CMS Higgs Results - Caltech High Energy Physicsbornheim/html/APS2014_Bornheim.pdf · Adi Bornheim,...

CMS Higgs Results

Adi Bornheim Caltech

06.04.2014 1

A brief history of recent times

2014 2004 1994 1984 1974 1964

W & Z Boson t-quark H Boson

This talk : Summary of 29 CMS publications and many preliminary results. https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsHIG

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Peter Higgs

Adi Bornheim, CMS Higgs Results, APS Meeting 2014,

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The CMS Collaboration

06.04.2014 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,

The LHC Accelerator

06.04.2014 4

20 MHz

Average 400 MHz

Pile up : 40 vertices, 14 jets, 2 TeV


1380 1.5 X 1011

4 TeV

0.8 X 1034

5 σ H discovery

Five production processes, cross section varying by factor >200. Nine different decay modes, varying by almost four orders of magnitude.

Any possible combinations of final state objects.

Cross sections and branching ratios

06.04.2014 5 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,

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More than 300 CMS publications are evidence for a very good understanding of our detector, simulation and backgrounds.

https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResults

CMS SM Precision Measurements

Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 06.04.2014

06.04.2014 7

The CMS Detector

All Silicon Tracker, High resolution Crystal ECAL Brass-Scintillator HCAL 3.8 Tesla Magnet Drift Tube and Resitive Plate Chamber Muon System


H→WW


HIG-13-023

H→WW

06.04.2014 9

Very large branching ratio, but large backgrounds. Missing energy in final state ⇒ poor mass resolution. Use RAZOR variables to optimize signal line shape.


HIG-13-023

H→WW

06.04.2014 10

Analysis in many event categories (ee, µµ, eµ, 0/1/2 jets)

Significance : 4.3 σ at 125.6 GeV, observed cross section µ=0.72+0.20

Signal yield from LHC Run 1 in clean categories (eµ 0/1 jet) order 100 events.

HIG-13-023

-0.18


H→WW - Mass

06.04.2014 11

Large variation of σ∗BR(H→WW) with mH at fixed signal strength.

Linear dependency of mR peak on mH with approximately constant resolution.

mH=125.5±3.8 GeV

HIG-13-023


mH=128.2+6.6 GeV -5.3

H→WW - Coupling and Spin

06.04.2014 12

Spin-parity JP=0+ favored against narrow JP=2+ or JP=0-

Production cross section consistent with SM

Coupling consistent with SM expectation.

µ ggH

µVBF,VH

κ f

κV

HIG-13-023


H→ZZ→4l

06.04.2014 13

HIG-13-002


H→ZZ→4l


At low Higgs masses steep drop of acceptance x efficiency.

Analysis challenge : Low pT lepton acceptance and performance.

HIG-13-002 Mass Resolution H→ZZ→4e

Muon Mass Scale acceptance x efficiency H→ZZ→4l

∆m < 0.1%

σE=2.0 GeV

Clean, narrow peak over a modest, well simulated background. Significance of 6.8 σ, µ =

H→ZZ→4l signal

06.04.2014 15

121.5 < m4l< 130.5

4 ee, 13 µe, 8 µµ events

HIG-13-002

Invariant Mass Spectrum ZZ→4l


H→ZZ→4l - Mass and Spin

06.04.2014 16

Mass : 125.6 ± 0.4 (stat) ± 0.2 (sys)

Pseudo scalar and all spin 1 hypothesis excluded at >99%, spin 2 excluded at > 95% confidence level.

HIG-13-002

Spin Hypothesis Tests


H→ZZ→4l - Production Mode

06.04.2014 17

Gluon fusion and VBF production rates as expected from SM.

HIG-13-002

Dijet

0/1-jet

best fit µ


H→ZZ→4l - Width from Interference

06.04.2014 18

Interference cause ZZ event rate change of ~8% for m4l>2mZ for ΓH = ΓH SM

Obs. (exp.) @ 95% C.L. : ΓH < 4.2 (8.5) ΓH SM , ΓH < 17.4 (35.3) MeV

HIG-14-002

ΓH /ΓH SM

MELA Dgg m4l (GeV) Adi Bornheim, CMS Higgs Results, APS Meeting 2014,

06.04.2014 19

H→γγ


H→γγ : Narrow peak - width determined by experimental resolution - over a large background.

Expect >500 H→γγ events in LHC run 1 data after final selection. Background in final analysis categories dominated by QCD di-photon

production – irreduceable. Analysis strategy : Improve S/B by categorizing events according to Higgs

production mode, Higgs kinematics and photon reconstruction performance.

H→γγ

06.04.2014 20

HIG-13-001

Calibration with > 3x109 π0 H→γγ Signal Model : σm ~1%

mγγ (GeV)

H→γγ

06.04.2014 21

Preliminary results from Moriond 2013 : Observed excess 3.2 σ , µ = 0.78+0.28

mH : 125.4±0.5(stat)±0.6(stat) Final results for LHC run 1 expected for summer conferences : Improved ECAL calibration, improved

detector simulation, refined categorization, optimized energy reconstruction and photon identification.

HIG-13-001

- 0.26

Channel compatibility for two alternative analysis


Properties measured in H→γγ

06.04.2014 22

Preliminary results : Acceptance of current analysis drops in region of largest sensitivity. Particular spin-2 model tested cannot be ruled out. Observed data is compatible with the SM with a χ2 p-value of 0.68.

|cos(𝜽𝜽CS)| fqq(%) *

HIG-13-016


Photon

Photon

Jet

Jet

H→γγ VBF Production

Jet

µggH, ttH

µ VB

F,VH

HIG-13-001

mγγ in γγ +2 jets category

06.04.2014 Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 23

VH→bb

06.04.2014 24

HIG-13-012

Mass Resolution H→bb

m(jj) (GeV)

Muon 0, pT : 161.8 GeV

Muon 1, pT : 27.3 GeV


VH→bb

06.04.2014 25

Very large backgrounds from SM processes.

Use associated production mode to enhance S/B.

HIG-13-012

Dijet mass cross-check S/B from BDT, all channels combined


VH→bb

06.04.2014 26

Six topologies considered. Significance around 2 sigma at 125 GeV. WH and ZH production modes consistent with SM expectations

HIG-13-012


H→ττ


H→ττ

06.04.2014 29

Observed significance 3.2 σ at mH =125 GeV

Couplings consistent with SM expectations.

HIG-13-004


H→ff Combination

06.04.2014 30

Combination of H→bb and H→ττ results.

Combined significance of 3.8 σ with a signal strength of 0.83±0.24.

HIG-13-033


ttH Analysis

06.04.2014 31


ttH - Combination

06.04.2014 32

HIG-12-025 HIG-13-015 HIG-13-019 HIG-13-020

Observed yields and distributions are compared to SM expectations.

Median expected combined limit : 1.8σ @ 95% C.L. in the absence of a signal, 2.9 assuming the presence of SM ttH.

Observed limit is 4.3σ @ 95% C.L. , reaching sensitivity to SM.


H→Zγ & H→γ*γ→µµγ

06.04.2014 33

Limits at ~10 times the SM cross section for H→Zγ and H→γ*γ→µµ. Only leptonic Z decays used.

Loop mediated, sensitive to BSM physics. Need 100 times more luminosity

⇒ HL-LHC.

HIG-14-003 HIG-13-006


H→µµ

06.04.2014 34

Lowes branching ratio. Efficiency for final state high.

Target for HL-LHC.

HIG-13-007


BSM Higgs Searches

06.04.2014 35

MSSM direct search : φ→µµ (w/o b-tag) neutral Higgs production in ττ channel.


HIG-13-021

NMSSM : additional gauge singlet wrt MSSM, one CP-even, one CP-odd. Most recent search h→a1a1→4µ

HIG-13-010

BSM Higgs Searches

36 Adi Bornheim, CMS Higgs Results, APS Meeting 2014,

Combined limit for Heavy Higgs and A (Type II) 2HDM. α an β determine the cross section for H and A production, the branching ratio Br(H → hh), Br(A → Zh) and Br(h → WW, ZZ, ττ, γγ).

Heavy Higgs from H→ZZ→2l2ν, assuming additional EWK singlet added to the SM.

HIG-13-025

06.04.2014

HIG-13-014

Precision Higgs Physics with HL-LHC

06.04.2014 37

High Luminosity LHC aims to deliver 3 ab-1

Precision Higgs physics, di-Higgs production, Higgs as a portal.


FTR-13-024

FTR-13-004

Study for 3 ab-1, A→Zh, φ→µµ, H→ZZ→4l

Upgrade studies for muon system, assuming increased forward acceptance for H→ZZ→4µ

Precision Higgs Physics with HL-LHC

06.04.2014 38

Upgrade R&D studies currently ongoing, aiming for a technical proposal later in 2014 or early 2015.


Track-Trigger

Forward Calorimeter & Precision Timing

Forward Muon System

Summary

06.04.2014 39

A wide range of Higgs production and decay modes have been analyzed with CMS data.

All measured signal strengths and properties are in agreement with expectation for a standard model Higgs boson. The mass measurements are consistent across channels.

Precision Higgs physics is opening the door to new territories.

Large amounts of luminosity are now needed to reveal the nature of the new boson and its role in fundamental physics.



Does this answer all our questions ?

CMS Higgs Results - Caltech High Energy Physicsbornheim/html/APS2014_Bornheim.pdf · Adi Bornheim,...

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