Page 1

CLIC Higgs talks at ECFA LC 2013

Booked:

Astrid Muennich Measurement of H -> tautau at 350 GeV and 1.4 TeV CLICTBN Measurement of the Higgs self-coupling at 1.4 TeV and 3 TeV CLICSophie Redford Measurement of the top Yukawa coupling at 1.4 TeV CLICTBN Extraction of H -> bb, H -> cc and H -> gg at 350 GeV and 1.4 TeV CLICTBN Higgs to gamma+gamma and Z+gamma at 1.4 TeV CLICTBN Measurement of H -> mumu at 1.4 TeV CLIC

Philipp Roloff Measurement of the top Yukawa coupling at sqrt(s) = 1 TeV using the SiD detector

(20+5 min, eventually 15+5 min)These are placeholders: titles may be changed; abstracts to be submitted

Higgs decay to b, c, and gluons @ 1.4 TeV (update)

Tomáš Laštovička

IoP Prague

LCD-WG Analysis Meeting, April 9th, 2013

Page 3

Summary of changes

1) Dominant background sample ee → qqvv (2096) with 126 GeV Higgs was replaced by 2201 sample with mH = 12 TeV.

2) ee → qqlv (2159) sample added.

3) 4Q background samples (qqqqνν, qqqq, qqqqll) from HHνν analysis added.

4) Neural net input variables added: ymin, ymax , pT of jets

Page 4

Data samples

126 GeV Higgs, 1.4 TeV, full sim/rec CLIC_SiD, γγ overlay, 1500 fb–1

Sample prodID σ [fb] # Requested # Prod/Twiki # Analyzed

ee → hvv inclusive 2019 244.1 1M 1M 980k

ee → qqvv 2201 (2096) 788 (933.8) 500k 445k (482k) 163k (458k)

ee → qq 2098 4008.8 500k 175k 166k

ee → qqlv 2159 4312.9 200k 500 66k

ee → qqll 2144 n/a 200k - -

ee → qqqqvv 1081 24.72 - - 221k

ee → qqqq 1097 1325 - - 249k

ee → qqqqll 1089 71.68 - - 164k

Page 5

Results Update

h → bb h → cc h → gg

σhνν uncertainty 0.32 % 2.9 % 1.7 %

Signal efficiency 67% (137k) 31% (3k) 22% (5.4k)

Signal purity 73% 39% 65%

h → bb h → cc h → gg

σhνν uncertainty 0.315 % 3.7 % 2.27 %

Signal efficiency 63% (127k) 26% (2.6k) 26.3% (6.4k)

Signal purity 79.5% 29% 30.2%

UP

DA

TE

D

(BR: 56.1 %) (BR: 2.83 %) (BR: 8.38 %)

Page 6

Results UpdateU

PD

AT

ED

Page 7

Next steps

Isolated lepton finder, requires to re-LCFI all samples. Data samples

– Increase statistics of • ee → qqvv, ee → qq, ee → qqlv

– No events available for• ee → qqll

– Address e-γ and γ-γ backgrounds.

Simultaneous determination of cc and gg. Whole NN classifier rather than cut and count.

– Investigate limits of the classification.

Repeat the 3 TeV Higgs decay analysis with the 126 GeV Higgs?• Re-simulate 2025 in the SiD framework

Page 8

BACKUPS slides from the last presentation

Page 9

Analysis Chain

Adapted from 3 TeV Higgs branching ratio analysis+ experience from hhνν and some minor improvements

SelectedPandoraPFOCollection with FastJet kT, R = 1.0 and exclusive 2 jets

Channel separation and jet true flavour tag– From quarks originating from initial Higgs

LCFI Flavour Tagging– Neural nets retrained on a fraction of qqνν sample– No significant improvement in analysis results (b-tag) when compared to 3 TeV

flavour tag nets.

Page 10

Neural Net Inputs

Current inputsInvariant mass and total energy of jets

Distance of jets in η – ϕ plane

Number of leptons and number of photons

Acoplanarity

Sums of jet flavour tags (b-, c-, c(b)- and b(l))

max(|ηi|)

Additional (implemented but not used at the moment)

– Event invariant mass, ymin, ymax, pTmax, pT

min, ETmiss, Σ|ηi|, isolated leptons, etc…

Highest NN input significance

Page 11

Control Plots (for the b-channel signal)

Disclaimer: does not include full set of SM backgrounds.

Page 12

Control Plots II (linear scale, normalized to 1)

Page 13

Neural Net Classification

b-channel (BR: 56.1 %) : is nice and easy– Note the linear histogram scale and good hνν inter-channel separation due to flavour tag.

c-channel (BR: 2.83 %) : is the most difficult one gluons (BR: 8.38 %) : has sizeable background from hνν

Disclaimer: does not include full set of SM backgrounds.

h → bb h → cc h → gg