Heavy flavour and quarkonia measurements from LHCb · designed for studies of heavy ﬂavour quarks in pp collisions - excellent vertexing, tracking and PID capability but is becoming

Heavy flavour and quarkonia measurements from LHCb

Jana Crkovskaa

aLos Alamos National Laboratory

RHIC & AGS Annual Users’ MeetingBNL, 04-07 June 2019

[email protected] 2019RHIC/AGS 04/06/2019 1 / 23

Introduction

LHCb detector

• fully instrumented in 2 < η < 5

• designed for studies of heavy flavour quarks in pp collisions - excellent vertexing, tracking and PID capability

• but is becoming more of a general purpose detector also measuring pPb and PbPb


Introduction

Heavy quark production in nuclear collisions

Charm and beauty quarks are produced in the initial stages of a nuclear collisions→ they experience the whole evolutionof the system.

• In A-A heavy quarks measurements serve to characterise the produced hot and dense QCD matter - the QuarkGluon Plasma (QGP).

• In p-A they serve as a clean probe of the Cold Nuclear Matter (CNM) effects.• Modification of nuclear parton distribution functions (nPDFs), gluon saturation, initial state/final state radiation,

coherent energy loss.• CNM are also present in A-A collisions - good understanding of CNM is also vital for correct interpretation of AA

results and characterising the QGP.

• Other thing to study in pA and/or AA are nucleon structure, intrinsic charm content of a nucleon, dark mattersearches . . .


Introduction

Recent heavy ion results from LHCb

Heavy flavour production in pPb

• Measurement of B+, B0 and Λ0b production in pPb collisions at

√sNN = 8.16 TeV, PRD 99 (2019) 052011

• Study of Υ production in pPb collisions at√

sNN = 8.16 TeV, JHEP 11 (2018) 194

• Prompt Λ+c production in pPb collisions at

√sNN = 5.02 TeV, JHEP 02 (2019) 102

• Study of prompt D0 meson production in pPb collisions at√

sNN = 5.02 TeV, JHEP 10 (2017) 090

• Prompt and nonprompt J/ψ production and nuclear modification in pPb collisions at√

sNN = 8.16 TeV, PLB 774(2017) 159

Fixed target measurements

• First measurement of charm production in fixed-target configuration at the LHC, PRL 122 (2019) 132002

• Measurement of antiproton production in pHe collisions at√

sNN = 110 GeV, PRL 121 (2018) 222001

Ultra-peripheral PbPb collisions

• Study of coherent J/ψ production in lead-lead collisions at√

sNN = 5.02 TeV with the LHCb experiment,LHCb-CONF-2018-003


pPb measurements

pPb measurements


pPb measurements

pPb collisions in LHCb

• pPb and Pbp are asymmetric systems→ centre-of-mass rapidity shift by ∆y =±0.465

1.5 < y∗ < 4.0 ⇒ xPb ∼ 10−6

√sNN = 5.02 TeV with 1.1 nb−1


−5.0 < y∗ <−2.5 ⇒ xPb ∼ 10−2




pPb measurements

Cold nuclear matter effects in theory

Modifications of nuclear PDFs

• Gluon shadowing/antishadowing: Parton distribution functions are modified by the nuclear environment⇒suppression or enhancement of HF hadrons as a function of the parton momentum fraction x in the nucleon.• HELAC-Onia: H.-S. Shao, Comp. Phys. Comm. 198 (2016) 238.• FONLL: M. Cacciari et al., JHEP 05 (1998) 007.

• Gluon saturation: Result of gluon recombination at small x at the LHC⇒ suppression of HF hadrons.• Colour Glass Condensate (CGC): B. Ducloue et al., PRD 94 (2016) 074031.

Coherent energy loss

• The medium induced gluon radiation in initial and/or final state modifies the HF hadron yields.• F. Arleo, S. Peigne, JHEP 03 (2013) 122.

Dissociation with comovers

• Interaction of HF hadrons with the comoving matter breaks the bound states⇒ suppression.• E. G. Ferreiro, PLB 731 (2014) 57; E. G. Ferreiro and J. P. Lansberg, JHEP 1810 (2018) 094.


pPb measurements

J/ψ production in pPb at√

sNN = 8.16 TeV

• J/ψ → µ+µ−

• Separated prompt and non-prompt.

• Nuclear modification factor

RpPb(pT,y) =1

208d2

σpPb/dpTdy

d2σpp/dpTdy

−5.0 −2.5 0.0 2.5 5.0y∗

0.0

0.5

1.0

1.5

2.0

RpP

b

0< pT < 14GeV/c

LHCb

prompt J/ψ

HELAC−Onia with EPS09LOHELAC−Onia with nCTEQ15HELAC−Onia with EPS09NLOEnergy LossCGCLHCb (5TeV)LHCb (8.16TeV)

−5.0 −2.5 0.0 2.5 5.0y∗

0.0

0.5

1.0

1.5

2.0

RpP

b

0< pT < 14GeV/c

LHCb

J/ψ -from-b-hadrons

FONLL with EPS09NLOLHCb (5TeV)LHCb (8.16TeV)

• Strong suppression of prompt J/ψ at forward rapidity, non-prompt consistent with unity.

• Suppression pattern described by calculations including modificatons of nPDFs and coherent energy loss.

• No evidence of energy dependence for CNM effects at LHC energy scales.


PLB 774 (2017) 159

pPb measurements

Prompt Λ+c production in pPb at

√sNN = 5.02 TeV

]c [GeV/T

p2 4 6 8 10

FBR

0

0.5

1

EPS09LOEPS09NLO

nCTEQ15

data

=5 TeVNNsPb pLHCb

c 7.0 GeV/≥ T

p*| < 3.5 y2.5 < |

c < 7.0 GeV/T

p*| < 4.0 y2.5 < |

(a)

*|y|2.5 3 3.5 4

FBR

0

0.5

1

EPS09LOEPS09NLO

nCTEQ15

data

=5 TeVNNsPb pLHCb

c < 10.0 GeV/T

p2.0 <

(b)

• Λ+c measured down to low pT from Λ+

c −→ pK−π+.

• Forward-to-backward ratio studies difference in CNM effects between forward and backward rapidity.

• Larger production rate in backward region reproduced in HELAC-Onia.


JHEP 02 (2019) 102

pPb measurements

Prompt Λ+c production in pPb at

√sNN = 5.02 TeV (cont.)

• Light and strange hadrons show increase inbaryon-to-meson ratio in central A-A collisions⇒consistent with hadronisation via coalescence.

• Recent measurements show the same behaviour forcharmed hadrons.

• Baryon-to-meson ratio consistent at low pT with theorycalculations based on pp data but are overestimated athigh pT.

]c [GeV/T

p2 4 6 8 10

0D/

+ cΛ

R

0

0.2

0.4

0.6

EPS09LOEPS09NLOnCTEQ15data

LHCb* < 4.0y1.5 <

=5 TeVNNsPb p


JHEP 02 (2019) 102

pPb measurements

Open beauty hadron production in pPb at√

sNN = 8.16 TeV

• First measurement of B+, B0, and Λ0b down to low pT in nuclear collisions.

• Clear signal reconstructed from exclusive decays.

5000 5200 5400 5600

]2c) [MeV/+π0D(m

050

100150200250300350400450500)2 c

Can

dida

tes

/ (10

MeV

/

Data

Fit

Signal

Partial

Combinatorial+K

0D→+B

LHCb = 8.16 TeVNNs

Pbp

5000 5200 5400 5600]2c) [MeV/+π−D(m

0

50

100

150

200

250

)2 cC

andi

date

s / (

10 M

eV/

Data

Fit

Signal

Partial

Combinatorial+K−D→0B

LHCb = 8.16 TeVNNs

Pbp

5400 5600 5800]2c) [MeV/−π+

cΛ(m

0

20

40

60

80

100

120)2 cC

andi

date

s / (

10 M

eV/

Data

Fit

Signal

Partial

Combinatorial−K+

cΛ→b0Λ

LHCb = 8.16 TeVNNs

Pbp


PRD 99 (2019) 052011

pPb measurements


sNN = 8.16 TeV (cont.)• Suppression pattern consistent with J/ψ-from-b.• Baryon-to-meson ratio consistent with the pp result.

4− 2− 0 2 4y

00.20.40.60.8

11.21.41.61.8

2

+B

Pbp

R

LHCb pPb/Pbp

= 8.16 TeVNNs

c < 20 GeV/T

p2 <

DataEPPS16nCTEQ15EPPS16*

ψ/JNonprompt

0 5 10 15 20]c [GeV/

Tp

00.20.40.60.8

11.21.41.61.8

2

+B

Pbp

R

LHCb Pbp

= 8.16 TeVNNs

< 3.5y2.5 <


ψ/JNonprompt

0 5 10 15 20]c [GeV/

Tp

00.20.40.60.8

11.21.41.61.8

2

+B

Pbp

R

LHCb pPb

= 8.16 TeVNNs

2.5− < y3.5 < −


ψ/JNonprompt

0 5 10 15 20]c [GeV/

Tp

0

0.5

1

1.5

2

2.5Tp

/dσdR

LHCb < 3.5yPb, 2.5 < p

= 8.16 TeVNNs

+B/0B0B/0

bΛ

0 5 10 15 20]c [GeV/

Tp

0

0.5

1

1.5

2

2.5Tp

/dσdR

LHCb 2.5− < y3.5 < −, pPb

= 8.16 TeVNNs

+B/0B0B/0

bΛ


PRD 99 (2019) 052011

pPb measurements


sNN = 8.16 TeV (cont.)

5 10 15 20]c [GeV/

Tp

00.20.40.60.8

11.21.41.61.8

2

FBR

| < 3.5y2.5 < |

+B0B

b0Λ

pPb/Pbp LHCb = 8.16 TeVNNs

0 1 2 3 4y

00.20.40.60.8

11.21.41.61.8

2

FBR

+B0B

b0Λ

pPb/Pbp LHCb = 8.16 TeVNNs

c < 20 GeV/T

p2 <

0 5 10 15 20]c [GeV/

Tp

00.20.40.60.8

11.21.41.61.8

20B/ b0

Λ Pbp

R

PbppPb

LHCb

= 8.16 TeVNNs

| < 3.5y2.5 < |

4− 2− 0 2 4y

00.20.40.60.8

11.21.41.61.8

20B/ b0

Λ Pbp

R

c < 20 GeV/T

p2 <

LHCb = 8.16 TeVNNs

• Forward-to-backward ratios show the samesuppression in both pPb and Pbp for all threespecies.

• Ratio of Λ0b/B0 modification factors allows to study

the difference in overall CNM effects relevant forthe two species.

Hints of deviation from unity in pT, however moredata required to make strong conclusions.


PRD 99 (2019) 052011

pPb measurements

Υ production in pPb at√

sNN = 8.16 TeV

9 10 11

310×

]2c) [GeV/−µ+µ(M

0

100

200

300

400

500

600

)2 cC

andi

date

s / (

20 M

eV/ LHCb Pbp=8.16 TeV, NNs

)nS(ϒBackgroundTotal

9 10 11

310×

]2c) [GeV/−µ+µ(M

0

100

200

300

400

500

600

700

800

)2 cC

andi

date

s / (

20 M

eV/ LHCb p=8.16 TeV, PbNNs

)nS(ϒBackgroundTotal

• LHCb measured Υ(nS)→ µ+µ−.

• The three states are clearly separated in both rapidity regions.


JHEP 11 (2018) 194

pPb measurements



4− 2− 0 2 4y*

00.20.40.60.8

1

1.21.41.61.8

2)S(1

ϒ Pbp

R

=8.16 TeVNNs

c<25 GeV/T

p

LHCbpPb, Pbp

EPPS16nCTEQ15EPS09LO+comoversnCTEQ15+comovers

4− 2− 0 2 4y*

00.20.40.60.8

1

1.21.41.61.8

2)S(2

ϒ Pbp

R=8.16 TeVNNs

c<25 GeV/T

p

LHCbpPb, Pbp

EPPS16nCTEQ15EPS09LO+comoversnCTEQ15+comovers

4− 2− 0 2 4y*

00.20.40.60.8

1

1.21.41.61.8

2)S(1

ϒ)/S

(3ϒ

pp)/

pPb

|Pb

p(ℜ

=8.16 TeVNNs

c<25 GeV/T

p

LHCb LHCb

comovers

• Υ(nS) suppression is consistent with models and previous measurements.

• Υ(3S) shows stronger suppression in the backward region than Υ(1S) and Υ(2S).


JHEP 11 (2018) 194

pPb measurements



• Cross-section ratio of Υ(1S)/J/ψ-from-b comparedbetween measurement in pp and pPb.

• Different hadronisation of close and open beauty⇒different sensitivity to final state CNM effects.

Hionts of different final CNM effects at forward rapidity.

4− 2− 0 2 4y*

00.020.040.060.08

0.10.120.140.160.180.2)b

fro

m

ψJ/(σ

))/

S(1

ϒ(σ c<25 GeV/T

p

LHCb 8.16 TeVpPb, Pbp

8 TeVpp


Υ: JHEP 11 (2018) 194J/ψ: PLB 774 (2017) 159

pPb measurements

Fixed target results



p-Gas collisions in LHCb

System for Measuring Overlap with Gas (SMOG)

• Originally conceived to perform precise luminosity measurements(2014 JINST 9 P12005).

• Gas target created by injecting noble gases Ne, Ar, He at pressure oforder 10−6−10−7 mbar into the VELO.

• Energies cover the gap between SPS and RHIC.

• Collisions with protons, newly in 2018 also with Pb!



Charm production in fixed target

• First J/ψ and D0 measurements in pHe at√

sNN = 86.6 GeV and pAr at√

sNN = 110.4 GeV.

• J/ψ and cc integrated cross section extrapolated to full phase-space to allow comparison with other available results

⇒ good agreement with NLO NRQCD (Nucl. Phys. B 373 (1992) 295).

[GeV]NNs210

) [n

b/nu

cleo

n]ψ/J(σ 210

310

This measurement

NLO NRQCD

LHCb

[GeV]NNs10 210 310

b/nu

cleo

n]µ

) [

cc(σ

10

210

310

NLO pQCD

This measurement

LHCb


PRL 122 (2019) 132002


Charm production in fixed target (cont.)

y*2− 1− 0

[nb

/nuc

leon

]y*

/d ψ/

Jσd 100200300400500600700800

LHCb data 1.78 CT14NLO+nCTEQ15×He p

1.78 CT14NLO× ppLinear interpolationLogarithmic interpolation

Hep = 86.6 GeV NNsLHCb

y*2− 1− 0

data

/CT

14N

LO

0.40.60.8

11.21.41.6

]c [GeV/T

p0 2 4 6 8

)]c [

nb/n

ucle

on/(

GeV

/T

p/d

ψ/Jσd

210

310


1.78 CT14NLO× ppLinear interpolationLogarithmic interpolation


]c [GeV/T

p0 2 4 6 8

data

/CT

14N

LO

0.40.60.8

11.21.41.6

y*2− 1−

y*d ψ/

J/N

ψ/J

dN

0.2

0.4

0.6

0.8

1 LHCb dataAr CT14NLO+nCTEQ15p CT14NLOpp

Linear interpolationLogarithmic interpolation

Arp = 110.4 GeV NNsLHCb

y*2− 1−

data

/CT

14N

LO

0.40.60.8

11.21.41.6

]c [GeV/T

p0 2 4 6 8

-1 )c(G

eV/

T

pd ψ/J

/N ψ/J

dN

1−10

1

LHCb dataAr CT14NLO+nCTEQ15p CT14NLOpp

Linear interpolationLogarithmic interpolation


]c [GeV/T

p0 2 4 6 8

data

/CT

14N

LO

0.40.60.8

11.21.41.6

• Differential cross-sections comparedwith HELAC-Onia.

• σ(J/ψ) underestimated, rescaledcalculations describe the shape well inpT and y∗.

• Similar conclusion for D0 (plots inbackup).

No evidence of substantial intrinsiccharm content.


PRL 122 (2019) 132002


Antiproton production in p-He collisions

LHCb performed the first p measurement in pHe at√

sNN = 110 GeV.

• The p fraction in cosmic rays is a sensitive indirect probe ofdark matter.

• PAMELA and AMS-02 observe an excess in the p/p flux ratiofor high energy cosmic rays.

• The uncertainty on the predictions is limited by thedetermination of the p production cross section in pH and pHecollisions.

• Measurement of p/p ration in pHe will help to improve theaccuracy of future predictions.

arXiv:1504.04276 [astro-ph.HE]


PRL 121 (2018) 222001


Antiproton production in p-He collisions (cont.)

25 30 35 40]c [GeV/p

20406080

100120140160180200220

/GeV

]c

b µ [

p/dσd

LHCb Xp →pHe

= 110 GeVNNs

c < 0.7 GeV/T

p 0.4 <

20 30 40 50]c [GeV/p

20

40

60

80

100

120

140

/GeV

]c

b µ [

p/dσd

LHCb Xp →pHe

= 110 GeVNNs

c < 1.2 GeV/T

p 0.7 <

20 40 60 80 100]c [GeV/p

5

10

15

20

25

30

35

/GeV

]c

b µ [

p/dσd

DATA

EPOS LHC

EPOS 1.99

QGSJETII-04

QGSJETII-04m

HIJING 1.38

PYTHIA 6.4

LHCb Xp →pHe

= 110 GeVNNs

c < 2.8 GeV/T

p 1.2 <

• p momentum distributions in several kinematic bins compared withmultiple predictions:• EPOS LHC PRC92 (2015) 034906• EPOS 1.99 Nucl.Phys.Proc.Suppl. 196 (2009) 102• QGSJETII-04 PRD83 (2011) 014018• QGSJETII-04m Astr. J. 803 (2015) 54• HIJING 1.38 Comp. Phys. Comm. 83 307• PYTHIA 6.4 2(pp+pn) JHEP 05 (2005) 026

• The momentum shapes are well reproduced save for the lowestmomenta.

• Absolute yields on the other hand deviate by up to factor 2.

The relative uncertainty on the data of . 10% is way below thespread from the models.


PRL 121 (2018) 222001

Measurements in ultra-peripheral PbPb collisions

Ultra-peripheral collisions



Coherent J/ψ photoproduction in PbPb at√

sNN = 5.02 TeV

LHCb studied the photoproduction of J/ψ in UPCcollisions

Pb + Pb→ Pb + J/ψ + Pb

• Coherent photoproduction of forward J/ψ in PbPbprobes the gluon nPDFs at low-to-intermediate Bjorken x

2 < y < 4.6 ⇒ 10−5 . xBj . 10−2

• Clean J/ψ signal, hints of ψ(2S).

• The coherent and incoherent photoproduction can bedistinguished from their pT shape:• Signal and backround fit with different STARlight

templates.• Non-resonant component constraint from the invariant

mass fit.

Dimuon mass [MeV]3000 3500 4000

Can

dida

tes

/ ( 1

3 M

eV )

1−10

1

10

210

310 LHCb Preliminary = 5 TeVNNsPb-Pb

dataψJ/(2S)ψ

non-resonantsum

10− 5− 0)2/GeV2

Tlog(p

0

10

20

30

40

50

Can

dida

tes

/ 0.1

5 datacoherentincoherent+feed-downnon-resonantsum

LHCb Preliminary = 5 TeVNNsPb-Pb


LHCb-CONF-2018-003


Coherent J/ψ photoproduction in PbPb at√


0 1 2 3 4 5y

00.5

11.5

22.5

33.5

44.5

5

/dy

[mb]

σd

Guzey et al.

LTA_W

LTA_S

EPS09

Goncalves et al.

IP-SAT+GLC

IIM+BG

Cepila et al.

GG-hs+BG

GS-hs+BG

ntysaari et al.aM

IS fluct. +GLC

no fluct. +GLC

=5 TeVNNsPb-Pb

LHCb Preliminary

Results for coherent cross section were compared withmultiple phenomenological models - several reproduce therapidity dependence.

• Guzey et al.: PRC 93 (2016) 055206

• Goncalves et al.: PRC 84 (2011) 011902, PRD 96(2017) 094027

• Cepila et al.: PRC 97 (2018) 024901

• Mantysaari et al.: PLB 772 (2017) 832-838

2018 PbPb data 20× more statistics than in 2015⇒more precise measurements in the future!


LHCb-CONF-2018-003

Summary

Summary

LHCb has an extensive heavy ion physics programme with some unique measurements.

• Measurements in pPb in collider mode provide new data to constrain CNM and hadronisation in nuclear medium.• Open and close HF RFB, RpPb, baryon-to-meson ratios,. . .

• Measurements in fixed target mode to fill the energy gap between SPS and RHIC.• At present uncertainty found no evidence of intrinsic charm content.• Results on p production will help improve models for dark matter searches.

• New results on coherent photoproduction are reproduced in models.• 2018 statistics 20× the one in 2015 expected to provide more conclusive data.

And the future?

• More precise results to come from Run 2 data: more quarkonia states, vector bosons, dihadron correlations, flowmeasurements. . .

• Higher statistics pNe and PbPb data from Run 2 are being analysed, also new PbNe datasample.

• Upgrade of LHCb detector for Run 3 also includes SMOG2 - higher pressure under more precise control, more gasspecies.


Back-up


Charm production in fixed target - D0

y*2− 1− 0

b/nu

cleo

n]µ [

y* /d 0

Dσd 1020304050607080


1.44 CT14NLO× pp


y*2− 1− 0

data

/CT

14N

LO

0.40.60.8

11.21.41.6

]c [GeV/T

p0 2 4 6 8

)]cb/

nucl

eon/

(GeV

/µ [

Tp

/d 0Dσd 1−10

1

10

210 LHCb data 1.44 CT14NLO+nCTEQ15×He p

1.44 CT14NLO× pp


]c [GeV/T

p0 2 4 6 8

data

/CT

14N

LO

0.51

1.52

2.5

y*2− 1− 0

y*d 0D

/N 0D

dN

0.2

0.4

0.6

0.8

1 LHCb dataAr CT14NLO+nCTEQ15p CT14NLOpp


y*2− 1− 0

data

/CT

14N

LO

0.40.60.8

11.21.41.6

]c [GeV/T

p0 2 4 6 8

-1 )c(G

eV/

T

pd 0D

/N 0D

dN

2−10

1−10

1LHCb data

Ar CT14NLO+nCTEQ15p CT14NLOpp


]c [GeV/T

p0 2 4 6 8

data

/CT

14N

LO

0.51

1.52

2.5



sNN = 8.16 TeV

• First measurement of B+, B0, and Λ0b down to low pT in nuclear collisions.

• Baryon-to-meson ratio consistent with the pp result.

4− 2− 0 2 4y

00.20.40.60.8

11.21.41.61.8

2y/dσd

R

+B/0B0B/b

0Λ

+B/0B0B/b

0Λ c < 20 GeV/T

p2 <

LHCb = 8.16 TeVNNs

pPb/Pbp

0 5 10 15 20]c [GeV/

Tp

0

0.5

1

1.5

2

2.5Tp

/dσdR

LHCb < 3.5yPb, 2.5 < p

= 8.16 TeVNNs

+B/0B0B/0

bΛ

0 5 10 15 20]c [GeV/

Tp

0

0.5

1

1.5

2

2.5Tp

/dσdR

LHCb 2.5− < y3.5 < −, pPb

= 8.16 TeVNNs

+B/0B0B/0

bΛ


PRD 99 (2019) 052011

Documents

Heavy flavour and quarkonia measurements from LHCb · designed for studies of heavy ﬂavour quarks in pp collisions - excellent vertexing, tracking and PID capability but is becoming