| 38 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | |
| 39 | CMS Collaboration | The CMS trigger system | JINST 12 (2017) P01020 | CMS-TRG-12-001 1609.02366 |
| 40 | CMS Collaboration | Performance of the CMS high-level trigger during LHC run 2 | JINST 19 (2024) P11021 | CMS-TRG-19-001 2410.17038 |
| 41 | CMS Collaboration | Particle-flow reconstruction and global event description with the CMS detector | JINST 12 (2017) P10003 | CMS-PRF-14-001 1706.04965 |
| 42 | CMS Collaboration | Performance of reconstruction and identification of $ \tau $ leptons decaying to hadrons and $ \nu_\tau $ in pp collisions at $ \sqrt{s}= $ 13 TeV | JINST 13 (2018) P10005 | CMS-TAU-16-003 1809.02816 |
| 43 | CMS Collaboration | Identification of hadronic tau lepton decays using a deep neural network | JINST 17 (2022) P07023 | CMS-TAU-20-001 2201.08458 |
| 44 | M. Cacciari, G. P. Salam, and G. Soyez | The anti-$ k_{\mathrm{T}} $ jet clustering algorithm | JHEP 04 (2008) 063 | 0802.1189 |
| 45 | M. Cacciari, G. P. Salam, and G. Soyez | FastJet user manual | EPJC 72 (2012) 1896 | 1111.6097 |
| 46 | CMS Collaboration | Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV | JINST 12 (2017) P02014 | CMS-JME-13-004 1607.03663 |
| 47 | CMS Collaboration | Performance of missing transverse momentum reconstruction in proton-proton collisions at $ \sqrt{s} = $ 13\,TeV using the CMS detector | JINST 14 (2019) P07004 | CMS-JME-17-001 1903.06078 |
| 48 | CMS Collaboration | Measurements of Higgs boson properties in the diphoton decay channel in proton-proton collisions at $ \sqrt{s} = $ 13 TeV | JHEP 11 (2018) 185 | CMS-HIG-16-040 1804.02716 |
| 49 | J. Alwall et al. | The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations | JHEP 2014 (2014) | 1405.0301 |
| 50 | T. Gleisberg et al. | Event generation with SHERPA 1.1 | JHEP 02 (2009) 007 | 0811.4622 |
| 51 | R. Frederix et al. | The automation of next-to-leading order electroweak calculations | JHEP 2018 (2018) | 1804.10017 |
| 52 | CMS Collaboration | Event generator tunes obtained from underlying event and multiparton scattering measurements | EPJC 76 (2016) 155 | CMS-GEN-14-001 1512.00815 |
| 53 | CMS Collaboration | Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements | EPJC 80 (2020) 4 | CMS-GEN-17-001 1903.12179 |
| 54 | \GEANTfour Collaboration | GEANT 4 --- a simulation toolkit | NIM A 506 (2003) 250 | |
| 55 | A. Hayrapetyan et al. | Performance of the CMS electromagnetic calorimeter in pp collisions at $ \sqrt{s} $ = 13 tev | JINST 19 (2024) | 2403.15518 |
| 56 | CMS Collaboration | Electron and photon reconstruction and identification with the CMS experiment at the CERN LHC | JINST 16 (2021) P05014 | CMS-EGM-17-001 2012.06888 |
| 57 | CMS Collaboration | Performance of electron reconstruction and selection with the CMS detector in proton-proton collisions at $ \sqrt{s} $ = 8 TeV | JINST 10 (2015) P06005 | CMS-EGM-13-001 1502.02701 |
| 58 | CMS Collaboration | Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $ \sqrt{s}= $ 13 TeV | JINST 13 (2018) P06015 | CMS-MUO-16-001 1804.04528 |
| 59 | CMS Collaboration | Performance summary of AK4 jet b tagging with data from proton-proton collisions at 13 TeV with the CMS detector | CDS | |
| 60 | E. Bols et al. | Jet flavour classification using \textscDeepJet | JINST 15 (2020) | 2008.10519 |
| 61 | T. Chen and C. Guestrin | XGBoost: A scalable tree boosting system | in Proc. 22nd ACM SIGKDD Intern. Conf. on Knowledge Discovery and Data Mining, KDD, . ACM, New York, NY, USA, 2016 Proc. 2 (2016) 785 |
|
| 62 | R. Fisher | On the interpretation of $ \chi^2 $ from contingency tables, and the calculation of p | Journal of the Royal Statistical Society 85 (1922) | |
| 63 | CMS Collaboration | A measurement of the Higgs boson mass in the diphoton decay channel | PLB 805 (2020) 135425 | CMS-HIG-19-004 2002.06398 |
| 64 | P. D. Dauncey, M. Kenzie, N. Wardle, and G. J. Davies | Handling uncertainties in background shapes | JINST 10 (2015) P04015 | 1408.6865 |
| 65 | J. Butterworth et al. | PDF4LHC recommendations for LHC Run II | JPG 43 (2016) 023001 | 1510.03865 |
| 66 | C. T. Potter et al. | Handbook of lhc higgs cross sections: 3. higgs properties: Report of the lhc higgs cross section working group | link | |
| 67 | CMS Collaboration | Precision luminosity measurement in proton-proton collisions at $ \sqrt{s} = $ 13 TeV in 2015 and 2016 at CMS | EPJC 81 (2021) 800 | CMS-LUM-17-003 2104.01927 |
| 68 | CMS Collaboration | CMS luminosity measurement for the 2017 data-taking period at $ \sqrt{s} = $ 13 TeV | CMS Physics Analysis Summary, 2018 CMS-PAS-LUM-17-004 |
CMS-PAS-LUM-17-004 |
| 69 | CMS Collaboration | CMS luminosity measurement for the 2018 data-taking period at $ \sqrt{s} = $ 13 TeV | CMS Physics Analysis Summary, 2019 CMS-PAS-LUM-18-002 |
CMS-PAS-LUM-18-002 |
| 70 | CMS Collaboration | Measurement of the inclusive W and Z production cross sections in pp collisions at $ \sqrt{s}= $ 7 TeV | JHEP 10 (2011) 132 | CMS-EWK-10-005 1107.4789 |
| 71 | T. Junk | Confidence level computation for combining searches with small statistics | NIM A 434 (1999) 435 | hep-ex/9902006 |
| 72 | A. L. Read | Presentation of search results: the $ \text{CL}_\text{s} $ technique | JPG 28 (2002) 2693 | |
| 73 | G. Cowan, K. Cranmer, E. Gross, and O. Vitells | Asymptotic formulae for likelihood-based tests of new physics | EPJC 71 (2011) 1554 | 1007.1727 |
| 74 | CMS Collaboration | The CMS statistical analysis and combination tool: Combine | Comput. Softw. Big Sci. 8 (2024) 19 | CMS-CAT-23-001 2404.06614 |
| 75 | W. Verkerke and D. Kirkby | The \textscRooFit toolkit for data modeling | in Proc. 13th International Conference on Computing in High Energy and Nuclear Physics (CHEP ): La Jolla CA, United States, March 24--28, . . . [eConf C0303241 MOLT007], 2003 Proc. 1 (2003) 3 |
physics/0306116 |
| 76 | L. Moneta et al. | The \textscRooStats project | in Proc. 13th International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT ): Jaipur, India, 2010 link |
1009.1003 |
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