[PPT] - Intrinsic Charm at LHCb Philip Ilten on behalf of the LHCb PowerPoint Presentation

SLIDE 1

Intrinsic Charm at LHCb

Philip Ilten

n behalf of the LHCb Collaboration

Massachusetts Institute of Technology

February 1, 2017

7th Workshop of the APS Topical Group on Hadronic Physics

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SLIDE 2

Introduction

Overview

detector overview
intrinsic charm with Z + c
intrinsic charm using the System for Measuring the Overlap with

Gas (SMOG)

J/ψ production in jets

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SLIDE 3

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 0.5% 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)

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SLIDE 4

Introduction

Trigger

JINST 8 (2013) P04022

real-time calibration and full

event reconstruction in Run 2

full detector readout in Run 3

L0

µ: pT > 1.5 GeV 340 kHz µµ: p1

Tp2 T > 1.3 GeV

75 kHz h: ET > 3.5 GeV 405 kHz e: ET > 2.5 GeV 160 kHz γ: ET > 2.5 GeV 80 kHz µ: pT > 4.8(1) GeV 0.7(5) kHz µµ: m > 2.7(1)GeV 1.2(1.3) kHz track: pT > 1.7 GeV 33 kHz 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 5 kHz HLT1 HLT2 1 MHz 50 kHz

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SLIDE 5

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 5 2011 2012 2015 - 2019 2021 - 2023 2027 - 2029 2031 - ? 1 fb−1 2 fb−1 5 fb−1 15 fb−1 23 fb−1 54 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

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SLIDE 6

Intrinsic Charm with Z + c

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SLIDE 7

Intrinsic Charm with Z + c

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 [GeV2]

Tevatron HERA fixed target GPD 13 TeV LHCb 13 TeV

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SLIDE 8

Intrinsic Charm with Z + c

Intrinsic Charm PDFs

Phys. Rev. D 93, no. 3,

033006 (2016)

consider two models from CT14
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, xIC ≡

1

0 xIC(x, mc)dx

1: xIC = 0.6%
2: xIC ≈ 2% (maximally allowed from global fit)

0.0 0.2 0.4 0.6 0.8 1.0 x 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 1.0 x 10−3 10−2 10−1 100 101 102 103 (xfx − xfx CT14)/xfx CT14

CT14NNLO BHPS1 BHPS2 SEA1 SEA2 Ilten Intrinsic Charm at LHCb February 1, 2017 8 / 25

SLIDE 9

Intrinsic Charm with Z + c

Z Production with Charm

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

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SLIDE 10

Intrinsic Charm with Z + c

Jet Tagging

JINST 10 (2015) P06013

(jet) T (SV)/p T p 0.2 0.4 0.6 0.8 1 FractionbofbSV-TaggedbCandidates 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 b c u d s g SV corr mass [ ] 2 4 6 8 10 Fraction of SV-Tagged Candidates 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 b c u d s g GeV SV tracks 5 10 Fraction of SV-Tagged Candidates 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 Ilten Intrinsic Charm at LHCb February 1, 2017 10 / 25

SLIDE 11

Intrinsic Charm with Z + c

BDT Separation

JINST 10 (2015) P06013

) udsg | bc BDT(

1
0.5

0.5 1

) c | b BDT(

1
0.5

0.5 1

LHCb simulation

jets

udsg ) udsg | bc BDT(

1
0.5

0.5 1

) c | b BDT(

1
0.5

0.5 1

LHCb simulation

jets

c ) udsg | bc BDT(

1
0.5

0.5 1

) c | b BDT(

1
0.5

0.5 1

LHCb simulation

jets

b

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

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SLIDE 12

Intrinsic Charm with Z + c

Efficiencies

JINST 10 (2015) P06013

light-parton mistag probability

0.001 0.002 0.003 0.004 0.005

(b,c)-jet tag efficiency

0.2 0.4 0.6 0.8 1

jet

b

jet

c

LHCb simulation

(jet) < 4.2 η 2.2 < (jet) < 100 GeV

T

20 < p (jet) [GeV]

T

p

20 40 60 80 100

SV-tag efficiency

0.2 0.4 0.6 0.8 1

LHCb

jet

b

jet

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SLIDE 13

Intrinsic Charm with Z + c

Charm-Tagging Measurements

JINST 10 (2015) P06013: validation of performance
Phys. Rev. D 92 (2015): W + c and W + b measurement
Phys. Rev. Lett. 115 (2015): first forward top measurement
arXiv:1610.08142: t¯

t and W + Q ¯ Q

) [GeV] b + µ (

T

p ) W+b ( N

100 200

Data +top Wb Wb LHCb

20 45 70 95

∞

) [GeV] b + µ (

T

p Charge Asymmetry

0.4
0.2

0.2 0.4

Data +top Wb Wb LHCb

20 45 70 95

∞

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SLIDE 14

Intrinsic Charm with Z + c

Expected Sensitivity

Phys. Rev. D 93, no. 7,

074008 (2016)

2 2.5 3 3.5 4 4.5

) Zj ( σ )/ Zc ( σ

0.04 0.06 0.08

CT14NNLO BHPS1 BHPS2 SEA1 SEA2

= 13 TeV s

1

Ldt = 5 fb

∫

) Z ( y

2 2.5 3 3.5 4 4.5

CT14NNLO IC

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 TeV s

1

Ldt = 15 fb

∫

) Z ( y

2 2.5 3 3.5 4 4.5

CT14NNLO IC

1 2 3

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SLIDE 15

Intrinsic Charm with SMOG

(not to be confused with Smaug)

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SLIDE 16

Intrinsic Charm with SMOG

SMOG

JINST 9 P12005 (2014)

used for precision luminosity

measurements using beam gas imaging (uncertainty of 1.16%)

at √s = 110 GeV

y = ycom + 4.77

restriction

type √s [GeV] year time pNe 87 2012 30m PbNe 54 2013 30m pNe 110 2015 12h pHe 110 2015 7h pAr 110 2015 20h pAr 69 2015 11h PbAr 69 2015 100h pHe 110 2016 20h pHe 87 2016 87h

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SLIDE 17

Intrinsic Charm with SMOG

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 [GeV2]

Tevatron HERA fixed target GPD 13 TeV LHCb 110 GeV

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SLIDE 18

Intrinsic Charm with SMOG

Intrinsic Charm PDFs

Phys. Rev. D 93, no. 3,

033006 (2016)

test with open and hidden-charm production, Q of m(D)

0.0 0.2 0.4 0.6 0.8 1.0 x 10−6 10−5 10−4 10−3 10−2 10−1 100 xfx(c, x, Q = 2 GeV)

CT14NNLO BHPS1 BHPS2 SEA1 SEA2

0.0 0.2 0.4 0.6 0.8 1.0 x 10−4 10−3 10−2 10−1 100 101 102 103 (xfx − xfx CT14)/xfx CT14

CT14NNLO BHPS1 BHPS2 SEA1 SEA2 Ilten Intrinsic Charm at LHCb February 1, 2017 18 / 25

SLIDE 19

Intrinsic Charm with SMOG

Measurements

JHEP 1603, 159 (2016) 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

2 4 6 8 10 12 14 pT [GeV/c] 100 101 102 (d2σ)/(dydpT) [µb/(GeVc−1)]

LHCb D0

√s = 13 TeV 2.0 < y < 2.5 2.5 < y < 3.0 3.0 < y < 3.5 3.5 < y < 4.0 4.0 < y < 4.5

] c ) [GeV/ ψ J/ (

T

p

5 10

)] c ) [nb/(GeV/

T

p d y /(d σ

2

d

10

2

10

3

10

1

=3.05 pb

int

L = 13 TeV, s LHCb <2.5 y 2.0< <3.0 y 2.5< <3.5 y 3.0< <4.0 y 3.5< <4.5 y 4.0<

2 4 6 8 10 12 14 pT [GeV/c] 10−1 100 101 102 (d2σ)/(dydpT) [µb/(GeVc−1)]

LHCb D+

√s = 13 TeV 2.0 < y < 2.5 2.5 < y < 3.0 3.0 < y < 3.5 3.5 < y < 4.0 4.0 < y < 4.5

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SLIDE 20

Intrinsic Charm with SMOG

Future Measurements

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

y

2 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 GeV p ( s at D

CT14NNLO BHPS1 BHPS2 SEA1 SEA2

Ar) = 110 GeV p ( s at D y

2 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 TeV pp ( s at D

CT14NNLO BHPS1 BHPS2 SEA1 SEA2

y

2 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 GeV p ( s at

+

D

CT14NNLO BHPS1 BHPS2 SEA1 SEA2

Ar) = 110 GeV p ( s at

+

D y

2 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 TeV pp ( s at

+

D

CT14NNLO BHPS1 BHPS2 SEA1 SEA2

) = 13 TeV pp ( s at

+

D

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SLIDE 21

J/ψ Production in Jets

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SLIDE 22

J/ψ Production in Jets

Two Pictures

arXiv:1701.05116

understanding prompt J/ψ critical for intrinsic charm
prompt J/ψ calculated with non-relativistic QCD (NRQCD)
two pictures on how NRQCD is used
NRQCD hard process, octet states showered with QCD splittings
shower with NRQCD splittings, match with hard process

g g J/ψ g g g g J/ψ g

utilize J/ψ trigger that writes out fully reconstructed event
use jets with pT > 20 GeV which contain a J/ψ

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SLIDE 23

J/ψ Production in Jets

Results

arXiv:1701.05116

measure z ≡ pT(J/ψ)/pT(jet)
separate into prompt and displaced contributions

) ψ / J ( z

0.2 0.4 0.6 0.8 1

σ / σ d

0.1 0.2 0.3

Data (syst) Pythia 8

LHCb

= 13 TeV s ψ / J → b

) ψ / J ( z

0.2 0.4 0.6 0.8 1

σ / σ d

0.1 0.2 0.3

Data (syst) Pythia 8

LHCb

= 13 TeV s Prompt

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

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SLIDE 24

Outlook

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SLIDE 25

Outlook

forward detector with diverse datasets
robust and efficient c(b)-tagging algorithm validated against data
intrinsic charm studies underway both with pp and pAr
rule out BHSP models at xIC ≈ 1% . . . or demonstrate IC!

Thank you!

I discover intrinsic charm where I wish and none dare resist.

SMOG (if SMOG were Smaug)

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