D Meson Production in Heavy Ion Collisions in CMS experiment · Jing Wang (MIT), D0 meson production in HI collisions in CMS, SQM 2016 (Berkeley) 1 D0 Meson Production in Heavy Ion

Jing Wang (MIT), D0 meson production in HI collisions in CMS, SQM 2016 (Berkeley) 1

D0 Meson Production in Heavy Ion Collisions in CMS experiment

Jing Wang on behalf of the CMS Collaboration

The 16th International Conference on Strangeness in Quark Matter 27 June - 1 July 2016

Berkeley (United States)

Jing Wang (MIT), D0 meson production in HI collisions in CMS, SQM 2016 (Berkeley)

• Two energy loss mechanisms: Collisional + Radiative• Flavor-dependent

• Dead cone effect [1] (Radiative energy loss is suppressed at small angels)

• Expect: ΔElight > ΔEc > ΔEb

• Nuclear modification factor: • RlightAA < RDAA < RBAA

• Dead cone effect is expected to be important at low pT

2

Why studying heavy flavors in HI?Heavy quarks are produced via initial hard scatterings• Carry information about the system at early stage → Good probe of QGP

In-medium energy lossthe probe heavy quarks interact with the medium

?

[1] Y.L. Dokshitzer, D. E. Kharzeev, Phys. Lett. B 519 (2001) 199.


(GeV/c)T

p0 5 10 15 20 25 30 35 40

AA ,

RAA

R*

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

, CMS PreliminaryAA R*0Prompt D|y| < 1.0, Cent. 0-20%Syst. PbPb dataErr. pp reference

(JHEP 09 (2012) 112), Alice AA R0Prompt D|y| < 0.5, Cent. 0-20%Syst.

Filled markers: data-extrapolated referenceOpen markers: FONLL reference

= 2.76 TeVNNsPbPb

3

D0 measurements with CMS in Run IPbPb @ 2.76 TeV

CMS-PAS-HIN-15-005

• Dataset: MB events• pT: 2-40 GeV/c• pp reference: data-extrapolated

and FONLL

Run II 5.02 TeV• pT: 2-100 GeV/c• pp reference: direct data

Measurements reaching very high pT for the first time!


D0 meson production at 5.02 TeV

CMS-PAS-HIN-16-001First Run II heavy flavor analysis


D0 meson production

• c→D0: O(50%) of c cross-section• D0→Kπ: 3.93 ± 0.04%• D0 cτ = 122.9 µm D0

Primary vertex

Secondary vertex

Kπ

D0


D0 measurements in pp and PbPbD0→Kπ in pp and PbPb collisions at 5.02TeV, Centrality 0-10% and 0-100%, |y|<1

Datasets• Low pT ( < 20 GeV/c)

MinBias Events (pp: 2 billions events; PbPb: 150 million events)• High pT ( > 20 GeV/c)

Events triggered by dedicated HLT D0 filters to enhance the statistics at very high pT

(GeV/c)T

p0D10 20 30 40 50 60 70 80 90 100

HLT

D m

eson

trig

ger e

ffici

ency

0

0.2

0.4

0.6

0.8

1

1.2

1.4

> 20T

trigger p0D> 40

T trigger p0D

> 60T

trigger p0D

(5.02 TeV PbPb)-1

bµ404 CMSPerformance

) (GeV)0 (DT

p0 10 20 30 40 50 60

HLT

Effi

cien

cy

0

0.2

0.4

0.6

0.8

1

1.2

1.4

8≥ T

HLT D meson p15≥

THLT D meson p

20≥ T

HLT D meson p 30≥

THLT D meson p

= 5.02 TeV s pp,

CMSPreliminary


High-Level-Trigger (HLT) D0 triggers

Hardware L1 jet triggers selection

Track selection in software triggers D0 selection

K

π

D0 decayvertex

Primaryvertex

• Level-1 (L1) jet algorithm with online background subtraction

Track seed pT cut applied:• pT > 2 GeV for pp • pT > 8 GeV for PbPb

• D0 online reconstruction• loose selection based on

D0 vertex displacement



Hardware L1 jet triggers selection

Track selection in software triggers D0 selection

K

π

D0 decayvertex

Primaryvertex

• Level-1 (L1) jet algorithm with online background subtraction

Track seed pT cut applied:• pT > 2 GeV for pp • pT > 8 GeV for PbPb

• D0 online reconstruction• loose selection based on

D0 vertex displacement)2 (GeV/cKπm

1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

10

20

30

40

50DataFit

Signal0D+0D swappedπK-

Combinatorial

PreliminaryCMS = 5.02 TeVNNspp

< 200.0 GeV/cT

100.0 < p|y| < 1.0

• 5.02 TeV pp collisions• Extend to D0 high pT to 200

GeV/c


D0 measurements in pp and PbPbD0→Kπ in pp and PbPb collisions at 5.02TeV, Centrality 0-10% and 0-100%, |y|<1

Analysis strategy• Primary vertex reconstruction several tracks• D0 candidates (vertex) reconstruction pairing two tracks + kinematic fitter• D0 candidates selection (TMVA) decay topology

• Pointing angel (α) < ~0.12• 3D decay length (d0) normalized by its error > ~4• Secondary vertex probability > ~0.1

• Raw yields extraction Invariant mass• Cross-sections

Primaryvertex

Secondaryvertex

d0

pD α


Invariant mass spectra in pp (5.02 TeV)Raw yields extraction

Mass distributions fitted by• Double gaussian (Signal)• 3rd order polynomial (Combinatorial)• Single gaussian (K-π swapped)

No PIDCandidates with wrong mass assignment

)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

500

1000

1500

2000

2500

3000DataFit


Combinatorial


< 6.0 GeV/cT

5.0 < p|y| < 1.0

Fix in MC


Obtain cross-section from raw yieldsRaw yields → Cross-sections

Prompt D0 Cross-section Raw yields



Acceptance & efficiency

Trigger efficiency

(GeV/c)T

p0 20 40 60 80 100

sel

∈ x

re

co∈

x

α

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 PreliminaryCMS = 5.02 TeVNNspp

PromptNon-prompt

(GeV/c)T

p0D10 20 30 40 50 60 70 80 90 100

HLT

D m

eson

trig

ger e

ffici

ency

0

0.2

0.4

0.6

0.8

1

1.2

1.4

> 20T

trigger p0D> 40

T trigger p0D

> 60T

trigger p0D

(5.02 TeV PbPb)-1


from MC simulation fit turn on curve



Fraction of prompt D0

Branching fraction

Luminosity

Prompt: D0 mesons coming from c-quark fragmentation

B D0

X

K

π

Prompt:

Non-prompt:

c D0

K

π


fprompt: Fraction of prompt D0

DCA (cm)0D0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

)-1

DC

A) (c

m0

dN /

d(D

310

410

510

CMS Preliminary = 5.02 TeVNNspp

< 12.5 GeV/c |y| < 1.0T

10.0 < p

2.4 %±Prompt frac. = 76.7

Data0Prompt D

0Non-Prompt D

• Different shapes of distance of closest approach (DCA) distributions of prompt and non-prompt D0

• The shapes of DCA distributions come from MC

• Fit DCA distributions of data

α

D0 DCA

D0 flight distance

B D0

X

K

π

D0 DCA = flight distance * sin(α)



DCA (cm)0D0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

)-1

DC

A) (c

m0

dN /

d(D

310

410

510

CMS Preliminary = 5.02 TeVNNspp

< 12.5 GeV/c |y| < 1.0T

10.0 < p


Data0Prompt D

0Non-Prompt D

(GeV/c)T

p0D0 20 40 60 80 100

Frac

tion

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 PreliminaryCMS = 5.02 TeVNNsPP

|y| < 1.0PromptNon-prompt

fprompt vs. D0 pT

• Consistent with that from FONLL convoluted with MC efficiency


pT-differential cross-section in pp

• The first measurement of D0 cross-section in pp collisions at 5.02 TeV

• pT range covers from 2 to 100 GeV/c in |y| < 1

• Consistent with the upper bound of FONLL predictions [1]

10 210

c)-1( p

b G

eVT

/ dp

σd

10

210

310

410

510

610

710

810

910

1010

|y| < 1.0

Global uncert. 12.1%

dataFONLL pp ref.

(5.02 TeV pp)-125.8 pb

CMSPreliminary

(GeV/c)T

p10 210

Dat

a / F

ON

LL

00.5

11.5

22.5

[1] M. Cacciari, M. Greco, P. Nason, “The pT Spectrum in Heavy-Flavour Hadroproduction”, JHEP 007, 9805 (1998)


Invariant mass spectra in PbPbRaw yields extraction

)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

20

40

60

80

100

120

140

160

180

200

220DataFit


Combinatorial

PreliminaryCMS = 5.02 TeVNNsPbPb

< 30.0 GeV/cT

25.0 < p

Centrality 0-100%

|y| < 1.0

5.02 TeV, 0-100%

)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

5000

10000

15000

20000

25000

30000

35000

40000 DataFit


Combinatorial


< 6.0 GeV/cT

5.0 < p

Centrality 0-100%

|y| < 1.0


Systematic uncertainties summary

(GeV/c)T

p0D1 10

210

Syst

emat

ical

Unc

erta

inty

-0.6

-0.4

-0.2

0

0.2

0.4

0.6 (5.02 TeV PbPb)

-1bµ (5.02 TeV pp) + 404 -125.8 pb

CMSPerformance , |y| < 1

AA R0D

Centrality 0-100%

, Lumi)MB

Overall Normalization (NTotal SystematicsSignal ExtractionD Meson Selection and CorrectionB feed down subtraction

Signal extraction systematics ~5%• Varying signal and background fit

functions

D meson selection ~13%• Comparing data and MC driven

efficiencies of the different cut selections

• Systematics on trigger efficiency • Tracking efficiency systematic

(evaluated by 2 and 4 prongs D0 decays)

B-feed down uncertainty ~8%• Obtained by comparing fprompt

estimation with alternative method based on decay length and FONLL predictions

PbPb, Centrality 0-100%


D0 RAA in PbPb collisions at 5.02 TeV

• Strong suppression at pT 5-8 GeV/c• Less suppression for low and high pT

|y| < 1, Centrality 0-100%

CMS-PAS-HIN-16-001

(GeV/c)T

p1 10 210

AA R0 D

0

0.2

0.4

0.6

0.8

1

1.2

1.4

(5.02 TeV PbPb)-1bµ (5.02 TeV pp) + 404 -125.8 pb

CMSPreliminary

Centrality 0-100%|y| < 1

0 DAAR

and lumi.AATuncertainty



• Comparison with charged hadrons [1]• Less suppression at low pT• Similar suppression at high pT


[1] CMS-PAS-HIN-15-015CMS-PAS-HIN-16-001

(GeV/c)T

p1 10 210

AA R0 D

0

0.2

0.4

0.6

0.8

1

1.2

1.4


CMSPreliminary


0 DAAR

charged hadronsAAR and lumi.AAT

uncertainty



• Comparison with charged hadrons [1]• Less suppression at low pT• Similar suppression at high pT

• Comparison with theoretical predictions• S. Cao et al. [2] (Improved Langevin

eq, Linearized Boltzmann)• M. Djordjevic [3] (pQCD calculations in

a finite size optically thin dynamical QCD medium)


[1] CMS-PAS-HIN-15-015

[2] arXiv:1605.06447v1.

[3] Phys. Rev. C 92 (Aug, 2015) 024918

CMS-PAS-HIN-16-001

(GeV/c)T

p1 10 210

AA R0 D

0

0.2

0.4

0.6

0.8

1

1.2

1.4


CMSPreliminary


0 DAAR

charged hadronsAAR

S. Cao et al. 0-80%

M. Djordjevic and lumi.AAT

uncertainty



CMS-PAS-HIN-16-001 (GeV/c)

Tp

1 10 210

AA R0 D

0

0.2

0.4

0.6

0.8

1

1.2

1.4


CMSPreliminary


0 DAAR


(GeV/c)T

p1 10 210

AA R0 D

0

0.2

0.4

0.6

0.8

1

1.2

1.4


CMSPreliminary


0 DAAR


Centrality 0-100% Centrality 0-10%



• Comparison with charged hadrons [1]• Similar behavior with 0-100%


CMS-PAS-HIN-16-001[1] CMS-PAS-HIN-15-015

(GeV/c)T

p1 10 210

AA R0 D

0

0.2

0.4

0.6

0.8

1

1.2

1.4


CMSPreliminary


0 DAAR

charged hadronsAAR and lumi.AAT

uncertainty



• Comparison with charged hadrons [1]• Similar behavior with 0-100%

• Comparison with theoretical predictions• S. Cao et al. [2] (Improved Langevin eq,

Linearized Boltzmann)• M. Djordjevic [3] (pQCD calculations in

a finite size optically thin dynamical QCD medium)

• CUJET3.0 [4] (jet quenching model based on DGLV opacity expansion theory)

• PHSD [5] (Parton-Hadron-String Dynamics transport approach)

• I. Vitev [6] (jet propagation in matter, soft-collinear effective theory with Glauber gluons (SCETG))


CMS-PAS-HIN-16-001[1] CMS-PAS-HIN-15-015

[2] arXiv:1605.06447v1.

[3] Phys. Rev. C 92 (Aug, 2015) 024918

[4] JHEP 02 (2016) 169

[5] Phys. Rev. C 93 (Mar, 2016) 034906

[6] Phys. Rev. D 93 (Apr, 2015) 074030

(GeV/c)T

p1 10 210

AA R0 D

0

0.2

0.4

0.6

0.8

1

1.2

1.4


CMSPreliminary


0 DAAR charged hadronsAAR

M. Djordjevic0CUJET3.0 D

S. Cao et al.PHSD w/ shadowing PHSD w/o shadowing I.Vitev (g=1.8-2.0)



Summary


Summary

D0 and charged particle RAA agree up to very high pT• Putting strong constraints on theoretical calculations• Forcing theories to describe HF production in a much

wider kinematic range where different processes dominate

Conclusions

Outlook• D meson at very low pT

• Down to ~1 GeV/c• The hadronization mechanisms and the cold

medium properties• D meson vn measurements

• Collective behavior • B meson RAA

• Coming soon!


Back up

Thanks for your attention!


D0 measurements with CMS in Run IPbPb @ 2.76 TeV

(GeV/c)T

p0 5 10 15 20 25 30 35 40

AA ,

RAA

R*

0

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= 2.76 TeVNNsPbPb

partN0 50 100 150 200 250 300 350 400

AA ,

RAA

R*

0

0.2

0.4

0.6

0.8

1

1.2

1.4AA R*0Prompt D

< 16.0 GeV/c, |y| < 1.0T

8.0 < p

PbPb data+Syst.+BRMB+NAAT

Err. pp reference

AA Rψ J/Non-prompt < 30.0 GeV/c, |y| < 1.2

T6.5 < p

Total Syst.

AA R particleCharged| < 1.0η < 9.6 GeV/c, |

T7.2 < pCMS, EPJC 72 (2012) 1945Total Syst.

CMS Preliminary = 2.76 TeVNNsPbPb

(GeV/c)T

p0 5 10 15 20 25

CP

R

0

0.2

0.4

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1

1.2

1.4

1.6

1.8

2

0-10% / 50-100%10-30% / 50-100%30-50% / 50-100%


|y| < 1.0

RAA vs. pT

CMS-PAS-HIN-15-005

RAA vs. Npart RCP vs. pT

• Measurements reaching very high pT (>100GeV/c) for the first time!• PP reference directly from data

RunII: pp + PbPb @ 5.02 TeV


Comparison with CMS 2.76 TeVPbPb 0-100%

(GeV/c)T

p1 10

210

AA R0

D

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6 (5.02 TeV PbPb)

-1bµ (5.02 TeV pp) + 404

-125.8 pb

CMS PreliminaryCMS, 5.02 TeV, |y|<1CMS, 2.76 TeV, |y|<1CMS, 5.02 TeV, |y|<1CMS, 2.76 TeV, |y|<1

and lumi.AA

Tuncertainty


Comparison with ALICE 5.02 TeV

(GeV/c)T

p1 10

210

AA R0

D

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6 (5.02 TeV PbPb)

-1bµ (5.02 TeV pp) + 404

-125.8 pb

CMS PreliminaryCMS, 5.02 TeV, |y|<1ALICE, 2.76 TeV, |y|<0.5CMS, 5.02 TeV, |y|<1ALICE, 2.76 TeV, |y|<0.5

and lumi.AA

Tuncertainty

PbPb 0-10%

CMS: 0-10%, ALICE: 0-7.5%


Heavy flavor measurements with CMS

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|<1.21.2<|y|<1.61.6<|y|<2.4


ψNon-prompt J/

<30 GeV/cT

6.5<p

(GeV/c)T

p0 5 10 15 20 25 30 35 40

AA ,

RAA

R*

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2




= 2.76 TeVNNsPbPb

LHC Run I 2.76 PbPb + 5.02 pPb

1. b-jet RAA in PbPb2. J/ψ RAA in PbPb3. D0 meson RAA in PbPb4. B meson RpPb in pPb

① ② ③ ④

[1] Phys. Rev. Lett. 113, 132301 (2014)[2] CMS-PAS-HIN-12-014[3] CMS-PAS-HIN-15-005[4] Phys. Rev. Lett. 116, 032301 (2016)


CMS detector

Muon HCAL ECAL

Tracker |η|< 2.5

|η|< 3.0

|η|< 5.2

|η|< 2.4

Inner tracker: charged particles

EM and hadronic calorimeters Photons, Jet

Muon detectors

Forward Calorimeter: MB triggers, centrality


Mass spectra

)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

500

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Combinatorial


< 6.0 GeV/cT

5.0 < p|y| < 1.0

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)2En

tries

/ (5

MeV

/c

0

100

200

300

400

500

600

700

800 DataFit


Combinatorial


< 30.0 GeV/cT

25.0 < p|y| < 1.0

pp


)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

5000

10000

15000

20000

25000

30000

35000

40000 DataFit


Combinatorial


< 6.0 GeV/cT

5.0 < p

Centrality 0-100%

|y| < 1.0

34

Mass spectraPbPb 0-100%

)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

20

40

60

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100

120

140

160

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220DataFit


Combinatorial


< 30.0 GeV/cT

25.0 < p

Centrality 0-100%

|y| < 1.0


Mass spectraPbPb 0-10%

)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

02000400060008000

1000012000140001600018000200002200024000

DataFit


Combinatorial


< 6.0 GeV/cT

5.0 < p

Centrality 0-10%

|y| < 1.0

)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

10

20

30

40

50

60

70 DataFit


Combinatorial


< 30.0 GeV/cT

25.0 < p

Centrality 0-10%

|y| < 1.0



)2 (GeV/cKπm1.7 1.75 1.8 1.85 1.9 1.95 2

)2En

tries

/ (5

MeV

/c

0

10

20

30

40

50DataFit


Combinatorial


< 200.0 GeV/cT

100.0 < p|y| < 1.0

• 5.02 TeV pp collisions• Extend to D0 high pT to 200

GeV/c



(GeV/c)T

p0D10 20 30 40 50 60 70 80 90 100

HLT

D m

eson

trig

ger e

ffici

ency

0

0.2

0.4

0.6

0.8

1

1.2

1.4

> 20T

trigger p0D> 40

T trigger p0D

> 60T

trigger p0D

(5.02 TeV PbPb)-1


) (GeV)0 (DT

p0 10 20 30 40 50 60

HLT

Effi

cien

cy

0

0.2

0.4

0.6

0.8

1

1.2

1.4

8≥ T

HLT D meson p15≥

THLT D meson p

20≥ T

HLT D meson p 30≥

THLT D meson p

= 5.02 TeV s pp,

CMSPreliminary

Triggers performance



PbPb

(GeV/c)T

p0D0 20 40 60 80 100

Frac

tion

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 PreliminaryCMS = 5.02 TeVNNsPbPb

|y| < 1.0PromptNon-prompt

DCA (cm)0D0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

)-1

DC

A) (c

m0

dN /

d(D

410

510

610


< 12.5 GeV/c |y| < 1.0T

10.0 < p


Data0Prompt D

0Non-Prompt D


Systematics

(GeV/c)T

p0D1 10

210

Syst

emat

ical

Unc

erta

inty

-0.6

-0.4

-0.2

0

0.2

0.4

0.6 (5.02 TeV PbPb)

-1bµ (5.02 TeV pp) + 404 -125.8 pb


T / dp

AA R0D

Centrality 0-10%

, Lumi)MB

Overall Normalization (NTotal SystematicsSignal ExtractionD Meson Selection and CorrectionB feed down subtraction

(GeV/c)T

p0D1 10

210

Syst

emat

ical

Unc

erta

inty

-0.6

-0.4

-0.2

0

0.2

0.4

0.6 (5.02 TeV pp)-125.8 pb


T / dpσ d0D

Overall Normalization (Lumi + BR)Total SystematicsSignal ExtractionD Meson Selection and CorrectionB feed down subtraction

pp PbPb 0-10%


Heavy flavor measurements with CMS

b-jet RAA in PbPb B meson RpPb in pPb J/ψ RAA in PbPb

LHC Run I (2.76 PbPb + 5.02 pPb)

Phys. Rev. Lett. 113, 132301 (2014)

Phys. Rev. Lett. 116, 032301 (2016) CMS-PAS-HIN-12-014

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|<1.21.2<|y|<1.61.6<|y|<2.4


ψNon-prompt J/

<30 GeV/cT

6.5<p

Documents

D Meson Production in Heavy Ion Collisions in CMS experiment · Jing Wang (MIT), D0 meson production in HI collisions in CMS, SQM 2016 (Berkeley) 1 D0 Meson Production in Heavy Ion