DIS07

1
LHeC
John Dainton Cockcroft Institute and Univ
Liverpool, Daresbury Science and Innovation
Campus, GB and the University of Liverpool, GB
with M Klein (Univ Liverpool) P Newman (Univ
Birmingham), E Perez (CERN) F Willeke (DESY
Hamburg and BNL) and more and more !

• Why
• How
• 3. When
• 4. Summary

hep-ex/0603016, JINST 1 (2006) P10001, and DIS06
Proceedings
2

• Why?

3
Why Leptons ? Quarks ?
how are leptons and quarks related ?

ICHEP86 Berkeley
put them together at the highest energy at
finest detail
4
TeV eq Kinematic Reach
e?
RL
?
space-like gtTeV
?2007 HERA
-Q2 30,000 GeV2
-seq (300 GeV)2 in 0.7 am
310-7
?2016? LHeC
-Q2 2106 GeV2
-seq (2000 GeV)2 in 0.1 am !
seq gtTeV
LHeC
5
Leptonquark _at_ TeV
?leptoquark systems new physics SM
LHC
LHeC
Re resonance
SM (hadronic) signal LqLq productionS few
0.1 fb (?0.1)
SM (electroweak) signal Lq formation 100 fb
(?0.1)
6
Leptonquark _at_ TeV
?leptoquark systems new physics SM
1 TeV
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Leptonquark _at_ TeV
LHC Lq pairs
LHeC Lq formationdecay
e F0 e- F2
fermion number
_
_
defined formation (eLR) ? precision BRs (NC
CC) inclusive coherence unique PWA SM signal
interference
qq ? g ? Lq Lq production mechanism
? disentangle mass spectrum ?
spin parity and chirality
expl sig
jets leptons
jet(lepton)pT (im)balance
8
Leptonquark _at_ TeV
LHC Lq
LHeC Lq formationdecay
e F0 e- F2
fermion number
_
defined formation (eLR) ? precision BRs (NC
CC) inclusive coherence unique PWA SM signal
interference
gq ? Lq l production mechanism ? disentangle
mass spectrum ?
spin parity and chirality
expl sig
jet leptons
jet(lepton)pT (im)balance
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Leptonquark _at_ TeV
Structure of Matter _at_ TeV
?unique chiral probe _at_ 0.0001 fm ?
e?
?70 ? 7000 GeV e p cm energy 1400
GeV
e?
Manchester
?
Cambridge
Chadwick
SLAC
Q2 y
nucleus
e?
x
nucleon
RL
protonsneutrons
?
Z W
quark
?
QCD
?
NCCCgluon

gEW
SM new Lq physics _at_ 0.0001 fm ?
SM q structure _at_ 0.0001 fm ?
LHeC
?
10
Unification ?
precision ? QCD at highest energy
?short distance structure of SM
- 2006 ? _at_ 10-9 - 2006 GF _at_ 10-5 - 2006 G _at_
0.1 - 2006 ?S _at_ 1-2 - LHeC detector ?
?S few/mil
? precision ? discovery probe new chromodynamic
physics beyond SM ?
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Leptonquark _at_ TeV
Heavy Flavour in HadronChromodynamics
?unique chiral probe _at_ 0.0001 fm ?
?70 ? 7000 GeV e p cm energy 1400
GeV
e?
e?
Manchester
?
Cambridge
Chadwick
SLAC
Q2 y
NC ? Z
nucleus
e?
nucleon
RL
b
protonsneutrons
x
?
Z W
quark
?
?
NCCCgluon

gEW
SM new Lq physics _at_ 0.0001 fm ?
SM _at_ 0.0001 fm heavy flavour
LHeC
?
12
Heavy Flavour in HadronChromodynamics
underpins discovery
?Higgs at LHC
what we know now
what we could know
X?
what we have to find
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Why Dense Colour ?
the origin of mass in the Universe

• "Most of the mass of ordinary matter is
  concentrated in protons and neutrons. It arises
  from a profound, and beautiful, source.
• Numerical simulation of QCD shows that if we
  built protons and neutrons in an imaginary world
  with no Higgs mechanism - purely out of quarks
  and gluons with zero mass - their masses would
  not be very different from what they actually
  are. Their mass arises from pure energy,
  associated with the dynamics of confinement in
  QCD, according to the relation mE/c2. This
  profound account of the origin of mass is a crown
  jewel in our Theory of Matter.
• Frank Wilcek CERN October 11, 2000

probe hadronic matter at highest parton
density at lowest Bjørken-x
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TeV eq Kinematic Reach
Growing Field Energy Density
?2007 HERA
?2016? LHeC
-Q2 1 GeV2
-Q2 1 GeV2
space-like gtTeV
-xBj 510-5
-xBj 510-7
e?
e?
Q2 y
x
310-7
seq gtTeV
LHeC
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Gluon recombination
Growing Field Energy Density
Q2 ? size of gluons
?2016? LHeC
-Q2 1 GeV2
xBj ? phase space for gluons
-xBj 510-7
e?
e?
Q2 y
x
low x large nuclei
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Gluon recombination _at_ LHeC
?ep saturation Q2 5 GeV2 eA saturation Q2
20 GeV2
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Dense Chromodynamics
?low-x rise of F2 - LHeC precision eg x gt
310-3 _at_ Q210000 GeV2 x ßxIP
? low x P physics QCD ? reggeon calculus ?
I
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2.How?
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Proton beam
?standard LHC protons
with electrons?
antiprotons
protons
protons
electrons?
protons
Np epN
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ep Luminosity
?few 10s GeV electrons (LEP 70 GeV!) ?RF power
50 MW 0.86 LEP 28 CERN site ?RF power
synchrotron radiation ? Ie 74 mA
luminosity
7410-31.6710117000/.938

perfect bunch x-ing
4p1.610-193.7510-6?
(m2) cm-2 s-1
L 1.151033/?
L 1033 cm-2s-1 for reasonable p-beam ß 1 m
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ep Luminosity
?astounding !
?102 LNMC µp _at_ 0.01 fm
?LeRHIC epolppol eA _at_ 0.007 fm
?102 LHERA epolp _at_ 0.001 fm
?LLHeC ep eA _at_ 0.00014 fm
indisputably a next step is it feasible ?
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Lepton Ring
?in LEP tunnel so like LEP - FODO in eight
arcs ß-tron phase advance fH108o fV90o -
bending radius 3133.3 m - (dE/Ebeam)rms
1.110-3 - SR 26 W/cm (Ec254 KeV) - scRF _at_
1GHz resonators _at_ 12 MV/m 100 m structure
670 cells ? sync. phase 31o ? bucket takes
10 (dE/Ebeam)rms - unlikely e-beam
instability single bunch current modest
impedance ltlt LEP
7
8
1
6
2
5
3
4
LEP9 W/cm HERA13.5 W/cm
scRF proven _at_ gt 6 MV/m
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ep Collisions
?after B physics _at_ LHC
e
p
civil engineering tunnel 2250m2m Ø _at_IP
LHeC
ep alongside pp data-taking _at_ LHC
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Interaction Region
?highest lumi - low ße close sc quads -
low X-ing angle hard bend SR fan ? sc
p-beam HERA - crab RF cavity
p-bunch rotation
top elevation
crabbed (rotated) p-bunch
V-displaced
3.4 kW
3.2 kW
11.4 kW
3.5 mrad
0.5 mrad
?1o beam access low-lumi/low-x option (cf HERA)
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Operational Luminosity
?beam-beam - hour-glass - dynamic ß lt
HERA - long range beam-beam (parasitic
interactions)
marginal
operational luminosity
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LHeC
?tunnel exists (LEP, LHC) ?injection once
existed (LEP) ? ?operating p-beam (from 2008)
?operating A-beam (from 2008) ?ep eA operating
alongside pp pA AA ?the TeV ep collider
! ?minimal mods to LHC !
?LHC upgrade ?cost ?
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IR and Experiment
?IR many m ?IR 9.4o around beam
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Asymmetric Collider
?asymmetric beam momenta LHeC
TeV
quark
quads ?
p 7 TeV
e 70 GeV
electron
?forward hemisphere detection to multiTeV
topological challenge precision challenge
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3.When?
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Timeline
? 2007 form working groups steering committee
initial meeting of conveners
committee SAC overview ? 2008 workshop I
? 2009 workshop II LHeC
Design Study LHCC ? 2011 TDR -
construction 8 years - installation e-ring above
LHC 1 year - LHeC part of LHC upgrade - be
aware of CLIC progress
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Working Group Structure

• Accelerator (injector, ring)
• Interaction region
• Detector
• The new physics
• High precision QCD
• Low x physics
• eA

tbc (SAC)
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LHeC Scientific Advisory Committee

• Joel Feltesse (Saclay/DESY)
• Guido Altarelli (Roma)
• Rolf Heuer (DESY)
• Aharon Levy (Tel Aviv)
• Lev Lipatov (Petersburg)
• Allen Caldwell (MPI Muenchen)
• Young-Kee Kim (Fermilab)
• Jos Engelen (CERN)
• Roland Horisberger (PSI)
• Stephen Myers (CERN)
• Stan Brodsky (SLAC)
• Roland Garoby (CERN)
• Ferdinand Willeke (DESY/BNL)
• Swapan Chattopadhyay (Cockcroft Institute)
• Peter Bond (BNL)
  
• Richard Milner (MIT)
• John Dainton (University of Liverpool)

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4.Summary
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Now
?LHeC 70e ? 7000p GeV - can be built -
has startlingly good luminosity 1033 cm-2s-1
grows with LHC pp luminosity - adds
substantially, uniquely, and with synergy to
LHCTeV discovery physics - probes
chromodynamics _at_ new density frontier in
uniquely comprehensive manner with
unchallengable precision synergetically with LHC
pp pA AA
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Lepton quark _at_ TeV
?energy for eq discovery extreme
chromodynamics ?precision for eq discovery eq
understanding extreme chromodynamics ?luminosity
for eq discovery
LHeC and LHC
LHeC and ILC
LHeC and LHC
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In case you were wondering ?
Sir John Cockcroft doing accelerator physics
ca 1950 with 1950 DAQ pencil and paper!
with 1950 graphics ammeter!
voltmeter!
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Lepton-Parton and Parton-Parton ?
ep ? eX
pp ? (jetjet)X
probe-parton
jet
e?
?
?
RL
g q
?
Z W
?
?
jet
pp energy scale 7000?7000 GeV
LHeC energy scale 70?7000 GeV
probep at LHeC scale
xprobe/p 0.01
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LHC probe parton
?probe-parton _at_ x ? 0.01

- xq xU xD xU xD
g q 21
?probe-parton _at_ x 0.01
g q ? 0
mixed LHC probe _at_ LHeC energy
q LHC probe _at_ LHC top energy
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Lepton-Parton and Parton-Parton
ep ? eX
pp ? (jetjet)X
probe-parton
jet
e?
?
?
RL
g q
?
Z W
?
?
jet
precise probe e precise kinematics smaller
kinematic reach but - eq?eq formation ?TeV -
precision at lower xBj10-7
probe g and q kinematics ? larger kinematic
reach x larger ? probe q q/gq/g?eqeq pair
production
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Dense Chromodynamics
?relentless low-x rise of F2 - saturation?
partons must someday recombine - LHeC
precision eg x gt 210-4 _at_ Q21000 GeV2
F2
Q21000 GeV2
x g/p
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Dense Chromodynamics
?relentless low-x rise of F2 - LHeC precision
for x gt 210-4 _at_ Q21000 GeV2
precision pdfs - BFKL? CCFM ? high
density - recombination - saturation ? -
instantons ? - other ons ? - condensates ? -
other ates ?
F2
Q21000 GeV2
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8 gluons/ln x _at_ HERA
xg/p 210-4 _at_ LHeC
10
10-3
x g/p
20 g/nucleon/ln x _at_LHeC in heavy ion ?
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Barber
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Whats been achieved
?Sokolov-Ternov spin-rotators _at_ HERA
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Whats been achieved
?Sokolov-Ternov _at_ LEP70 GeV
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