Top quark properties and rare decays - SLAC Indico (Indico)

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Top quark propertiesTop quark propertiesand rare decaysand rare decays

Andreas Jung (Purdue University)Andreas Jung (Purdue University)

4747thth SLAC Summer Institute SLAC Summer InstituteAugust 16August 16thth, 2019, 2019

Disclaimer: Impossible tocover wealth of top physics,nor the prospects for future,including new colliders!

Fundamental building blocks:Matter (quarks, leptons)Forces (gauge bosons)

Development “guided” by the idea of

unifying forces, ultimately one force

2Top quark properties and rare decaysA. Jung

The Standard ModelThe Standard Model

Top quark discovery in 1995at Fermilab (CDF & D0)

Higgs discovery in 2012 (ATLAS & CMS)

Unification of weak and electromagnetic forces

Beautiful – but symmetry is broken: photons massless, W/Z massive

→ solution is the Higgs field which breaks EWK symmetry and manifests itself with a new particle: the Higgs boson


Success of the SMSuccess of the SM

LHC


The Large Hadron ColliderThe Large Hadron Collider

p p

√s=7/8/13 TeV

Peak luminosities: 8 x 1033 cm-2s-1

~5 / 20 / 160 fb-1 per experiment LHC shutdown is next

27 km circumference


The CMS DetectorThe CMS Detector

Weight: 14000t


The ATLAS DetectorThe ATLAS Detector

Weight: 7000t

Detectors – comparisonDetectors – comparison

NIM A 634:8-46 (2011)

Huge difference in all aspects of the silicon detector, e.g. No channels and area Consequences for object IDs using silicon

detector, e.g. b-tagging

CMS silicon tracker:

D0 silicon tracker:


http://arxiv.org/abs/1005.0801


Proton-proton collision @13 TeVProton-proton collision @13 TeV


● Top quark physics requires precise b- and c-physics (oh, well: uds-physics)

Particle flow Combines detector

information to ID particles

Jets and missing ET

Gamma & Z-jet balance Pile-up subtraction

Isolated Leptons Dilepton resonances (Z,

upsilon, J/psi)

“b-tagging” of jets Several techniques,

dominated by silicontracker information

Relative b-jet correction:0.998 ± 0.005

CMS-JME-13001

Object ID: CMS as exampleObject ID: CMS as example

https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsJME13001


How to extract signalevents ?

Pioneered atTevatron Allowed single top

observation “Wide-spread” use in all

experiments... Overtraining, bias, etc. Not your old-school

event counting technique

Cross sections & “purity”Cross sections & “purity”


● Kinematic plane, Q vs. x, for production of top quarks and W, Z bosons● Horizontal lines indicate production thresholds

● Measurements of t, W, Z constrain αS and proton structure (PDFs)

● Differential top quark cross sections

Tev

atr

on

@1.

96 T

eV

Heavy Particle ProductionHeavy Particle Production

Top is the heaviest fundamental particlediscovered so far→ mt = 173.34 ± 0.76 GeV

Unique quark:

→ Observe bare quark properties

Large Yukawa coupling to Higgs boson → λt ~ 1 only mt is natural mass

Special role in EW symmetry breaking ?

No fine-tuning if top quark partner exists

[arxiv:1403.4427]

Elementary mass particle spectra:The top quarkThe top quark




If we could calculate the Higgs mass: → Large corrections to the Higgs mass from top quark “loops”

(Hierarchy problem)

Higgs mass at ~ 125 GeV!→ New physics can appear in

these loops

The top – Higgs connectionThe top – Higgs connection

The Big Bang Theory

dilepton

lepton+jets

All hadronicBR, bgincrease

Strong interaction: Top pairs

gg fusion

qq: ~15/13%gg: ~85/87%

(~10%, 13 TeV)

(~90%, 13 TeV)

LHC (7/8/13 TeV):


Top quark introductionTop quark introduction

Top quark decay: t → Wb in ~ 100% of the cases

...to be exact: 99.82%

http://www.cbs.com/shows/big_bang_theory/


The past...The past...Discovery atTevatron: 1995 1000's events

(Tevatron Run II)100,000's events(LHC Run I)

Establish top quark SM First differential

measurements Searches...

SM top quark ? Multi-differential Precision measurements


The present...LHC Run IIThe present...LHC Run II

Outline of the talk: (Ultimate) precision frontier

Cross sections, angular correlations, massImplications, any evidence for non-SM contribution

New frontiers: tt+W, tt+Z, tt+H, tt+n-jets

Full Run II provides about~ 120 million tt pairs~ 30 million single top~ 120k ttZ, tZ

The precision frontierThe precision frontier


New measurements at 2, 5, 8 and 13 TeV – agreement with the SM

Profile log-LH fit by D0:Reduced uncertainties


σ = 7.26 ± 0.13 (stat.) ± 0.57/0.50 (syst.) pbδσ/σ = 7.6%

The precision frontier: topThe precision frontier: top

Phys. Rev. D 94 092004 (2016)

ATLAS cross section at 13 TeV in eμ channelRelative precision: δσ/σ = 2.4%

ATLAS-CONF-2019-041

σ = 826.4± 3.6 (stat) ± 11.5 (syst) ± 15.7 (lumi) ± 1.9 (beam) pb

CMS 2nd cross section Relative precision: δσ/σ = 13%

σ = 68.9 ± 6.5 (stat.) ± 6.1 (syst.) ± 1.6 (lumi.) pb

PRL 119 (2017) 242001

NEW

http://journals.aps.org/prd/abstract/10.1103/PhysRevD.94.092004

First 2D cross section measurement of this type at the LHC Dilepton eμ channel – very good S/B Provide single & double differential cross sections

2D cross sections more sensitive to large x PDFsConstrain PDFs at large x


CMS-TOP-14-013

Add 2D top quarkcross sections

Differential cross sectionsDifferential cross sections

→ BSM physics at high scales requires initial parton x at > 0.1

https://arxiv.org/abs/1703.01630

Typical theoretical uncertainties are about 2-3% (scale + PDF)

Typical experimental: ~3.7%


Czakon et al. [arXiv:1705.04105]

Challenges: UncertaintiesChallenges: Uncertainties



Extract yt by using l+jets differential cross

sections in 3, 4, and 5 jet bins

Relies on Hathor to extract scale factors for Powheg, templates in y

t

Likelihood fit in 55 bins to extract yt:

Extraction of YukawaExtraction of YukawaCMS-PAS-TOP-17-004

Templates of yt:

Extract top quark Yukawa coupling:

Sensitive to yt

http://cds.cern.ch/record/2665937

p p

t

t

W–

b

W+

bl

nl

q

q'

Top mass (difference)Top width, LifetimeTop Charge

Branching Ratios |Vtb|

Anomalous couplingsRare decays

Spin CorrelationProduction Asymmetries

Spin CorrelationsProduction AsymmetriesPolarization

Production cross sectionsTop kinematicsProduction via resonanceNew particles

W helicity

→ Selection of results, focus on most recent and/or precise results

tt + W, Z, γ


Top quark physicsTop quark physics

Interference appears at NLO QCD:

→ Only occurs in qq initial state; gg is fwd-bwd symmetric

This is a forward-backward asymmetry at Tevatron No valence anti-quarks at LHC → t more central

SM predictions at NLO (QCD+EWK) → Tevatron: AFB ~ 10 % vs. LHC: AC ~ 1 %

(These are NNLO pQCD predictions, there is also the PMC approach)

Experimentally: Asymmetries based on decay leptons or fully reconstructed top quarks

Positive asymmetry Negative asymmetry

“easier”

“harder”


Top Quark AsymmetriesTop Quark Asymmetries

Production asymmetry due to NLO interferences

→ Final Tevatron combination agrees with SM (at 1.5 SD)


Tevatron (2018)

Tevatron Preliminary (2017)

● Inclusive combinations via BLUE● Differential combinations employing

full covariance matrices


CautionTevatron

Phys. Rev. Lett. 120, 042001 (2018)

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.042001


CDF observed a 3 SD tension between data and SM theory > 450 GeV D0 observed agreement to SM theory, but also agrees with CDF

Tevatron Preliminary (2017)




Measurements at the LHC much harder:

→ LHC results agree with SM (but not yet significant)→ Associated production (ttbar + photon, ttbar + W)

Czakon et al.[arXiv:1711.03945]





Measurements at the LHC much harder:

→ LHC results agree with SM (but not yet significant)→ Associated production (ttbar + photon, ttbar + W)

Czakon et al.[arXiv:1711.03945]


ATLAS-CONF-2019-026

Update by ATLAS Used 139\fb of data l+jets decay channel Inclusive and

differential in m(tt)

Different from 0 with > 4 SD, but

No real test of SM

NEW

Ac = 0.006 ± 0.0015 (stat+syst)

Evidence for Ac being non-zero



Spin correlationsSpin correlations Double-differential cross section allows to access spin correlation and

polarization information in top quark events

Charged lepton is perfect spin analyzer, well reconstructed as well Can probe top quark spin in 3 dimensions Sensitive to BSM physics (more spin corr's =

s-channel dark matter; less spin corr's = new scalars)

Schulze et al.


Spin correlationsSpin correlations● ATLAS measures dPhi in 1D and as a function of mttbar, B and C as well

as cross correlations● Discrepancy between NLO simulations and data at the 3s level in dPhi at

particle and parton level, also seen in differential in mttbar bins:● f

SM of 1 agrees with NLO SM, observe

Extrapolate from particle to full phase space

ATL-PHYS-PUB-2018-034/


Spin correlationsSpin correlations Further insights to spin correlations:

NLO effects in decay (modeled by MCFM) similar to Powheg+Pythia8 (noNLO effects in decay)

Discrepancy likely explained by missing higher order correction to top quark kinematics relevant to fiducial phase space


Spin correlationsSpin correlations CMS employs 13 TeV dilepton data Opening angle maximally sensitive to alignment of top

quark spins Most precise direct measurement via cosj

Systematic: pT and BG modeling

Indirect measurement via dPhi shows about 1s discrepancy to NLO simulations

fSM

= 0.97±0.05

fSM

= 1.10±0.16

NEW


EFT and SUSY constraintsEFT and SUSY constraints ATLAS employs spin correlation to constrain

SUSY top quark partner, low mass preferred bynaturalness arguments

Signature: Top quark spins more uncorrelatedsince stop is scalar

CMS uses EFT approach for interpretation ofspin density matrix measurement

Stringent constrain on chromomagnetic dipolemoment: -0.07 < CtG/L2 < 0.16 TeV-2

p p

t

t

W–

b

W+

bl

nl

q

q'




Spin CorrelationProduction AsymmetriesSpin CorrelationsProduction AsymmetriesPolarization


W helicity


tt + W, Z, γ



The low Cross Section FrontierThe low Cross Section Frontier


Single top cross section as high as tt at 8 TeV – large samples Single top production: Test of EW interactions


Single Top Quark ProductionSingle Top Quark Production

Nov 2018

t-channel tW-channels-channel

tZ/γq-channel(rare process)

Heavy use of BDT to enhance sensitivity – multiple signal regions CMS measurement of tZq single top production @13 TeV

Observation of tZq36Top quark properties and rare decaysA. Jung

Single top quark productionSingle top quark production

tZ/γq-channel(rare process)

SM NLO prediction: σ = 94.2 ± 3.1 fb

Phys. Lett. B 779 (2018)358

Phys. Lett. B 779 (2018)358

σ = 111 ± 13 (stat) ± 10 (syst) pbobs. (exp.) significance: 8.2 (7.7) SD

PRL122(2019)132003

NEW


FCNC's in top quark sectorFCNC's in top quark sector

[arxiv:1707.01404]

→ Vtb enters in production and decay: σ ~ |Vtb|2, FCNCs highly suppressed but limits start to reach relevant BSM BRsno BSM signal yet NEW

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2016-26/

ttH


ttbar+X: Highlightsttbar+X: Highlightstt+tt

ttZ

CMS-PAS-TOP-18-003

arXiv:1907.11270

ttZ: Most precise measurement, allowed for 1st differential cross sections

ttγ: Not shown, first evidence for ttγby ATLAS

tZq: Discussed before, evidence by ATLASand Observation by CMS

ttH: Observation at CMS and ATLAS tt+tt: Full Run 2 close to evidence at CMS

CMS, PRL 122 (2019) 132003ATLAS, PLB 780 (2018) 557

EPJC 79 (2019) 382

p p

t

t

W–

b

W+

bl

nl

q

q'






W helicity


tt + W, Z, γ



Self-consistency of SM & stability of the EW vacuum rely on the pole mass Indirect extraction from e.g. cross section, end point, J/psi method

→ top quark pole mass Direct methods e.g. template, matrix element, likelihood, ideogram

→ “MC” mass, close to pole mass Efforts to “calibrate” the “MC” mass to pole mass

→ Estimates: GeV difference to pole mass

The top quark massThe top quark mass

PRL 117, 232001 (2016)

[arXiv:1803.01853]


[arXiv:1707.08124]


Tools, Complications, ...Tools, Complications, ...


jet

jet

W boson fully reconstructed:→ In-situ calibration, Constrain

reconstructed mW to m

W

mW

→ Make use of all-hadronic decays of W bosons, serves as in-situ calibration

→ Pile-up complicates reconstruction of objects, needs “compensation”, all do-able but adds to systematic uncertainties

Eur. Phys. J. C (2016) 76:581

Eur. Phys. J. C(2016) 76:581


Direct measurements combined using BLUE Latest CMS combination, δm

t/m

t = 0.28%

World combination, δmt/m

t = 0.44%

Final D0 combination, δmt/m

t = 0.43%

mtop

= 174.95 ± 0.75 GeV

– consistent among methods/channels

[arXiv:1703.06994]

CMS-PAS-TOP-15-012Top Quark MassTop Quark Mass

NEW


http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/TOP-15-012/index.html


CMS measurement at 13 TeV, dilepton Use y(tt), M(tt), N(add. jet) Unfolded to parton level & NLO fixed order, 7

PDF sets in simultaneous fit PDF, aS, m

t

Weak correlation of 0.3 aS and m

tpole

mtop

= 170.5 ± 0.7 (fit) ± 0.1 (mod) ± 0.1 (scale) GeVpole

Indirect methods: diff. Indirect methods: diff. ss

δmt/m

t = 0.47% CMS-TOP-18-004

Sensitive to gluonstructure of theproton, xg(x)

http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-18-004

Consistent picture in boosted and resolved phase space Parton/Particle level results receive larger/reduced systematic uncertainties CMS 13 TeV all-hadronic combined resolved and boosted analysis


Boosted RegimeBoosted Regime

CMS-PAG-TOP-16-013

CMS-PAS-TOP-19-005


https://cds.cern.ch/record/2682624?ln=en


Mtop

= 172.6 ± 2.5 (tot) GeV

Boosted RegimeBoosted Regime CMS-PAS-TOP-19-005

Hadronic decay products reconstructed with single jet R = 1.2

Peak position of mjet

sensitive to mt

Detailed understanding of jet substructure observable crucial for boosted topologiesδm

t/m

t = 1.4%

NEW

https://cds.cern.ch/record/2682624?ln=en

Relative b-jet correction:0.998 ± 0.005


Direct methods: Most precise results, δm

t/m

t = 0.28% (!)

Does not include theoretical “scheme” uncertainty No single large uncertainty left:

Color reconnection: “off vs. on” yields smalleruncertainty than detailed study

Alternative methods: larger uncertainties but perpendicular

Indirect methods: Relies on theoretical predictions (various choices) Fully corrected data, more complex Larger uncertainties

5% theory, 2% experiment → 0.5% pole mass

Challenges/PerspectivesChallenges/Perspectives

● Employ different decay channels (different systematics, in-situ jet energy scale)● Use direct (classical), direct (alternative), and indirect (based on σ, dX/dσ)

[arXiv:1707.08124]

A very fundamental question: What happens with the SM theory at highest physically allowed scales ? → extrapolate to 1018 GeV

Vacuum meta-stable if Unstable once:

(corresponds to mt ~ 178 GeV)

In classical physics “stable” means minimum of potential energy:

SM vacuum stabilitySM vacuum stability


Tevatron

CMSATLAS


Very subjective but illustrative, latest results from LHC & Tevatron – SM true

ttH observation by CMS:

Modified from originalby Degrassi et al.

Caveat: New physics changes the vacuum stability, even if at Planck scale Theoretical uncertainties apply! PRL 117, 232001 (2016)

Most recent combinatons

yt ~ 0.96

point shifted


[arXiv:1804.03682]



→ SM EW fit closer to the unstable boundary ? Beware of uncertainties...butcould indicate SM is not enough to describe nature

→ Need more data!

SM vacuum stability & EW fitSM vacuum stability & EW fit Latest EW-fit by GFitter

[arXiv:1803.01853]

“Don't panic!” (D. Adams) Lifetime is much much larger than current age of the universe: 1080 – 10320 tUniverse


x

[arXiv:1707.08124]

EW-ft by GFiter

Worldaverage

E. Branchina et al.

SM Higgspotential

dim 6 & 8 BSMmodifications

With the Higgs discovery the SM can be extrapolated to Planck scale energies “Test” the stability of the electroweak

vacuum, under assumption of no new physics: → meta-stable, life time > O(1080) t

universe

→ but new physics can change that dramatically



[arXiv:1707.08124]

Worldaverage

Future upgrade plansFuture upgrade plans


Difficult to project, depends on physics outcome of Run IISM precision tests & BSM scenarios

“Keep running” does not work → Need improved detectors



p p √s=13 TeV

Unprecedented luminosities at ahadron collider: 5.0 x 1034 cm-2s-1

Expect ~ 3000 fb-1 per experiment Major upgrades of LHC and detectors needed

2035

Pha

se II

upg

rade

s


LHC

Billions of top quarks !


High-luminosity phase of the LHC Instantaneous luminosities up by factor 5 Collected data up by factor 10

→ Rates of lepton-based trigger are too high

ATLAS+CMS exposed to significantly higher rates, radiation damage, pile-up Tracking information for the trigger system Higher granularity of tracking devices (→ more channels) Radiation-hard devices Reduce amount of “dead” material

78 reconstructed vertices



Barrel & Forward Pixel Detector: 3D silicon sensor R&D

CMSbeam-pipe

Support structures:Carbon fiber & foam based,Tight tolerances of 100's microns160 kg's of detector

Beam interactionpoint

CMS inner tracker region (half of it)CMS inner tracker region (half of it)● CMS Instrumentation R&D

Current challenge: Remove 35 kW of heat


Need all avenues to pin down BSM:→ Precision/Energy frontier (e.g. Yukawa)→ Extend reach for searches→ Intensity Frontier

The future...The future...


HERA shutdown, Tevatron shutdown, but LHC continues!→ We will get about 3 billion tt events→ Allows for multi-dimensional measurements of σ, αS, PDFs

and any properties, associated production as well→ FCNCs and other statistically limited processes improve

160/fb in the can!150 million tt events

Extrapolations to HL-LHC:→ watch out for the bar:

Caveats: Some are“inclusive”...and also, we tendto do (much) better thanprojections, so we can hope toexclude more phase space

The future...FCNC prospectsThe future...FCNC prospects


private

CERN-LPCC-2018-03

https://cds.cern.ch/record/2650160

Next 2 years will show what 150 million ttbar events teach us Precision frontier of top quark physics

“Deviations” in the top quark sector, not yet conclusive enough:

→ Spin correlations: 3 – 1 SD→ Forward-backward asymmetry at Tevatron: 1.5 SD→ tt+H observation indicates μ~ 1.2-1.3 SM

Exciting times for top quark physics...stay tuned!

Instrumentation R&D is an absolutely essential ingredient tomake progress in elementary particle physics!

Thank you!

ConclusionsConclusions



BackupBackup

Use differential distributions to extract the well defined top quark pole mass Fixed αS and PDF set, translated into uncertainties

ATLAS: 0.9%; CMS precision at <1%D0 precision (best at Tevatron): ~ 1.5%

With ~5% theory uncertainty and ~2%exp → can reach 0.5% on pole mass

Indirect methodsIndirect methods

ATLAS-CONF-2017-044

D0 conference note 6473

60Top quark physics at the precision frontierA. Jung

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2017-044/

https://www-d0.fnal.gov/Run2Physics/WWW/results/prelim/TOP/T113/

61Top quark properties and electroweak measurementsA. Jung

BSM physics in top sector ?BSM physics in top sector ?→ Detailed study of the Wtb vertext to identify any BSM contributions→ Use triple-differential angular decay rates in single t-channel production

→ Data agrees with SMno BSM signal yet

[arxiv:1707.01404]JHEP 07 (2017) 003

→ FCNCs in tZ (ATLAS & CMS) and t →cH(ATLAS) – no BSM signal yet

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2016-26/

http://dx.doi.org/10.1007/JHEP07(2017)003

62Latest news on top quark physicsA. Jung

Expand Lagrangian in orders of 1/L 59 (B and L-conserving) dim-6 operators

This analysis: Simultaneous fit to ttW and ttZ (for now) One operator at a time (clear limitation) Only operators with significant impact on

ttW, ttZ, ttH CL for Wilson coefficients:

SM expected very similar

Effective Field TheoryEffective Field Theory

63Top quark properties: mass, spin correlations, polarizationA. Jung

CMS measurement at 13 TeV, dilepton 12 categories based on N(b-jets), N(light jets) Employ m

lb , p

T, event yield

Simultaneous fit to measure cross sectionand top mass

888 ± 2 (stat.) ± 27 (syst.) ± 20 (theo.) pbExtract MC mass from cross section:

min

mtop

= 172.33 ± 0.14 (stat.) ± 0.66/0.72 (syst.) GeVMC

Dominant systematics: → Jet energy (0.57 GeV)→ MC statistics (0.36 GeV)→ Background (0.28 GeV)

Extract most precise MS mass:

Indirect methods: incl. Indirect methods: incl. ss

δmt/m

t = 0.42%

EPJC 79 (2019) 368

Nuisance fit to constrainsystematics on mt(MC)

64Top quark properties: mass, spin correlations, polarizationA. Jung

Use differential distributions to extract the top quark pole and MS mass ATLAS also measures ratio in ttbar+1 jet events to extract top mass

Partial cancellation of systematic uncertainties

Indirect methods: l+jetsIndirect methods: l+jets

[arXiv:1905:02302]m

top = 171.1 ± 0.4 (stat.) ± 0.9 (syst.) ± 0.5 (theo.) GeVpole

δmt/m

t = 0.65%


Measurements at Tevatron & LHC are complimentary

Variety of models with wideparameter space stillallowed→ W', G, w , j, W

Top quark asymmetriesTop quark asymmetries

65Precision top quark measurements and searches for new physicsA. Jung

CMS: 13 TeV data shows less jets than MCRegime of the parton showers (PS)Already systematically limited, betterunderstanding of signal model needed

Use 8 TeV dilepton channel results to tuneMC parameters, than check description in 8TeV l+jets and in 13 TeV for both channels

Improve high Njets phase spaceh

damp:: control ME/PS matching

αISR

: αS for initial state radiation


CMS-PAS-TOP-16-011

PS regime

CMS-PAS-TOP-16-008

Dileptonl+jets

Differential cross section asa function of event variables:

Phys. Rev. D 94 (2016) 052006CMS-PAS-TOP-16-021


https://cds.cern.ch/record/2140061/files/TOP-16-011-pas.pdf

https://cds.cern.ch/record/2141097/files/TOP-16-008-pas.pdf

http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-12-042/index.html


Many Run I & Run II top pT measurements at ATLAS/CMS not described by NLO and most MCs – pQCD calculation do a better job

Data is more soft: consistently seen in all decay channels, also at 13 TeV

→ The pT spectra in 8 TeV are described by pQCD NNLO calculations, but→ First indications of a slope wrt NNLO in 13 TeV data, not yet significant


EPJC 76 (2016) 128



CDF observed a 3 SD tension between data and SM theory > 450 GeV D0 observed agreement to SM theory, but also agrees with CDF Both results used regularized unfolding, but different strategies which

resulted in largely different correlations between bins:



CDF observed a 3 SD tension between data and SM theory > 450 GeV D0 observed agreement to SM theory, but also agrees with CDF Final Tevatron combination agrees with SM and takes all correlations

between the experiments properly into account


2D as well:


Spin correlationsSpin correlations

“Running” of the Higgs quarticself-coupling:

Higgs closely tied to the top:→ Top mass significant impact

Need to keep “mexican-hat” shape



→ Top quark as a window to new physics

SM Vacuum isonly metastable

Degrassi et al.


Extraction from production cross sectionnot (yet) competitive with directmeasurements – but getting closer CMS precision at 1%; ATLAS: 1.45%

D0 precision (best at Tevatron): ~ 1.9%

With ~5% theory uncertainty and ~2% exp→ can reach 0.5% on pole mass

CMS [arXiv:1603.02303]

Phys. Rev. D 94 092004 (2016)

Top Quark Mass: poleTop Quark Mass: pole




Extraction from production cross section not (yet) competitive with direct measurements – but getting closer

ATLAS: 0.9%; CMS precision at 1%D0 precision (best at Tevatron): ~ 1.5%

With ~5% theory uncertainty and ~2% exp→ can reach 0.5% on pole mass

CMS [arXiv:1603.02303]

Phys. Rev. D 94 092004 (2016)ATLAS-CONF-2017-044

CMS-TOP-16-006

D0 6473

Top Quark Mass: poleTop Quark Mass: pole




http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-16-006/


p p

t

t

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W helicity


tt + H, W, Z, γ




Observation of tt+H a major goal for ATLAS & CMS:→ Correct modeling of associated HF production is crucial→ Theoretical and experimental challenge

Measurements at 8 TeV (ATLAS & CMS) and 13 TeV (CMS)

CMS-TOP-16-010(Subm. to PLB)ttbar+X: heavy flavorsttbar+X: heavy flavors

http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-16-010/


Ttbar + X: W, ZTtbar + X: W, Z

σ(ttZ) = 1.00 ± 0.09/0.08(stat.) ± 0.12/0.10(syst.) pbExpected (observed) significance of 4.6 (9.9)

σ(ttW)= 0.80 ± 0.12/0.11(stat.) ± 0.13/0.12(syst.) pbExpected (observed) significance of 4.6 (5.5)

→ Sensitive to FCNC couplings (ttZ) and BSM (ttW and ttZ)→ Results consistent with the SM (NLO prediction)

ATLAS-CONF-2016-003

SM (NLO) σ(ttZ) = 839 ± 93 fb σ(ttW) = 601 ± 55 fb

CMS-TOP-17-005

http://cds.cern.ch/record/2138947

http://cms-results.web.cern.ch/cms-results/public-results/preliminary-results/TOP-17-005/

First 2D cross section measurement of this type at the LHC Dilepton eμ channel – very good S/B Provide single & double differential cross sections


CMS-TOP-14-013




Expand Lagrangian in orders of 1/L 59 (B and L-conserving) dim-6 operators

This analysis: Simultaneous fit to ttW and ttZ (for now) One operator at a time (clear limitation) Only operators with significant impact on

ttW, ttZ, ttH CL for Wilson coefficients:

SM expected very similar

Effective Field TheoryEffective Field Theory

ATLAS (13 TeV) & CMS (8 TeV) measurements on tZq

Rely on NN and BDT to enrich signal Dominant SM production @leading order:


Single top quark productionSingle top quark productionATLAS-CONF-2017-052

JHEP 07 (2017) 003

σ = 600 ± 170 (stat.) ± 140 (syst.) fb(Expected is 5.4 SD, observed 4.2 SD) 13 TeV

σ = 10 ± 8/7 (tot.) fb(Observed 2.4 SD) 8 TeV


http://dx.doi.org/10.1007/JHEP07(2017)003


Direct measurementscombined using BLUE

● Takes correlations intoaccount

Latest ATLAS combinationPrecision of 0.4% (!)

Latest CMS combinationPrecision of 0.3% (!)

World averagePrecision of 0.4% (!)

Final D0 combination Precision of 0.4% (!)m

top = 174.95 ± 0.76 GeV D0 note 6485

PRD 93 (2016) 072004

Top Quark MassTop Quark Mass


http://dx.doi.org/10.1103/PhysRevD.93.072004


Employ the 7 TeV data: low pile up environmentHuge effort to control systematic uncertaintiesHigher pile-up at 8 and 13 TeV challenging

W mass: 1W mass: 1stst LHC measurement LHC measurement

mW

= 80370 ± 7 (stat) ± 11 (exp. syst.) ± 14 (modeling syst.) MeV

δmW/m

W = 0.024%

[arXiv:1701.07240]

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2014-18/

82CMS Top quark resultsA. Jung

Top quark massTop quark mass


Cross section summariesCross section summaries

CMS: First differential measurement of t-channel top production @13 TeV Muon-channel only employing a BDT discriminator and maximum likelihood fit Correct detector and measure parton level cross section for pT and y


Single top quark productionSingle top quark production

Run I & Run II top pT measurements at ATLAS/CMS not described by NLO and most MCs

Data is more soft: consistently seen in all decay channels

Spectra are described by NNLO+NNLLcalculations


LHCTopWG

EPJC 76 (2016) 128


TOP-16-021

https://twiki.cern.ch/twiki/bin/view/LHCPhysics/LHCTopWG

f0=0.70 f

R=0f

L=0.30 W helicity in SM:

W helicity in top pair l+jets channel CMS also measured W helicity in single top events

Similar precision but orthogonal systematic uncertainties in single top channels

Signal model & template statistics

W helicityW helicity


F0 = 0.681 ± 0.012 (stat.) ± 0.023 (syst.)

FL = 0.323 ± 0.008 (stat.) ± 0.014 (syst.)

FR = 0.004 ± 0.005 (stat.) ± 0.014 (syst.)

Most accurate experimental determination

PLB 762 (2016) 512

http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-13-008/index.html

Top quark massTop quark mass


Top quark properties and rare decays - SLAC Indico (Indico)

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