Heavy Flavor Production in Hadronic and Nuclear · PDF fileHeavy Flavor Production in Hadronic and Nuclear Collisions at LHCb Philip Ilten on behalf of the LHCb Collaboration Massachusetts

Heavy Flavor Production in Hadronic and NuclearCollisions at LHCb

Philip Iltenon behalf of the LHCb Collaboration

Massachusetts Institute of Technology

February 15, 2017

Santa Fe Jets and Heavy Flavor Workshop

Ilten Heavy Flavor at LHCb February 15, 2017 1 / 34

Introduction

Overview

• detector introduction

• inclusive heavy flavor jet tagging

• heavy quarks with W + jet

• intrinsic charm

• J/ψ production in jets


Introduction

Detector LHCb, ĲMPA 30 (2015)

VELO

RICH1

TT

magnet

OT

IT

T1

T2

T3

RICH2

M1

M2 M3 M4 M5

HCAL

ECALmuon system5 m

5 m 15 mz-axis →

y-ax

is→

SPD/PRS

• fully instrumented between 2 < η < 5• momentum resolution between 0.5% at 5 GeV to 1% at 200 GeV• impact parameter resolution of 13− 20 µm for tracks• secondary vertex precision of 0.01− 0.05(0.1− 0.3) mm in xy(z)


http://arxiv.org/abs/1412.6352

Introduction

Trigger LHCb, JINST 8 (2013) P04022

• real-time calibration and fullevent reconstruction in Run 2

• jet triggers in Run 2• full detector readout in Run 3

L0

µ: pT > 1.5 GeV

µµ:√

p1Tp2

T > 1.3 GeV

h: ET > 3.5 GeV

e: ET > 2.5 GeV

γ: ET > 2.5 GeV

µ: pT > 4.8(1) GeV

µµ: m > 2.7(1)GeV

track: pT > 1.7 GeV

e: pT > 10 GeV

. . .

µ: pT > 10(4.8) GeV

µµ: m > 4.8(3) GeV

displaced vertex

inclusive topological

beauty BBDT

inclusive and

exclusive charm

. . .

15 MHz 12 kHz

HLT1 HLT2

1 MHz 150 kHz



Introduction

Datasets V. Vagnoni (2015) HL-LHC

• projected luminosity per run

LHC era HL-LHC era

Run 1(a) Run 1(b) Run 2 Run 3 Run 4 Run 52011 2012 2015 - 2019 2021 - 2023 2027 - 2029 2031 - ?

1 fb−1 2 fb−1 5 fb−1 15 fb−1 23 fb−1 300 fb−1?

• LHCb upgrade during LS 2• LHCb-PUB-2014-040• replacement of readouts and photo-detectors for the RICHs• replacement of tracking detectors• full software trigger, see LHCb-TDR-016

• currently limited by hardware readout at 1 MHz• upgrade will read out entire detector at 40 MHz


https://indico.cern.ch/event/315626/session/12/contribution/31/material/slides/0.pdf

https://cds.cern.ch/record/1748643

https://cds.cern.ch/record/1701361

Heavy Flavor Jets

Heavy Flavor Jets


Heavy Flavor Jets

SV Observables LHCb, JINST 10 (2015)

(jet)T

(SV)/pT

p0 0.2 0.4 0.6 0.8 1F

ract

ion

bofb

SV

-Tag

ged

bCan

did

ates

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18b

c

u d s g

SV cor r mass [ ]0 2 4 6 8 10F

ract

ion

of

SV

-Tag

ged

Can

did

ates

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

b

c

u d s g

GeV

SV tr acks0 5 10F

ract

ion

of

SV

-Tag

ged

Can

did

ates

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

b

c

u d s g

Mcor =√

M 2 + p2 sin2 θ+p sin θ

SV

PV

p

θ

jet



Heavy Flavor Jets

BDT Separation LHCb, JINST 10 (2015)

)udsg|bcBDT(-1 -0.5 0 0.5 1

)c|bB

DT

(

-1

-0.5

0

0.5

1

LHCb simulation

-jetsudsg

)udsg|bcBDT(-1 -0.5 0 0.5 1

)c|bB

DT

(

-1

-0.5

0

0.5

1

LHCb simulation

-jetsc

)udsg|bcBDT(-1 -0.5 0 0.5 1

)c|bB

DT

(

-1

-0.5

0

0.5

1

LHCb simulation

-jetsb

• BDT(bc|udsg): c and b as signal, udsg as background• BDT(b|c): b as signal c as background• fit 2-dimensional BDT(bc|udsg) versus BDT(b|c) distribution



Heavy Flavor Jets

Efficiencies LHCb, JINST 10 (2015)

light-parton mistag probability0.001 0.002 0.003 0.004 0.005

(b,c

)-je

t tag

eff

icie

ncy

0

0.2

0.4

0.6

0.8

1

-jetb-jetc

LHCb simulation

(jet) < 4.2η2.2 <

(jet) < 100 GeVT

20 < p

(jet) [GeV]T

p20 40 60 80 100

SV-t

ag e

ffic

ienc

y

0

0.2

0.4

0.6

0.8

1LHCb

-jetb

-jetc



W+jet Measurements

W +jet Measurements


W+jet Measurements

Forward Kinematics

σ =∫

xfx(f1, x1,Q2)xfx(f2, x2,Q2)σ dx1dx2, x = Qe∓y√

s

10−6 10−5 10−4 10−3 10−2 10−1 100

x

100

101

102

103

104

105

106

107

108

Q2

[GeV

2 ]

Tevatron

HERA

fixed target

GPD 13 TeV

LHCb 13 TeV


W+jet Measurements

W +jet Production

g

qi

qj

W

g

s

c

W

qj

qi

b

b

W

W + udsg-jet W + c-jet W + b-jet

• sensitive to valence PDFs and strange quark asymmetries

tg

g

b

W

t

t

q

q

b

W

t

t

qj

qi

b

W

b

gluon fusion quark fusion single top

• sensitive to the gluon PDF and top asymmetries


W+jet Measurements

Strange and Top Asymmetries

• expect ≈ 2% uncertainty on A(W c) from Run 2• roughly 2% top asymmetry with 0.5% uncertainty from Run 3

)µ(η2 3 4 5

c)-c+

W+

c)/(

W-

c-W

+(W

0.6−

0.4−

0.2−

0

0.2

0.4 CT14NNLO 1-s 2-s 3-s 4-s

Boettcher, Ilten, Williams

lη

2 2.5 3 3.5 4 4.5us

7lη

<vdl

dA01

2

34

5

67

8910

Denominatorv=vNNPDF263vNLOv119Denominatorv=vNNPDF263vLOv119Denominatorv=vNNPDF263vLOv130Scalevenvelope

=v14vTeVslX7b→tut→pp

Numeratorv=vNNPDF263vNLOv119=v173625vGeVtm

ul<b7v>v20<60vGeVT

pulbb7v<v465η260v<

Phys. Rev. D 91 (2015)

A` = N (`+)−N (`−)N (`+) + N (`−)



W+jet Measurements

Analyses

• LHCb, JINST 10 (2015): validation of performance• LHCb, PRD 92 (2015): W + c and W + b measurement• LHCb, PRL 115 (2015): first forward top measurement• LHCb, PLB 767 (2017): tt, W + cc, and W + bb

) [GeV]b+µ(T

p

)W

+b

(N

0

100

200

Data+topWb

Wb

LHCb

20 45 70 95 ∞) [GeV]b+µ(

Tp

Cha

rge

Asy

mm

etry

-0.4

-0.2

0

0.2

0.4

Data

+topWb

Wb

LHCb

20 45 70 95 ∞





https://arxiv.org/abs/1610.08142

W+jet Measurements

W +jet Results LHCb, PRD 92 (2015)LHCb, PRL 115 (2015)

−0.09± 0.08± 0.04 A(Wc)0.51± 0.20± 0.09 A(Wb)5.80± 0.44± 0.75 σ(Wc)/σ(Wj)× 102

0.66± 0.13± 0.13 σ(Wb)/σ(Wj)× 102

6.61± 0.19± 0.33 σ(W−j)/σ(Zj)10.49± 0.28± 0.53 σ(W+j)/σ(Zj)

−0.01± 0.05± 0.04 A(Wc)0.27± 0.13± 0.09 A(Wb)5.62± 0.28± 0.73 σ(Wc)/σ(Wj)× 102

0.78± 0.08± 0.16 σ(Wb)/σ(Wj)× 102

6.02± 0.13± 0.30 σ(W−j)/σ(Zj)9.44± 0.19± 0.47 σ(W+j)/σ(Zj)

7TeV

8TeV

(exp - thr)/max(δthr)-5 0 5 10 239± 53± 41 [fb]7TeV

289± 43± 49 [fb]8TeV

(exp - thr)/max(δthr)-1 0 1 2




W+jet Measurements

W + QQ Results LHCb, PLB 767 (2017)

)b+b-(Wσ)b+b+(Wσ

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 [pb]σ

)c+c-(Wσ)c+c+(Wσ

0.1 0.2 0.3 0.4 [pb]σ

)t(tσ

0.02 0.04 0.06 0.08 0.1 [pb]σ

MCFM CT10 statData

totData = 8 TeVsLHCb,



Intrinsic Charm

Intrinsic Charm with Z + c and SMOG(not to be confused with Smaug)


Intrinsic Charm

Intrinsic Charm

• extrinsic heavy-flavor content from soft gluon splittingxfx(c, x,Q2) ≈ (1− x)xfx(g, x,Q2)

• intrinsic content also possible, bound to valence quarks• see Adv. High Energy Phys. 2015, 231547 (2015)• percent-level charm content possibly seen in DIS• Q ≈ 1− 10 GeV, high-x• excluded from some global PDF fits

Adv. High Energy Phys. 2015, 231547 (2015)




Intrinsic Charm

Intrinsic Charm PDFs• consider two models from CT14 (Phys. Rev. D 93, no. 3, 033006

(2016))• BHPS: valence-like via the light-cone picture of nucleon structure• SEA: sea-like assuming IC ∝ [u(x,Q0) + d(x,Q0)] for Q0 < mc

• two normalization points, 〈x〉IC ≡∫ 1

0 xIC(x,mc)dx• 1: 〈x〉IC = 0.6%• 2: 〈x〉IC ≈ 2% (maximally allowed from global fit)

0.0 0.2 0.4 0.6 0.8 1.0x

10−6

10−5

10−4

10−3

10−2

10−1

100

xfx

(c,x,Q

=91

GeV

)

CT14NNLO

BHPS1

BHPS2

SEA1

SEA2

0.0 0.2 0.4 0.6 0.8 1.0x

10−3

10−2

10−1

100

101

102

103

(xfx−

xfx

CT

14)/

xfx

CT

14

CT14NNLO

BHPS1

BHPS2

SEA1

SEA2




Intrinsic Charm

Z Production with Charm Boettcher, PI, and Williams,PRD 93 (2016)

• measure ratio of Z + c-jet to Z+jet

g

c

c

Z

g

c

c

Z

• not all Z + c-jet final states from intrinsic charm

g

g

c

c

Z

g

g

c

c

Z

g

g

c

Z

c




Intrinsic Charm

Expected Sensitivity Boettcher, PI, and Williams,PRD 93 (2016)

LHCb Run 2 LHCb Run 3

2 2.5 3 3.5 4 4.5

)Z

j(σ

)/Z

c(σ

0.04

0.06

0.08

CT14NNLO BHPS1

BHPS2 SEA1

SEA2

= 13 TeVs-1Ldt = 5 fb∫

)Z(y2 2.5 3 3.5 4 4.5

CT

14N

NL

OIC

1

2

3 2 2.5 3 3.5 4 4.5)

Zj

(σ)/

Zc

(σ

0.04

0.06

0.08

CT14NNLO BHPS1

BHPS2 SEA1

SEA2

= 14 TeVs-1Ldt = 15 fb∫

)Z(y2 2.5 3 3.5 4 4.5

CT

14N

NL

OIC

1

2

3




Intrinsic Charm

SMOG LHCb, JINST 9 P12005 (2014)

• System for MeasuringOverlap with Gas

• used for precision luminositymeasurements using beamgas imaging (uncertainty of1.16%)

• at√

s = 110 GeVy = ycom + 4.77

type√

s [GeV] year time

pNe 87 2012 30mPbNe 54 2013 30m

pNe 110 2015 12hpHe 110 2015 7hpAr 110 2015 20hpAr 69 2015 11h

PbAr 69 2015 100hpHe 110 2016 20hpHe 87 2016 87h



Intrinsic Charm

Bjorken-x Coverage

• parton distribution function (PDF) parameter space in Q2 and x

10−6 10−5 10−4 10−3 10−2 10−1 100

x

100

101

102

103

104

105

106

107

108

Q2

[GeV

2 ]

Tevatron

HERA

fixed target

GPD 13 TeV

LHCb 13 TeV

LHCb 110 GeV


Intrinsic Charm

Measurements LHCb, JHEP 1603, 159 (2016)LHCb, JHEP 1510, 172 (2015)

• open and hidden-charm cross-sections with pp data• use the J/ψ[µµ], D0[K+π−], and D+[K+π−π+] channels

0 2 4 6 8 10 12 14pT [GeV/c]

100

101

102

(d2 σ

)/(d

ydp T

)[µ

b/(G

eVc−

1 )]

LHCb D0√

s = 13 TeV

2.0< y< 2.52.5< y< 3.03.0< y< 3.53.5< y< 4.04.0< y< 4.5




Intrinsic Charm

Measurements LHCb, JHEP 1603, 159 (2016)LHCb, JHEP 1510, 172 (2015)

• can also reduce low-x gluon uncertainty by up to factor of 4(arXiv:1610.09373 [hep-ph])

0 2 4 6 8 10 12 14pT [GeV/c]

10−1

100

101

102

(d2 σ

)/(d

ydp T

)[µ

b/(G

eVc−

1 )]

LHCb D+√

s = 13 TeV

2.0< y< 2.52.5< y< 3.03.0< y< 3.53.5< y< 4.04.0< y< 4.5





Intrinsic Charm

Future Measurements

• same measurements but with pHe and pAr data• rough predictions in LHCb acceptance from Pythia 8

y2 2.5 3 3.5 4 4.5

A.U

.

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Ar) = 110 GeVp(s at 0D

CT14NNLO

BHPS1

BHPS2

SEA1

SEA2

Ar) = 110 GeVp(s at 0D

y2 2.5 3 3.5 4 4.5

A.U

.

0.09

0.092

0.094

0.096

0.098

0.1

0.102

0.104

0.106

0.108

) = 13 TeVpp(s at 0D

CT14NNLO

BHPS1

BHPS2

SEA1

SEA2

y2 2.5 3 3.5 4 4.5

A.U

.

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Ar) = 110 GeVp(s at +D

CT14NNLO

BHPS1

BHPS2

SEA1

SEA2

Ar) = 110 GeVp(s at +D

y2 2.5 3 3.5 4 4.5

A.U

.

0.09

0.092

0.094

0.096

0.098

0.1

0.102

0.104

0.106

) = 13 TeVpp(s at +D

CT14NNLO

BHPS1

BHPS2

SEA1

SEA2

) = 13 TeVpp(s at +D


J/ψ Production in Jets




A Tale of Two Pictures LHCb, arXiv:1701.05116

1 NRQCD hard process, octet states showered with QCD splittings2 shower with NRQCD splittings, match with hard process

g

g

J/ψ

g

g

g

g

J/ψ

g

[arXiv:1603.06981] • J/ψ trigger writes out fullevents

• select jets with J/ψs• measure

z ≡ pT(J/ψ)/pT(jet)





Signal Determination LHCb, arXiv:1701.05116

• determine J/ψ signal yield with mass fits• separate prompt from displaced yields with pseudo-lifetime fits

τ ≡ (xz − xz(PV))m/pz

) [GeV]−µ+µ(m3 3.05 3.1 3.15 3.2

Can

dida

tes

/ 5 M

eV

0

5000

10000

LHCb = 13 TeVs

(jet) < 30 GeVT

p20 <

) < 0.5ψ/J(z0.4 <

Data

Total Fit

ψ/J

Background

[ps]t~-10 -5 0 5 10

Can

dida

tes

/ 0.1

ps

1

10

210

310

410LHCb = 13 TeVs

(jet) < 30 GeVT

p20 <

) < 0.5ψ/J(z0.4 < Data

Total Fitψ/JPrompt

ψ/J→b

Background

Wrong PV




Results LHCb, arXiv:1701.05116

)ψ/J(z0 0.2 0.4 0.6 0.8 1

σ/σd

0

0.1

0.2

0.3

Data (syst)

Pythia 8

LHCb = 13 TeVs

ψ/J→b

)ψ/J(z0 0.2 0.4 0.6 0.8 1

σ/σd

0

0.1

0.2

0.3

Data (syst)

Pythia 8

LHCb = 13 TeVsPrompt

• Pythia 8 implements the LO hard process picture• not the end of the story, need different predictions and more

measurements




QCD SplittingsLHCb, arXiv:1701.05116

PI, Rodd, Thaler, andWilliams, arXiv:1702.02947

)ψ/J(z0 0.2 0.4 0.6 0.8 1

σ/σd

0

0.1

0.2

0.3

0.4

Pythia 8

-splitgno

no MPI

LHCb simulation = 13 TeVs • g → QQ still not yet fully

understood• major contributor to

systematics for topmeasurements

Pq,g '1− z

z + z1− z + 1

2

Pg→QQ = z2 + (1− z)2 + 2m2

Q

m2QQ

PQ→Qg = 1− zz + z

2 − 2m2

Q

m2Qg −m2

Q

g

Q

Q






SoftDrop PI, Rodd, Thaler, andWilliams, arXiv:1702.02947

-�� -�� -�� -��

-��

-��

��

��

��

��

Δ�

Δϕ

�� (��)

�� β = �� = ��

-�� -�� -�� -��

-��

-��

��

��

��

��

Δ�

Δϕ

�� (��)�

�� β = �� = ��

-�� -�� -�� -��

-��

-��

��

��

��

��

Δ�

Δϕ

�� (��)�

�� β = �� = ��

-�� -�� -�� -��

-��

-��

��

��

��

��

Δ�

Δϕ

�� (��)�

�� β = �� = ��

0.0 0.2 0.4 0.6 0.8 1.0

zg

0

1

2

3

4

5

(1/σ

)(dσ/dz g

)

c-hadron tag

Pythia

R = 1.0

LHCb: pT > 20 GeV, ztag > 0.1, η ∈ [3, 4]

(0, 0)c

(0, 1)c

(1, 1)c

0.0 0.2 0.4 0.6 0.8 1.0

zg

0

1

2

3

4

5

6

7

(1/σ

)(dσ/dz g

)

c-hadron tag

Pythia

R = 1.0

LHCb: pT > 20 GeV, ztag > 0.1, η ∈ [3, 4]

(0, 1)c

(0, 2)c

(0, 1)J/ψ




Outlook

Outlook


Outlook

Outlook

• robust and efficient c(b)-tagging algorithm validated against data• could see strange asymmetries at end of Run 2• strong constraints on high-x gluon from top• top asymmetries should be observable by end of Run 3

• intrinsic charm studies underway both with pp and pAr• rule out BHSP models at 〈x〉IC ≈ 1% . . . or demonstrate IC!

• exciting new quarkonia physics underway• new methods to directly test heavy flavor splitting

Thank you!Ilten Heavy Flavor at LHCb February 15, 2017 34 / 34

Documents

Heavy Flavor Production in Hadronic and Nuclear · PDF fileHeavy Flavor Production in Hadronic and Nuclear Collisions at LHCb Philip Ilten on behalf of the LHCb Collaboration Massachusetts