measurement of higgs boson couplings in the di-tau final state€¦ · students' poster...
TRANSCRIPT
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qqH -0.42 +0.45=1.13µ
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Combined -0.27 +0.29=1.24µ
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Doyeong Kim, presented on behalf of the CMS collaboration, [email protected]' Poster Session at the 2020 Winter LHCC meeting, 19 Feb 2020, CERN, Geneva (Switzerland)
Measurement of Higgs Boson Couplingsin the Di-tau Final State
ABSTRACT The Higgs boson decays to tau leptons was observed using Run1 and 2016 Run2 data recorded by the CMS experiment at theLHC. The observed significance of the H→ττ signal exceeds five standard deviations. Anomalous couplings to vector bosons are measured via the vectorboson fusion production, and lead to the tightest constraints on HVV couplings at the 95% confidence level.
Main Production Mechanisms
Tau Lepton Decay
Signal Extraction and Result :
The First Observation of H→ττ
Gluon Gluon Fusion(ggH)
Vector Boson Fusion(VBF)
Associated production with a vector boson
● Maximum likelihood fit of 2D distributions in eachcategory
● The observed significance of H→ττ is 4.9σ● The combination with Run1 measurement lead to the
first observation of H→ττ with significance of 5.9σ
Combined Result with VH :
● The observed significance of H→ττ in associatedwith a W or a Z boson is 2.3 σ
The Tightest Constraints on HVV from H→ττ
Using full kinematic build discriminant for processes SM vs BSM from ME based probabilities● Discriminant: ratio of probabilities● Optimal observable: D = PSM / (PSM + PBSM)
Combined Result with H→4l :
Significant excess around Higgs mass
The most constrained production in H→ττ
MELA(Matrix Element Likelihood Approach) :Additional Optimal Observable for HVV Anomalous Couplings in VBF category
Coupling Parameters :
H→ττ is the first leptonic decay of Higgs accessible atthe LHC thanks to the largest branching fraction out ofall leptonic decay channels.
MELA discriminant for CP-violating(left) and one of the CP-conserving(right) coupling
+
Although cross-section for VBF and VH productions which have HVVcoupling are much lower than that of ggH production, H→ττ decaychannel becomes a major channel to study HVV production couplingdue to its large branching fraction and relatively clean signature.
4 final states(ττ, μτ, eτ, eμ) withthe largest branching fractionswere considered in the analyses.
H
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References[1] CMS Collaboration, “Observation of the SM scalar boson decaying to a pair of τ leptons with the CMS experiment at the LHC” Phys. Lett. B 779 (2018) 10.1016/j.physletb.2018.02.004, arXiv: 1708.00373.[2] CMS Collaboration, “Constraints on anomalous HVV couplings from the production of Higgs bosons decaying to τ lepton pairs” Phys. Rev. D 100, 112002 (2019) 10.1103/PhysRevD.100.112002, arXiv:1903.06973[3] CMS Collaboration, “Search for the associated production of the Higgs boson and a vector boson in proton-proton collisions at √s= 13 TeV via Higgs boson decays to τ leptons”, JHEP 06 (2019) 093, arXiv:1809.03590
● The combination with the ggH and VBF results setthe tightest constraints on H→ττ at 13 TeV as
+ 0.29- 0.27
The combination further constraints HVV coupling
1) 0-jet: Targets gluon fusion events and constrain background2) VBF: Events with 2 jets present, high di-jet mass/high Higgs pT
3) Boosted: Events with 1jet or failed selection of other categories
Event Categorization Events are categorized to target to ggH and VBF productions :
µ = 1.24 for a significance of 5.5 σ
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This combination places the most stringent constraints on anomalous HVV couplings.
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