Exclusive Production at LHCb Philip Ilten on behalf of the LHCb - - PowerPoint PPT Presentation

Exclusive Production at LHCb

Philip Ilten

• n behalf of the LHCb Collaboration

Massachusetts Institute of Technology

December 1, 2016

Multiple Partonic Interactions at the LHC

Ilten Exclusive Production at LHCb December 1, 2016 1 / 20

Introduction

Outline

• motivation
• LHCb detector
• datasets
• dimuon continuum
• χcJ production
• J/ψ and ψ(2S) production
• double J/ψ and ψ(2S) production
• J/ψ and ψ(2S) production at 13 TeV

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Introduction

Central Exclusive Production

pp → pXp γ-γ γ-pomeron pomeron-pomeron

p p + µ

• µ

γ γ p p ψ J/ g g γ c p p

c

χ g g g c

ℓℓ, WW J/ψ, Υ, ρ, Z, . . . χcJ, χbJ, gg, . . . photon PDF, QED tests diffractive PDF,

• dderon searches

gluon PDF, glueball searches, QCD tests

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Introduction

Event Signatures

single diffraction double diffraction CEP elastic CEP inelastic elastic inelastic

5 10 15

• 5
• 10
• 15

p p p p p p p p p p η Ilten Exclusive Production at LHCb December 1, 2016 4 / 20

Introduction

Detector

JINST 3 (2008) S08005

VELO RICH1 TT magnet OT IT T1 T2 T3 RICH2 M1 M2 M3 M4 M5 HCAL ECAL muon system

5 m 5 m 15 m

z-axis → y-axis → SPD/PRS

• fully instrumented between 2 < η < 5
• momentum resolution between 0.4% at 5 GeV to 1% at 300 GeV
• secondary vertex precision of 0.01 − 0.05(0.1 − 0.3) mm in xy(z)
• dedicated CEP trigger lines

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Introduction

Forward Kinematics

10−6 10−5 10−4 10−3 10−2 10−1 100 x 100 101 102 103 104 105 106 107 108 Q2 [GeV2]

√s = 14 TeV LHCb ATLAS/CMS Tevatron HERA fixed target

Q2(x) = e±2yx2s σ =

• xfx(f1, x1, Q2)

xfx(f2, x2, Q2)ˆ σ dx1dx2 Q ≡ momentum transfer xfx ≡ parton PDF for flavor f x ≡ momentum fraction

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Introduction

Backward Tracks

LHCb VELO

20 m 1 m 10 m 8.4 cm

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Introduction

HERSCHEL

• high rapidity shower counters for LHCb

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Introduction

LHCb Rapidity Gap

single diffraction double diffraction CEP elastic CEP inelastic elastic inelastic

5 10 15

• 5
• 10
• 15

p p p p p p p p p p η

LHCb HERSCHEL

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Introduction

Datasets

JINST 9 (2014) 12, P12005

• 36 pb−1 at √s = 7 TeV (2010)
• 1 fb−1 at √s = 7 TeV (2011)
• 2 fb−1 at √s = 7 TeV (2012)
• 200 pb−1 at √s = 13 TeV (2015)

P(N) = eµµN N!

• 2010 µ = 1.6 P(1) ≈ 21%
• 2011 µ = 1.4 P(1) ≈ 25%
• 2012 µ = 1.7 P(1) ≈ 19%
• 2015 µ = 1.08

P(1) ≈ 35%

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Results

Dimuon Continuum

LHCb-CONF-2011-022

• uses 36 pb−1 of 2010 data at √s = 7 TeV
• no backwards tracks, two muons in acceptance, pT(µ) > 80 MeV
• m(µµ) > 2.5 GeV and exclude 100 MeV from resonances

DiMuon Pt (GeV)

0.2 0.4 0.6 0.8

Number of events per 100 MeV

5 10 15 20 25 30 35 40

DiMuon Pt (GeV)

0.2 0.4 0.6 0.8

Number of events per 100 MeV

5 10 15 20 25 30 35 40

Preliminary LHCb

2010 Data LPAIR Semi Inelastic LPAIR Fully Inelastic Pomwig DPE

DiMuon Pt (GeV)

0.2 0.4 0.6 0.8

Number of events per 100 MeV

10 20 30 40 50

DiMuon Pt (GeV)

0.2 0.4 0.6 0.8

Number of events per 100 MeV

10 20 30 40 50

Preliminary LHCb

2010 Data Background from 2010 Data Signal from LPAIR MC

more than two forward tracks

• nly two forward tracks

σµµ(data) = 67±10±5±15 pb σµµ(LPAIR) = 42± 1

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Results

χcJ Production

LHCb-CONF-2011-022

• same as dimuon but require exactly two muons and photon in

acceptance

Mass (GeV)

2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4

Events per 5 MeV

20 40 60 80 100 120 140 160 180

LHCb Preliminary

= 7 TeV s

)

2

ChiC Mass (GeV/c

3.2 3.4 3.6 3.8

Number of events per 20 MeV

10 20 30 40 50

)

2

ChiC Mass (GeV/c

3.2 3.4 3.6 3.8

Number of events per 20 MeV

10 20 30 40 50 = 7 TeV Data s

Preliminary LHCb

2010 Data ChiC0 from SuperChiC MC ChiC1 from SuperChiC MC ChiC2 from SuperChiC MC ChiC from Psi’ Starlight MC

dimuon invariant mass dimuon+photon invariant mass σχc0→µµγ = 9.3±2.2±3.5±1.8 pb σχc1→µµγ = 16.4±5.3±5.8±3.2 σχc2→µµγ = 28.0±5.4±9.7±5.4

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Results

J/ψ and ψ(2S) Production (1) J. Phys. G 41 (2014) 055002

• uses 930 pb−1 of 2011 data at √s = 7 TeV
• no backwards tracks, exactly two muons in acceptance,

pT(µ) > 400 MeV

]

2

Invariant mass [MeV/c

2500 3000 3500 4000

2

Events per 10 GeV/c

10

2

10

3

10

4

10

LHCb

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Results

J/ψ and ψ(2S) Production (2) J. Phys. G 41 (2014) 055002

fele−belp2

T + fine−binp2 T + ffdPfd(p2

T)

]

2

/c

2

[GeV

2 T

p

0.5 1 1.5 2

2

/c

2

Events per 0.02 GeV

500 1000 1500 2000 2500 3000 3500 4000 4500

LHCb

Signal Inelastic bkg Feed-down bkg

(a) ]

2

/c

2

[GeV

2 T

p

0.5 1 1.5 2

2

/c

2

Events per 0.1 GeV

50 100 150 200 250 300 350 400 450

LHCb

Signal Inelastic bkg Feed-down bkg

(b)

J/ψ ψ(2S) bel = 5.70 ± 0.11 GeV−2 bel = 5.1 ± 0.7 GeV−2 bin = 0.97 ± 0.04 GeV−2 bin = 0.8 ± 0.2 GeV−2

• extrapolated from HERA bel ≈ 6 GeV−2 and bin ≈ 1 GeV−2

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Results

J/ψ and ψ(2S) Production (3) J. Phys. G 41 (2014) 055002

Rapidity

2 2.5 3 3.5 4 4.5

/dy [nb] σ d

1 2 3 4 5 6

Data with uncorrelated uncertainty Data total uncertainty LO prediction (JMRT) NLO prediction (JMRT)

LHCb

(a) Rapidity

2 2.5 3 3.5 4 4.5

/dy [nb] σ d

0.2 0.4 0.6 0.8 1 1.2 1.4

Data with uncorrelated uncertainty Data total uncertainty LO prediction (JMRT) NLO prediction (JMRT)

LHCb

(b) Rapidity

2 2.5 3 3.5 4 4.5

/dy [nb] σ d

1 2 3 4 5 6

Data with uncorrelated uncertainty Data total uncertainty Saturation model of Gay Ducati, Griep & Machado Saturation model of Motyka & Watt

LHCb

(a) Rapidity

2 2.5 3 3.5 4 4.5

/dy [nb] σ d

0.2 0.4 0.6 0.8 1 1.2 1.4

Data with uncorrelated uncertainty Data total uncertainty Saturation model of Gay Ducati, Griep & Machado

LHCb

(b)

J/ψ ψ(2S)

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Results

J/ψ and ψ(2S) Production (4) J. Phys. G 41 (2014) 055002

dσpp→pJ/ψp dy = r+k+ dn dk+ σγp→J/ψp(W+) + r−k− dn dk− σγp→J/ψp(W−)

W (GeV)

2

10

3

10

(nb) σ

10

2

10

3

10

LHCb (W+ solutions) LHCb (W- solutions) H1 ZEUS Fixed target experiments Power law fit to H1 data

LHCb

• dn

dk± are photon

fluxes, k ≈ m(J/ψ)/2e±|y|

• W±2 = 2k±

√s

• W+ is photon emitter
• W− is photon target
• r± are absorptive

corrections

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Results

J/ψ and ψ(2S) at 13 TeV (1)

LHCb-CONF-2016-007

• uses 204 pb−1 of 2015 data at √s = 13 TeV
• HERSCHEL veto in place and used

signal background

without HERSCHEL with HERSCHEL

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Results

J/ψ and ψ(2S) at 13 TeV (2)

LHCb-CONF-2016-007

rapidity ψ J/

2 3 4

/dy (nb) σ d

1 2 3 4 5 6 7 8 9 JMRT 'LO' JMRT 'NLO' LHCb Preliminary

(2S) rapidity ψ

2 3 4

/dy (nb) σ d

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 JMRT 'LO' JMRT 'NLO' LHCb Preliminary

W (GeV)

2

10

3

10

(nb)

p ψ J/ → p γ

σ

2

10

3

10

= 13 TeV) s LHCb ( = 7 TeV) s LHCb ( ALICE H1 ZEUS Fixed target experiments Power law fit to H1 data JMRT NLO prediction

LHCb preliminary

W (GeV)

2

10

3

10

(nb)

(2S) p ψ → p γ

σ

10

2

10

= 13 TeV) s LHCb ( = 7 TeV) s LHCb ( H1 power law scaled by 0.166 ψ H1 J/

L H C b p r e l i m i n a r y

J/ψ ψ(2S)

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Results

Double ψ Production

• J. Phys. G 41 (2014) 15002
• uses 1 fb−1 of 2011 data at √s = 7 TeV
• uses 2 fb−1 of 2012 data at √s = 8 TeV

J/ψ c J/ψ c c c p p J/ψ c J/ψ c c c p p

J /ψ J /ψ ψ(2S)

σJ/ψ,J/ψ = 58 ± 6 pb σJ/ψ,ψ(2S) = 63+27

−18 ± 10 pb

σχc0χc0 < 69 nb σχc1χc1 < 45 nb σχc2χc2 < 141 nb

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Conclusions

Outlook

• comprehensive exclusive production program at LHCb
• important for odderon and glueball searches
• provides data for understanding PDFs
• HERSCHEL performing well
• more results using final states other than muons and photons

underway!

Thank you!

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