Diffractive particle production as a probe of high-energy QCD · QCD at high...

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Diffractive particle production as a probe of high-energy QCD Heikki M¨ antysaari University of Jyv¨ askyl¨ a, Finland Zim´ anyi school’19 December 5, 2019 Heikki M¨ antysaari (JYU) Diffraction and CGC Dec 5, 2019 1 / 18

Transcript of Diffractive particle production as a probe of high-energy QCD · QCD at high...

Page 1: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Diffractive particle production as a probe of high-energy QCD

Heikki Mantysaari

University of Jyvaskyla, Finland

Zimanyi school’19December 5, 2019

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 1 / 18

Page 2: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Why diffraction

Exclusive production of a vectormeson/dijet/diffracive system

γ + A→ V + A

γ + A→ jet1 + jet2 + A

γ + A→ MX + A

Pocket formula for VM production (2-gluon exchange), [Ryskin 1993]

dσγ∗H→VH

dt

∣∣∣∣t=0

=16π3α2

sΓee

3αemM5V

[xg(x,Q2)

]2

Diffraction is very sensitive to (small-x) gluons!Measure t (conjugate to impact parameter) ⇒ access to geometryBut PDFs are inclusive quantities, this is exclusive...

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 1 / 18

Page 3: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

QCD at high energy: Color Glass Condensate

(DGLAP)

(BK)

CGC = QCD at high energies

x (energy) dependence:BK/JIMWLK (perturbative)

Gluon saturation at small x at scale Q2s

Non-linear effects enhanced in nucleiQ2

s ∼ A1/3

Natural framework to describe high energy scattering,which probes QCD in the non-linear regime

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 2 / 18

Page 4: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Deep inelastic scattering at high energy: dipole picture

Optical theorem:σγ

∗p ∼ dipole amplitude σγ∗p→Vp ∼ |dipole amplitude|2

Univesal dipole amplitude

Same universal QCD evolved dipole amplitude N

N ∼ gluon

Structure function ∼ gluon

Diffractive cross sections ∼ gluon2 ⇒ saturation effects especially in nuclei!

Perturbative x evolution (BK, JIMWLK), non-perturbative initial condition: fit HERA F2

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 3 / 18

Page 5: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Dipole model fits to DIS (γ∗p) data

Successful fits to precise σr data at small x (LO, NLO in preparation Beuf, Lappi, Hanninen, Mantysaari )

Initial condition for perturbative small-x evolution of the dipoleDiffraction more complicated, perturbative geometry evolution → Coulomb tailsAlbacete et al 2009, Albacete et al 2010, Berger, Stasto, 2012, Lappi, Mantysaari 2013, Mantysaari, Schenke 2018, Bendova et al 2019

Parametrized x dependence and geometry (e.g. IPsat)Kowalski, Teaney 2003, Rezaeian et al, 2012, Mantysaari, Zurita 2018,...0.4

0.6

0.8

1.0

1.2

1.4

1.6

�r

Q2 = 2.7 GeV2

IPsat

Q2 = 18 GeV2 Q2 = 120 GeV2

10�4 10�3 10�2

x

0.4

0.6

0.8

1.0

1.2

1.4

1.6

�r

Q2 = 2.7 GeV2

10�4 10�3 10�2

x

Q2 = 18 GeV2

10�4 10�3 10�2

x

Q2 = 120 GeV2

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 4 / 18

Page 6: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Probe of the geometry: exclusive J/Ψ production

High energy factorization:

1 γ∗ → qq: Ψγ(r ,Q2, z)

2 qq dipole scatters elasticallyAmplitude N

3 qq → J/Ψ: ΨV (r ,Q2, z)

Diffractive scattering amplitude

Aγ∗p→Vp ∼∫

d2bdzd2rΨγ∗ΨV (r , z ,Q2)e−ib·∆N(r , x ,b)

Impact parameter is the Fourier conjugate of the momentum transfer→ Access to the spatial structure

Total F2: forward elastic scattering amplitude (∆ = 0) for V = γ

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 5 / 18

Page 7: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Average over target configurations

Coherent diffraction:Target remains in the same quantum stateProbes average density

dσγ∗A→VA

dt∼ |〈Aγ∗A→VA〉|2

Incoherent/target dissociation:Total diffractive − coherent cross sectionTarget breaks up

dσγ∗A→VA∗

dt∼ 〈|Aγ∗A→VA|2〉 − |〈Aγ∗A→VA〉|2

Variance, measures the amount of fluctuations (“lumpiness”)!

dσ/d

t

|t|

Coherent/Elastic

Incoherent/Breakup

t1 t2 t3 t4

Good, Walker, PRD 120, 1960Miettinen, Pumplin, PRD 18, 1978Kovchegov, McLerran, PRD 60, 1999Kovner, Wiedemann, PRD 64, 2001

〈 〉: average over target configurations [N(r, x, b)]

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 6 / 18

Page 8: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Average over target configurations

Coherent diffraction:Target remains in the same quantum stateProbes average density

dσγ∗A→VA

dt∼ |〈Aγ∗A→VA〉|2

Incoherent/target dissociation:Total diffractive − coherent cross sectionTarget breaks up

dσγ∗A→VA∗

dt∼ 〈|Aγ∗A→VA|2〉 − |〈Aγ∗A→VA〉|2

Variance, measures the amount of fluctuations (“lumpiness”)!

dσ/d

t

|t|

Coherent/Elastic

Incoherent/Breakup

t1 t2 t3 t4

Good, Walker, PRD 120, 1960Miettinen, Pumplin, PRD 18, 1978Kovchegov, McLerran, PRD 60, 1999Kovner, Wiedemann, PRD 64, 2001

〈 〉: average over target configurations [N(r, x, b)]

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 6 / 18

Page 9: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Beyond the round proton

Recall: coherent cross section ∼ average, incoherent ∼ variance⇒ need event-by-event fluctuating N(r,b)

Constituent quark inspired picture

Sample hot spot substructure, geometry and density fluctuation

Use constraints from coherent and incoherent cross sections(average profile and amount of fluctuations)Mantysaari, Schenke 2016, 2017, Cepila, Contreras, Takaki 2017, 2018

Tproton(b) =3∑

i=1

Tq(b− bi ) Tq(b) ∼ e−b2/(2Bq)

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 7 / 18

Page 10: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Proton structure from HERA data on γ + p → J/Ψ + p

Sample color charges, solve Yang-Mills equations ⇒ Wilson lines ⇒ dipole amplitude NH.M., B. Schenke, PRL 117 (2016), 052301, PRD94 (2016), 034042

0.0 0.5 1.0 1.5 2.0

|t| [GeV2]

10−1

100

101

102

103

dσ/dt

[nb/G

eV2]

Incoherent

Coherent

Round protonGeometry and Qs fluctuationsH1 coherentH1 incoherent

−1

0

1

y[f

m]

−1 0 1x[fm]

−1

0

1

y[f

m]

−1 0 1x[fm]

0.0

0.2

0.4

0.6

0.8

1.0

1.2

HERA data (at x ≈ 10−3) preferes large fluctuations

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 8 / 18

Page 11: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Perturbative JIMWLK energy evolution from CGC

Size fixed at W = 30GeV, αs and ΛQCD fixed by charm-F2

102 103

W [GeV]

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

BG

[GeV−

2]

Fixed αsRunning αsIPsat

H1 (2005)H1 (2013)ZEUS

Fit range 0.1 < |t| < 0.6 GeV2

Running αs : faster evolution at long distance scales. rRMS ≈√

2BG

Dashed: no geometry evolution (only density). H.M, B. Schenke, 1806.06783

x = 10−2

x = 10−4

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 9 / 18

Page 12: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Energy evolution from CGC → smoother proton at small x

Fluctuations fixed at W = 75 Gev, then JIMWLK evolution H.M, B. Schenke, 1806.06783

102 103

W [GeV]

0.4

0.6

0.8

1.0

inco

her

ent/

coh

eren

t

MV + JIMWLK+ UV damping at x0

IPsatH1

Evolution parameters constrained by the charm-F2 dataSolid and dashed: JIMWLK with different initial conditionsDotted: no geometry evolution

W = 75 GeV:

W = 680 GeVH.M, B. Schenke, 1806.06783

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 10 / 18

Page 13: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Exclusive J/Ψ production at small x at the LHC

Ultraperipheral p + A:Photon flux ∼ Z 2

γ + p dominatesE

Pb

p

Low energy γ − A: coherent and incoherent visible ALICE: 1406.7819

Dimuon pT

Larger COM energies:incoherent → 0 (?)⇒ smoother proton?ALICE:1809.03235

x ∼ 10−2 → 10−5

Energy dependence of exclusive J/y photoproduction ... ALICE Collaboration

)c (GeV/TpDielectron

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

)cD

iele

ctro

n co

unts

/ (1

00 M

eV/

0

10

20

30

40

50

60

= 5.02 TeVNNsALICE p-Pb -e+ e→ψJ/

< 0.8y-0.8 < 2c < 3.2 GeV/-e+em2.9 <

SumψExclusive J/

Non-exclusive bkg.-e+ e→ γγ

+Pbγ

)c (GeV/TpDimuon

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

)cD

imuo

n co

unts

/ (8

0 M

eV/

0

20

40

60

80

100 = 5.02 TeVNNsALICE p-Pb -µ+µ → ψJ/

< 0.8y-0.8 < 2c < 3.2 GeV/-µ+µm3.0 <

SumψExclusive J/

Non-exclusive bkg.-µ+µ → γγ

+Pbγ

)c (GeV/TpDimuon

0 0.5 1 1.5 2 2.5

)cD

imuo

n co

unts

/ (1

50 M

eV/

0

10

20

30

40

50

60

70

80 = 5.02 TeVNNsALICE p-Pb -µ+µ → ψJ/

< 2.7y1.2 < 2c < 3.2 GeV/-µ+µm2.9 <

SumψExclusive J/

Non-exclusive bkg.-µ+µ → γγ

)c (GeV/TpDimuon

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

)cD

imuo

n co

unts

/ (2

00 M

eV/

0

5

10

15

20

25

30

35

40 = 5.02 TeVNNsALICE Pb-p -µ+µ → ψJ/

< -1.2y-2.5 < 2c < 3.2 GeV/-µ+µm2.9 <

SumψExclusive J/

Non-exclusive bkg.-µ+µ → γγ

Figure 2: Transverse momentum distributions of dileptons around the J/y mass for the dielectron (upper left)and dimuon (upper right) samples for the central analysis and dimuon samples for the semi-forward (lower left)and semi-backward (lower right) analyses. In all cases the data are represented by points with error bars. Theblue, magenta (dash) and green (dash-dot-dot) lines correspond to Monte Carlo templates for J/y coming fromexclusive photoproduction off protons or off lead and continuous dilepton production respectively. The red (dash-dot) line is a template for dissociative and hadronic background obtained from data. The solid black line is the sumof all contributions.

The systematic uncertainty on the yield was obtained by varying the range of fit to the transverse momen-tum template, the width of the binning and the selections and smoothing algorithms used to determinethe non-exclusive template. (See section 3.3.) Furthermore, the value of the b parameter used in theproduction of the exclusive J/y template was varied, taking into account the uncertainties reported byH1 [10]. The uncertainty varies from 1.9% to 3.6%. (See “signal extraction” in Table 2.)

The polarization of the J/y coming from y(2S) feed-down is not known. The uncertainty on the amountof feed-down has been estimated by assuming that the J/y was either not polarised or that it was fullytransversely or fully longitudinally polarised. This uncertainty is asymmetric and varies from +1.0% to�1.4%. (See “feed-down” in Table 2.)

10

Energy dependence of exclusive J/y photoproduction ... ALICE Collaboration

)c (GeV/TpDielectron

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

)cD

iele

ctro

n co

unts

/ (1

00 M

eV/

0

10

20

30

40

50

60

= 5.02 TeVNNsALICE p-Pb -e+ e→ψJ/

< 0.8y-0.8 < 2c < 3.2 GeV/-e+em2.9 <

SumψExclusive J/

Non-exclusive bkg.-e+ e→ γγ

+Pbγ

)c (GeV/TpDimuon

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

)cD

imuo

n co

unts

/ (8

0 M

eV/

0

20

40

60

80

100 = 5.02 TeVNNsALICE p-Pb -µ+µ → ψJ/

< 0.8y-0.8 < 2c < 3.2 GeV/-µ+µm3.0 <

SumψExclusive J/

Non-exclusive bkg.-µ+µ → γγ

+Pbγ

)c (GeV/TpDimuon

0 0.5 1 1.5 2 2.5

)cD

imuo

n co

unts

/ (1

50 M

eV/

0

10

20

30

40

50

60

70

80 = 5.02 TeVNNsALICE p-Pb -µ+µ → ψJ/

< 2.7y1.2 < 2c < 3.2 GeV/-µ+µm2.9 <

SumψExclusive J/

Non-exclusive bkg.-µ+µ → γγ

)c (GeV/TpDimuon

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

)cD

imuo

n co

unts

/ (2

00 M

eV/

0

5

10

15

20

25

30

35

40 = 5.02 TeVNNsALICE Pb-p -µ+µ → ψJ/

< -1.2y-2.5 < 2c < 3.2 GeV/-µ+µm2.9 <

SumψExclusive J/

Non-exclusive bkg.-µ+µ → γγ

Figure 2: Transverse momentum distributions of dileptons around the J/y mass for the dielectron (upper left)and dimuon (upper right) samples for the central analysis and dimuon samples for the semi-forward (lower left)and semi-backward (lower right) analyses. In all cases the data are represented by points with error bars. Theblue, magenta (dash) and green (dash-dot-dot) lines correspond to Monte Carlo templates for J/y coming fromexclusive photoproduction off protons or off lead and continuous dilepton production respectively. The red (dash-dot) line is a template for dissociative and hadronic background obtained from data. The solid black line is the sumof all contributions.

The systematic uncertainty on the yield was obtained by varying the range of fit to the transverse momen-tum template, the width of the binning and the selections and smoothing algorithms used to determinethe non-exclusive template. (See section 3.3.) Furthermore, the value of the b parameter used in theproduction of the exclusive J/y template was varied, taking into account the uncertainties reported byH1 [10]. The uncertainty varies from 1.9% to 3.6%. (See “signal extraction” in Table 2.)

The polarization of the J/y coming from y(2S) feed-down is not known. The uncertainty on the amountof feed-down has been estimated by assuming that the J/y was either not polarised or that it was fullytransversely or fully longitudinally polarised. This uncertainty is asymmetric and varies from +1.0% to�1.4%. (See “feed-down” in Table 2.)

10

Medium E Large EHeikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 11 / 18

Page 14: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Searching for saturation effects

Saturation models (“sat”) and linearized models (“nonsat”), describe inclusive HERA dataSimilar predictions for diffractive J/Ψ production.

0.4

0.6

0.8

1.0

1.2

1.4

1.6

�r

Q2 = 2.7 GeV2Q2 = 2.7 GeV2

IPsatIPnonsat

Q2 = 18 GeV2Q2 = 18 GeV2 Q2 = 120 GeV2Q2 = 120 GeV2

10�4 10�3 10�2

x

0.80.91.01.11.21.31.41.5

�r

Q2 = 120 GeV2Q2 = 120 GeV2

10�4 10�3 10�2

x

Q2 = 200 GeV2Q2 = 200 GeV2

10�4 10�3 10�2

x

Q2 = 120 GeV2Q2 = 120 GeV2

102 103 104

W [GeV]

102

103

σ[n

b]

IPsatIPnonsatH1 (2005)

H1 (2013)ZEUSALICE (2014)

γ + p→ J/Ψ + p,Q2 = 0 GeV2

IPsat and IPnonsat fitted to the same σr dataH.M, P. Zurita, 1804.05311

Need higher gluon densities than accessible in γ + p(?)Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 12 / 18

Page 15: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

High gluon densities in nuclei

Enhance saturation effects:Q2

s,A ∼ A1/3x−λ

(larger A is cheaper than smaller x)Already data from UPCs,momentum fraction x = MV e

y/√s

E

Z e1

Z e2

y0.5− 0 0.5 1 1.5 2 2.5 3 3.5

/ dy

[mb]

coh

σd

0

1

2

3

4

5

6

7

8

9CMS dataALICE dataImpulse approximationLeading twist approximation

(2.76 TeV)-1bµ 159 ψ Pb+Pb+J/→Pb+Pb

CMS

CMS, 1605.06966Clear nuclear effects: impulse approximation is scaled γ + p

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 13 / 18

Page 16: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Coherent diffraction, model comparison

y

­4 ­2 0 2 4

/dy (

mb

d

0

1

2

3

4

5

6

7

8

RSZ­LTA

STARLIGHTGM

AB­EPS09

AB­MSTW08

AB­EPS08

AB­HKN07

CSS

LM­fIPSat

ψALICE Coherent J/

Reflected

a) = 2.76 TeVNN

s ψ Pb+Pb+J/→Pb+Pb

ALICE, 1305.1467

Shadowing/saturation needed

LM-fIPsat (CGC)

AB-PS09 (nPDF)

Linear models fail

AB-MSTW08 (proton PDF)

CGC: inclusive and diffractive observables from the same framework (depend on dipole N)Exclusive data difficult to include in nPDF fits (PDFs are inclusive)

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 14 / 18

Page 17: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Extract nuclear geometry

Full EIC simulation with expected uncertainties in γ + A→ J/Ψ + A

|t | (GeV2) |t | (GeV2)0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18

J/ψ φ

|η(edecay)| < 4p(edecay) > 1 GeV/cδt/t = 5%

∫Ldt = 10/A fb-11 < Q2 < 10 GeV2, x < 0.01

∫Ldt = 10/A fb-11 < Q2 < 10 GeV2, x < 0.01

|η(Kdecay)| < 4p(Kdecay) > 1 GeV/cδt/t = 5%

104

103

102

10

1

10-1

10-2

105

104

103

102

10

1

10-1

10-2

coherent - no saturationincoherent - no saturationcoherent - saturation (bSat)incoherent - saturation (bSat)

coherent - no saturationincoherent - no saturationcoherent - saturation (bSat)incoherent - saturation (bSat)

(a) (b)

dσ(e

Au →

e' A

u' J/ψ

) /dt (

nb/G

eV2 )

dσ(e

Au →

e' A

u' φ)

/dt (

nb/G

eV2 )

Coherent J/Ψ spectra ⇒ FT⇒ Density profile

-10 -5 1050 -10 -5 1050

-10 -5 1050-10 -5 1050

0

0.02

0.04

0.06

0.08

0.1

0

0.02

0.04

0.06

0.08

0.1

0

0.02

0.04

0.06

0.08

0.1

0

0.02

0.04

0.06

0.08

0.1

φ bNonSatWoods-Saxon

F(b)

/ ∫F(b

) db

F(b)

/ ∫F(b

) db

F(b)

/ ∫F(b

) db

F(b)

/ ∫F(b

) db

b (fm)

b (fm)b (fm)

b (fm)

J/ψ bNonSatWoods-Saxon

φ bSatWoods-Saxon

J/ψ bSatWoods-Saxon

(a) (b)

(c) (d)Extract transverse density profile of small-x gluons T. Toll, T. Ullrich, 1211.3048

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 15 / 18

Page 18: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Fluctuations at different length scales

Small |t| . 0.2GeV2: long length scale, fluctuating nucleon positionsLarge |t| & 0.2GeV2: short length scale, fluctuating nucleon substructure

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

|t| [GeV2]

10−2

10−1

100

101

102

103

dσ/dtdy

[mb/G

eV2]

Geometric and Qs fluctuations in the nucleonsNo subnucleon fluctuations

Pb + Pb→ J/Ψ + Pb + Pb,√s = 5.02 TeV, y = 0

−3 −2 −1 0 1 2 3

y

0.1

0.2

0.3

0.4

0.5

0.6

0.7

inco

her

ent/

coh

eren

t

Geometric and Qs fluctuationsNo subnucleon fluctuationsALICE

Pb + Pb→ J/Ψ + Pb + Pb,√sNN = 2760 GeV

Subnucleon fluctuations preferred by the ALICE dataSome model uncertainties cancel in ratios (e.g. J/Ψ wave function)! H.M, B. Schenke, 1703.09256

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 16 / 18

Page 19: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

More differential imaging: diffractive dijets

Two transverse momenta (sum and difference) ⇒ more detailed probe

Cross section modulation ∼ Wigner distribution Hatta, et al, 1601.01585

Dipole-proton scattering depends on orientation⇒ dijet anisotropies

dN ∼ 1 + 2v2 cos(2θ(P,∆))

r

Altinoluk et al, 1511.07452

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0 1 2 3 4 5 6θ(r, b)

0.90

0.95

1.00

1.05

1.10

1.15

N(r,b,y

)/v 0

CGC, |r|= 0.35 fm, |b|= 0.35 fm

y= 0.0, v0 = 0.10, v2 = 2.87%y= 1.5, v0 = 0.15, v2 = 1.89%y= 3.0, v0 = 0.21, v2 = 1.20%

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 2.0e-03 4.0e-03 6.0e-03

150 100 60

v 2 [%

]

average xP

m~

=0.4, m=0.2, αs =0.21m~

=0.4,no JIMWLK evolution

Dipole size r-impact parameter b angular dependence from CGC.At small x larger proton, smaller density gradients, small v2 H.M, N. Mueller, B. Schenke, 1902.05087

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 17 / 18

Page 20: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Conclusions

Color Glass Condensate: an effective theory of QCD, same framework to describeinclusive and diffractive processes and predict energy evolution

Exclusive particle production is a powerful probe of high energy QCD

Probe ∼ squared gluon distributionAccess to geometry

Two classes of diffractive events

Coherent ∼ average shapeIncoherent ∼ event-by-event fluctuations

HERA J/Ψ data prefers large proton shape fluctuations

Fluctuating protons in p+A hydro: good description of the LHC data (backup)

γA scattering at the LHC points towards significant saturation effects

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 18 / 18

Page 21: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

BACKUPS

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 19 / 18

Page 22: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Implications on heavy ion phenomenology: p+A

Hydro + fluctuations from HERA J/Ψ data: success

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Fluctuations

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 20 / 18

Page 23: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Implications on heavy ion phenomenology: p+A

Hydro + fluctuations from HERA J/Ψ data: success

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0.0

1.0

2.0

3.0

4.0

Rout (

fm)

0.0

1.0

2.0

3.0

4.0

Rsi

de (f

m)

0-20% pPb @ 5.02 TeV

0.0 0.2 0.4 0.6 0.8kT (GeV)

0.0

1.0

2.0

3.0

4.0

5.0

Rlo

ng (f

m)

decays onlyfull UrQMD

0.0 0.2 0.4 0.6 0.8kT (GeV)

0.50.60.70.80.91.01.1

Rou

t/R

side

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 21 / 18

Page 24: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Fluctuating protons in pA collisions

Hydro calculations with proton fluctuations from HERA

Hydro numbers

τ0 = 0.4 fm

Tfo = 155 MeV

Shear and bulk viscosity

Initial πµν

η/s = 0.2��

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Large v2 and v3 at largest centrality bins reproduced well.H.M, B. Schenke, C. Shen, P. Tribedy, 1705.03177

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 22 / 18

Page 25: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Large nuclear suppression in vector meson production

100 101 102 103

Q2 [GeV2]

0.0

0.2

0.4

0.6

0.8

1.0

σγ∗ A→VA/(

1 2A

4/3σγ∗ p→Vp)

IPsat J/Ψ IPsat φ IPsat ρ IPnonsat

W = 100, 1000 GeV

H.M, P. Zurita, 1804.05311

Especially for heavy mesons expect large nuclear effectsNo suppression with linear IPnonsat parametrizationQ2 and A scan at the EIC!

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 23 / 18

Page 26: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Inclusive diffraction

Higher Fock states are suppressed in the black disk limit

√s =

90

GeV

x IP =

0.0

1

√s =

40

GeV

x IP =

0.0

1

√s =

90

GeV

x IP =

0.0

01

qq

qqg(F

AD−

A F pD

) / (A

FpD

)

Mx2 (GeV2)

001011

1.0

0.5

0

-0.5

-1.0

Q2 = 5 GeV2

xIP = 0.01xIP = 0.001

E. Aschenauer et al, 1708.01527, based on Kowalski,Lappi, Marquet,Venugopalan 0805.4071

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 24 / 18

Page 27: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Ultraperipheral collision as a deep inelastic scattering

b & 2RA: strong interactions are suppressed

E

Z e1

Z e2

J. Nystrand et al, nucl-ex/0502005

1 Nucleus creates a (real) photon flux n(ω)

2 Photon-nucleus scattering

σAA→AA+V ∼ n(ω)σγA→VA(ω)

Interesting QCD part: high-energy γ-nucleus or γ-proton scattering.

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 25 / 18

Page 28: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Dipole amplitude from IP-Glasma

Obtain saturation scale Qs(xT ) from IPsat (with fluctuations)

MV-model: Sample color charges, density ∼ Qs(xT )

Solve Yang-Mills equations to obtain the Wilson lines

V (xT ) = P exp

(−ig

∫dx−

ρ(x−, xT )

∇2 + m2

)Dipole amplitude: N(xT , yT ) = 1− TrV (xT )V †(yT )/Nc

Fix parameters Bqc ,Bq and m with HERA data

Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 26 / 18

Page 29: Diffractive particle production as a probe of high-energy QCD · QCD at high energy:ColorGlassCondensate s CGC= QCD at high energies x (energy) dependence: BK/JIMWLK (perturbative)

Lumpiness matters, not details of the density profile

3 valence quarks that are connected by ”color flux tubes” (Gaussian density profile, width Bq).Also good description of the data

0.0 0.5 1.0 1.5 2.0 2.5

|t| [GeV2]

10−1

100

101

102

103

dσ/dt

[nb/G

eV2]

IPsat

Strigyn proton H1CoherentIncoherent

H.M, B. Schenke, PRD94 034042

Example density profiles

−1

0

1

y[f

m]

−1 0 1x[fm]

−1

0

1

y[f

m]

−1 0 1x[fm]

0.00

0.05

0.10

0.15

Flux tubes implementation following results from hep-lat/0606016, used also e.g. in 1307.5911Heikki Mantysaari (JYU) Diffraction and CGC Dec 5, 2019 27 / 18