Spin/CP Combination in ATLAS Higgs Hunting 2015, LAL Orsay YSF - - PowerPoint PPT Presentation

Not reviewed, for internal circulation only Spin/CP Combination in ATLAS Higgs Hunting 2015, LAL Orsay 
 YSF - July 30th Lars Egholm Pedersen* on behalf on the ATLAS Collaboration *The Niels Bohr Institute, University of Copenhagen 1

Outline Not reviewed, for internal circulation only 1 : • Analyses aim to examine the Higgs Spin/CP nature • Test pure BSM spin-0 and spin-2 models against the Standard Model • Constrain possible SM and BSM mixing of Spin-0 boson 2 with updated spin-2 results and HVV EFT approach • Extend previous publication • Combine results from all sensitive vector boson channels: 3 and H → γγ • H → ZZ* → 4l, H → WW* → e νμν (+ ≦ 1jet) • ZZ* and WW* are used to examine both spin-0 and spin-2 models, whereas γγ contributes to spin-2 1: Study of the spin and parity of the Higgs boson in di-boson decays with the ATLAS detector 2: Evidence for the spin-0 nature of the Higgs boson using ATLAS data 3: Determination of spin and parity of the Higgs boson in the WW* → e νμν decay channel with the ATLAS detector Lars Egholm Pedersen, The Niels Bohr Institute 2 Higgs Hunting 2015, Orsay, July 30th

Models • Classification framework proposed in ‘A framework for Higgs characterisation’* Not reviewed, for internal circulation only • SM without Higgs plus generic boson described with EFT. 
 (EFT scale here chosen to Λ =1 TeV) Spin-0: a) Testing SM against pure BSM scalar (0 +h ) and pseudo-scalar (0 - ) 
 • ✓ ◆ κ X = 1 ν ˜ Λ κ X 
 4 (˜ κ AV V / κ SM ) · tan α , ˜ κ HV V / κ SM b) Constrain continuum of BSM / SM couplings: CP-odd CP-even W J P Model Values of tensor couplings W * κ SM κ HV V κ AV V α , 0 + SM Higgs boson 1 0 0 0 Z Z * 0 + BSM spin-0 CP-even 0 1 0 0 h π / 2 0 − BSM spin-0 CP-odd 0 0 1 • Test SM against graviton-like spin-2. Including only quark and gluon couplings in production • Others estimated to be insignificant: σ EW / σ QCD ≅ 0.03% W p X Values of spin-2 quark and gluon couplings T selections (GeV) W * S p κ q = κ g Universal couplings – – , i Z n Z * κ q = 0 Low light-quark fraction < 300 < 125 - 2 , κ q = 2 κ g Low gluon fraction < 300 < 125 γ γ Testing SM against three spin-2 coupling configurations: κ q / κ g = 0,1 and 2 • *JHEP11(2013)043 Lars Egholm Pedersen, The Niels Bohr Institute 3 Higgs Hunting 2015, Orsay, July 30th

Hypothesis discrimination • Different approaches used in final states Not reviewed, for internal circulation only H → WW * → e νμν H → ZZ * → 4l H → γγ 2 discriminant 120 0.5 ATLAS Entries Signal fraction Data 0.12 Data ATLAS ATLAS P + H → ZZ* → 4l Signal J = 0 SM P + 100 P J =0 SM − J = 0 1.5 -1 0.4 s = 8 TeV, 20.3 fb P + J =2 = -1 κ κ Background ZZ* + Zjets s = 7 TeV, 4.5 fb q g -1 0.1 P + s = 8 TeV , 20.3 fb J =2 =0 κ ZZ -1 q s = 8 TeV, 20.3 fb H WW*, n = 0, e 80 → µ + P Data - Bkg BDT J =2 κ =2 κ q g j 0.3 1 + − 0 vs 0 0.08 60 0.2 0.5 40 0.06 0.1 20 0 0.04 0 0 − 0.5 0.02 20 − 0 2 4 6 8 10 12 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 BDT output Category 0 − 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 P J -MELA discriminant Possible to fully Discriminant based on Each test based on two BDTs: reconstruct final state polar angle, |cos( θ * )| Spin-0: SM vs Bkg.+ SM vs Alt. 
 10 categories from 0 to 1 0 Jet category 
 Discriminants constructed from BSM, SM matrix Extend with 11th category 
 Spin-2: SM vs Bkg + Alt. vs Bkg. 
 elements with p T ∈ [125, 300] GeV 0+1 Jet categories BDT suppresses BDTs trained on lepton 
 Per-category m γγ -fit 
 kinematics and MET determines signal fraction backgrounds Lars Egholm Pedersen, The Niels Bohr Institute 4 Higgs Hunting 2015, Orsay, July 30th

Results-I: Fixed hypotheses Not reviewed, for internal circulation only ATLAS H ZZ* 4 l → → Tests examining the Spin/CP nature of the Higgs boson: • -1 s = 7 TeV, 4.5 fb Observed -1 Expected s = 8 TeV, 20.3 fb + 0 SM ± 1 σ H WW* → → e ν µ ν + 0 SM ± 2 σ Spin-0: CP-even BSM and pseudo-scalar -1 • + s = 8 TeV, 20.3 fb 0 SM 3 ± σ P J 1 ± σ H → γ γ P J 2 ± σ -1 s = 7 TeV, 4.5 fb P J 3 ± σ -1 s = 8 TeV, 20.3 fb Spin-2: Universal couplings and κ q / κ g = 0 and 2 ~ q • 40 30 20 Combining diboson final states: WW*, ZZ* and γγ • 10 0 p ( J P alt ) -10 CL S ( J P alt ) = Exclusion determined from CL S : • -20 1 − p ( J P SM ) -30 P + P − P + P + P + P + P + J = 0 J = 0 J = 2 J = 2 J = 2 J = 2 J = 2 h κ = κ =0 =0 =2 =2 κ κ κ κ κ κ q g q q q g q g p <300 GeV p <125 GeV p <300 GeV p <125 GeV T T T T p alt p alt p SM p alt Tested Hypothesis Obs. CL s (%) exp ,µ =1 exp ,µ =ˆ obs obs µ 0 + 2 . 5 · 10 − 2 4 . 7 · 10 − 3 7 . 1 · 10 − 5 4 . 7 · 10 − 2 0 . 85 ZZ+WW h 1 . 8 · 10 − 3 1 . 3 · 10 − 4 < 3 . 1 · 10 − 5 < 2 . 6 · 10 − 2 0 − 0 . 88 2 + ( κ q = κ g ) 4 . 3 · 10 − 3 2 . 9 · 10 − 4 4 . 3 · 10 − 5 1 . 1 · 10 − 2 0 . 61 2 + ( κ q = 0; p T < 300 GeV ) < 3 . 1 · 10 − 5 < 3 . 1 · 10 − 5 < 3 . 1 · 10 − 5 < 6 . 5 · 10 − 3 0 . 52 2 + ( κ q = 0; p T < 125 GeV ) 3 . 4 · 10 − 3 3 . 9 · 10 − 4 4 . 3 · 10 − 5 1 . 5 · 10 − 2 0 . 71 γγ 2 + ( κ q = 2 κ g ; p T < 300 GeV ) < 3 . 1 · 10 − 5 < 3 . 1 · 10 − 5 < 3 . 1 · 10 − 5 < 4 . 3 · 10 − 3 0 . 28 2 + ( κ q = 2 κ g ; p T < 125 GeV ) 7 . 8 · 10 − 3 1 . 2 · 10 − 3 7 . 3 · 10 − 5 3 . 7 · 10 − 2 0 . 80 SM is favoured and alternative models excluded > 95%CL S Lars Egholm Pedersen, The Niels Bohr Institute 5 Higgs Hunting 2015, Orsay, July 30th

Results-II: Spin-0 coupling ratios Not reviewed, for internal circulation only C P C - E C C P v - o o e O n n n d t t r r B d i i b b S u u M t t i i o o n n Combined fit performed on ZZ * and WW * final states • Results translated to effective BSM cross section fraction • Data in agreement with Standard Model expectations Lars Egholm Pedersen, The Niels Bohr Institute 6 Higgs Hunting 2015, Orsay, July 30th

Conclusions and outlook Not reviewed, for internal circulation only • Analysis of Higgs Spin/CP nature: • Pure BSM CP-even scalar (0 + h ) and pseudo-scalar (0 - ) excluded in favour of SM • SM furthermore favoured over spin-2 models with different κ q / κ g coupling configurations • Spin-0 BSM/SM coupling ratio fits indicate that data is agreement with SM • Looking forward to Run-II: • Continue development of EFT approach to study HVV interaction • Add different Higgs production mechanisms • Simultaneous fit of couplings Lars Egholm Pedersen, The Niels Bohr Institute 7 Higgs Hunting 2015, Orsay, July 30th

Not reviewed, for internal circulation only Backup 8

Models - Expanded Not reviewed, for internal circulation only Spin-0 J P Model Values of tensor couplings κ SM κ HV V κ AV V α 0 + SM Higgs boson 1 0 0 0 0 + BSM spin-0 CP-even 0 1 0 0 h π / 2 0 − BSM spin-0 CP-odd 0 0 1 Spin-2 p X Values of spin-2 quark and gluon couplings T selections (GeV) κ q = κ g Universal couplings – – κ q = 0 Low light-quark fraction < 300 < 125 κ q = 2 κ g Low gluon fraction < 300 < 125 Lars Egholm Pedersen, The Niels Bohr Institute 9 Higgs Hunting 2015, Orsay, July 30th

Per final state results Not reviewed, for internal circulation only Lars Egholm Pedersen, The Niels Bohr Institute 10 Higgs Hunting 2015, Orsay, July 30th

Per final state results, tensor structure Not reviewed, for internal circulation only Lars Egholm Pedersen, The Niels Bohr Institute 11 Higgs Hunting 2015, Orsay, July 30th

H → ZZ * → 4l Background discriminant from production • Not reviewed, for internal circulation only related observables: 
 η 4l , p T , 4l , m 4l , cos( θ *) and Φ 1 P ( H 1 ) J P − MELA = P ( H 1 ) + P ( H 2 ) Hypothesis tests Discriminants Normalisations Lars Egholm Pedersen, The Niels Bohr Institute 12 Higgs Hunting 2015, Orsay, July 30th

H → ZZ * → 4l Background discriminant from production • Not reviewed, for internal circulation only related observables: 
 η 4l , p T , 4l , m 4l , cos( θ *) and Φ 1 Tensor structure fit discriminants Lars Egholm Pedersen, The Niels Bohr Institute 13 Higgs Hunting 2015, Orsay, July 30th

H → WW * → 4l Spin-2 tests training parameters: pTll, mll, Δ Φ ll, mT • Not reviewed, for internal circulation only SM vs 0+h Training parameters: pTll, mll, Δ Φ ll, pmiss • SM vs 0- Training parameters: mll, pTl1 -0.5pTl2 + 0.5pTmiss, Δ pT, Δ Φ ll • Spin-2, UC Spin-0 Lars Egholm Pedersen, The Niels Bohr Institute 14 Higgs Hunting 2015, Orsay, July 30th