Lomonosov 2021
ATLAS and CMS Highlights
Paul Jackson (University of Adelaide),
on behalf of the ATLAS and CMS collaborations
August 22nd, 2021

LHC physics program

See dedicated ATLAS and CMS talks throughout the conference for more details

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LHC data

Many thanks to the LHC team for theexcellent data they provided to us in
Run 1 and Run 2 and for theircommitment in view of Run 3
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Run 2 Breakthroughs•Higgs– Observation of all main production mechanisms– Observation of Yukawa interactions w/ 3rd generation fermions– Constraints on Higgs self-interaction via HH cross section– Evidence for H→ 𝜇𝜇 and H→ 𝑙𝑙𝛾•

Rare processes±ggF VH
VBF ttHtb

𝜈𝜏( )( )±– Observation of weak boson scattering modes (incl. W W )– Observation of ttW, ttZ and tZq– Evidence for tttt production•Searches– Excluded a wide range of BSM parameter space with a broad search program• SUSY and resonances: gluino, squark, stop and Z’ exclusions* up to m= 2.3, 2.0, 1.3
and 5.0 TeV respectively• Dark matter constraints, incl. H → invisible <~10%• Experimentally challenging signatures such as compressed spectra, displaced vertices,long-lived particles and unconventional signatures

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* all limits given in this talk are at 95% confidence level

4Detector performance
Results from Run 2 only possible thanks to excellent understanding of detector
performance, and development of reconstruction and identification algorithms

Very highly efficient object reconstruction.
Percent-level (or better) understanding of this performance in data.
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Detector performanceLomonosov 20216

E/𝜸 reconstruction and muon trigger

Very highly efficient object reconstruction.
Percent-level (or better) understanding of this performance in data.
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Z-boson + jets production

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ATLAS-CONF-2021-033

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Z invisible width
Ratio of Γ𝜈𝜈 /Γ!! from a simultaneous fit of 𝑍 → 𝜈𝜈, 𝑍 → 𝜇𝜇, 𝑍 → 𝑒𝑒 enriched categories

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SMP-18-014

9Vector-boson Scattering-CERN-EP-2021-137
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ATLAS_CONF_2021-038
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WWW Production

ATLAS_CONF_2021-039
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WWW Production
candidate event
W+(e+ν) W+(e+ν) W−(μ−ν)

12Triple J/𝝍 production

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BPH-21-004

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TopLomonosov 202114

top-quark production

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ATLAS-CONF-2021-031

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CP violation in semileptonic ttbar

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TOP-20-005

16Single top-quark polarization

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ATLAS-CONF-2021-027

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HiggsLomonosov 2021

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Higgs Couplings to 𝝉 leptons

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ATLAS_CONF_2021-044

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Evidence for 𝐻 → 𝝁! 𝝁"

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CMS-HIG-19-006
ATLAS-HIGG-2019-14

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Higgs to 2nd generation quarks

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ATLAS-CONF-2021-021
CMS-HIG-18-031

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Higgs to 2nd generation
Z(μμ) H(cc)candidate event

22Di-Higgs production

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ATLAS-CONF-2021-030

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Di-Higgs production
H(bb) H(ττ)
candidate event

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SEARCHES

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SUSY 𝑯𝑯 → 𝟒𝒃

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SUS-20-004

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SUSY Electroweak

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arXiV:2108.07586
SUSY-2018-41

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Heavy Particle Search

ATLAS-CONF-2021-043
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ATLAS-CONF-2021-040
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Triboson resonanceLomonosov 2021

B2G-21-002

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Flavour Anomalies

LQ Summary plots
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SUSY-2019-1830

Lepton Flavour Violation

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ATLAS-CONF-2021-042
EXOT-2020-28
EXOT-2018-36

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Low Mass Long-Lived Particles
CMS Displaced Di-Muons w/ Data Scouting• Lower trigger thresholds by recording
reduced information• Record O(kHz), low threshold, unprescaled,by throwing away information• Gives low muon pT sensitivity (>3 GeV @HLT)• Gives sensitivity to mμμ~300 MeV• Veto regions of SM resonances

Example exclusion plot for one value of c𝜏32

Standard Model Summary

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Standard Model Summary
CMS Preliminary

Production Cross Section, σ [pb]June 2021
5104≥n jet(s)10≥n jet(s)7 TeV CMS measurement (L ≤ 5.0 fb-1)
8 TeV CMS measurement (L ≤ 19.6 fb-1)
13 TeV CMS measurement (L ≤ 137 fb-1)
Theory prediction
CMS 95%CL limits at 7, 8 and 13 TeV

103102=n jet(s)10110−1

10−2
10−310−4W

EW γ γ → EW EW EW EW EWZ Wγ Zγ WWWZ ZZ VVV WWWWWZ WZZ ZZZ WVγ Wγ γ Zγ γ EWtt tt-ch tW ts-ch ttγ tZq ttZ tγ ttW tttt ggH VBF
VH WH ZH ttH tH HHqqW qqZ WW qqWγssWW qqZγ qqWZqqZZqqHEW,Zγ γ ,Wγ γ : fiducial with W →lν , Z→ll, l=e,µTh. ΔσH in exp. Δσ

All results at: http://cern.ch/go/pNj7

LS2 Activities

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Ready for Run3•••

B-parkingo Low pT displaced triggers save asample of unbiased B-hadronso Enables several LFV analyseso Studying how to further optimise
trigger for Run3Scouting
o Aim to run particle flow at higherrate, possibly with additional L1triggers (on GPUs or pixel tracks)
Long-lived particle improvementso L1 trigger to improve displaced
signature efficiency
o HLT developments also ongoing

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Run 3 Preparation

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Summaryo An enormous body of work in recent times from ATLAS and CMS
o Results presented herein include final states with all SM particles!
o Preparations for Run 3 are ramping up as we prepare > 13 TeV!

•All ATLAS Physics Analysis Public Results appear at–•All CMS Physics Analysis Summaries appear at:–•

https://twiki.cern.ch/twiki/bin/view/AtlasPublic/ResultswithData2018
http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/CMS/index.html

ATLAS Physics Briefings at– https://atlas.cern/updates/briefing•CMS Physics Briefings at:– https://cms.cern/tags/physics-briefing

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Backup

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CMS: Upgrade plans

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Ready for Run3

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CMS
tt+bb production now exceeding theoretical knowledge! − Importantbackground in study of top-Higgs Yukawa coupling

FCNC top decays: t->Hu andt->Hc are expected
to be O(10-17) and O(10-15)in SM.
Clear NP if we observe them.

t̅tγu/cHγ

S/(S+B) Weighted Events / GeV

Also tt+cc with 19% precision − key role of c-tagging for current
and future analyses
CMS Preliminary

137 fb-1 (13 TeV)

H→γ γmH = 125.38 GeV
BF(t → Hu) = 0.031%

All Categories
S/(S+B) weightedData
S+B model (exp.)
B component±1 σ±2 σ120
100806040200HtB component subtracted

3020γu/cγ100−10−20100

110120130140150160170180700

MB4ME1/3

ME2/2

ME3/2 ME4/2

Steel

0.8
0.7

600 MB30.6
500 MB20.4

ME1/2

400

0.5MB1Solenoid

0.3

700

800

HCAL

100
400

ME4/1

500 600

200

ME3/1

SteelME2/1300

900 1000 1100

z decay position [cm]0.20.10Signal Efficiency

CMS Simulation Preliminary

ME1/1r decay position [cm]mγ γ (GeV)

Search for Long-lived Particles Decaying in theCMS Endcap Muon SystemCMS-PAS-EXO-20-015

Displaced decay in muon
endcap produces hadronic
shower (w/ ~1k CSC hits!) inlow BG environment
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Di-Higgs production

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ATLAS-CONF-2021-035
ATLAS-CONF-2021-016

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Effective Field Theory

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Detectors/Computing

LHCP2021
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