Javier Llorente Merino, on behalf of the ATLAS and CMS ...€¦ · Javier Llorente Production of top quarks, jets and photons 3/23. Properties of jet fragmentation at ATLAS [STDM-2017-16]

Production of top quarks, jets and photons

Javier Llorente Merino,on behalf of the ATLAS and CMS Collaborations

Simon Fraser University

LHCP 2019. Puebla, Mexico

Javier Llorente Production of top quarks, jets and photons 1 / 23

Jet analyses

Jet analyses


Properties of jet fragmentation at ATLAS [STDM-2017-16]

Measurement of observables sensitive to fragmentation functions Dhq,g (ζ, µ).

Number of charged particles 〈nch〉 in jet.

Momentum fraction ζ = pchT /p

jetT .

Transverse profile prelT = pch

T sin θjc .

Radial profile ρ = 1/(2πrNjet)dnch/dr ; r = ∆Rjc .

Extraction of quark and gluon profiles from data.500 1000 1500 2000 2500

[GeV]T

Jet p

2−

1−

0

1

2ηJe

t

0

0.2

0.4

0.6

0.8

1

Glu

on fr

actio

n

Simulation PreliminaryATLAS = 13 TeV, NNPDF2.3LO + Pythia 8.2s

500 1000 1500 2000 2500 [GeV]

TJet p

10

20

30

40

⟩ ch

n⟨

Data (stat. uncert.) syst. uncert.⊕Stat.

Pythia 8.186 A14Herwig++ 2.7Sherpa 2.1

PreliminaryATLAS -1 = 13 TeV, 33 fbs

All selected jets

500 1000 1500 2000 2500 [GeV]

TJet p

0.8

1

1.2

MC

/ D

ata

500 1000 1500 2000 2500 [GeV]

TJet p

0.02

0.04

0.06

0.08

0.1

⟩ r

⟨

Data (stat. uncert.) syst. uncert.⊕Stat.

Pythia 8.186 A14Herwig++ 2.7Sherpa 2.1

PreliminaryATLAS -1 = 13 TeV, 33 fbs

All selected jets

500 1000 1500 2000 2500 [GeV]

TJet p

0.8

1

1.2

MC

/ D

ata


Properties of jet fragmentation at ATLAS [STDM-2017-16]

Quark and gluon-like distributions obtained using two different methods

Solve the system of equations for bin i of each observable:

hfi = f fq h

qi + (1− f fq )hg

i ; hci = f cq h

qi + (1− f cq )hg

i

Determine distributions for topics T1 (q-like) and T2 (g -like)

hT1i =

hfi −minj{hf

j /hcj } × hc

i

1−minj{hfj /h

cj }

; hT2i =

hci −minj{hc

j /hfj } × hf

i

1−minj{hcj /h

fj }

0 20 40 60

chn

0

0.1

0.2

0.3

0.4

0.5ch)

dN /

dnje

t(1

/N

PreliminaryATLAS-1 = 13 TeV, 33 fbs

/ GeV < 1000T

900 < Jet p

Topic 1 Data

Topic 2 Data

Topic 1 Pythia 8.186 A14

Topic 2 Pythia 8.186 A14

Quarks Pythia 8.186 A14

Gluons Pythia 8.186 A14

500 1000 1500 2000 2500 [GeV]

TJet p

0

10

20

30

40⟩ ch

n⟨

PreliminaryATLAS-1 = 33 fb

int = 13 TeV, Ls

Topic 1 Data

Topic 2 Data

Topic 1 Pythia 8.186

Topic 2 Pythia 8.186

Quarks Pythia 8.186

Gluons Pythia 8.186


g → bb at small angles in ATLAS [Phys. Rev. D 99, 052004 (2019)]

Measurement of topology of the bb system.

Trimmed anti-kt jet with R = 1.0 as a proxy for the gluon.

Anti-kt track jets with R = 0.2 as proxies for b-quarks.

Flavour fractions extracted from fits to signed impactparameter of tracks in both b-jets with respect to jet axis.

instead of parton-splitting e�ects) and were limited in their kinematic reach due in part to small datasetsand low momentum transfers.

The high transverse momentum and low angular separation regime for g ! bb can be probed at the LHCusing b-tagged small-radius jets within large-radius jets. This topology is used to calibrate b-taggingin dense environments [50–52] and is studied phenomenologically [53, 54]. The measurement shownin this paper builds on these studies by using data collected by the ATLAS detector from

ps = 13 TeV

pp collisions in order to perform a di�erential cross-section measurement of g ! bb inside jets at hightransverse momentum – see Figure 1 for a representative Feynman diagram. Small-radius jets built fromcharged-particle tracks are used as proxies for b-quarks and can be used as precision probes of the smallopening-angle regime.

This paper is organized as follows. After a brief introduction to the ATLAS detector in Section 2, thedata and simulations used for the measurement are documented in Section 3. Section 4 describes theevent selection and Section 5 lists and motivates the observables to be measured. The key challengein the measurement is the estimation of background processes, which is performed using a data-drivenapproach illustrated in Section 6. The data are unfolded to correct for detector e�ects to allow directcomparisons to particle-level predictions. This procedure is explained in Section 7 and the associatedsystematic uncertainties are detailed in Section 8. The results are presented in Section 9 and the paperconcludes with Section 10.

q

g

q

b

b

Figure 1: A representative diagram for the high-pT g ! bb process studied in this paper.

2 ATLAS detector

The ATLAS detector [55] is a multipurpose particle detector with a forward/backward-symmetric cylindricalgeometry. The detector has a nearly 4⇡ coverage in solid angle1 and consists of an inner tracking detector,electromagnetic and hadronic calorimeters, and a muon spectrometer. The inner detector (ID) is surroundedby a superconducting solenoid providing a 2 T magnetic field and covers a pseudorapidity range of |⌘ | < 2.5.The ID is composed of silicon pixel and microstrip detectors as well as a transition radiation tracker. Forthe LHC

ps = 13 TeV run, the silicon pixel detector has been upgraded to include an additional layer

close to the beam interaction point [56]. The lead/liquid-argon electromagnetic sampling calorimetersmeasure electromagnetic energies with high granularity for the pseudorapidity region of |⌘ | < 3.2. Hadron

1 ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the center of the detectorand the z-axis along the beam pipe. The x-axis points from the IP to the center of the LHC ring, and the y-axis pointsupward. Cylindrical coordinates (r , �) are used in the transverse plane, � being the azimuthal angle around the beam pipe. Thepseudorapidity is defined in terms of the polar angle as ⌘ = � ln tan(polar angle/2).

3

0

5

10

15

20

25

30

35

40

45

50310×

Eve

nts

Component (pre-fit %, post-fit %)

L+C (45%, 34%)

B (34%, 50%)

BB (20%, 17%)

MC Uncertainty

Data

R(b,b) < 0.3∆0.25 <

= 13.5 (9.5) / 19 DoF2χ) 1

Total (lead, j

ATLAS-1 = 33 fb

int = 13 TeV, Ls

40− 20− 0 20 40 60

)1

(jsub0ds

0.80.9

11.11.2

Dat

a/M

C

0.2 0.3 0.4 0.5 0.6 0.7R(b,b)∆

0

0.2

0.4

0.6

0.8

1

Fla

vor

Fra

ctio

n

Data (post-fit) MC (pre-fit)

BB BB

B B

L+C L+C

ATLAS -1 = 33 fbint

= 13 TeV, Ls


g → bb at small angles in ATLAS [Phys. Rev. D 99, 052004 (2019)]

Measured observables include:

Angular distance ∆Rbb =√

(∆ηbb)2 + (∆φbb)2

Momentum sharing z = pT2/(pT1 + pT2)

Dimensionless mass ρ = mbb/pT

Angle ∆θppg,gbb between jet-beam and bb planes.

p

p

b

gb

DR(b,b)

Dqppg,gbb

b

b p

p

Dqppg,gbb

DR(b,b)

Side view

Top view

0

1

2

3

4

) T/d

z(p

σ) dσ

(1/

2016 DataTotal UncertaintySherpa 2.1

)±Pythia 8.230 (A14 + Var2/4)2

bbPythia 8.230 (A14, m

ATLAS-1 = 33 fb

int = 13 TeV, Ls

0 0.1 0.2 0.3 0.4 0.5

)T,2

+ pT,1

/ (pT,2

) = pT

z(p

0.5

1

1.5

MC

/Dat

a

0

0.5

1

1.5

π/gp

p,gb

bθ∆

/dσ) dσ

(1/

2016 DataTotal UncertaintySherpa 2.1

)±Pythia 8.230 (A14 + Var2Pythia 8.230 (A14, no g pol.)

ATLAS-1 = 33 fb

int = 13 TeV, Ls

0 0.2 0.4 0.6 0.8 1

π/gpp,gbbθ∆

0.8

1

1.2M

C/D

ata

Significant disagreement at low z , “less polarization” is preferred.Javier Llorente Production of top quarks, jets and photons 6 / 23

Event shapes at CMS [JHEP 12 (2018) 117]

Transverse thrust and thrust axis nT : τ⊥ = 1−maxnT

∑i |~pTi · nT |∑

i pTiU and L hemispheres: ~pTi · nT > 0 (< 0).

Define hemisphere coordinates: ηX =

∑i∈X pTiηi∑i∈X pTi

; φX =

∑i∈X pTiφi∑i∈X pTi

BX =1

2PT

∑i∈X

pTi√

(ηi − ηX )2 + (φi − φX )2; Btot = BU + BL

bayes-8 -7 -6 -5 -4 -3 -2

) τ

1/N

dN

/dln

(

-210

-110

DataPy8+CUETP8M1Py8+MonashMadGraphHerwig++Total uncertaintyStatistical uncertainty




< 93 GeVT,273 < H


) τln(-8 -7 -6 -5 -4 -3 -2

MC

/ D

ata

0.8

1

1.2

1.4

(13 TeV)-12.2 fbCMS

bayes-3 -2.5 -2 -1.5 -1

) T

ot1/

N d

N/d

ln(B

-110





< 93 GeVT,273 < H


) Tot

ln(B-3 -2.5 -2 -1.5 -1

MC

/ D

ata

0.8

1

1.2

1.4

(13 TeV)-12.2 fbCMS


Event shapes at CMS [JHEP 12 (2018) 117]

Total jet mass: ρX =M2

X

P2; ρtot = ρU + ρL

Total transverse jet mass: ρTX =M2

X

P2T

; ρTtot = ρTU + ρTL

bayes-6 -5 -4 -3 -2 -1

)T

otρ

1/N

dN

/dln

(

-310

-210

-110





> 557 GeVT,2H


)Tot

ρln(-6 -5 -4 -3 -2 -1

MC

/ D

ata

0.8

1

1.2

1.4

(13 TeV)-12.2 fbCMS

bayes-7 -6 -5 -4 -3 -2

)T

otT ρ

1/N

dN

/dln

(

-210

-110





> 557 GeVT,2H


)TotTρln(

-7 -6 -5 -4 -3 -2

MC

/ D

ata

0.8

1

1.2

1.4

(13 TeV)-12.2 fbCMS

Important test of the back-to-back and collinear regime (low thrust).

Significant discrepancies observed in all variables across pT bins.


∆φ12 in back-to-back topologies at CMS [arXiv:1902.04374 (hep-ex)]

Test of QCD at angles ∆φ . π, sensitive to resummation details.

Two and three jet events studied (pT1 > pT2 > 100 GeV, pT3 > 30 GeV).

Measurement of the normalized distribution of azimuthal difference ∆φ12.

[deg]12

φ∆

]-1

[deg

12φ∆dσd

m

axTpσ1

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

170 171 172 173 174 175 176 177 178 179 180

CMS

(13 TeV)-135.9 fb

< 300 GeVmax

T200 < p

< 600 GeVmax

T500 < p

< 1000 GeVmax

T800 < p

R=0.4Tanti-kInclusive 2-jetHerwig++ CUETHppS1 (solid lines)PYTHIA8 CUETP8M1 (dotted lines)

[deg]12

φ∆

]-1

[deg

12φ∆dσd

m

axTpσ1

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

170 171 172 173 174 175 176 177 178 179 180

CMS

(13 TeV)-135.9 fb

< 300 GeVmax

T200 < p

< 600 GeVmax

T500 < p

< 1000 GeVmax

T800 < p

R=0.4Tanti-kInclusive 3-jetHerwig++ CUETHppS1 (solid lines)PYTHIA8 CUETP8M1 (dotted lines)


∆φ12 in back-to-back topologies at CMS [arXiv:1902.04374 (hep-ex)]

Comparison to LO+PS and NLO+PS are provided.

In particular, Powheg (2→ 2 and 2→ 3) are studied.

2 and 3-jet measurements not simultaneously described by any model.

[deg]12

φ∆

0.91

1.11.2

< 400 GeVmax

T300 < p

[deg]12

φ∆

0.91

1.11.2

< 300 GeVmax

T200 < p

[deg]12

φ∆

0.91

1.11.2

< 600 GeVmax

T500 < p

[deg]12

φ∆

0.91

1.11.2

< 500 GeVmax

T400 < p

[deg]12

φ∆

0.91

1.11.2

< 800 GeVmax

T700 < p

[deg]12

φ∆

0.91

1.11.2

< 700 GeVmax

T600 < p

[deg]12

φ∆

0.91

1.11.2

170 171 172 173 174 175 176 177 178 179 180

< 1200 GeVmax

T1000 < p

[deg]12

φ∆

0.91

1.11.2

< 1000 GeVmax

T800 < p

[deg]12

φ∆

0.91

1.11.2

170 171 172 173 174 175 176 177 178 179 180

> 1200 GeVmax

Tp

R=0.4 Tk−anti

Inclusive 2-jet Total exp. unc.

PH-2J + PYTHIA8

PH-3J + PYTHIA8PH-2J + Herwig++CMS

Pre

dict

ion/

Dat

a (n

orm

alis

ed 2

-jet c

ross

sec

tion)

(13 TeV)-135.9 fb


Photon analyses

Photon analyses


Photon cross section ratios 13 / 8 TeV [JHEP 04 (2019) 093]

Ratio of two measurements: [JHEP 08 (2016) 005, PLB 770 (2017) 473]

Reduction of uncertainties by considering their correlations:

Experimental uncertainties below 5% in the full EγT range (γES).

Theoretical uncertainties below 2% in the full EγT range (scale).

Ratios come in two flavours:

Ratio of double-differential cross sections: Rγ13/8

versus EγT and |yγ |

Double ratio to Z fiducial cross sections Dγ,Z13/8

= Rγ13/8

/RZ ,fid13/8

.

200 300 400 500

[GeV]γ

TE

0.2−

0

0.2

13

/8

γR

ela

tive u

ncert

ain

ty in R

ATLAS1 and 13 TeV, 3.2 fb18 TeV, 20.2 fb

| < 1.81γ

η1.56 < |

125

ESγSystematic uncertainty

extra2015⊕uncorrelated Correlated components:complete correlation modelno correlation assumed

200 300 400 500

[GeV]γ

TE

0.04−

0.02−

0

0.02

0.04

13

/8

γ

Rela

tive u

ncert

ain

ty in R

ATLAS Simulation

= 8 TeV and 13 TeVs

| < 1.81γ

η1.56 < |

125

Uncertainties:

Scale variation

Total

sα

PDF

Beam energy


Photon cross section ratios 13 / 8 TeV [JHEP 04 (2019) 093]

Comparison of ratios to NLO QCD (+NNLO for Z)

0

5

10

15

13/8

γR


Data

NLO QCD (JETPHOX): MMHT2014

| < 0.6γη|

200 300 400 1000

[GeV]γ

TE

0.6

0.8

1

1.2

1.4

Theory

/Data CT14

NNPDF3.0

HERAPDF2.0

ABMP16

125

0

2

4

6

8

10

13/8

/Zγ

D


Data

(JETPHOX);γNLO QCD for

NNLO QCD for Z (DYTURBO): MMHT2014nnlo

| < 0.6γη|

200 300 400 1000

[GeV]γ

TE

0.6

0.8

1

1.2

1.4

Theory

/Data CT14nnlo

NNPDF3.0nnlo

HERAPDF2.0nnlo

125

Recent NNLO predictions for γ production [arXiv:1904.01044 (hep-ph)]


Inclusive photon and photon + jets in CMS [Eur. Phys. J. C 79 (2019) 20]

Measurement of isolated photons inclusively and in association with jets

EγT > 190 GeV and |yγ | < 2.5.

pjetT > 30 GeV and |y jet| < 2.4.

BDT to discriminate from background, validated with isolation sidebands.

Inclusive γ

(GeV)TE210×2 210×3 210×4 210×5 310

(p

b/G

eV)

γd

yTγ

/ d

Eσ2 d

-310

1

310

610

910 )6 10×| < 2.5 (

γ2.1 < |y

)4 10×| < 2.1 ( γ

1.57 < |y

)2 10×| < 1.44 ( γ

0.8 < |y

| < 0.8γ

|y

NLO JETPHOX NNPDF 3.0

(13 TeV)-12.26 fbCMS Preliminary

γ+jets

(GeV)TE210×2 210×3 210×4 210×5 310

(p

b/G

eV)

jet

dy

γd

yTγ

/ d

Eσ3 d

-410

-110

210

510

810

1010 )6 10× > 30GeV (

jet

T| < 2.4, p

jet| < 2.5, 1.5 < |y

γ1.57 < |y

)4 10× > 30GeV ( jet

T| < 1.5, p

jet| < 2.5, |y

γ1.57 < |y

)2 10× > 30GeV ( jet

T| < 2.4, p

jet| < 1.44, 1.5 < |y

γ|y

> 30GeV jet

T| < 1.5, p

jet| < 1.44, |y

γ|y

NLO JETPHOX NNPDF 3.0



Inclusive photon and photon + jets in CMS [Eur. Phys. J. C 79 (2019) 20]

Comparison of inclusive γ (top) and γ+jet (bottom) to NLO pQCD (JetPhox)

(GeV)TE210×2 210×3 210×4 210×5 310

Th

eory

/ D

ata

0.5

1

1.5

2| < 0.8

γ|y

Data stat. uncertainty

Data total unc.

NLO JETPHOX scale unc.

NLO JETPHOX total unc.


(GeV)TE210×2 210×3 210×4 210×5 210×6

Th

eory

/ D

ata

0.5

1

1.5

2| < 2.5

γ2.1 < |y


Data total unc.




(GeV)TE210×2 210×3 210×4 210×5 310

Th

eory

/ D

ata

0.5

1

1.5

2 > 30GeV

jet

T| < 1.5, p

jet| < 1.44, |y

γ|y


Data total unc.




(GeV)TE210×2 210×3 210×4 210×5 210×6

Th

eory

/ D

ata

0.5

1

1.5

2 > 30GeV

jet

T| < 2.4, p

jet| < 2.5, 1.5 < |y

γ1.57 < |y


Data total unc.





Top quark analyses

Top quark analyses


Boosted, fully hadronic tt at ATLAS [Phys. Rev. D 98 (2018) 012003]

Fully hadronic tt events in boosted regime

Two R = 1.0 jets with pT > 350 GeV, |η| < 2.0, |mJ −mt | < 50 GeV.

Both jets are associated to a small (R = 0.4) b-tagged jet (∆RjJ < 1.0)

Multijet background estimated in a data-driven way.

Collins-Soper angle cos θ∗

|* θ /

d |c

osttσ

d

⋅ ttσ1/

0

0.5

1

1.5

2

2.5DataPOWHEG+Py8POWHEG+H7MG5_aMC@NLO+Py8Sherpa 2.2.1Stat. Unc.

Syst. Unc.⊕Stat.

ATLAS-1 = 13 TeV, 36.1 fbs

Fiducial phase space

|*

θ|cos0 0.2 0.4 0.6 0.8 1

Dat

aP

redi

ctio

n

0.81

1.2

Angular distance χ = e|yt−yt |

tt χ /

d ttσ

d

⋅ ttσ1/

3−10

2−10

1−10

1

10DataPOWHEG+Py8POWHEG+H7MG5_aMC@NLO+Py8Sherpa 2.2.1Stat. Unc.

Syst. Unc.⊕Stat.

ATLAS-1 = 13 TeV, 36.1 fbs

Fiducial phase space

ttχ1 2 3 4 5 6 7 8 9 10

Dat

aP

redi

ctio

n

0.81

1.2


tt+jets differential cross sections at ATLAS [JHEP 1810 (2018) 159]

Single lepton channel e or µ with pT > 25 GeV, |η| < 2.5.

Jets reconstructed with R = 0.4, pT > 25 GeV and |η| < 2.5

Out-of-plane momentum: |ptout| =

∣∣∣∣∣~pthad ·

~ptlep × z

|~ptlep × z |

∣∣∣∣∣

Eve

nts

10

20

30

40

50

60

70

80

90

310×

DatattSingle topW+jetsZ+jetsDibosonVtt

MultijetsStat.+Syst. unc.

ATLAS

4-jet inclusive

-1 = 13 TeV, 3.2 fbs

Jet multiplicity

4 5 6 7 8

Dat

a/P

red.

0.81

1.2

3−10

2−10

1−10

1

10

210

]-1

GeV

⋅| [

pb

tt out

/ d|

pttσ

d

Data

t=mdampPWG+PY6 h

t=1.5 mdampPWG+PY8 h

t=1.5 mdampPWG+H7 h

)2T

+ p2tmaMC@NLO+PY8 (

Sherpa 2.2.1

Stat. unc.

Stat.+Syst. unc.

ATLASFiducial phase-space

-1 = 13 TeV, 3.2 fbs6-jet inclusive

0.5

1

1.5D

ata

Pre

dict

ion

20 30 40 50 60 100 200 300 400

| [GeV]tt

out|p

0.5

1

1.5

Dat

aP

redi

ctio

n


tt cross section, αs and mt at CMS [Eur. Phys. J. C 79 (2019) 368]

Combined fit to e+e−, µ+µ− and e±µ∓ channels.

Likelihood fit to extract σtt , αs(mZ ) and mt .

σtt = 815± 2 (stat.)± 29 (sys.)± 20 (lumi.) from mt , σ simultaneous fit.

Eve

nts

/ G

eV

500

1000

Datatt othertt

W+jetsVV

WttW / DYSystMC stat

[GeV]T

Leading lepton p20 40 60 80 100 120 140 160 180 200

Pre

d.

Da

ta

0.81

1.2

CMS

(13 TeV)-135.9 fb

CMS

channel-µ+µ (13 TeV)-135.9 fb

PDF set αS(mZ)

ABMP16 0.1139 ± 0.0023 (fit + PDF) +0.0014−0.0001 (scale)

NNPDF3.1 0.1140 ± 0.0033 (fit + PDF) +0.0021−0.0002 (scale)

CT14 0.1148 ± 0.0032 (fit + PDF) +0.0018−0.0002 (scale)

MMHT14 0.1151 ± 0.0035 (fit + PDF) +0.0020−0.0002 (scale)

CMS 35.9 fb-1 (13 TeV)

σtt_

ABMP16nnlomt(mt) = 160.86 GeV

NNPDF3.1nnlomt(mt) = 162.56 GeV

MMHT14nnlomt(mt) = 163.47 GeV

CT14nnlomt(mt) = 163.30 GeV

PDG

2018

αS(mZ)0.105 0.11 0.115 0.12

PDF set mpolet [GeV]

ABMP16 169.9 ± 1.8 (fit + PDF + αS) +0.8−1.2 (scale)

NNPDF3.1 173.2 ± 1.9 (fit + PDF + αS) +0.9−1.3 (scale)

CT14 173.7 ± 2.0 (fit + PDF + αS) +0.9−1.4 (scale)

MMHT14 173.6 ± 1.9 (fit + PDF + αS) +0.9−1.4 (scale)


tt dilepton differential cross sections at CMS [JHEP 02 (2019) 149]

Differential cross sections versus a large variety of observables.

Comparison to high-order predictions in QCD

Full NNLO + α3EW (LUXQED17)

Full NNLO + double resummation (NNLO+NNLL’)

Approximate N3LO @ NNLL.

Approximate NNLO.

0 100 200 300 400 500

GeV tT

p

1−10

1

10

pb/G

eV

t Tdp

σd

(13 TeV)-135.9 fbCMS

Dilepton, parton level

Data

POWHEGV2 + PYTHIA8

POWHEGV2 + HERWIG++

MG5_aMC@NLO + PYTHIA8 [FxFx]

0 100 200 300 400 500GeV t

Tp

1

1.2

Dat

aT

heor

y

Syst⊕Stat

Stat

1000

GeV tt

m

3−10

2−10

1−10

1

10

[pb/

GeV

]tt

dmσd

DataPOWHEGV2 + PYTHIA8

= 173.3 GeVt

(LUXQED17) m3EWαNNLO+

= 172.5 GeVt

(LUXQED17) m3EWαNNLO+

= 173.3 GeVt

(NNPDF3.1) m3EWαNNLO+

= 173.3 GeVt

NNLO+NNLL' (NNPDF3.1) m = 172.5 GeV

tNNLO+NNLL' (NNPDF3.1) m

1000 [GeV]

ttm

0.6

0.8

1

1.2

1.4D

ata

The

ory Syst⊕Stat

Stat

CMS (13 TeV)-135.9 fb

Dilepton, parton level


tt multi-differential cross sections at CMS [arXiv:1904.05237 (hep-ex)]

Dilepton channels ee, eµ, µµ.

Cross sections as a function of pairs of variables:

{pT (t), yt ,Mtt , ytt ,∆ηtt ,∆φtt , pT (tt)}

Triple-differential cross sections of jet multiplicity Njet

Extraction of strong coupling αs , top mass mt and PDFs.

500 1000 1500

50000

100000

Eve

nts

/ 10

0 G

eV

500 1000 15000.8

11.2

Rat

io

Data

signaltt

othertt

tNon-t

Syst. unc.

) [GeV]tM(t

CMS (13 TeV)-135.9 fb

200 400

0.002

0.004

0.006 )<1500GeVt650<M(t

200 400

0.81

1.2200 400

0.002

0.004

0.006 )<650GeVt500<M(t

200 400

0.81

1.2200 400

0.002

0.004

0.006 )<500GeVt400<M(t

200 400

0.81

1.2200 400

0.002

0.004

0.006

]-1

) [G

eVt(t T

/dp

σ dσ

1/

)<400GeVt300<M(t

200 400

0.81

1.2

Rat

io

Data, dof=15

=212χPOW+PYT,

=222χPOW+HER,

=292χMG5+PYT,

POW+PYT unc.

) [GeV]t(tT

p

CMS (13 TeV)-135.9 fb


tt multi-differential cross sections at CMS [arXiv:1904.05237 (hep-ex)]

Values of strong coupling and top pole mass obtained from NLO QCD analysis:

αs(mZ ) = 0.1135±0.0016 (fit) +0.0002−0.0004 (mod.) +0.0008

−0.0001 (par.) +0.0011−0.0005 (scale)

mpolet = 170.5± 0.7 (fit) ± 0.1 (mod.) +0.0

−0.1 (par.) ± 0.3 (scale)

Uncertainties estimated according to the general approach of HERAPDF2.0

0.09 0.1 0.11 0.12 0.13)

Z(mSα

World average [PDG2018]

CT14

HERAPDF20

ABMP16

)]t),y(tt,M(t0,1+

jet[N

) with total unc.Z

(mSα

data unc.

PDF unc.

unc.µ

1 GeV unc.± poletm

CMS (13 TeV)-135.9 fb

165 170 175 [GeV]pole

tm

World average [PDG2018]

CT14

HERAPDF20

ABMP16

)]t),y(tt,M(t0,1+

jet[N

with total unc.poletm

data unc.

PDF unc.

unc.µ

0.001 unc.± sα

CMS (13 TeV)-135.9 fb


Summary and conclusions

New results on jet, photon and top quark production have been presented.

Higher order theoretical predictions have been recently developed, inparticular for photon and top production.

In general, good qualitative agreement is observed with the state of the arttheoretical predictions.

Some significant discrepancies are also observed for some jet observables(event shapes)

Huge ongoing effort from both ATLAS and CMS to provide newmeasurements. Stay tuned for future updates!

See next talk by C. Pollard for another nice set of jet substructure and topmeasurements.


Documents

Javier Llorente Merino, on behalf of the ATLAS and CMS ...€¦ · Javier Llorente Production of top quarks, jets and photons 3/23. Properties of jet fragmentation at ATLAS [STDM-2017-16]