AT THE LHC Mariola Kusek-Gawenda INSTITUTE OF NUCLEAR PHYSICS - - PowerPoint PPT Presentation
MESON2018 FUSION IN HEAVY ION UPC I MPORTANCE OF MESONS EPA IN L IGHT - BY -L IGHT SCATTERING SCATTERING E > 5 G E V E < 5 G E V IN ULTRAPERIPHERAL LEAD - LEAD COLLISIONS E < 2 G E V C ONCLUSION AT THE LHC Mariola
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION
INSTITUTE OF NUCLEAR PHYSICS POLISH ACADEMY OF SCIENCE Kraków, Poland
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 1 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION
➳
Light-by-light scattering in ultraperipheral Pb-Pb collisions at energies available at the CERN Large Hadron Collide, Phys. Rev. C93 (2016) 044907, ➳
Two-gluon exchange contribution to elastic γγ → γγ scattering and production of two-photons in ultraperipheral ultrarelativistic heavy ion and proton-proton collisions, Phys. Lett. B761 (2016) 399, ➳
Measurements of light-by-light scattering in UPC of heavy ions at the LHC - smaller diphoton collision energies, in preparation. γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 2 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION EPA
A A γ γ γ γ A A A A γ γ γ γ A A R A A π0 π0 γ γ A A γ γ γ γ
CONTINUUM RESONANCES BACKGROUND
abs (b)
b1 b2 b
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 3 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
WELL-KNOWN
γ γ γ γ γ γ γ γ W W W W
WE ADD
γ γ γ γ
IP, IR
V V
γ γ γ γ g g
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 4 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
Γ Γ Γ Γ W W W Γ Γ Γ Γ W W W Γ Γ Γ Γ W W W Γ Γ Γ Γ W W W Γ Γ Γ Γ W W W Γ Γ Γ Γ W W W Γ Γ Γ Γ F F F F Γ Γ Γ Γ W W W W Γ Γ Γ Γ F F F F Γ Γ Γ Γ W W W W Γ Γ Γ Γ F F F F Γ Γ Γ Γ W W W W Γ Γ Γ Γ W W Γ Γ Γ Γ W W Γ Γ Γ Γ W W
Γ Γ
Γ
(GeV) s
10
10
10 1 10
2
10
3
10
(pb) σ
10
10
10 1 10
2
10
3
10
4
10
5
10
6
10
7
10
γ γ → γ γ
total leptons quarks W-bosons Fermionic box LO QED - FormCalc. The one-loop W box diagram - LoopTools. We have compared our results with:
◮
Jikia et al. (1993),
◮
Bern et al. (2001),
◮
Bardin et al. (2009). Bern et al. consider QCD and QED corrections (two-loop Feynman diagrams) to the one-loop fermionic contributions in the ultrarelativistic limit (ˆ s, |ˆ t|, |ˆ u| ≫ m2
f ). The corrections are quite small
numerically. γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 5 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
W = 10 GeV ✔ boxes ✔ VDM-Regge ✔ 2-gluon exchange W = 50 GeV W = 200 GeV
γ
t
p
1 2 3 4 5
(nb/GeV)
γ
t
/dp
γ γ → γ γ
σ d
10
10
10
10
10
10
10
10 boxes VDM-Regge =4
f
2-gluon exchange, n =0.75 GeV
g
m =0
g
m W=10 GeV
γ
t
p
1 2 3 4 5
(nb/GeV)
γ
t
/dp
γ γ → γ γ
σ d
10
10
10
10
10
10
10
10 boxes VDM-Regge =4
f
2-gluon exchange, n =0.75 GeV
g
m =0
g
m W=50 GeV
γ
t
p
5 10 15 20
(nb/GeV)
γ
t
/dp
γ γ → γ γ
σ d
10
10
10
10
10
10
10
10 boxes VDM-Regge =4
f
2-gluon exchange, n =0.75 GeV
g
m =0
g
m W=200 GeV
γ − γ Collider (the International e+e− Linear Collider) ?
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 6 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
(GeV)
γ γ
M
10 20 30 40 50
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
2
10
3
10
4
10
5
10
6
10
realistic
F ,
monopole
F boxes VDM-Regge
>5.5 GeV
γ γ
W =5.5 TeV, UPC
NN
s
γ γ γ γ γ γ γ γ
IP, IR
V V
σmonopole σrealistic
ր for larger values of kinematic variables
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 7 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
number of count
(GeV)
γ γ
M
5 10 15 20 25
(1/GeV)
γ γ
dN/dM
10 20 30 40 50 60
=5.5 TeV, UPC
NN
s γ γ PbPb → PbPb
=1 nb
int
L |<2.5
γ
η >5.5 GeV, |
γ γ
W
several events / GeV Photon collisions: Photonic billiards might be the newest game!
www.eurekalert.org/pub_releases/ 2016-05/thni-pcp051916.php
boxes VDM-Regge cuts Frealistic Fmonopole Frealistic Fmonopole Wγγ > 5 GeV 306 349 31 36 Wγγ > 5 GeV, pt,γ > 2 GeV 159 182 7E-9 8E-9 L Eγ > 3 GeV 16 692 18 400 17 18 Eγ > 5 GeV 4 800 5 450 9 611 H Eγ > 3 GeV, |yγ| < 2.5 183 210 8E-2 9E-2 Eγ > 5 GeV, |yγ| < 2.5 54 61 4E-4 7E-4 C pt,γ > 0.9 GeV, |yγ| < 0.7 (ALICE cuts) 107 pt,γ > 5.5 GeV, |yγ| < 2.5 (CMS cuts) 10 F Wγγ > 5 GeV 6 169 882 C Eγ > 3 GeV 4 696 268 574 C γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 8 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
➳ ATLAS Collaboration (M. Aaboud et al.), Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC, Nature Phys. 13 (2017) 852 ✗ ptγ > 3 GeV ✗ |ηγ| < 2.4 ✗ Mγγ > 6 GeV ✗ ptγγ < 2 GeV ✗ Aco < 0.01 ✔ γγ → γγ - using our calculations ✔ background: ✔ γγ → e+e− ✔ gg → γγ ✔ γγ → q¯ q ✔ 13 events were observed ATLAS ⇒ σ = 70 ± 20(stat.)±17(syst.) nb from ours model ⇒ σ = 49 ± 10 nb PRL (2013)/(2016) ⇒ σ = 45 ± 9 nb
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 9 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
➳ CMS Collaboration, Measurement of light-by-light scattering in ultraperipheral PbPb collisions at √sNN = 5.02 TeV, CMS-PAS-FSQ-16-012
6 8 10 12 14 16 18 20
(GeV)
γ γ
M
2 4 6 8 10 12 14 16
(1/2.5 GeV)
γ γ
dN/dM
γ γ PbPb → PbPb = 5.02 TeV, UPC
NN
s
b µ = 390
int
L
CMS preliminary data 2 − 1 − 1 2
γ
y
2 4 6 8 10 12 14 16 18 20
(1/0.8)
γ
dN/dy
γ γ PbPb → PbPb = 5.02 TeV, UPC
NN
s
b µ = 390
int
L
CMS preliminary data
✗ Etγ > 2 GeV ✗ |ηγ| < 2.4 ✗ Mγγ > 5 GeV ✗ ptγγ < 1 GeV ✗ Aco < 0.01 CMS ⇒ σ = 122 ± 46(stat.)±29(syst.) nb from ours model ⇒ σ = 103 ± 0.034 nb
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 10 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E > 5 GEV
➳ M. K-G, A. Szczurek, π+π− and π0π0 pair production in photon-photon and in ultraperipheral ultrarelativistic heavy ion collisions,
➫ Wγγ ∈ (2mπ − 6) GeV ➫ total cross section & angular distributions ➫ simultaneously for γγ → π+π− & π0π0
[GeV]
π π
= M
γ γ
W
1 2 3 4 5 6
) [nb] π π → γ γ ( σ
10
10 1 10
2
10
3
10
Crystal Ball Belle
x c h a n g e ρ + sum
A A π0 π0 γ γ A A γ γ γ γ
γγ → π0π0
π+ π− ρ π0 π0 π+ π− ρ π0 π0 π
f2(1270) π π f0(980) f0(600) f0(1500) f′
2(1525)
f0(1710) f2(1565) f2(1950) f4(2050)
π+/0 π−/0
p Q C D
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 11 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 5 GEV
signal
A A γ γ γ γ A A
background
A A π0 π0 γ γ A A γ γ γ γ
experiment pseudorapidity range
ALICE
Eγ > 200 MeV LHCb 2.0 < ηγ < 4.5 pt,γ > 200 MeV
(GeV)
γ γ
M
2 4 6 8 10
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
4
10
5
10
6
10
7
10
8
10
9
10 =5.02 TeV, UPC
NN
s > 200 MeV
γ
| < 0.9, E
γ
η | background π π signal γ γ → γ γ (GeV)
γ γ
M
2 4 6 8 10
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
3
10
4
10
5
10
6
10
7
10
8
10
9
10 =5.02 TeV, UPC
NN
s > 200 MeV
γ t,
< 4.5, p
γ
η 2 < background π π signal γ γ → γ γ
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 12 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 5 GEV
γ(p1) γ(p2) γ(p3) γ(p4) ps γ(p1) γ(p2) γ(p3) γ(p4) pt γ(p1) γ(p2) γ(p4) γ(p3) pu
f0(500) f0(980) a0(980) f0(1370) χc0(1P) π0 η η′(958) ηc(1S) ηc(2S) f2(1270) a2(1320) f ′
2(1525)
f2(1565) a2(1700) f4(2050) (GeV) s
1 2 3 4
(pb) σ
10
10 10
3
10
5
10
7
10
γ γ → γ γ fermionic contributions leptons quarks mesonic contributions scalars psudoscalars tensors (2050)
4
f
s−channel diagrams (leading to peaks at √s ∼ = mM) t− and u−channels (leading to broad continua) ➳ P. Lebiedowicz, A. Szczurek, The role of meson exchanges in light-by-light scattering,
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 13 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 5 GEV
η η′(958)
2 4 6 8 10
(GeV)
1
γ
E
5 − 5
1
γ
η
4
10
5
10
6
10
7
10
8
10
9
10
10
10
ALICE LHCb
(pb/GeV)
1γ
dE
1γ
η /d σ
2
d γ γ → η =5.02 TeV,
NN
s
2 4 6 8 10
(GeV)
1
γ
E
5 − 5
1
γ
η
4
10
5
10
6
10
7
10
8
10
9
10
ALICE LHCb
(pb/GeV)
1γ
dE
1γ
η /d σ
2
d γ γ → ’(958) η =5.02 TeV,
NN
s
2 4 6 8 10
(GeV)
1
γ
E
5 − 5
1
γ
η
1 −
10 1 10
2
10
3
10
4
10
ALICE LHCb
(pb/GeV)
1γ
dE
1γ
η /d σ
2
d γ γ → (1S)
C
η =5.02 TeV,
NN
s
2 4 6 8 10
(GeV)
1
γ
E
5 − 5
1
γ
η
1 −
10 1 10
2
10
3
10
4
10
ALICE LHCb
(pb/GeV)
1γ
dE
1γ
η /d σ
2
d γ γ → (1P)
C0
χ =5.02 TeV,
NN
s
2 4 6 8 10
(GeV)
1
γ
E
5 − 5
1
γ
η
1 −
10 1 10
2
10
3
10
4
10
ALICE LHCb
(pb/GeV)
1γ
dE
1γ
η /d σ
2
d γ γ → (2S)
C
η =5.02 TeV,
NN
s
ηc(1S) χc0(1P) ηc(2S)
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 14 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 5 GEV
Mγγ→R→γγ(λ1, λ2) =
γγΓ2 RBr2(R → γγ)
ˆ s − m2
R − imRΓR
× 1 √ 2π δλ1−λ2 ALICE cuts ✔ boxes ✔ bkg ✔ mesons LHCb cuts
(GeV)
γ γ
M
2 4 6 8 10
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
4
10
5
10
6
10
7
10
8
10
9
10
10
10
11
10
12
10
13
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ
| < 0.9, E
γ
η | background π π signal γ γ → γ γ η ’(958) η (1S)
C
η (1P)
C0
χ (2S)
C
η
(GeV)
γ γ
M
2 4 6 8 10
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
4
10
5
10
6
10
7
10
8
10
9
10
10
10
11
10
12
10
13
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ t,
< 4.5, p
γ
η 2 < background π π signal γ γ → γ γ η ’(958) η (1S)
C
η (1P)
C0
χ (2S)
C
η γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 15 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 5 GEV
ENERGY RESOLUTION σEγ Eγ = 1% σEγ Eγ = 0.085
+ 0.003 Eγ + 0.008 ALICE cuts LHCb cuts
(GeV)
γ γ
M
2 4 6 8 10
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
4
10
5
10
6
10
7
10
8
10
9
10
10
10
11
10
12
10
13
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ
| < 0.9, E
γ
η | background π π signal γ γ → γ γ η ’(958) η (1S)
C
η (1P)
C0
χ (2S)
C
η
(GeV)
γ γ
M
2 4 6 8 10
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
4
10
5
10
6
10
7
10
8
10
9
10
10
10
11
10
12
10
13
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ t,
< 4.5, p
γ
η 2 < background π π signal γ γ → γ γ η ’(958) η (1S)
C
η (1P)
C0
χ (2S)
C
η
Energy resolution modifies resonant signals
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 16 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 2 GEV
SCALAR ASYMMETRY AS = p1,t − p2,t p1,t + p2,t
p1,t = pt +
E1
p2,t = pt +
E2
ALICE cuts LHCb cuts
|
t2
p |+|
t1
p | |
t2
p |-|
t1
p |
=
S
A
0.2 0.4 0.6 0.8 1
(pb)
S
)/dA γ γ PbPb → (PbPb σ d
50 100 150 200 250 300 350 400
6
10 ×
=5.02 TeV, UPC
NN
s > 200 MeV
γ
| < 0.9, E
γ
η | background π π signal γ γ → γ γ
|
t2
p |+|
t1
p | |
t2
p |-|
t1
p |
=
S
A
0.2 0.4 0.6 0.8 1
(pb)
S
)/dA γ γ PbPb → (PbPb σ d
20 40 60 80 100 120 140
6
10 ×
=5.02 TeV, UPC
NN
s > 200 MeV
γ t,
< 4.5, p
γ
η 2 < background π π signal γ γ → γ γ
Difficult to separate a region where the γγ → γγ signal wins
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 17 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 2 GEV
ALICE cuts LHCb cuts
(GeV)
γ γ
M
2 3 4 5 6 7 8
(1/100 MeV)
γ γ
dN/dM
2 4 6 8 10 12 14 16 18
γ γ PbPb → PbPb = 5.02 TeV, UPC
NN
s
= 1 nb
int
L > 200 MeV
γ
| < 0.9, E
γ
η |
(GeV)
γ γ
M
2 3 4 5 6 7 8
(1/100 MeV)
γ γ
dN/dM
2 4 6 8 10 12 14 16 18
γ γ PbPb → PbPb = 5.02 TeV, UPC
NN
s
= 1 nb
int
L > 200 MeV
γ t,
< 4.5, p
γ
η 2 <
Energy Wγγ = (0 − 2) GeV Wγγ > 2 GeV Fiducial region ALICE LHCb ALICE LHCb boxes 4 890 3 818 146 79 π0π0 background 135 300 40 866 46 24 η 722 573 568 499 η′(958) 54 241 40 482 ηc(1S) 9 5 χc0(1P) 4 2 ηc(2S) 2 1 γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 18 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 2 GEV
pt,γγ = (| pt1 + pt2|) ALICE cuts LHCb cuts
(GeV)
γ γ t,
p
0.05 0.1 0.15 0.2
(pb/GeV)
γ γ t,
)/dp γ γ PbPb → (PbPb σ d
6
10
7
10
8
10
9
10
10
10
11
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ
| < 0.9, E
γ
η | background π π signal γ γ → γ γ
(GeV)
γ γ t,
p
0.05 0.1 0.15 0.2
(pb/GeV)
γ γ t,
)/dp γ γ PbPb → (PbPb σ d
6
10
7
10
8
10
9
10
10
10
11
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ t,
< 4.5, p
γ
η 2 < background π π signal γ γ → γ γ
Very limited region where the signal overestimates the background
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 19 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION γγ SCATTERING E < 2 GEV
ALICE cuts LHCb cuts
(GeV)
γ γ
M
1 2 3 4
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
4
10
5
10
6
10
7
10
8
10
9
10
10
10
11
10
12
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ
| < 0.9, E
γ
η | background π π sig. γ γ → γ γ η ’(958) η (1S)
C
η (1P)
C0
χ (2S)
C
η
(GeV)
γ γ
M
1 2 3 4
(pb/GeV)
γ γ
)/dM γ γ PbPb → (PbPb σ d
4
10
5
10
6
10
7
10
8
10
9
10
10
10
11
10
12
10
=5.02 TeV, UPC
NN
s > 200 MeV
γ t,
< 4.5, p
γ
η 2 < background π π sig. γ γ → γ γ η ’(958) η (1S)
C
η (1P)
C0
χ (2S)
C
η pt,γγ < 0.005 GeV 0.010 GeV 0.020 GeV
The cuts on pt,γγ seems the most efficient to reduce the background
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 20 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION CONCLUSION
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 21 / 22
MESON2018 γγ FUSION IN
HEAVY ION UPC
EPA γγ SCATTERING
E > 5 GEV E < 5 GEV E < 2 GEV
CONCLUSION CONCLUSION
2 4 6 8 10 12 14
3 −
10
2 −
10
1 −
10 1 10
2
10
3
10
4
10
5
10
6
10
+
µ
+
e
+
τ p p b b c c ρ ρ
+
π π π γ γ
γγ FUSION IN HEAVY ION UPC MESON2018 KRAKÓW, 7-12 JUNE 2018 22 / 22