Probing for anomalous couplings in production and decay 4 at CMS - PowerPoint PPT Presentation

1 Animated gifs on some slides. See ppt version or separate indico attachment. Probing for anomalous 𝐼𝑊𝑊 couplings in production and decay 𝐼 → 4ℓ at CMS Heshy Roskes (Johns Hopkins University) for the CMS collaboration The 26th International Workshop on Weak Interactions and Neutrinos (WIN2017) UC Irvine June 20, 2017

2 Anomalous couplings • Search for anomalous 𝐼𝑊𝑊 couplings in production and decay in the 𝐼 → 4𝑚 channel • Kinematics of decay • New: kinematics of jets from VBF and 𝑊𝐼 production • Use matrix element (MELA) discriminants • optimally select VBF and 𝑊𝐼 events • optimally separate different contributions to the amplitude • Combine with Run 1 CMS analysis

3 𝐼 125 → 4ℓ References: Run 1: • CMS-HIG-14-018 spin anomalous couplings Run 2: • CMS-PAS-HIG-16-041 properties • CMS-PAS-HIG-17-011 anomalous couplings • What is it? • How does it interact with other particles?

4 CMS&ATLAS results • Run 1: exclude spin 1 and 2 • Set limits on spin 0 anomalous couplings CMS ATLAS • • Study of the mass and spin-parity of the Higgs Evidence for the spin-0 nature of the Higgs boson candidate via its decays to Z boson pairs boson using ATLAS data ATLAS arXiv:1307.1432 CMS-HIG-12-041, arXiv:1212.6639 • Study of the spin and parity of the Higgs boson • Measurement of the properties of a Higgs in diboson decays with the ATLAS detector boson in the four-lepton final state ATLAS arXiv:1506.05669 arXiv:1312.5353, CMS-HIG-13-002 • • Test of CP Invariance in vector-boson fusion Constraints on the spin-parity and anomalous HVV couplings of the Higgs boson in proton production of the Higgs boson using the collisions at 7 and 8 TeV arXiv:1411.3441, CMS- Optimal Observable method in the ditau decay HIG-14-018 channel with the ATLAS detector ATLAS arXiv:1602.04516 • Limits on the Higgs boson lifetime and width 𝑔 from its decay to four charged leptons Λ𝑅 arXiv:1507.06656, CMS-HIG-14-036 VV Production (decay to 𝑔 ҧ 𝑔 ) • Combined search for anomalous pseudoscalar HVV couplings in VH production and H to VV decay arXiv:1602.04305, CMS-HIG-14-035 • • Measurement of inclusive and differential cross Measurements of properties of the Higgs boson sections in the H → ZZ ∗ → 4l decay channel at and search for an additional resonance in the four- lepton final state at √s = 13 TeV, CMS-PAS- 13 TeV with the ATLAS detector ATLAS-CONF- HIG-16-033 2017-032 • Run 2 results Constraints on anomalous Higgs boson couplings in production and decay H→4ℓ, CMS - PAS-HIG-17-011 This analysis

5 Kinematics 𝐼 → 𝑎𝑎 → 4ℓ 𝑊𝐼 VBF • For a given 𝑛 4ℓ , four-fermion system in production or decay is defined by: • 5 angles 2 of difermion systems • Two 𝑟 𝑊 𝑗 • For the production+decay: two 𝐼𝑊𝑊 vertices • 13 independent observables remain

6 HVV amplitude 2 +𝑟 𝑊2 2 𝑟 𝑊1 𝑊𝑊 + 2 𝜗 𝑊 ∗ 𝜗 𝑊 ∗ + • 𝐵 𝐼𝑊𝑊 ~ 𝑏 1 𝑛 𝑊 𝑊𝑊 2 1 1 2 Λ 1 ∗ 1 𝑔 ∗ 2 ,𝜈𝜉 + 𝑏 3 ∗ 1 ሚ 𝑊𝑊 𝑔 𝑊𝑊 𝑔 𝑔 ∗ 2 ,𝜈𝜉 𝑏 2 𝜈𝜉 𝜈𝜉 • 𝑊𝑊 = 𝑎𝑎, 𝑋𝑋, 𝑎𝛿, 𝛿𝛿 𝑎𝑎 = 𝑏 1 𝑋𝑋 = 2 , others = 0 • SM, tree level: 𝑏 1 𝑎𝑎 = 𝑏 𝑗 𝑋𝑋 , call it “ 𝑏 𝑗 ” • Assume 𝑏 𝑗 • Assume no 𝑟 2 cutoff for anomalous couplings 𝑎𝛿 • Measure 𝑏 2 , 𝑏 3 , Λ 1 , Λ 1 𝑎𝛿,𝛿𝛿 are already constrained from onshell photons • 𝑏 2,3 𝑏 𝑗 2 𝜏 𝑗 • Parameterize as fractional cross section 𝑔 𝑏𝑗 = 2 𝜏 𝑘 σ 𝑘 𝑏 𝑘 𝑏 𝑗 and relative phase 𝜚 𝑏𝑗 = arg 𝑏 1

7 Tools • JHUGen • Generate samples with arbitrary couplings • Τ Τ 𝑕𝑕 𝑟ത 𝑟 → 𝑌 → 𝑎𝑎 𝑋𝑋 → 4𝑔 for 𝑌 spin 0, 1, 2 • VBF, 𝑊𝐼 , 𝑕𝑕𝐼 with 0, 1, or 2 QCD jets, 𝑢𝑢𝐼 , 𝑐𝑐𝐼 , 𝑢𝑟𝐼 • MELA — Matrix Element Likelihood Approach • Matrix element calculations • JHUGen for signal • MCFM for background • Calculate discriminants to distinguish hypotheses • Reweight generated samples to different hypotheses

8 Contributions • Background • Τ 𝑟ത 𝑟 𝑕𝑕 → 𝑎𝑎 • 𝑎 + 𝑌 • Signal • 𝑕𝑕𝐼 , VBF, VH, 𝑢𝑢𝐼 • 𝐼𝑊𝑊 couplings in decay • 𝐼𝑊𝑊 couplings in production and decay • SM, anomalous, and interference contributions • Want to isolate each component to constrain couplings • 7 or 13 kinematic observables ( +𝑛 4ℓ for bkg separation) • too many to use them all

9 Discriminants • Two basic types of discriminants: 𝑞 𝑡𝑗𝑕 • 𝐸 𝑏𝑚𝑢 = 𝑞 𝑡𝑗𝑕 +𝑞 𝑏𝑚𝑢 • Optimal to distinguish pure SM signal from alternate hypothesis • Alternate hypothesis could be background, another coupling model, or another signal production mode 𝑞 𝑗𝑜𝑢 • 𝐸 𝑗𝑜𝑢 = 𝑞 𝑡𝑗𝑕 +𝑞 𝑏𝑚𝑢 • Together with 𝐸 𝑏𝑚𝑢 , optimal to also isolate the interference contribution • 𝑞 𝑡𝑗𝑕 , 𝑞 𝑏𝑚𝑢 , 𝑞 𝑗𝑜𝑢 are calculated through MELA using matrix element probabilities

10 Discriminants 1 𝑊𝐶𝐺 𝑎𝐼 𝑋𝐼 = 𝑞 Τ Τ Τ 𝑊𝐶𝐺 𝑎𝐼∕𝑋𝐼 • 𝐸 2𝑘𝑓𝑢 𝑞 𝑊𝐶𝐺 𝑎𝐼∕𝑋𝐼 +𝑞 𝐼𝑘𝑘 Τ • Separate associated production from QCD jets 𝑊𝐶𝐺,𝑇𝑁 𝐸 2𝑘𝑓𝑢 • VBF-jet category: 𝑊𝐶𝐺,𝑇𝑁 > 0.5 or 𝐸 2𝑘𝑓𝑢 𝑊𝐶𝐺,𝐶𝑇𝑁 > 0.5 • 𝐸 2𝑘𝑓𝑢 • VH-jet category: 𝑎𝐼,𝑇𝑁 > 0.5 or 𝐸 2𝑘𝑓𝑢 𝑎𝐼,𝐶𝑇𝑁 > 0.5 • 𝐸 2𝑘𝑓𝑢 𝑋𝐼,𝑇𝑁 > 0.5 or 𝐸 2𝑘𝑓𝑢 𝑋𝐼,𝐶𝑇𝑁 > 0.5 or 𝐸 2𝑘𝑓𝑢 • Untagged category: • Everything else 𝑎𝐼,𝑇𝑁 , 𝐸 2𝑘𝑓𝑢 𝑋𝐼,𝑇𝑁 max 𝐸 2𝑘𝑓𝑢 𝑇𝑁 and 𝐸 2𝑘𝑓𝑢 𝐶𝑇𝑁 to get optimal separation • Use 𝐸 2𝑘𝑓𝑢 for both extreme hypotheses

11 Discriminants 2 • Use 3D templates to parameterize the signal and background for each category • 𝑬 𝒄𝒍𝒉 , 𝐸 𝑏𝑗 , 𝐸 𝑗𝑜𝑢 𝑞 𝑡𝑗𝑕 • 𝐸 𝑐𝑙𝑕 = 𝑞 𝑡𝑗𝑕 +𝑞 𝑐𝑙𝑕 • Used for all 3 categories • 𝑛 4ℓ + decay kinematics 105 GeV < 𝑛 4ℓ < 140 GeV

12 Discriminants 3 • 𝐸 𝑐𝑙𝑕 , 𝑬 𝒃𝒋 , 𝐸 𝑗𝑜𝑢 𝑞 𝑡𝑗𝑕 • 𝐸 𝑏𝑗 = 𝑞 𝑡𝑗𝑕 +𝑞 𝑏𝑗 • Tagged categories: use production × decay probabilities • Untagged: use decay probabilities only • Example: 𝐸 0− for the 𝑔 𝑏3 analysis

13 Discriminants 4 • 𝐸 𝑐𝑙𝑕 , 𝐸 𝑏𝑗 , 𝑬 𝒋𝒐𝒖 𝑞 𝑗𝑜𝑢 • 𝐸 𝑗𝑜𝑢 = 𝑞 𝑡𝑗𝑕 +𝑞 𝑏𝑚𝑢 • Tagged categories: use production probabilities • Untagged: use decay probabilities

14 𝑏 𝑗 2 𝜏 𝑗 𝑔 𝑏𝑗 = 𝑏 1 2 𝜏 1 + 𝑏 𝑗 2 𝜏 𝑗 + ⋯ Likelihood fit • Assume real couplings, 𝜚 𝑏𝑗 = 0 or 𝜌 • ggH, only one HVV vertex: 𝑏 𝑗 𝑔 𝜏 1 𝑏𝑗 = 𝑏 1 𝑔 𝜏 𝑗 𝑏1 • 𝑞 𝑔 𝑏𝑗 , Ω ~ 𝑏 1 𝐵 1 + 𝑏 𝑗 𝐵 𝑗 2 2 ∼ 𝑈 0 Ω + 𝑏 𝑗 1 Ω + 𝑏 𝑗 cos 𝜚 𝑏𝑗 𝑈 𝑈 2 Ω 𝑏 1 𝑏 1 • VBF or VH, two HVV vertices • 𝑞 𝑔 𝑏𝑗 , Ω 2 𝑞𝑠𝑝𝑒 + 𝑏 𝑗 𝐵 𝑗 𝑒𝑓𝑑 + 𝑏 𝑗 𝐵 𝑗 𝑞𝑠𝑝𝑒 )(𝑏 1 𝐵 1 𝑒𝑓𝑑 ) ~ (𝑏 1 𝐵 1 4 𝑘 𝑏 𝑗 cos 𝑘 𝜚 𝑏𝑗 𝑈 ∼ ෍ 𝑘 Ω 𝑏 1 𝑘=0

15 Signal strength • Want to decouple ratios of couplings 𝑔 𝑏𝑗 from the signal strengths 𝜈 𝑗 • Allow signal strength for production via fermion couplings 𝜈 𝑔 and boson couplings 𝜈 𝑊 to float independently • Constrained by category distribution of events

16 Event distribution • First number is for SM, (second) is for 𝑔 𝑏3 = 1 • Use categorization for 𝑔 𝑏3 analysis, others are a bit different • (In particular, fewer observed events in VBF-jets)

17 Results • Scans for each parameter • 13 TeV only, and combination with Run 1 result

18 More details: 𝑔 𝑏3 • 1D projections help to explain • Small excess of events at smaller 𝑒𝑓𝑑 values of 𝐸 0− • Minimum away from 0 • 𝐸 𝐷𝑄 has small excess on the right • +0.3 is favored over -0.3 • Combine with Run 1: minimum at 𝑔 𝑏3 = 0

19 More details: 𝑔 𝑏3 • VBF and VH are sensitive to very small 𝑔 𝑏3 • Once 𝑔 𝑏3 ≳ 0.01 , more favorable to set 𝜈 𝑊 → 0

20 𝜈 𝑊 𝜈 𝑊 = 0.03 𝜈 𝑊 = 0.76 • Observe fewer VBF and VH events than expected • Best fit 𝜈 𝑊 for 𝑔 𝑏𝑗 = 0 is < 1 𝜈 𝑊 = 0.24 𝜈 𝑊 = 0.20 (values on plots)  Narrow minima not as deep as expected

21 More details: 𝑔 𝑏3 • Animations: each frame uses the best fit 𝜈 𝑊 and 𝜈 𝑔 𝑊𝐶𝐺∕𝑊𝐼 are the cross section • 𝑔 𝑏3 fractions for those processes • Watch what happens when 𝑔 𝑏3 ≲ 0.01 See ppt version for animations or separate indico attachment