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Search for Rare Higgs - Boson Decays Into Quarkonium Pairs

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Search for Rare Higgs - Boson Decays Into Quarkonium Pairs Search for Rare Higgs - Boson Decays into Quarkonium Pairs Himal Acharya University of Tennessee CMS Collaboration PAS Publication arXiv DPF Meeting 2019 July 30 Outline ● Motivation 4 Search Channels ● Muon Detection pp → X → J/�J/� → 4 � pp → X → YY → 4 � ● Results X = Higgs , Z – boson ● Polarization Y=Y(nS) (n=1,2,3) ● Summary & Outlook 2 Himal Acharya, DPF Meeting - 2019 Motivation: BF calculation ― - SM: expeCt Higgs-boson deCays into quarkonium pairs (aCCess to ―CC, bb Yukawa Couplings) - PrediCtions of the SM branChing fraCtions are still a moving target … Typical diagrams Previous CalCulation [1] Most reCent CalCulation [2] DireCt coupling + IndireCt Coupling -10 -9 BF(H→ΥΥ ) ≈ 6 ⨉ 10-5 BF (H →J/�J/� ≈ 1.5 ⨉ 10 ; H→ΥΥ ≈ 2 ⨉ 10 ) [1] M. Bander, A. Soni, PLB 82 (1979) 411 ⊕ Internal motion of quarks [2] [2] V. Kartvelishvili, A.V. Luchinsky, A.A. Novoselov, PRD 79 (2009) 114015 3 Himal Acharya, DPF Meeting - 2019 Motivation: Possible modification in BF ● In SM additional diagrams exists e.g. related to H → J/� g with g → g * ; g * → J/�, Y [1] ● Many BSM models prediCt additional diagrams e.g. related to H → Y g ; can cause orders of magnitude increase of BF [2] ….not yet calculated for quarkonium pairs J/y, U H J/y, U H …⊕ ⊕ ⊕ BSM J/y, U J/y, U Enhancement ? [1] K. Abe et al. , Phys. Rev. Lett. 89 (2002) 142001 [2] Geoffrey Bodwin et.al. Phys. Rev. D 88, 053003 4 Himal Acharya, DPF Meeting - 2019 CMS Detector: Muon Detection CMS detector Cross-Sectional View Trigger Muon Chambers: 1. Drift Tube Chambers 2. Cathode Strip Chambers Track 3. Resistive Plate Chamber (Trigger) MatCh Inner/Outer TraCk 5 Himal Acharya, DPF Meeting - 2019 CMS Detector: Event Display & Trigger e.g. H→YY Simulated Event Trigger Muons + Dimuon Invariant Mass (HLT) Dedicated Triggers require 3 muons + ● Di-muon resonance + Muon ● Efficiencies > 85 % 6 Himal Acharya, DPF Meeting - 2019 Efficiencies Tag & Probe Method [1] Low-level Muon Trigger Efficiency ● Compare effiCiencies to full-deteCtor (MC) -1 simulation CMS Work in Progress 10 fb (13 TeV) ● Exploit di-muon deCay of J/� J/� → �trigger . � J/� Signal [2] tag probe � ≈ 30 MeV L3 Efficiency L3 ⊕ Selection (L3) e.g. Barrel 10 100 Muon pT [GeV] ● Total efficienCies agree Closely between [1] https://twiki.cern.ch/twiki/bin/view/CMSPublic/TagAndProbe data and MC (sCale faCtor ≈ 1); [2] https://cds.cern.ch/record/2276459 ● Uncertainty ≈ 3% 7 Himal Acharya, DPF Meeting - 2019 Reconstruction CMS Work in progress 37.5 fb-1 (13 TeV) Strategy: 20 J/ 350 y µ • 300 Modest requirement on kinematiCs and topology [ GeV ] 15 T Trigger Data 250 200 Muon: muon p 10 150 • pT > 3 GeV & |h| < 2.4 5 100 50 0 0 0 0.5 1 1.5 2 Dimuon: | muon h | • Kalman vertex fit Muon ACCeptanCe CMS Simulation Work in progress (13 TeV) 20 • pT > 3.5 GeV 45 + - 40 H→J/ • µ µ invariant mass range [ GeV ] T 15 35 30 y 25 muon p 10 J/ Four-Muon: 20 y 15 • Kalman vertex fit 5 10 • |ΔU| < 3.0 5 Efficiency ⨉ Acceptance ~ 25 % 0 0 0 0.5 1 1.5 2 | muon h | 8 Himal Acharya, DPF Meeting - 2019 Results: J/�J/� Channel Fit RooFit - Extended ML Fit [1] Signal Model ● H: double Gaussian ● Z: Voigtian function Background Model ● SourCe: prompt non-resonant J/� pair production [2] ● Exponential + Uniform funCtion 4 � Invariant Mass [1] https://root.cern.ch/roofit #186 Candidates [2] C. Qiao, J. Wang, and Y. Zheng, Chin. Phys. C 35 (2011) 209 9 Himal Acharya, DPF Meeting - 2019 Results: ΥΥ Channel RooFit - Extended ML Fit [1] practically zero counting Signal Model ● H: double Gaussian ● Z: Voigtian function Background Model ● SourCe: non-resonant ΥΥ production [2] ● Exponential funCtion 4 � Invariant Mass [1] https://root.cern.ch/roofit [2] C. Qiao, J. Wang, and Y. Zheng, Chin. Phys. C 35 (2011) 209 #106 Candidates 10 Himal Acharya, DPF Meeting - 2019 Results: Upper limit Exclusion limits @ 95% CL ● Upper limits Calculation CLs, Modified frequentist approach [1,2]. ● Expected limits are set with the background only hypothesis with 68% CL bands ● Impact of systematic uncertainty (including efficiency, momentum scale/resolution, fit, theory, luminosity, BF) on upper limit is less than 2 % ● observed limit within expected limit bands ● No deviation from SM prediction [1] J. Thomas, Nucl. Instrum. Meth. A 434 (1999) 435 [2] Read, Alexander L., J. Phys. G 28 (2002) 2693 11 Himal Acharya, DPF Meeting - 2019 Polarization Effect + ● Acceptance depends on decay angular distribution � � CMS Work in Progress J/� Acceptance H Decreases - Arbitrary Unit Arbitrary � 2 transversal P(θ)∝ 1 + λθcos θ longitudinal Simulation with λθ = 0 Acceptance Transversely polarized (λθ = + 1) Increases BF upper limits increases by ≈ 13% ● Ref. [1,2] predict longitudinal Longitudinally polarized (λθ = − 1) polarization will dominate BF upper limits decreases by ≈ 26% [1] A. Likhoded and A. Luchinsky, Mod. Phys. Lett. A 33 (2018) 1850078 [2] V. Kartvelishvili, A. Luchinsky, and A. Novoselov, Phys. Rev. D 79 (2009) 114015, 12 Himal Acharya, DPF Meeting - 2019 Summary • Rare deCays of Higgs boson are a promising laboratory for the searCh of new physiCs beyond SM • Very first searChes of Higgs and Z boson deCays into J/� and Υ-pairs are performed with the CMS deteCtor at the LHC, and upper limits are accepted for publication in Phys. Lett. B • Renewed CalCulations of branching fraCtions for Higgs deCays into quarkonium pairs deCays in the SM, and beyond SM are needed • Only a few positive signal events would indiCate the presence of beyond SM physiCs 13 Himal Acharya, DPF Meeting - 2019 Outlook • In Run 2 obtained 3⨉ more statistiCs in all-muon final states and additional 2µ 2e final states • HL-LHC expeCted to aCCess the Higgs deCays with BF ~ 10-5 • Other signals are expeCted in Quarkonium pair final states such as low mass pseudo-sCalar Higgs e.g. prediCted in NMSSM [1] and such as tetra-quark bound states [2] • Measurement of Quarkonium pair final states Complements/improves H → a a searChes [3] [1] https://arxiv.org/abs/0805.1115. [2] https://arxiv.org/pdf/1706.00610.pdf [3] https://arxiv.org/pdf/1812.00380.pdf 14 Himal Acharya, DPF Meeting - 2019 Thank You 15 Himal Acharya, DPF Meeting - 2019.
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