Quarkonia in pPb collisions in LHCb
Jana Crkovskaa
aLos Alamos National Laboratory
2nd LHCb Heavy Ion WorkshopSardinia, 04-06 September 2019
[email protected] 2nd IFT Workshop 05/09/2019 1 / 15
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.
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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
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Introduction
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
√sNN = 8.16 TeV with 13.6 nb−1
−5.0 < y∗ <−2.5 ⇒ xPb ∼ 10−2
√sNN = 5.02 TeV with 0.5 nb−1
√sNN = 8.16 TeV with 20.8 nb−1
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Introduction
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.
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Introduction
Quarkonia measurements in pPb in LHCb
Run 2
• Study of Υ production in pPb collisions at√
sNN = 8.16 TeV, JHEP 11 (2018) 194
• Prompt and nonprompt J/ψ production and nuclear modification in pPb collisions at√
sNN = 8.16 TeV, PLB 774(2017) 159
Run 1
• Study of ψ(2S) production and cold nuclear matter effects in pPb collisions at√
sNN = 5 TeV, JHEP 02 (2014) 72
• Study of Υ production and cold nuclear matter effects in pPb collisions at√
sNN = 5 TeV, JHEP 07 (2014) 094
• Study of J/ψ production and cold nuclear matter effects in pPb collisions at√
sNN = 5 TeV, JHEP 02 (2014) 72
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Introduction
Prompt and non-prompt J/ψ production in pPb collisions
]2c [MeV/-µ+µM3000 3050 3100 3150 3200
)2 cC
andi
date
s / (
6 M
eV/
0
50
100
150
200
250
300
-hadronsb-from-ψJ/
background
ψJ/prompt
LHCb
Pbp=8.16 TeV: NNs
c < 7 GeV/T
p6 <
< 4.0y*3.5 <
[ps]zt0 5 10
Can
dida
tes
/ ( 0
.15
ps )
1
10
210
310
LHCb
Pbp=8.16 TeV: NNs
c < 7 GeV/T
p6 <
< 4.0y*3.5 <
• J/ψ → µ+µ− measured in pPb collisions at 5 and 8 TeV.
• Separated prompt and non-prompt via the pseudo-proper time tz =(zJ/ψ −zPV×MJ/ψ
)/pz .
[email protected] 2nd IFT Workshop 05/09/2019 7 / 15
PLB 774 (2017) 159
Introduction
Prompt and non-prompt J/ψ production in pPb collisions (cont.)
• Nuclear modification factor
RpPb(pT,y) =1
208d2
σpPb/dpTdy
d2σpp/dpTdy
• Strong suppression of prompt J/ψ at forward rapidity,non-prompt consistent with unity.
• Stronger suppression at lower pT for prompt J/ψ.
• Suppression pattern described by calculations includingmodifications of nPDFs and coherent energy loss.
• No evidence of energy dependence for CNM effects atLHC energy scales.
−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)
0 5 10pT [GeV/c ]
0.0
0.5
1.0
1.5
2.0
RpP
b
LHCb1.5< y∗ < 4.0
prompt J/ψ , pPb
HELAC−Onia with EPS09LOHELAC−Onia with nCTEQ15HELAC−Onia with EPS09NLOCGCLHCb (8.16 TeV)
0 5 10pT [GeV/c ]
0.0
0.5
1.0
1.5
2.0
RpP
b
LHCb−5.0< y∗ <−2.5
prompt J/ψ , Pbp
HELAC−Onia with EPS09LOHELAC−Onia with nCTEQ15HELAC−Onia with EPS09NLOLHCb (8.16 TeV)
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PLB 774 (2017) 159
Introduction
Prompt and non-prompt J/ψ production in pPb collisions (cont.)
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 <
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 pPb
= 8.16 TeVNNs
2.5− < y3.5 < −
DataEPPS16nCTEQ15EPPS16*
ψ/JNonprompt
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
• Open beauty production (B+→ J/ψ + π+ and B+→ D0π+) also measured in pPb at 8 TeV.
• Suppression pattern consistent with non-prompt J/ψ.
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J/ψ: PLB 774 (2017) 159B: PRD 99 (2019) 052011
Introduction
Nuclear modification of ψ(2S) at 5 TeV
• LHCb measured ψ(2S)→ µ+µ− in pPb collisions at√sNN = 5 TeV.
• Measured the ratio of RpPb between ψ(2S) and J/ψ
R ≡σ
ψ(2S)pPb (5 TeV)
σJ/ψ
pPb (5 TeV)× σ
J/ψpp (7 TeV)
σψ(2S)pp (7 TeV)
to compensate for the lack of σψ(2S)pp (5 TeV) measurement.
• Results from ALICE and LHCb at forward y and PHENIX atmid-y suggest stronger suppression for inclusive and promptψ(2S).
y-4 -2 0 2 4
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6 = 5 TeVNNsLHCb,
= 5 TeVNNsALICE,
= 0.2 TeVNNsPHENIX,
= 5 TeVNNspPb LHCb
c < 14 GeV/T
p
)S(2ψInclusive
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LHCb: JHEP 1603 (2016) 133ALICE: JHEP 12 (2014) 073PHENIX: PRL 111 (2013) 202301
Introduction
Nuclear modification of ψ(2S) at 5 TeV (cont.)
y-4 -2 0 2 4
pPb
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
EPS09 LOEPS09 NLOnDSg LOE. lossE. loss + EPS09 NLO
)S(2ψLHCb, prompt
ψJ/LHCb, prompt = 5 TeVNNspPb
LHCb
c < 14 GeV/T
p
y-4 -2 0 2 4
pPb
R
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
EPS09 LOnDSg LO
b) from S(2ψLHCb, b from ψJ/LHCb,
= 5 TeVNNspPb LHCb
c < 14 GeV/T
p
• Nuclear modification factor computed from the ratio Rψ(2S)pPb = RJ/ψ
pPb ×R.
• Observe similar level of suppression at both forward and backward rapidity.
• Models with initial final state effects cannot explain the difference between the two cc states⇒ different final stateeffects.
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JHEP 1603 (2016) 133
Introduction
Υ production in pPb collisions
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− in pPb at 5 and 8 TeV.
• At 8 TeV, the three states are clearly separated in both rapidity regions.
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JHEP 11 (2018) 194
Introduction
Υ production in pPb collisions (cont.)
• Suppression of prompt Υ(1S) and Υ(2S) at forwardrapidity, backward consistent with unity.
• The 2S and 2S states show a similar suppressionpattern consistent with comover models, hint of strongersuppression at y < 0.
• Υ(3S) shows a stronger suppression at backwardrapidity than 1S.
• Stronger suppression of excited states at backwardrapidity observed both for charm and beauty.
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
(2ϒ
pp)/
pPb
|Pb
p(ℜ
=8.16 TeVNNs
c<25 GeV/T
p
LHCb LHCb
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
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JHEP 11 (2018) 194
Introduction
Υ production in pPb collisions (cont.)
• Cross section ratio of Υ(1S) over non-prompt J/ψ
measured in pp and pPb.
• Different hadronisation of close and open beauty⇒different sensitivity to final state CNM effects.
• At backward rapidity, pp and pPb consistent withinuncertainty while at forward the ratio is lower i pPb thanin pp.
Hints of different final CNM effects affecting beautyproduction at forward rapidity. 4− 2− 0 2 4
y*
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
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JHEP 11 (2018) 194
Summary
Summary
LHCb has an ever-growing heavy ion physics programme with some unique measurements.
So far LHCb measured J/ψ, ψ(2S), and Υ(nS) in pPb at 5.02 and 8.16 TeV from dimuon decay channel.
Suppression pattern of J/ψ shows no evidence of energy dependence at LHCb energies.
Separation of prompt/non-prompt J/ψ - comparison with B hadrons and Υ resuts allows to study the final CNM effects.
Measurements of charmonia and bottomonia in pPb show stronger suppression of excited states, which is reproduced inmodels with final-state effects (comovers, CGC).
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