quarkonium production in cmshim.phys.pusan.ac.kr/pds_him/him/2012/2012-02/07...2012/02/21 ·...

Quarkonium production in CMS

Hyunchul Kim 김현철 (Korea University)

For the CMS collaboration

Content •  CMS detector@LHC

•  Quarkonia physics motivation

•  Result from CMS –  Charmonia : J/ψ –  Bottomonia : ϒ

•  Summary

HIM@Pyeongchang, Korea, 2012/02/21 Hyunchul Kim (Korea University) 2

LHC (Large Hadron Collider)

3 HIM@Pyeongchang, Korea, 2012/02/21 Hyunchul Kim (Korea University)

ATLAS

CMS

ALICE

LHCb FRANCE

SWITZERLAND

ATLAS

CMS

ALICE

LHCb

Accelerate proton : 99.9999991% of speed of light From surface ~100m

LHC (Large Hadron Collider)


ATLAS

CMS

ALICE

LHCb FRANCE

SWITZERLAND

27 km in circumference

28.7m

15.0m

Total weight : 14000 t

CMS (Compact Muon Solenoid) detector


Superconducting Solenoid B=3.8T, 6m internal diameter

Inner tracker Silicon pixel(100×150 µm2, ~66M channels) Microstrips(80~180 µm, ~9.6M channels) pT resolution at barrel

≤ 1.5%, pT<100GeV/c

Muon system Tracking

Barrel : Drift Tube (DT) Endcap : Cathode Strip Chamber (CSC)

Trigger (Barrel, Endcap) Resistive Plate Chamber (RPC)

Muon reconstruction mechanism in CMS

•  With information from inner tracker and muon stations, global muons reconstructed

•  Because of the magnetic field and energy loss(2~3 GeV) in the iron yoke, Global muons need p ≥ 3~5 GeV to reach the muon stations, (depending on eta)

•  Further muon ID based on track quality (χ2, # of hits,…)


Dimuon mass plot by the CMS experiment

HIM@Pyeongchang, Korea, 2012/02/21 Hyunchul Kim (Korea University)

•  Cover from low mass to high mass region •  Good dimuon resolution thanks to the tracking •  pT > 4.0 GeV/c : to remove background around the upsilon mass region

•  At 2010, the integrated luminosity used in the HI analysis corresponds to 7.28 µb-1 for 2.76 TeV PbPb and 225 nb-1 for 2.76 TeV pp collisions

7

5

Different variables to select good quality global muons have been studied in Monte-Carlo gen-erated PbPb events. Prior to these studies, checks were made to ensure that the MC distribu-tions of the J/ψ decay muons are in good agreement with those from data. The agreement wasfound to be better than 2%, which is within the systematic uncertainty that was estimated onthe data/MC efficiency comparison (see Sec. 5.2). In order to resolve ambiguities when twomuons share the same segment in the muon stations, a requirement on the arbitration of eachmuon is made. The transverse (longitudinal) impact parameter from the measured vertex isrequired to be less than 3 (15) cm. Tracks are only kept if they have 11 hits or more in the sil-icon tracker and the χ2 per degree of freedom of the global (tracker) track fit is required to belower than 20 (4). The probability of the two tracks to belong to a common vertex is requestedto be better than 1%, removing background arising from B-meson semileptonic decays. Theseselection criteria result in a 6.6%, 5.1% 3.9% loss of the prompt J/ψ, non-prompt J/ψ and Υ(1S)MC signals respectively.

Fig. 3 shows the dimuon spectrum in PbPb collisions at 2.76 TeV, between 2 and 200 GeV/c2

with a single muon pT cut at 4 GeV/c, after applying all of the above mentioned event filtersand single-muon selection criteria.

)2 (GeV/cµµm10 210

)2E

vent

s/(G

eV/c

1

10

210

310CMS Preliminary

= 2.76 TeVNNsPbPb -1bµ = 7.28 intL

!J/(1,2,3S)"

Z

> 4.0 GeV/cµ

Tp

Figure 3: Invariant mass spectrum of µ+µ− pairs over the mass range 2.0 ≤ mµµ < 200 GeV/c2

for single muons with pT > 4.0 GeV/c. Visible are the J/ψ, Υ and Z peaks.

4 Signal Extraction4.1 J/ψ Analysis

4.1.1 Inclusive J/ψ

The J/ψ analysis follows closely the pp analysis published in Ref. [21]. The invariant mass spec-trum of µ+µ− pairs with pT < 30 GeV/c, in the region 2 ≤ mµµ < 4 GeV/c, after applying thesingle muon quality cuts, is shown in Fig. 4 as black circles for all µ+µ− pairs in |y| < 2.4. Thesame sign muon pair spectrum (µ+µ− − µ−µ−) is overlaid as red squares for the same selec-tion. The curve is an unbinned maximum log-likelihood fit with a “Crystal Ball” function [22]

Quarkonia candidate in PbPb at CMS


ϒ candidate in PbPb at √sNN = 2.76 TeV

4

µ+µ! pair:mass:" 9.46 GeV/c2

pT:" " 0.06 GeV/crapidity:"!0.33

µ+:pT" =" 4.74 GeV/c2

η" =" !0.39

µ!:pT" =" 4.70 GeV/c2

η" =" !0.28

Physics motivation of quarkonia study (1) •  Quarkonium : flavorless meson whose constituents are a

quark and its own antiquark –  Charmonium(c-cbar), Bottomonium(b-bbar)

•  Suppression of quarkonium states : Good candidates to probe the QGP in Heavy-Ion collisions –  Because of their large mass (mc~1.27 GeV, mb~4.19 GeV), heavy

quarks are produced in parton-parton collisions with large momentum transfer Q2, at the initial stage of the reaction.

–  T<Td, heavy quark pair make strongly bound resonance. –  T>Td, by Debye screening of the heavy quark binding potential no

resonance can be formed. –  Td is depend on the binding energy and radius of the resonance. –  Sequential suppression of the resonances thermometer for the

temperature reached in the HI collisions.


State Υ (1S) J/Ψ (1S) Χb’ (2P) Χc (1P) Υ (3S) Ψ’ (2S) ΔE (GeV/c2) 9.46 3.10 10.26 3.53 10.36 3.68 R0 (fm) 0.28 0.50 0.68 0.72 0.78 0.90

Physics motivation of quarkonia study (2)

•  Owing to the long lifetime of the b hadrons, compared to the QGP lifetime, non-prompt J/ψ should not suffer from color screening, but instead may reflect the b-quark energy loss in the medium.

•  Energy loss would lead to a reduction of the b-hadron yield at high pT in PbPb collisions compared to the binary-collision-scaled pp yield.


Inclusive J/ψ

Prompt J/ψ Non-Prompt J/ψ from B decays

Direct J/ψ Feed-down from ψ’ and χc

•  Prompt J/ψincludes the information of the initial state of hot-dense matter.

J/ψ in pp at √s = 7 TeV

EPIC@LHC

J/ in pp at = 7 TeV

Reconstruct µ+µ vertex Simultaneous fit of µ+µ mass and pseudo-proper decay length

Mihee Jo (Korea Univ.) 8

B Lxy

J/ µ µ+

Inclusive J/

Prompt J/

Direct J/ Feed-down from c

Non-Prompt J/ from B decays

EPJC 71:1515 (2011)

Inclusive J/ψ

Prompt J/ψ Non-Prompt J/ψ

from B decays

Direct J/ψ

Feed-down from ψ’ and χc


)2 invariant mass (GeV/c-µ +µ2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

)2Ev

ents

/ ( 0.

02 G

eV/c

200

400

600

800

1000

)2 invariant mass (GeV/c-µ +µ2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

)2Ev

ents

/ ( 0.

02 G

eV/c

200

400

600

800

1000 = 7 TeVsCMS - -1L = 37 pb

< 15 GeV/cT

12 < p0.9 < |y| < 1.2

datatotal fitbackground

= 45.5/44DoF/n2χ

-0.5 0 0.5 1 1.5 2

Even

ts / (0

.06 m

m)

-110

1

10

210

-0.5 0 0.5 1 1.5 2

Even

ts / (0

.06 m

m)

-110

1

10

210

= 7 TeVsCMS - -1L = 37 pb

datatotal fitpromptnon-promptbackground

< 15 GeV/cT

12 < p

1.6 < |y| < 2.4

(mm)(2S)ψl-0.5 0 0.5 1 1.5 2

Fit pu

ll

-4-3-2-101234

(mm)(2S)ψl-0.5 0 0.5 1 1.5 2

Fit pu

ll

-4-3-2-101234

•  Reconstruct µ+µ- vertex •  Simultaneous 2D unbinned maximum

likelihood fit of µ+µ- mass and pseudo-proper decay length (lJ/ψ)

J/ψ in pp at √s = 7 TeV


(GeV/c)T

p6 7 8 910 20 30 40 50

dy (n

b/(G

eV/c

))T

/dp

ψJ/σ2

d×B

-110

1

10

210

(GeV/c)T

p6 7 8 910 20 30 40 50

dy (n

b/(G

eV/c

))T

/dp

ψJ/σ2

d×B

-110

1

10

210

-1 = 7 TeV L = 37 pbsCMS

Luminosityuncertainty not shown

, corrected for acceptance-µ +µ →ψnon-prompt J/

625)×0.0 < |y| < 0.9 (125)×0.9 < |y| < 1.2 (25)×1.2 < |y| < 1.6 (5)×1.6 < |y| < 2.1 (1)×2.1 < |y| < 2.4 (

FONLL

(GeV/c)T

p6 7 8 910 20 30 40 50

dy (n

b/(G

eV/c

))T

/dp

ψJ/σ2

d×B

-210

-110

1

10

210

310

(GeV/c)T

p6 7 8 910 20 30 40 50

dy (n

b/(G

eV/c

))T

/dp

ψJ/σ2

d×B

-210

-110

1

10

210

310-1 = 7 TeV L = 37 pbsCMS

Luminosity and polarizationuncertainties not shown

, corrected for acceptance-µ +µ →ψprompt J/

625)×0.0 < |y| < 0.9 (125)×0.9 < |y| < 1.2 (25)×1.2 < |y| < 1.6 (5)×1.6 < |y| < 2.1 (1)×2.1 < |y| < 2.4 (

prompt NLO NRQCD

•  Prompt J/ψ well described by NRQCD •  Non-prompt J/ψ fall faster at high pT than expected from

FONLL

arXiv : 1111.1557 (accepted by JHEP)

ψ(2S) in pp at √s = 7 TeV


•  Prompt ψ(2S) well described by NRQCD •  Non-prompt ψ(2S) overestimated by FONLL

(however, large uncertainty on BR(B→ψ(2S)X) •  falls faster with pT than expected from FONLL

(GeV/c)T

p6 7 8 9 10 20 30

dy (n

b/(G

eV/c

))T

/dp

(2S)

ψσ2

d×B

-310

-210

-110

1

(GeV/c)T

p6 7 8 9 10 20 30

dy (n

b/(G

eV/c

))T

/dp

(2S)

ψσ2

d×B

-310

-210

-110

1

-1 = 7 TeV L = 37 pbsCMS

Luminosityuncertainty not shown

, corrected for acceptance-µ +µ →(2S)ψnon-prompt

25)×0.0 < |y| < 1.2 (5)×1.2 < |y| < 1.6 (1)×1.6 < |y| < 2.4 (

FONLL

(GeV/c)T

p6 7 8 9 10 20 30

dy (n

b/(G

eV/c

))T

/dp

(2S)

ψσ2

d×B

-310

-210

-110

1

10

(GeV/c)T

p6 7 8 9 10 20 30

dy (n

b/(G

eV/c

))T

/dp

(2S)

ψσ2

d×B

-310

-210

-110

1

10 -1 = 7 TeV L = 37 pbsCMS

Luminosity and polarizationuncertainties not shown

, corrected for acceptance-µ +µ →(2S)ψprompt

25)×0.0 < |y| < 1.2 (5)×1.2 < |y| < 1.6 (1)×1.6 < |y| < 2.4 (

prompt NLO NRQCD

arXiv : 1111.1557 (accepted by JHEP)

J/ψ in PbPb at √sNN = 2.76 TeV

•  Same mechanism used as in pp •  For the first time, prompt and non-prompt J/ψ have been separated

in heavy-ion collisions


8 4 Signal Extraction

point back to the primary vertex within six times the primary vertex resolution. This reducesthe reconstruction efficiency for J/ψ with large values of �J/ψ, i.e. it causes a difference in theprompt and non-prompt J/ψ reconstruction efficiencies that increases with the J/ψ meson pT.

The prompt J/ψ result is presented (in Section 7.1) in the centrality bins 0–10%, 10–20%, 20–30%,30–40%, 40–50%, and 50–100%, while the non-prompt J/ψ result, given the smaller sample,is presented (in Section 7.2) in only two centrality bins, 0–20% and 20–100%. Examples ofmµ+µ− and �J/ψ distributions are shown in Fig. 4. The two-dimensional fit results are shownas projections onto the mass and �J/ψ axes. Integrated over centrality, the numbers of promptand non-prompt J/ψ mesons with |y| < 2.4 and 6.5 < pT < 30 GeV/c are 307 ± 22 and 90 ± 13,respectively.

)2 (GeV/cµµm2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

)2Ev

ents

/ ( 0

.02

GeV

/c

0

20

40

60

80

100

120 = 2.76 TeVNNsCMS PbPb -1bµ = 7.28 intL

Cent. 0-100%, |y| < 2.4 < 30 GeV/c

T6.5 < p 2 = 34 MeV/c!

datatotal fitbkgd + non-promptbackground

(mm)!J/l-1 -0.5 0 0.5 1 1.5 2

Even

ts /

(0.0

88 m

m)

1

10

210

310

= 2.76 TeVNNsCMS PbPb -1bµ = 7.28 intL Cent. 0-100%, |y| < 2.4

< 30 GeV/cT

6.5 < p


)2 (GeV/cµµm2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

)2Ev

ents

/ ( 0

.02

GeV

/c

0

5

10

15

20

25

30

35


Cent. 0-10%, |y| < 2.4 < 30 GeV/c

T6.5 < p 2 = 34 MeV/c!


(mm)!J/l-1 -0.5 0 0.5 1 1.5 2

Even

ts /

(0.0

88 m

m)

1

10

210

310 = 2.76 TeVNNsCMS PbPb -1bµ = 7.28 intL Cent. 0-10%, |y| < 2.4

< 30 GeV/cT

6.5 < p


Figure 4: Invariant-mass spectra (left) and pseudo-proper decay length distributions (right) ofµ+µ− pairs integrated over centrality (top) and for the 0–10% centrality bin (bottom). The spec-tra are integrated over the rapidity range |y| < 2.4 and the pT range 6.5 < pT < 30 GeV/c. Theprojections of the two-dimensional fit onto the respective axes are overlaid as solid black lines.The dashed red lines show the fitted contribution of non-prompt J/ψ. The fitted backgroundcontributions are shown as dotted blue lines.

In order to determine the systematic uncertainty on the yield extraction, the signal and back-

8 4 Signal Extraction

point back to the primary vertex within six times the primary vertex resolution. This reducesthe reconstruction efficiency for J/ψ with large values of �J/ψ, i.e. it causes a difference in theprompt and non-prompt J/ψ reconstruction efficiencies that increases with the J/ψ meson pT.

The prompt J/ψ result is presented (in Section 7.1) in the centrality bins 0–10%, 10–20%, 20–30%,30–40%, 40–50%, and 50–100%, while the non-prompt J/ψ result, given the smaller sample,is presented (in Section 7.2) in only two centrality bins, 0–20% and 20–100%. Examples ofmµ+µ− and �J/ψ distributions are shown in Fig. 4. The two-dimensional fit results are shownas projections onto the mass and �J/ψ axes. Integrated over centrality, the numbers of promptand non-prompt J/ψ mesons with |y| < 2.4 and 6.5 < pT < 30 GeV/c are 307 ± 22 and 90 ± 13,respectively.

)2 (GeV/cµµm2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

)2Ev

ents

/ ( 0

.02

GeV

/c

0

20

40

60

80

100


Cent. 0-100%, |y| < 2.4 < 30 GeV/c

T6.5 < p 2 = 34 MeV/c!


(mm)!J/l-1 -0.5 0 0.5 1 1.5 2

Even

ts /

(0.0

88 m

m)

1

10

210

310

= 2.76 TeVNNsCMS PbPb -1bµ = 7.28 intL Cent. 0-100%, |y| < 2.4

< 30 GeV/cT

6.5 < p


)2 (GeV/cµµm2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

)2Ev

ents

/ ( 0

.02

GeV

/c

0

5

10

15

20

25

30

35


Cent. 0-10%, |y| < 2.4 < 30 GeV/c

T6.5 < p 2 = 34 MeV/c!


(mm)!J/l-1 -0.5 0 0.5 1 1.5 2

Even

ts /

(0.0

88 m

m)

1

10

210

310 = 2.76 TeVNNsCMS PbPb -1bµ = 7.28 intL Cent. 0-10%, |y| < 2.4

< 30 GeV/cT

6.5 < p


Figure 4: Invariant-mass spectra (left) and pseudo-proper decay length distributions (right) ofµ+µ− pairs integrated over centrality (top) and for the 0–10% centrality bin (bottom). The spec-tra are integrated over the rapidity range |y| < 2.4 and the pT range 6.5 < pT < 30 GeV/c. Theprojections of the two-dimensional fit onto the respective axes are overlaid as solid black lines.The dashed red lines show the fitted contribution of non-prompt J/ψ. The fitted backgroundcontributions are shown as dotted blue lines.

In order to determine the systematic uncertainty on the yield extraction, the signal and back-

arXiv : 1201.5069 (submitted by JHEP)

Prompt J/ψ RAA vs pT, y

EPIC@LHC

Prompt J/ RAA vs. pT and y : Comparison

CMS pTJ/ > 6.5 GeV/c

STAR pTJ/ < 8 GeV/c , PHENIX lower pT


High pT J/RHIC (and SPS) is not seen at the LHC CMS shows opposite trend than PHENIX but different pT

Increasing RAA going towards ALICE y range

Watch out for anti-shadowing

ALICE low pTJ/

RAA = 0.49±0.03±0.11 pT=0 up to x1~0.06(x2~2.10-5)

CMS pT > 3 GeV/c RAA = 0.39±0.06±0.03 pT=10 up to x1~0.02(x2~5.10-4)


•  RHIC : lower pT, but RAA increase with pT

•  CMS : factor 3 suppression for pT > 6.5 GeV/c almost no pT dependence

(do not seem to be observed by RHIC)

•  PHENIX : stronger suppression in forward range

•  CMS : less suppression in forward range

•  Increasing RAA going towards ALICE y range

15

Prompt J/ψ RAA vs. pT and y

• CMS: pT > 6.5 GeV/c

‣ Factor 3 suppression for pT > 6.5 GeV/c and at y = 0

‣ Trend to less suppression at forward rapidity

• STAR: no suppression at high pT

• PHENIX: lower pT

‣ opposite rapidity dependence

• ALICE: inclusive J/!, pT > 0 GeV/c, 0–80%

‣ RAA = 0.49 ± 0.03 ± 0.11 (Pillot, QM2011)

• Careful when comparing RAA of prompt J/! (CMS) and inclusive J/! (ALICE)

‣ In pp at low pT: !10% b-fraction

‣ From RHIC we know that open charm cross section is unmodified(can assume the same for open bottom)

‣ non-prompt J/! could shift RAA by 10% 14

RAA =Lpp

TAANMB

NPbPb(J/ψ)Npp(J/ψ)

εpp

εPbPb(cent)

y-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

!Prompt J/

= 200 GeVNNsAuAu PHENIX: |y|<0.35PHENIX: 1.2<|y|<2.2(both PRL 98, 232301 (2007))

CMS Preliminary = 2.76 TeVNNsPbPb

0-100% < 30.0 GeV/c

T6.5 < p

CMS-HIN-10-006arXiv:1201.5069

(submitted to JHEP)

y-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4 = 2.76 TeVNNsPbPb !CMS: prompt J/

Cent. 0-100% < 30 GeV/c

T6.5 < p

= 200 GeVNNsAuAu (|y|<0.35)!PHENIX: J/ (1.2<|y|<2.2)!PHENIX: J/

(both PRL 98 (2007) 232301)

(GeV/c)T

p0 5 10 15 20 25 30

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4


(both PRL 98 (2007) 232301) (preliminary)!STAR: J/

Cent. 0-60%, |y|<1.0

= 2.76 TeVNNsPbPb !CMS: prompt J/

Cent. 0-100%, |y| < 2.4

Prompt J/ψ RAA vs. pT and y

• CMS: pT > 6.5 GeV/c

‣ Factor 3 suppression for pT > 6.5 GeV/c and at y = 0

‣ Trend to less suppression at forward rapidity

• STAR: no suppression at high pT

• PHENIX: lower pT

‣ opposite rapidity dependence

• ALICE: inclusive J/!, pT > 0 GeV/c, 0–80%

‣ RAA = 0.49 ± 0.03 ± 0.11 (Pillot, QM2011)

• Careful when comparing RAA of prompt J/! (CMS) and inclusive J/! (ALICE)

‣ In pp at low pT: !10% b-fraction

‣ From RHIC we know that open charm cross section is unmodified(can assume the same for open bottom)

‣ non-prompt J/! could shift RAA by 10% 14

RAA =Lpp

TAANMB

NPbPb(J/ψ)Npp(J/ψ)

εpp

εPbPb(cent)

y-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

!Prompt J/

= 200 GeVNNsAuAu PHENIX: |y|<0.35PHENIX: 1.2<|y|<2.2(both PRL 98, 232301 (2007))

CMS Preliminary = 2.76 TeVNNsPbPb

0-100% < 30.0 GeV/c

T6.5 < p

CMS-HIN-10-006arXiv:1201.5069

(submitted to JHEP)

y-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4 = 2.76 TeVNNsPbPb !CMS: prompt J/

Cent. 0-100% < 30 GeV/c

T6.5 < p


(both PRL 98 (2007) 232301)

(GeV/c)T

p0 5 10 15 20 25 30

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4


(both PRL 98 (2007) 232301) (preliminary)!STAR: J/

Cent. 0-60%, |y|<1.0


Cent. 0-100%, |y| < 2.4


Prompt J/ψ RAA vs Npart

•  0~10% : suppressed by factor 5 with respect to pp

•  50~100% : suppressed by factor 1.6 remains

•  Similar suppression seen at PHENIX though CMS is high pT while PHENIX is low pT

HIM@Pyeongchang, Korea, 2012/02/21 Hyunchul Kim (Korea University) EPIC@LHC








ALICE low pTJ/

RAA = 0.49±0.03±0.11 pT=0 up to x1~0.06(x2~2.10-5)


16

Prompt J/ψ RAA vs. centrality

• Prompt J/!:

‣ 0-10% suppressed by factor 5with respect to pp

‣ 50-100% suppressed by factor ~1.6

• Similar suppression seen by PHENIX

‣ though at lower pT

15

partN0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4


(both PRC 84 (2011) 054912)


|y| < 2.4 < 30 GeV/c

T6.5 < p

CMS-HIN-10-006arXiv:1201.5069

(submitted to JHEP)


Prompt J/ψ RAA vs. centrality

• Prompt J/!:

‣ 0-10% suppressed by factor 5with respect to pp

‣ 50-100% suppressed by factor ~1.6

• Similar suppression seen by PHENIX

‣ though at lower pT

• STAR measures less suppression at high pT

16

partN0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

= 200 GeVNNsAuAu (preliminary)!STAR: J/

> 5 GeV/c, |y|<1.0T

p


|y| < 2.4 < 30 GeV/c

T6.5 < p

CMS-HIN-10-006arXiv:1201.5069

(submitted to JHEP)

Prompt J/ψ RAA vs Npart

•  0~10% : suppressed by factor 5 with respect to pp

•  50~100% : suppressed by factor 1.6 remains

•  Similar suppression seen at PHENIX though CMS is high pT while PHENIX is low pT

•  STAR measured less suppression at high pT

HIM@Pyeongchang, Korea, 2012/02/21 Hyunchul Kim (Korea University) EPIC@LHC








ALICE low pTJ/

RAA = 0.49±0.03±0.11 pT=0 up to x1~0.06(x2~2.10-5)


17 arXiv : 1201.5069 (submitted by JHEP)

Non-prompt J/ψ RAA

•  Suppression of non-prompt J/ψ observed in minimum bias and central PbPb collisions, no centrality dependence

•  First indications of high-pT b-quark quenching like light quarks


partN0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

!Prompt J/!Non-prompt J/

= 2.76 TeVNNsCMS PbPb

|y| < 2.4 < 30 GeV/c

T6.5 < p

0-20%20-100%

Open heavy-flavour: Non-Prompt J/ψ RAA

• Suppression of non-prompt J/! observed in min. bias and central PbPb collisions

‣ First indications of high-pT b-quark quenching!

19

CMS-HIN-10-006arXiv:1201.5069

(submitted to JHEP)

partN0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4



|y| < 2.4 < 30 GeV/c

T6.5 < p

0-20%20-100%

Open heavy-flavour: Non-Prompt J/ψ RAA

• Suppression of non-prompt J/! observed in min. bias and central PbPb collisions

‣ First indications of high-pT b-quark quenching!

19

CMS-HIN-10-006arXiv:1201.5069

(submitted to JHEP)arXiv : 1201.5069 (submitted by JHEP)

b fraction compared with earlier results


20 7 Results

(GeV/c)T

p0 5 10 15 20 25 30

b fra

ctio

n

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 = 2.76 TeV (|y|<2.4)NNsCMS PbPb = 2.76 TeV (1.6<|y|<2.4)NNsCMS PbPb

= 2.76 TeV (|y|<2.4)sCMS pp = 2.76 TeV (1.6<|y|<2.4)sCMS pp = 7 TeV (1.6 < |y| < 2.4)sCMS pp = 7 TeV (1.2 < |y| < 1.6)sCMS pp = 7 TeV (|y| < 1.2)sCMS pp = 1.96 TeV (|y|<0.6)s pCDF p

Figure 13: b fraction of J/ψ production in pp and PbPb collisions at √sNN = 2.76 TeV as afunction of pT for the rapidity bins |y| < 2.4 and 1.6 < |y| < 2.4, compared to b fractionsmeasured by CDF in pp collisions at

√s = 1.96 TeV [41] and by CMS in pp collisions at

√s =

7 TeV [26]. Points are plotted at their measured average pT. Statistical (systematic) uncertaintiesare shown as bars (boxes).

partN0 50 100 150 200 250 300 350 400

/dy

(nb)

! d

N/d

y o

r d

AA1/

T

0

0.5

1

1.5

2

2.5 (PbPb)"Non-prompt J/ (pp)

= 2.76 TeVNNsCMS pp & PbPb

|y| < 2.4 < 30 GeV/c

T6.5 < p

0-20%20-100%

partN0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

!Non-prompt J/


|y| < 2.4 < 30 GeV/c

T6.5 < p

0-20%20-100%

Figure 14: Left: non-prompt J/ψ yield divided by TAA (orange stars) as a function of Npartcompared to the non-prompt J/ψ cross section measured in pp (black cross). Right: nuclearmodification factor RAA of non-prompt J/ψ as a function of Npart. A global uncertainty of 6%,from the integrated luminosity of the pp data sample, is shown as a grey box at RAA = 1.Statistical (systematic) uncertainties are shown as bars (boxes).

•  Good agreement within uncertainties, between the earlier results at other collision energies and the present measurements.


ϒ(nS) in pp at √s = 7 TeV ϒ(nS) in pp at √s = 7 TeV

• Separation of the 3 ! states with good mass resolution

• PYTHIA agrees in shape, but not in normalization

‣ Total cross section overestimated by about a factor 2

)2 mass (GeV/c-µ+µ8 8.5 9 9.5 10 10.5 11 11.5 12

)2Ev

ents

/ ( 0

.07

GeV

/c

0

2000

4000

6000

8000

10000

)2 mass (GeV/c-µ+µ8 8.5 9 9.5 10 10.5 11 11.5 12

)2Ev

ents

/ ( 0

.07

GeV

/c

0

2000

4000

6000

8000

10000 = 7 TeVsCMS Preliminary, -1 = 40 pbintL

| < 1µ!|2 = 67 MeV/c"

17

(GeV/c)YT

p0 5 10 15 20 25 30

) (n

b/(G

eV/c

))µµ

BR

(!

dy

T/d

p"2 d

-310

-210

-110

1

CMS data

PYTHIA (normalized)

|<2#|y

(1S)#

-1 = 7 TeV, L = 3 pbs

Phys. Rev. D 83 (2011) 112004

ϒ(nS) in pp at √s = 7 TeV

• Separation of the 3 ! states with good mass resolution

• PYTHIA agrees in shape, but not in normalization

‣ Total cross section overestimated by about a factor 2

)2 mass (GeV/c-µ+µ8 8.5 9 9.5 10 10.5 11 11.5 12

)2Ev

ents

/ ( 0

.07

GeV

/c

0

2000

4000

6000

8000

10000

)2 mass (GeV/c-µ+µ8 8.5 9 9.5 10 10.5 11 11.5 12

)2Ev

ents

/ ( 0

.07

GeV

/c

0

2000

4000

6000

8000

10000 = 7 TeVsCMS Preliminary, -1 = 40 pbintL

| < 1µ!|2 = 67 MeV/c"

17

(GeV/c)YT

p0 5 10 15 20 25 30

) (n

b/(G

eV/c

))µµ

BR

(!

dy

T/d

p"2 d

-310

-210

-110

1

CMS data

PYTHIA (normalized)

|<2#|y

(1S)#

-1 = 7 TeV, L = 3 pbs

Phys. Rev. D 83 (2011) 112004

1S

2S

3S

•  Separation of the 3 ϒ states with good mass resolution •  The normalized pT-spectrum prediction from PYTHIA is consistent with

the measurements


ϒ(nS) in PbPb at √sNN = 2.76 TeV ϒ(nS) in PbPb at √sNN = 2.76 TeV• Signal extraction

‣ Resolution fixed from MC

‣ Peak separation fixed to PDG

• Efficiencies from Monte Carlo

‣ Same method and validation process as J/!

• Acceptance to pT = 0 GeV/c

)2 (GeV/cµµm7 8 9 10 11 12 13 14

)2Ev

ents

/ ( 0

.14

GeV

/c

0

10

20

30

40

50

60CMS Preliminary

= 2.76 TeVNNsPbPb 0-100%, 0.0 < |y| < 2.4

< 20 GeV/cT

0 < p-1bµ = 7.28 intL

> 4 GeV/cµ

Tp

(fixed to MC)2 = 92 MeV/c!

datafit

25 (GeV/c)T

p0 5 10 15 20 25 30

Effic

ienc

y

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

(1S)!

CMS Simulation = 2.76 TeVNNsPbPb

PYTHIA+EvtGen+HYDJET(Bass)

•  Extended unbinned maximum likelihood fit

•  Signal •  Resolution fixed from MC

simulation •  Peak separation fixed to

PDG •  Background

•  Second order polynomial •  Obvious Upsilon(1S)



ϒ(2S+3S) Suppression

• Measure !(2S+3S) production relative to !(1S) production

• Simultaneous fit to pp and PbPb data at 2.76 TeV

• Probability to obtain measured value, or lower, if the real double ratio is unity, has been calculated to be less than 1% 20

PRL 107 (2011) 052302Υ (2S + 3S)/Υ (1S)|PbPb

Υ (2S + 3S)/Υ (1S)|pp= 0.31+0.19

−0.15 ± 0.03

)2 (GeV/cµµm7 8 9 10 11 12 13 14

)2Ev

ents

/ ( 0

.14

GeV

/c

0

10

20

30

40

50

60

70

80 = 2.76 TeVsCMS pp |y| < 2.4

< 20 GeV/cT

0 < p-1 = 231 nbintL > 4 GeV/cµ

Tp


datafit

NΥ (1S) = 101± 12

Υ (2S + 3S)/Υ (1S)|pp = 0.78+0.16−0.14 ± 0.02 Υ (2S + 3S)/Υ (1S)|PbPb = 0.24+0.13

−0.12 ± 0.02

)2 (GeV/cµµm7 8 9 10 11 12 13 14

)2Ev

ents

/ ( 0

.14

GeV

/c

0

10

20

30

40

50

60 = 2.76 TeVNNsCMS PbPb

Cent. 0-100%, |y| < 2.4 < 20 GeV/c

T0 < p

-1bµ = 7.28 intL > 4 GeV/cµ

Tp


dataPbPb fitpp shape

NΥ (1S) = 86± 12

ϒ(2S+3S) Suppression

• Measure !(2S+3S) production relative to !(1S) production

• Simultaneous fit to pp and PbPb data at 2.76 TeV

• Probability to obtain measured value, or lower, if the real double ratio is unity, has been calculated to be less than 1% 20

PRL 107 (2011) 052302Υ (2S + 3S)/Υ (1S)|PbPb

Υ (2S + 3S)/Υ (1S)|pp= 0.31+0.19

−0.15 ± 0.03

)2 (GeV/cµµm7 8 9 10 11 12 13 14

)2Ev

ents

/ ( 0

.14

GeV

/c

0

10

20

30

40

50

60

70

80 = 2.76 TeVsCMS pp |y| < 2.4

< 20 GeV/cT

0 < p-1 = 231 nbintL > 4 GeV/cµ

Tp


datafit

NΥ (1S) = 101± 12

Υ (2S + 3S)/Υ (1S)|pp = 0.78+0.16−0.14 ± 0.02 Υ (2S + 3S)/Υ (1S)|PbPb = 0.24+0.13

−0.12 ± 0.02

)2 (GeV/cµµm7 8 9 10 11 12 13 14

)2Ev

ents

/ ( 0

.14

GeV

/c

0

10

20

30

40

50

60 = 2.76 TeVNNsCMS PbPb

Cent. 0-100%, |y| < 2.4 < 20 GeV/c

T0 < p

-1bµ = 7.28 intL > 4 GeV/cµ

Tp


dataPbPb fitpp shape

NΥ (1S) = 86± 12

ϒ(2S+3S)/ϒ(1S) suppression

•  Measure ϒ(2S+3S) production relative to ϒ(1S) production •  Simultaneous fit to pp and PbPb data at 2.76 TeV

EPIC@LHC

(2S+3S) suppression (2S+3S) production relative to (1S) in pp and PbPb

Simultaneous fit to PbPb and pp data at 2.76 TeV


arXiv: 1105.4894 Accepted by PRL


arXiv : 1105.4894 PRL 107 (2011) 052302

22

21

conclusions on any pT or rapidity dependence. The Υ(1S) yield in PbPb collisions divided

by TAA and the Υ(1S) RAA are presented as a function of Npart in the left and right panels of

Fig. 17, respectively. Within uncertainties, no centrality dependence of the Υ(1S) suppression

is observed.

(GeV/c)T

p0 2 4 6 8 10 12 14 16 18 20

(nb

c/G

eV)

T/d

ydp

!2 o

r d

TN

/dyd

p2

dAA

1/T

-210

-110

(1S) (PbPb)" (pp)


Cent. 0-100%|y| < 2.4Cent. 0-100%|y| < 2.4

(GeV/c)T

p0 2 4 6 8 10 12 14 16 18 20

AAR

0

0.5

1

1.5

2

2.5

(1S)!


Cent. 0-100%|y| < 2.4

Figure 15: Left: Υ(1S) yield divided by TAA in PbPb collisions (green diamonds) as a function

of pT. The result is compared to the cross section measured in pp collisions (black crosses). The

global scale uncertainties on the PbPb data due to TAA (5.7%) and the pp integrated luminosity

(6.0%) are not shown. Right: nuclear modification factor RAA of Υ(1S) as a function of pT. A

global uncertainty of 8.3%, from TAA and the integrated luminosity of the pp data sample, is

shown as a grey box at RAA = 1. Points are plotted at their measured average pT. Statistical

(systematic) uncertainties are shown as bars (boxes). Horizontal bars indicate the bin width.

8 DiscussionThis paper has presented the first measurements of the prompt and non-prompt J/ψ, as well

as the Υ(1S) mesons, via their decays into µ+µ−pairs in PbPb and pp collisions at

√sNN

=

2.76 TeV. The results are based on data recorded with the CMS detector from the first LHC

PbPb run in 2010, and from a pp run during March 2011 at√

s = 2.76 TeV.

The prompt J/ψ cross section shows a factor of two suppression in central PbPb collisions with

respect to peripheral collisions for J/ψ with 6.5 < pT < 30 GeV/c. With respect to pp, a nuclear

modification factor of RAA = 0.20 ± 0.03 (stat.) ± 0.01 (syst.) has been measured in the 10%

most central collisions. Prompt J/ψ produced in peripheral collisions are already suppressed

with respect to pp: RAA = 0.61 ± 0.12 (stat.)± 0.10 (syst.) in the 50–100% centrality bin. While

no pT dependence is observed in the measured pT range, within uncertainties, less suppression

is observed at forward rapidity (RAA = 0.43 ± 0.06 (stat.)± 0.01 (syst.)) than at mid-rapidity

(RAA = 0.29 ± 0.04 (stat.)± 0.02 (syst.)).

A comparison of the RAA centrality dependence to results measured for pT < 5 GeV/c by

PHENIX [21] in AuAu collisions at√s

NN= 200 GeV shows a similar suppression, despite the

different collision energies and kinematic ranges. Integrated over centrality, CMS has mea-

sured an inclusive J/ψ nuclear modification factor of RAA = 0.41 ± 0.05 (stat.)± 0.02 (syst.) in

the most forward rapidity bin (1.6 < |y| < 2.4) in the pT range 3 < pT < 30 GeV/c.

22 8 Discussion

|y|0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4

/dy

(nb)

! d

N/d

y o

r d

AA1/

T

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

(1S) (PbPb)" (pp)


Cent. 0-100% < 20 GeV/cT

0 < p

|y|0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

(1S)!


Cent. 0-100% < 20 GeV/c

T0 < p

Figure 16: Left: Υ(1S) yield divided by TAA in PbPb collisions (green diamonds) as a function

of rapidity. The result is compared to the cross section measured in pp collisions (black crosses).

The global scale uncertainties on the PbPb data due to TAA (5.7%) and the pp integrated lumi-

nosity (6.0%) are not shown. Right: nuclear modification factor RAA of Υ(1S) as a function of

rapidity. A global uncertainty of 8.3%, from TAA and the integrated luminosity of the pp data

sample, is shown as a grey box at RAA = 1. Points are plotted at their measured average |y|.Statistical (systematic) uncertainties are shown as bars (boxes). Horizontal bars indicate the bin

width.

partN0 50 100 150 200 250 300 350 400

/dy

(pb)

! d

N/d

y o

r d

AA1/

T

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

(1S) (PbPb)" (pp)


|y| < 2.4 < 20 GeV/c

T0 < p

0-10%10-20%20-100%

partN0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

(1S)!


|y| < 2.4 < 20 GeV/c

T0 < p

0-10%

10-20%

20-100%

Figure 17: Left: Υ(1S) yield divided by TAA (green diamonds) as a function of Npart compared

to the Υ(1S) cross section measured in pp (black cross). Right: nuclear modification factor RAAof Υ(1S) as a function of Npart. A global uncertainty of 6%, from the integrated luminosity of

the pp data sample, is shown as a grey box at RAA = 1. Statistical (systematic) uncertainties

are shown as bars (boxes).

ϒ(1S) RAA vs pT, y and Npart

•  Are ϒ(1S) suppressed at high pT? •  No obvious rapidity dependence within the large statistical uncertainties

•  In CMS, ϒ(1S) suppressed by factor ~2.3 in 0~10%

•  STAR measures RAA of ϒ(1S+2S+3S) = 0.56 •  for CMS (0~100%) calculated RAA of ϒ(1S+2S+3S) = 0.43


(GeV/c)T

p0 2 4 6 8 10 12 14 16 18 20

AAR

0

0.5

1

1.5

2

2.5

(1S)!


Cent. 0-100%|y| < 2.4

|y|0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4

(1S)!


Cent. 0-100% < 20 GeV/c

T0 < p

partN0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4 = 2.76 TeVNNsPbPb (1S)!CMS:

|y|<2.4 < 20 GeV/c

T0.0 < p

= 200 GeVNNsAuAu (1S+2S+3S)!STAR:

|y|<0.5 (preliminary)

ϒ(1S) RAA

• !(1S) suppressed at low pT

• No obvious rapidity dependence

• CMS: !(1S)

‣ suppressed by factor ~2.2 in 0–10%

• STAR measures

‣ for CMS (0–100%):

22

RAA(Υ (1S + 2S + 3S)) = RAA(Υ (1S))×1 + Υ (2S + 3S)/Υ (1S)|PbPb

1 + Υ (2S + 3S)/Υ (1S)|pp

= 0.62× 1 + 0.24

1 + 0.78≈ 0.43

(arXiv:1109.3891)RAA(Υ (1S + 2S + 3S)) = 0.56± 0.21+0.08−0.16

CMS-HIN-10-006arXiv:1201.5069

(submitted to JHEP)


Summary of the results

•  prompt J/ψ and J/ψ from B decays suppressed

•  ϒ(1S) and ϒ(2S+3S) with respect to ϒ(1S) are suppressed

HIM@Pyeongchang, Korea, 2012/02/21 Hyunchul Kim (Korea University) 24 partN

0 50 100 150 200 250 300 350 400

AAR

0

0.2

0.4

0.6

0.8

1

1.2

1.4


(1S)"


|y| < 2.4 < 30 GeV/c!J/

T6.5 < p < 20 GeV/c"

T0 < p

0-20%20-100%

SummaryIn PbPb collisions at !sNN = 2.76 TeV

• Prompt J/! suppressed

• !(2S+3S) suppressed relative to !(1S)

‣ Observed !(1S) suppression consistent with melting of excited states only

• J/! from B decays suppressed

In pp collisions at !s = 7 TeV

• Differential cross sections described by models within theoretical and experimental uncertainties

24

In pp collisions at √s = 7 TeV,

In PbPb collisions at √sNN = 2.76 TeV,

•  prompt J/ψ and ϒ(1S) is well described by models within uncertainties

•  J/ψ from B decays is overestimated by FONLL model


CMS HI group is analyzing with 2011 HI data now !

Expect new excited result !


quarkonium production in cmshim.phys.pusan.ac.kr/pds_him/him/2012/2012-02/07...2012/02/21 ·...

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