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���eQCD at the
Large HadronElectron Collider
at CERNNéstor Armesto
Departamento de Física de Partículas and IGFAEUniversidade de Santiago de Compostela
for the LHeC Study group, http://cern.ch/lhec 1
International Spring School of the GDR PH-QCDQCD prospects for future ep and eA colliders
Laboratoire de Physique Théorique, Orsay, June 7th 2012
Contents:
QCD at the LHeC.
I. Introduction.
2. The Large Hadron Electron Collider.
3. Precision QCD:● Parton densities.● Coupling constant.● Heavy flavors.● Jets.● Photoproduction.
4. Small x and eA:● Inclusive measurements and small-x glue.● Inclusive diffraction.● Exclusive diffraction.● Final states.
5. Summary and outlook.
2
CDR to appear within one week;cern.ch/lhec;
LHeC workshop 14-15/6/2012
Related seminar byF. Sabatié on the EIC.
Motivation:
3
● Complementarity of the three kind of collisions for our understanding of the interaction of matter:
QCD at the LHeC: 1. Introduction.
Motivation:
3
● Complementarity of the three kind of collisions for our understanding of the interaction of matter:
QCD at the LHeC: 1. Introduction.
Messages from HERA:
4
● Very good description of F2(c,b) (FL?)within DGLAP, steep gluon in 1/x.
● Large fraction of diffraction σdiff/σtot∼10%(Cooper-Sarkar,
1206.0984).
QCD at the LHeC: 1. Introduction.
Motivation:
5
● HERA: successful but unfinished QCD program - eA, eD, high and small x, new concepts (TMDs,...), instantons, odderon,...
Preliminary; LH
eC D
esign Study Report, C
ERN
2012
QCD at the LHeC: 1. Introduction.
Motivation:
5
● HERA: successful but unfinished QCD program - eA, eD, high and small x, new concepts (TMDs,...), instantons, odderon,...
Preliminary; LH
eC D
esign Study Report, C
ERN
2012
LHC starts to be sensitiveto differences in pdfs!!!
|Z
|y0 0.5 1 1.5 2 2.5 3 3.5
Theo
ry/D
ata
0.91
1.1
| [pb
]Z
/d|y
d
20
40
60
80
100
120
140
160
= 7 TeV)sData 2010 (
MSTW08
HERAPDF1.5
ABKM09
JR09
-1 L dt = 33-36 pb-l+ lZ
Uncorr. uncertainty
Total uncertainty
ATLAS
QCD at the LHeC: 1. Introduction.
6
Global fits:
QCD at the LHeC: 1. Introduction.
nPDFs (I):
Eskola
7QCD at the LHeC: 1. Introduction.
nPDFs (I):
Eskola
7
● Lack of experimental data makes the small-x region unconstrained ⇒
uncertainties on observables.
Salgado
EPS09
‘LHC without HERA’QCD at the LHeC: 1. Introduction.
nPDFs (II):
8
Yellow Report on Hard Probes, 2004
● Lack of data ⇒ models give vastly different
results for the nuclear glues at small scales and x: problem for benchmarking in HIC.
● Available DGLAP analysis at NLO show large uncertainties at small scales and x.● eA colliders not available before ∼ 2020: EIC,LHeC?
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,1.69 GeVvu
PbR
EPS09nDSHKN07
DSSZFGS10
)2=4 GeV2(Q
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,1.69 GeVuPbR
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,1.69 GeVgPbR
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,100 GeVvu
PbR
EPS09nDSHKN07
DSSZFGS10
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,100 GeVuPbR
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,100 GeVgPbR
NLO analysis
QCD at the LHeC: 1. Introduction.
nPDFs (II):
8
Yellow Report on Hard Probes, 2004
● Lack of data ⇒ models give vastly different
results for the nuclear glues at small scales and x: problem for benchmarking in HIC.
● Available DGLAP analysis at NLO show large uncertainties at small scales and x.● eA colliders not available before ∼ 2020: EIC,LHeC?
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,1.69 GeVvu
PbR
EPS09nDSHKN07
DSSZFGS10
)2=4 GeV2(Q
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,1.69 GeVuPbR
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,1.69 GeVgPbR
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,100 GeVvu
PbR
EPS09nDSHKN07
DSSZFGS10
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,100 GeVuPbR
-610 -510 -410 -310 -210 -110 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
x
)2(x,100 GeVgPbR
NLO analysis
Inclusive J/ψQCD at the LHeC: 1. Introduction.
9
Our aims: understanding
● The implications of unitarity in a QFT.
● The behavior of QCD at large energies.
● The hadron wave function at small x.
● The initial conditions for the creation of a dense medium in heavy-ion collisions.
Origin in the early 80’s: GLR, Mueller et al, McLerran-Venugopalan.
xGA(x,Q2s)
πR2AQ2
s
∼ 1 =⇒ Q2s ∝ A1/3x∼−0.3
The ‘QCD phase’ diagram:
QCD at the LHeC: 1. Introduction.
9
Our aims: understanding
● The implications of unitarity in a QFT.
● The behavior of QCD at large energies.
● The hadron wave function at small x.
● The initial conditions for the creation of a dense medium in heavy-ion collisions.
Origin in the early 80’s: GLR, Mueller et al, McLerran-Venugopalan.
xGA(x,Q2s)
πR2AQ2
s
∼ 1 =⇒ Q2s ∝ A1/3x∼−0.3
The ‘QCD phase’ diagram:
QCD at the LHeC: 1. Introduction.
Questions:
● Theory: can the dense regime be described using pQCD techniques? Or non-perturbative - Regge, AdS/QCD,...?
● Phenomenology: where in this plane do present experimental data lie?
Saturation ideas: CGC
10
Hadron wave function
QCD at the LHeC: 1. Introduction.
Saturation ideas: CGC
10
Hadron wave function
Source (frozen)
Classical,Aμ∝1/αs
O(αs)
QCD at the LHeC: 1. Introduction.
DGLAP
BFKL
BK/JIMWLK
DILUTEREGION
DENSEREGION
saturat
ion scale
Q s(x)
ln Q
ln 1
/x
ln QCD
non-
pert
urba
tive
regi
on
DILUTEREGION
DENSEREGION
ln Aln
1/x
eA
ep
[fixed Q]
Status of small-x physics:● Three pQCD-based alternatives to describe small-x ep and eA data:→ DGLAP evolution (fixed order PT).→ Resummation schemes.→ CGC (dipole models and rcBK).Differences lie at moderate Q2(>Λ2QCD) and small x. Hints of deviations from NLO DGLAP at small x (Caola et al’09, Albacete et al’12).
● Unitarity (non-linear effects): where?
11
Two-pronged approach: ↓ x / ↑ A. eA: test/enhance density effects.
QCD at the LHeC: 1. Introduction.
Contents:
QCD at the LHeC.
I. Introduction.
2. The Large Hadron Electron Collider.
3. Precision QCD:● Parton densities.● Coupling constant.● Heavy flavors.● Jets.● Photoproduction.
4. Small x and eA:● Inclusive measurements and small-x glue.● Inclusive diffraction.● Exclusive diffraction.● Final states.
5. Summary and outlook.
12
CDR to appear within one week;cern.ch/lhec;
LHeC workshop 14-15/6/2012
Project:
13
●LHeC@CERN → ep/eA experiment using p/A from the LHC:Ep=7 TeV, EA=(Z/A)Ep=2.75 TeV/nucleon for Pb.● New e+/e- accelerator: Ecm∼1-2 TeV/nucleon (Ee=50-150 GeV).● Requirements:* Luminosity∼1033 cm-2s-1. * Acceptance: 1-179 degrees(low-x ep/eA).* Tracking to 0.1 mrad.* EMCAL calibration to 0.l %.* HCAL calibration to 0.5 %.* Luminosity determination to 1 %.* Compatible with LHCoperation.
x-610 -510 -410 -310 -210 -110
)2 (G
eV2
Q
-110
1
10
210
310
410
510
610 )2(x,Q2,Anuclear DIS - F
Proposed facilities:
LHeCFixed-target data:
NMC
E772
E139
E665
EMC
(Pb, b=0 fm)2sQ
perturbative
non-perturbative
(70 GeV - 2.5 TeV)e-Pb (LHeC)
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Project:
13
●LHeC@CERN → ep/eA experiment using p/A from the LHC:Ep=7 TeV, EA=(Z/A)Ep=2.75 TeV/nucleon for Pb.● New e+/e- accelerator: Ecm∼1-2 TeV/nucleon (Ee=50-150 GeV).● Requirements:* Luminosity∼1033 cm-2s-1. * Acceptance: 1-179 degrees(low-x ep/eA).* Tracking to 0.1 mrad.* EMCAL calibration to 0.l %.* HCAL calibration to 0.5 %.* Luminosity determination to 1 %.* Compatible with LHCoperation.
x-610 -510 -410 -310 -210 -110
)2 (G
eV2
Q
-110
1
10
210
310
410
510
610 )2(x,Q2,Anuclear DIS - F
Proposed facilities:
LHeCFixed-target data:
NMC
E772
E139
E665
EMC
(Pb, b=0 fm)2sQ
perturbative
non-perturbative
(70 GeV - 2.5 TeV)e-Pb (LHeC)
Requirements LHeC HERA How?
high lumi for high x and Q2 10^33 1-5×1031
large acceptance 1-179 deg. 7-177 deg. kinematic coverage
tracking 0.1 mrad 0.2-1 mrad modern Si
EMcal 0.1 ℅ 0.2-0.5 ℅ kinematic reconstruction
Hcal 0.5 ℅ 1 ℅ tracking + calo e/h
accurate lumi/pol 0.5 ℅ 1 ℅ demanding
QCD at the LHeC: 2. The Large Hadron Electron Collider.
!"#$%&$'()*'+(),-'.-/'!"#$%&$'
!0-&%$%1)'234'()*'
56-&701/-(8'!"#$%&$'
.9&6-(0''
:709&790-''
;'4#)(<%&$'
=%,"'!(071)'4-)$%>-$'
?(0,-'@'
!(071)$'
Physics goals:
14
● Proton structure to a few 10-20 m: Q2 lever arm.
● Precision QCD/EW physics.
● High-mass frontier (leptoquarks, excited fermions, contact interactions).
● Unambiguous access, in ep and eA, to a qualitatively novel regime of matter predicted by QCD.
● Substructure/parton dynamics inside nuclei with strong implications on QGP search.
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Power constraintsand designconsiderations:
15QCD at the LHeC: 2. The Large Hadron Electron Collider.
Machine: Ring-Ring option
16
BYPASS
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Machine: Ring-Ring option
16
BYPASS
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
eD: LeN=ALeA>∼1031 cm-2s-1.
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Machine: Linac-Ring option
17
Prel
imin
ary;
Boga
cz@
DIS
11; L
HeC
D
esig
n St
udy
Rep
ort,
CER
N 2
012
500 MeV
HE LR, 140 GeV
HE LR, ER, 140 GeV
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Machine: Linac-Ring option
17
Prel
imin
ary;
Boga
cz@
DIS
11; L
HeC
D
esig
n St
udy
Rep
ort,
CER
N 2
012
500 MeV
HE LR, 140 GeV
HE LR, ER, 140 GeV
eD: LeN=ALeA>∼3×1031 cm-2s-1.Large L for e+ challenging.
QCD at the LHeC: 2. The Large Hadron Electron Collider.
e
RR, high acceptance
p
The detector: low-x/eA setup
18
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
QCD at the LHeC: 2. The Large Hadron Electron Collider.
e
RR, high acceptance
p
The detector: low-x/eA setup
18
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
pe
LR
QCD at the LHeC: 2. The Large Hadron Electron Collider.
e
RR, high acceptance
p
The detector: low-x/eA setup
18
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
pe
LR
QCD at the LHeC: 2. The Large Hadron Electron Collider.
e
RR, high acceptance
p
The detector: low-x/eA setup
18
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
pe
LR● Other detector options: low acceptance (8o-172o), solenoid outside, also considered.● Plus luminosity detector, electron tagging, polarimeter, ZDC and leading proton detector.
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Ax
-510 -410
-310 -210 -110 1
)2
(G
eV
2;
Q2 T
; E
2 Tm
1
10
210
310
410
510
610Jets
Photons
|<0.9!Hadrons |
|<0.9!D’s |
|<-2.5!’s from B’s -4<|!
pA Ap
(x)2
satQ
Present
DIS+DY
data
ALICE expected reach in 1 yr. pA(Ap) collisions
Kinematics:
19Ax
-510 -410
-310 -210 -110 1
)2
(G
eV
2Q
1
10
210
310
410
510
610
|<5!Jets |
|<3!Photons |
|<2.5!Hadrons |
(x)2
satQ
Present
DIS+DY
data
CMS expected reach in 1 yr. pA(Ap) collisions
Salgado
● ep: access to the perturbative region below x ∼ a few 10-5.● eA: new realm.● No small-x physics without ∼ 1 degree acceptance.
Salgado
Black: 920+30 Green: 100+20
Q2sat,GBW
2081/3Q2sat,GBW
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Ax
-510 -410
-310 -210 -110 1
)2
(G
eV
2;
Q2 T
; E
2 Tm
1
10
210
310
410
510
610Jets
Photons
|<0.9!Hadrons |
|<0.9!D’s |
|<-2.5!’s from B’s -4<|!
pA Ap
(x)2
satQ
Present
DIS+DY
data
ALICE expected reach in 1 yr. pA(Ap) collisions
Kinematics:
19Ax
-510 -410
-310 -210 -110 1
)2
(G
eV
2Q
1
10
210
310
410
510
610
|<5!Jets |
|<3!Photons |
|<2.5!Hadrons |
(x)2
satQ
Present
DIS+DY
data
CMS expected reach in 1 yr. pA(Ap) collisions
Salgado
● ep: access to the perturbative region below x ∼ a few 10-5.● eA: new realm.● No small-x physics without ∼ 1 degree acceptance.
Salgado
Black: 920+30 Green: 100+20
Q2sat,GBW
2081/3Q2sat,GBW
Preliminary; LHeC Design Study Report, CERN 2012
QCD at the LHeC: 2. The Large Hadron Electron Collider.
LHeC scenarios:
20
● For FL: 10, 25, 50 + 2750 (7000); Q2≤sx; Lumi=5,10,100 pb-1 respectively; charm and beauty: same efficiencies in ep and eA.
10-310-410-4
I 50 3.5 Ca 5⋅10-4 ? 5⋅10-3 ? ? eCa
For F2
Preliminary; LH
eC D
esign Study Report, C
ERN
2012
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Kinematics: LHC vs. LHeC
21
Salgado
d’Enterria(Ee=140GeV and Ep=7TeV)
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
● Existing ep: pp@LHC at y=0; eA: not even dAu@RHIC.● LHeC: clean scan of the LHC x-Q2 domain.
Kinematics: LHC vs. LHeC
21
Salgado
d’Enterria(Ee=140GeV and Ep=7TeV)
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
● Existing ep: pp@LHC at y=0; eA: not even dAu@RHIC.● LHeC: clean scan of the LHC x-Q2 domain.
x -610 -510 -410 -310 -210 -110 1
)2 (G
eV2
Q
-210
-110
1
10
210
310
410
510 : QUltra-peripheral Q (|y| < 2.5)ΥLHC
(|y| < 2.5)ΨLHC J/
Nuclear DIS & DY data:NMC (DIS)SLAC-E139 (DIS)FNAL-E665 (DIS)EMC (DIS)FNAL-E772 (DY)
(Pb, b=0 fm)2sQ
perturbative
non-perturbative
Contents:
QCD at the LHeC.
I. Introduction.
2. The Large Hadron Electron Collider.
3. Precision QCD:● Parton densities.● Coupling constant.● Heavy flavors.● Jets.● Photoproduction.
4. Small x and eA:● Inclusive measurements and small-x glue.● Inclusive diffraction.● Exclusive diffraction.● Final states.
5. Summary and outlook.
22
CDR to appear within one week;cern.ch/lhec;
LHeC workshop 14-15/6/2012
One example of EW process:
23
Roh
ini a
t D
IS20
12
QCD at the LHeC: 3. Precision QCD.
Parton densities:
24
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
Valence quarksHERAPDF-like, GM VFNS
QCD at the LHeC: 3. Precision QCD.
Parton densities:
24
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
Valence quarksHERAPDF-like, GM VFNS
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
10-5
10-4
10-3
10-2
10-1
x
un
ce
rta
inty
on
d/u
Q2 = 4 GeV2
H1 + BCDMS
LHeC ep
LHeC ep+ed
(relaxed low x assumptions in the fit)
Gluon
QCD at the LHeC: 3. Precision QCD.
Parton densities:
24
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
Valence quarksHERAPDF-like, GM VFNS
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
10-5
10-4
10-3
10-2
10-1
x
un
ce
rta
inty
on
d/u
Q2 = 4 GeV2
H1 + BCDMS
LHeC ep
LHeC ep+ed
(relaxed low x assumptions in the fit)
Gluon
● Large improvement in proton and neutron PDFs, both at small and at large x.
QCD at the LHeC: 3. Precision QCD.
DIS extractions of αs
Coupling constant:
25
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
● Open issues on mc, scales, order of perturbation th.,...QCD at the LHeC: 3. Precision QCD.
DIS extractions of αs
Coupling constant:
25
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
● Open issues on mc, scales, order of perturbation th.,...
● Substantial improvement in the less known coupling constant, combination with jets still pending.
QCD at the LHeC: 3. Precision QCD.
● Compared to HERA: higher lumi plus better efficiencies.
Total cross sections in ep collisions
10-3
10-2
10-1
1
10
102
103
104
105
106
8 9 10 20 30 40 50 60 70 80 90 100 200 300
20 30 50 70 100 200
10-3
10-2
10-1
1
101
102
103
104
105
106 Charm γp
Charm DIS
Beauty γpBeauty DIS
tt γptt DIS
bW → tbW → t
CC e-p
sW → cCC e+p
sW → c
Ee (GeV)
σ (p
b)
10
102
103
104
105
106
107
108
109
1010
Even
ts pe
r 10
fb-1
LHeCHERA
Heavy flavors:
26
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
QCD at the LHeC: 3. Precision QCD.
● Compared to HERA: higher lumi plus better efficiencies.
Total cross sections in ep collisions
10-3
10-2
10-1
1
10
102
103
104
105
106
8 9 10 20 30 40 50 60 70 80 90 100 200 300
20 30 50 70 100 200
10-3
10-2
10-1
1
101
102
103
104
105
106 Charm γp
Charm DIS
Beauty γpBeauty DIS
tt γptt DIS
bW → tbW → t
CC e-p
sW → cCC e+p
sW → c
Ee (GeV)
σ (p
b)
10
102
103
104
105
106
107
108
109
1010
Even
ts pe
r 10
fb-1
LHeCHERA
Heavy flavors:
26
Prel
imin
ary;
LHeC
Des
ign
Stud
y R
epor
t, C
ERN
201
2
QCD at the LHeC: 3. Precision QCD.
x=0.0001
x=0.00025
x=0.00035
x=0.0005
x=0.001
x=0.0025
x=0.0035
x=0.005
x=0.01
x=0.012
x=0.018
x=0.025
x=0.040
x=0.055
x=0.08
Q2/GeV
2
an
ti-s
tra
ng
e d
ensi
ty [
3j ]
!c=0.1, bgdq=0.01
LHeC e-p 60*7000 GeV
2 10 fb
-1
102
103
104
10510
-2
10-1
100
101
102
103
104
105
106
107
108
Q2/GeV
2
an
ti-s
tra
ng
e d
ensi
ty [
3j ]
!c=0.1, bgdq=0.01
LHeC e-p 60*7000 GeV
2 10 fb
-1
102
103
104
10510
-2
10-1
100
101
102
103
104
105
106
107
108
Jets:
27
Prel
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● Jets: large ET even in eA.● Useful for studies of parton dynamics in nuclei (hard probes), and for photon structure.● Background subtraction, detailed reconstruction pending.
QCD at the LHeC: 3. Precision QCD.
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Photoproduction cross section:
28
Prel
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LHeC
Des
ign
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● Small angle electron detector 62 m far from the interaction point: Q2<0.01 GeV, y∼0.3 ⇒ W∼0.5 √s.
● Substantial enlarging of the lever arm in W.
Pancheri et al ‘08
QCD at the LHeC: 3. Precision QCD.
Implications for UHEν’s:
29
● ν-n/A cross section (τ energy loss) dominated by DIS structure functions / (n)pdfs at small-x and large (small) Q2.● Key ingredient for estimating fluxes.
σtotνn
Preliminary; LHeC Design Study Report, CERN 2012QCD at the LHeC: 3. Precision QCD.
Contents:I. Introduction.
2. The Large Hadron Electron Collider.
3. Precision QCD:● Parton densities.● Coupling constant.● Heavy flavors.● Jets.● Photoproduction.
4. Small x and eA:● Inclusive measurements and small-x glue.● Inclusive diffraction.● Exclusive diffraction.● Final states.
5. Summary and outlook.
30
CDR to appear within one week;cern.ch/lhec;
LHeC workshop 14-15/6/2012
QCD at the LHeC.
ep inclusive: comparison
31
● Extensive model comparison: LHeC will have discriminative power.● Note: size of radiative corrections pending(see the talk by Spiesberger at DIS2012).
Preliminary; LHeC Design Study Report, CERN 2012
x-610 -510 -410 -310 -210 -110 1
)2 (G
eV2
Q
1
10
210
310
410
NMC-pdNMCSLACBCDMSZEUSH1CHORUSFLH108NTVDMNZEUS-H2LHeC_F2+FL
QCD at the LHeC: 4. Small x and eA.
ep inclusive: extracting the glue
32
● LHeC substantially reduces the uncertainties in global fits: FL and heavy flavor decomposition most useful.
Prel
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QCD at the LHeC: 4. Small x and eA.
33
● Tension between F2 and FL in DGLAP fits as a sign of physics beyond standard DGLAP (GBW and CGC models).
Preliminary; LHeC Design Study Report, CERN 2012
ep inclusive: searching
QCD at the LHeC: 4. Small x and eA.
33
● Tension between F2 and FL in DGLAP fits as a sign of physics beyond standard DGLAP (GBW and CGC models).
Preliminary; LHeC Design Study Report, CERN 2012
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1e-06 1e-05 0.0001
F Lp (x
,Q2 )
x
Q2=2 GeV2
LHeC AAMS09NNPDF fit
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1e-06 1e-05 0.0001 0.001x
Q2=5 GeV2
LHeC AAMS09NNPDF fit
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1e-05 0.0001 0.001
F Lp (x
,Q2 )
x
Pseudo-data from AAMS09 (BK + running coupling)
Q2=13.5 GeV2
LHeC AAMS09NNPDF fit
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1e-05 0.0001 0.001x
Pseudo-data from AAMS09 (BK + running coupling)
Q2=30 GeV2
LHeC AAMS09NNPDF fit
ep inclusive: searching
QCD at the LHeC: 4. Small x and eA.
eA inclusive: comparison
34
● Good precision can be obtained for F2(c,b) and FL at small x (Glauberized 3-5 flavor GBW model, NA ’02).
F2cPb F2bPb
-510 -410 -310 -210 -1100
0.2
0.4
0.6
0.8
1
1.2
x
)2(x,5 GeVLF
PbR
EPS09nDSHKN07
FGS10AKST
Data: LHeC
Prel
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-510 -410 -310 -210 -1100
0.2
0.4
0.6
0.8
1
1.2
x
)2(x,5 GeV2F
PbR
EPS09nDSHKN07
DSSZFGS10AKST
Data: LHeC
QCD at the LHeC: 4. Small x and eA.
eA inclusive: constraining pdfs
35
● F2 data substantially reduce the uncertainties in DGLAP analysis; inclusion of charm, beauty and FL done.
QCD at the LHeC: 4. Small x and eA.
36
Prel
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2● F2 data substantially reduce the uncertainties in DGLAP analysis; inclusion of charm, beauty and FL produce minor improvements.
eA inclusive: constraining pdfs
QCD at the LHeC: 4. Small x and eA.
36
Prel
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2● F2 data substantially reduce the uncertainties in DGLAP analysis; inclusion of charm, beauty and FL produce minor improvements.
eA inclusive: constraining pdfs
QCD at the LHeC: 4. Small x and eA.
Note: FL in eA
37
● FL traces the nuclear effects on the glue (Cazarotto et al ’08).● Uncertainties in the extraction of F2 due to the unknown nuclear effects on FL of order 5 % (larger than expected stat.+syst.) ⇒
measure FL or use the reduced cross section (but then ratios at two energies...).
NA, Paukkunen, Salgado, Tywoniuk, ‘10
QCD at the LHeC: 4. Small x and eA.
ep diffractive pseudodata:
38
● Large increase in the M2, xP=(M2-t+Q2)/(W2+Q2), β=x/xP region studied.● Possibility to combine LRG and LPS.
e
10 3
10 4
10 5
10 6
10 7
10 8
0 50 100 150 200 250
LHeC (Ee = 50 GeV, 2 fb-1)
HERA (500 pb-1)
Diffractive event yield (xIP < 0.05, Q2 > 1 GeV2)
MX / GeV
Even
ts
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QCD at the LHeC: 4. Small x and eA.
ep diffractive pseudodata:
38
● Large increase in the M2, xP=(M2-t+Q2)/(W2+Q2), β=x/xP region studied.● Possibility to combine LRG and LPS.
e
10 3
10 4
10 5
10 6
10 7
10 8
0 50 100 150 200 250
LHeC (Ee = 50 GeV, 2 fb-1)
HERA (500 pb-1)
Diffractive event yield (xIP < 0.05, Q2 > 1 GeV2)
MX / GeV
Even
ts
Note: diffraction in ep is linked to shadowing in eA(Gribov): FGS, Capella-Kaidalov et al,...
Prel
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QCD at the LHeC: 4. Small x and eA.
Diffraction and non-linear dynamics:
39
0
0.02
0.04
0.06
0.08
0.1
10-2
10-1
xIP=0.00001Q2=3 GeV2x IP
F 2D
10-2
10-1
xIP=0.0001Q2=3 GeV2
10-3
10-2
10-1
xIP=0.001Q2=3 GeV2
0
0.05
0.1
0.15
10-2
10-1
10-2
10-1
xIP=0.0001Q2=30 GeV2
10-2
10-1
xIP=0.001Q2=30 GeV2
0
0.02
0.04
0.06
0.08
0.1
10-1
H1 fit BipsatbCGC
Ee=150 GeV, 1o
10-1
10-2
10-1
xIP=0.001Q2=300 GeV2
0
0.05
0.1
0.15
10-2
10-1
xIP=0.00001Q2=3 GeV2x IP
F 2D
10-2
10-1
xIP=0.0001Q2=3 GeV2
10-2
10-1
xIP=0.001Q2=3 GeV2
0
0.025
0.05
0.075
0.1
10-2
10-1
10-2
10-1
xIP=0.0001Q2=30 GeV2
10-2
10-1
xIP=0.001Q2=30 GeV2
0
0.02
0.04
0.06
0.08
0.1
10-1
H1 fit BipsatbCGC
Ee=50 GeV, 1o
10-1
10-1
xIP=0.001Q2=300 GeV2
● Dipole models show differences with linear-based extrapolations (HERA-based dpdf’s) and among each other: possibility to check saturation and its realization.
Prel
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β βQCD at the LHeC: 4. Small x and eA.
Diffractive dijets:
40
● Diffractive dijet and open heavy flavour production offer large possibilities for:→ Checking factorization in hard diffraction.→ Constraining DPDFs.
● Large yields upto large pTjet.
● Direct and resolved contributions: photon PDFs.Pr
elim
inar
y; LH
eC D
esig
n St
udy
Rep
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CER
N 2
012
QCD at the LHeC: 4. Small x and eA.
p(P) )Y
Y (P
IPx
IPz (v)
* (q)γ (u)
e(k) e(k’)
jet
jet)
XX(P
GAP
remnant
e(k) e(k’)
* (q)γ
(u)
jet 12M )X
X(P
(v)IPz
remnant
GAP
p(P) )Y
Y (P
jet
remnant
(a) (b)
12M
IPx
[GeV]jet1TP
15 20 25 30 35 40 45 50 55
]-1
[fb
GeV
jet1
T/d
Pσd
-510
-410
-310
-210
-110
1
10
210
310
410 ]-1
[GeV
jet1
TdN
/dE
-310
-210
-110
1
10
210
310
410
510
610
[GeV]jet1TP
15 20 25 30 35 40 45 50 55
]-1
[fb
GeV
jet1
T/d
Pσd
-510
-410
-310
-210
-110
1
10
210
310
410)-1>2 (100 fb2Diffractive DIS Q
NLOJET++ (NLO)
Diffractive DIS on nuclear targets:
41
● Challenging experimental problem, requires Monte Carlo simulation with detailed understanding of the nuclear break-up.
● For the coherent case, predictions available.
0
0.05
0.1
0.15
10 -2
xIP=0.00001Q2=3 GeV2x IP
F 2D
10 -2
xIP=0.0001Q2=3 GeV2
10 -3 10 -1
xIP=0.001Q2=3 GeV2
10 -3 10 -1
xIP=0.01Q2=3 GeV2
00.020.040.060.08
0.1
10 -1 10 -1
xIP=0.0001Q2=30 GeV2
10 -2
xIP=0.001Q2=30 GeV2
10 -2
xIP=0.01Q2=30 GeV2
00.020.040.060.08
0.1
10 -1 10 -1 10 -2
xIP=0.001Q2=300 GeV2
10 -2
xIP=0.01Q2=300 GeV2
00.010.020.030.040.05
10-1
H1 fit BipsatbCGC
10-1
Pb
10-1
10-1
xIP=0.01Q2=3000 GeV2Pr
elim
inar
y; LH
eC D
esig
n St
udy
Rep
ort,
CER
N 2
012
βQCD at the LHeC: 4. Small x and eA.
Elastic VM production in ep:
42
● Most promising!!!
Prel
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QCD at the LHeC: 4. Small x and eA.
Odderon:
43
● Odderon (C-odd exchange contributing to particle-antiparticle difference in cross section) seached inor through O-P interferences.
Prel
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QCD at the LHeC: 4. Small x and eA.
● Sizable charge asymmetry, yields and reconstruction pending.
Elastic VM production in eA:
44
● Many interesting features in the nuclear case (see also Lappi et al ‘10, Horowitz ’11).
Prel
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QCD at the LHeC: 4. Small x and eA.
!*A " J/# A
W (GeV)
1/A
2 d
$/d
t (
µb
/GeV
2)
0
0.5
1
1.5
2
2.5
0 200 400 600 800 1000
DVCS:
45
● Exclusive processes like γ*+h→ρ,ϕ,γ+h give information of GPDs, whose Fourier transform gives a tranverse scanning of the hadron: key importance for both non-perturbative and perturbative aspects, like the possibility of non-linear dynamics.
● Only small-x case where higher luminosity really helps!!!DVCS, Ee=50 GeV, 1o,pTγ,cut=2 GeV, 1 fb-1
DVCS, Ee=50 GeV, 10o,pTγ,cut=5 GeV, 100 fb-1
Preliminary; LHeC Design Study Report, CERN 2012QCD at the LHeC: 4. Small x and eA.
]2 [GeV2Q100 200 300 400 500 600 700
]2dx
[pb/
GeV
2/d
Qσ2
d4Q 1
10
210
x=1.3e-04x=2.4e-04x=4.2e-04x=7.5e-04
x=1.3e-03x=2.4e-03x=4.2e-03x=7.5e-03
]2 [GeV2Q5 10 15 20 25 30 35 40
]2dx
[pb/
GeV
2/d
Qσ2
d4Q
210
310 x=4.7e-05x=1.1e-04x=2.4e-04x=5.3e-04
x=1.2e-03x=2.7e-03x=6.0e-03x=1.3e-02
Transversity GPDs:
46
● Chiral-odd transversity GPDs are largely unknown.
● They can be accessed through double exclusive production:
Preliminary; LH
eC D
esign Study Report, C
ERN
2012
QCD at the LHeC: 4. Small x and eA.
10-4
10-3
10-2
10-1
100
101
102
103
104
105
10-5 10-4 10-3 10-2 10-1 100
d!
/dp
T2 d
t d
" [nb G
eV
-4]
"
pT2 = 2 GeV2
4 GeV2
6 GeV2
10-4
10-3
10-2
10-1
100
101
102
103
10-5 10-4 10-3 10-2 10-1 100
d!
/dp
T2 d
t d
" [
nb
Ge
V-4
]
"
Q2 = 2 GeV2
4 GeV2
6 GeV2
! "0
"+
p T
r
J
S
IP
p nF
Dijet azimuthal decorrelation:
47
● Studying dijet azimuthal decorrelation or forward jets (pT∼Q) would allow to understand the mechanism of radiation:→ kT-ordered: DGLAP.→ kT-disordered: BFKL.→ Saturation?● Further imposing a rapidity gap(diffractive jets) would be mostinteresting: perturbativelycontrollable observable.
Preliminary; LHeC Design Study
Report, CERN 2012
103
104
105
106
107
108
109
1010
d2 !
/dxd
|"#|
(pb
)
1 10-7
< x < 1 10-6
50 e x 7000 p
1 10-7
< x < 1 10-6
50 e x 7000 p
1 10-7
< x < 1 10-6
50 e x 7000 p
1 10-6
< x < 1 10-5
1 10-6
< x < 1 10-5
1 10-6
< x < 1 10-5
1 10-5
< x < 1 10-4
1 10-5
< x < 1 10-4
1 10-5
< x < 1 10-4
103
104
105
106
107
108
109
1010
1 2 3
1 10-4
< x < 1 10-3
1 10-4
< x < 1 10-3
1 10-4
< x < 1 10-3
1 2 3
"#
1 10-3
< x < 1 10-2
1 10-3
< x < 1 10-2
1 10-3
< x < 1 10-2
k = 0t
!"# < 120 o
!"#
j1
j2
j2
j1
QCD at the LHeC: 4. Small x and eA.
Forward jets:
48
● Studying dijet azimuthal decorrelation or forward jets (pT∼Q) would allow to understand the mechanism of radiation:→ kT-ordered: DGLAP.→ kT-disordered: BFKL.→ Saturation?● Further imposing a rapidity gap(diffractive jets) would be mostinteresting: perturbativelycontrollable observable.
Preliminary; LHeC Design Study
Report, CERN 2012
QCD at the LHeC: 4. Small x and eA.
Dihadron azimuthal decorrelation:
49
● Dihadron azimuthal decorrelation is currently discussed at RHIC as one of the most suggestive indications of saturation.
● At the LHeC it could be studied far from the kinematical limits.
Preliminary; LHeC Design Study
Report, CERN 2012
QCD at the LHeC: 4. Small x and eA.
Albacete-Marquet ’10 pTlead>3 GeVpTass>2 GeVzlead=zass=0.3
y=0.7Q2=4 GeV2
50
● Low energy: need of hadronization inside → formation time, (pre-)hadronic absorption,...
● High energy: partonic evolution altered in the nuclear medium, partonic energy loss.
● The LHeC (νmax∼105 GeV) would allow to study the dynamics of hadronization, testing the parton/hadron eloss mechanism by introducing a length of colored material which would modify its pattern (length/nuclear size, chemical composition).
Brooks at Divonne’09
In-medium hadronization (I):
QCD at the LHeC: 4. Small x and eA.
5o<θπ<25o, xπ>0.01
Daleo et al. ’04Data: H1 ’04
formation timeeffects
In-medium hadronization (II):
51
● Large (NLO) yields at small-x (H1 cuts, 3 times higher if relaxed).● Nuclear effects in hadronization at small ν (LO plus QW, Arleo ’03).
QCD at the LHeC: 4. Small x and eA.
In-medium hadronization (II):
51
● Large (NLO) yields at small-x (H1 cuts, 3 times higher if relaxed).● Nuclear effects in hadronization at small ν (LO plus QW, Arleo ’03).
QCD at the LHeC: 4. Small x and eA.
Prel
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2
0
1500
3000
4500
6000
0
200
400
600
d!
"/d
xB
(nb
)
2 # Q2 # 8 GeV
2MSTW-DSS (ep)
MSTW-DSS (ePb)
nDS-DSS (ePb)
nDS-nFF (ePb)
EPS09-DSS (ePb)
60+7000
60+2750
8 # Q2 # 20 GeV
2
xBj
20 # Q2 # 70 GeV
2
pT $ 3.5 GeV0
70
140
10-6
10-5
10-4
d!
"/d
pT
(pb
/GeV
)
2 # Q2 # 4.5 GeV
2
1
10
MSTW-DSS
MSTW-DSS (Pb)
nDSS-DSS (Pb)
nDS-nFF (Pb)
EPS-DSS (Pb)
60+7000
60+2750
4.5 # Q2 # 15 GeV
2
1
10
pT (GeV)
15 # Q2 #70 GeV
2
1
10
3 4 5 6 7 8 9 10 15
In-medium hadronization (II):
51
● Large (NLO) yields at small-x (H1 cuts, 3 times higher if relaxed).● Nuclear effects in hadronization at small ν (LO plus QW, Arleo ’03).
QCD at the LHeC: 4. Small x and eA.
Prel
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Summary:
52
● Many issues open about precision pQCD and small-x physics.
● Pdfs: current ep experiments cover pp@LHC at y=0; in eA, not even dAu@RHIC is really constrained.
● An ep/eA collider offers huge possibilities to test our ideas about QCD: hadron structure, high-energy behavior, radiation,...
● eA: amplifier of density effects, implications on UrHIC complementary to pA@LHC.
● At an LHeC@CERN:➜ Unprecedented access to small x in p and A for pdfs.➜ Novel sensitivity to physics beyond standard pQCD.➜ Stringent tests of the dynamics of QCD radiation.➜ High precision tests of collinear factorization(s).➜ Transverse scanning of the hadron at small x.➜ ...
QCD at the LHeC.
53
Prel
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2Commitees and authors:
QCD at the LHeC.
53
Prel
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LHeC
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2Commitees and authors:
QCD at the LHeC.
53
Prel
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The LHeC Study Grouphttp://cern.ch/lhec
June 14-15 2012
Commitees and authors:
QCD at the LHeC.
Tentative timeline:
54QCD at the LHeC.
Tentative timeline:
54
Preliminary; LHeC Design Study Report, CERN 2012QCD at the LHeC.
Tentative timeline:
54
Preliminary; LHeC Design Study Report, CERN 2012
→ LHC death by radiation damage estimated by 2030-2035.
→ LHeC should work for ∼ 10 years.
→ No disturbance to LHC operation: built on surface, installation during LS3.
⇒QCD at the LHeC.
Tentative timeline:
54
Preliminary; LHeC Design Study Report, CERN 2012
→ LHC death by radiation damage estimated by 2030-2035.
→ LHeC should work for ∼ 10 years.
→ No disturbance to LHC operation: built on surface, installation during LS3.
⇒QCD at the LHeC.
Tentative timeline:
54
Preliminary; LHeC Design Study Report, CERN 2012
→ LHC death by radiation damage estimated by 2030-2035.
→ LHeC should work for ∼ 10 years.
→ No disturbance to LHC operation: built on surface, installation during LS3.
⇒QCD at the LHeC.
Tentative timeline:
54
Preliminary; LHeC Design Study Report, CERN 2012
→ LHC death by radiation damage estimated by 2030-2035.
→ LHeC should work for ∼ 10 years.
→ No disturbance to LHC operation: built on surface, installation during LS3.
⇒Thanks to the organizers for the invitation!!!
Thanks to you all for your attention!!!
QCD at the LHeC.
Backup:
55QCD at the LHeC.
The detector: some details
56QCD at the LHeC: 2. The Large Hadron Electron Collider.
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The detector: some details
56QCD at the LHeC: 2. The Large Hadron Electron Collider.
Prel
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LHeC
Des
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/
Features in dAu@RHIC:
57
● Control experiment for initial state effects in AA: Cronin in dAu at midrapidity ruled out initial state effects as the explanation for the suppression observed in AA.● Suppression at forward rapidities predicted by small-x evolution.● Azymuthal decorrelation in the forward region also seen.
Albacete-Marquet ’10
QCD at the LHeC: 2. The Large Hadron Electron Collider.
/
Features in dAu@RHIC:
57
● Control experiment for initial state effects in AA: Cronin in dAu at midrapidity ruled out initial state effects as the explanation for the suppression observed in AA.● Suppression at forward rapidities predicted by small-x evolution.● Azymuthal decorrelation in the forward region also seen.
Albacete-Marquet ’10
QCD at the LHeC: 2. The Large Hadron Electron Collider.
/
Features in dAu@RHIC:
57
● Control experiment for initial state effects in AA: Cronin in dAu at midrapidity ruled out initial state effects as the explanation for the suppression observed in AA.● Suppression at forward rapidities predicted by small-x evolution.● Azymuthal decorrelation in the forward region also seen.
Albacete-Marquet ’10
QCD at the LHeC: 2. The Large Hadron Electron Collider.
/
Features in dAu@RHIC:
57
● Control experiment for initial state effects in AA: Cronin in dAu at midrapidity ruled out initial state effects as the explanation for the suppression observed in AA.● Suppression at forward rapidities predicted by small-x evolution.● Azymuthal decorrelation in the forward region also seen.
Albacete-Marquet ’10
● Saturation physics describes these data, but:➜ The normalization is not determined by the calculation ↔ problems to compute the b-dependence.
➜ A full NLO analysis is still missing.➜ RHIC data lie at the edge of phase space.
● Other descriptions exist: NLO pQCD (problems with pp reference), eloss models,...
● Note: these studies are very important to understand the mechanism of soft/semihard particle production: ridge, initial conditions for HIC, isotropization,...⇒ ‘benchmarking’
the bulk.
QCD at the LHeC: 2. The Large Hadron Electron Collider.
UPCs in pPb:
58
● Large luminosities in γp.● Interesting kinematical coverage.
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QCD at the LHeC: 2. The Large Hadron Electron Collider.
UPCs in pPb:
58
● Large luminosities in γp.● Interesting kinematical coverage.
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(Pb, b=0 fm)2sQ
perturbative
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Preliminary; LHeC Design Study Report, CERN 2012QCD at the LHeC: 2. The Large Hadron Electron Collider.
Kinematics: LHC vs. LHeC
59
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LHeCFixed-target data:
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E665
EMC
(Pb, b=0 fm)2sQ
perturbative
non-perturbative
(70 GeV - 2.5 TeV)e-Pb (LHeC)
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● Existing ep: pp@LHC at y=0; eA: not even dAu@RHIC.● LHeC: clean scan of the LHC x-Q2 domain.
pA@LHC, Salgado et al., 1105.3919
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Introduction:
60
● At the SPS and at RHIC, pA (dAu) runs have been an essential part of the heavy-ion programs. Prominent examples:
➜ SPS: J/ψ absorption in pA → anomalous suppression in PbPb.➜ RHIC: Cronin in dAu → jet quenching in AuAu as a final state effect.
● A pPb run @LHC with <L>∼1029(/3)cm-2s-1 for ∫Ldt∼0.1(/3)
pb-1 in the 2012 run (4.4-5 TeV/n instead of nominal 8.8).
● Rapidity shift (0.46) due to asymmetricsystem, smaller for dPb (0.12) but no injector:p+Pb and Pb+p (ALICE μ-arm, LHCb).
● All LHC experiments with capabilities for this running mode: ALICE, ATLAS, CMS, LHCb, LHCf,...
● Check in November 2011, approved in Chamonix last February.PHENIX, π0
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Introduction:
60
● At the SPS and at RHIC, pA (dAu) runs have been an essential part of the heavy-ion programs. Prominent examples:
➜ SPS: J/ψ absorption in pA → anomalous suppression in PbPb.➜ RHIC: Cronin in dAu → jet quenching in AuAu as a final state effect.
● A pPb run @LHC with <L>∼1029(/3)cm-2s-1 for ∫Ldt∼0.1(/3)
pb-1 in the 2012 run (4.4-5 TeV/n instead of nominal 8.8).
● Rapidity shift (0.46) due to asymmetricsystem, smaller for dPb (0.12) but no injector:p+Pb and Pb+p (ALICE μ-arm, LHCb).
● All LHC experiments with capabilities for this running mode: ALICE, ATLAS, CMS, LHCb, LHCf,...
● Check in November 2011, approved in Chamonix last February.
QCD at the LHeC: 2. The Large Hadron Electron Collider.
Introduction:
60
● At the SPS and at RHIC, pA (dAu) runs have been an essential part of the heavy-ion programs. Prominent examples:
➜ SPS: J/ψ absorption in pA → anomalous suppression in PbPb.➜ RHIC: Cronin in dAu → jet quenching in AuAu as a final state effect.
● A pPb run @LHC with <L>∼1029(/3)cm-2s-1 for ∫Ldt∼0.1(/3)
pb-1 in the 2012 run (4.4-5 TeV/n instead of nominal 8.8).
● Rapidity shift (0.46) due to asymmetricsystem, smaller for dPb (0.12) but no injector:p+Pb and Pb+p (ALICE μ-arm, LHCb).
● All LHC experiments with capabilities for this running mode: ALICE, ATLAS, CMS, LHCb, LHCf,...
● Check in November 2011, approved in Chamonix last February.
QCD at the LHeC: 2. The Large Hadron Electron Collider.
pPb at the LHC:
61
● Offers the best possibility (before lepton-ion colliders) to test:➜ The small-x glue far from the kinematical limits.➜ The production mechanism: clear differences between collinear factorization and saturation?
Jalilian-Marian & Rezaeian, 1110.2810QCD at the LHeC: 2. The Large Hadron Electron Collider.
pPb at the LHC:
61
● Offers the best possibility (before lepton-ion colliders) to test:➜ The small-x glue far from the kinematical limits.➜ The production mechanism: clear differences between collinear factorization and saturation?
Jalilian-Marian & Rezaeian, 1110.2810QCD at the LHeC: 2. The Large Hadron Electron Collider.
Summary:
62
● A pPb run at the LHC offers huge possibilities (unique before lA colliders) for:A) Benchmarking for the HIC program, particularly for reducing uncertainties coming from nPDFs:
B) Discovery: clarifying the relevance of saturation physics.
C) Others: UPCs, measurements of interest for UHECR.QCD at the LHeC: 2. The Large Hadron Electron Collider.
Summary:
62
● A pPb run at the LHC offers huge possibilities (unique before lA colliders) for:A) Benchmarking for the HIC program, particularly for reducing uncertainties coming from nPDFs:
B) Discovery: clarifying the relevance of saturation physics.
C) Others: UPCs, measurements of interest for UHECR.Ax
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QCD at the LHeC: 2. The Large Hadron Electron Collider.