a large hadron electron collider at the lhc · max klein glasgow 4.10.2008 a large hadron electron...

Max Klein Glasgow 4.10.2008

A Large Hadron electron Collider at the LHC

LHeC: 5-140 GeV on 1-7 TeV e±p, also eA

Max Klein

[email protected]

Talk at NuPECC, Glasgow, 4.10.08

First ECFA-CERN LHeC WorkshopDivonne (France) 1.-3.9.2008

http://www.lhec.org.uk

Project ScopeProton StructureNuclear StructureDetector StudiesBeam Options

Towards CDR 2009.


HERA*) - ‘an unfinished business’

*) M.K., R.Yoshida, ‘Collider Physics at HERA’’arXiv 0805.3334 [hep-ex], Prog.Part.Nucl.Phys.

HERA II analysis still ongoing

Low x: DGLAP holds though ln1/x is large Saturation not proven

High x: would have required much higher luminosity [u/d ?, xg ?]

Neutron structure not explored

Nuclear structure not explored

New concepts introduced, investigation just started:-parton amplitudes (GPD’s, proton hologram)-diffractive partons-unintegrated partons

Instantons not observed

Odderons not found…

Lepton-quark states not observed

Need:

Higher energy(Q2 =sxy, x≥ Q2/s)

High Luminosity

e+ and e-

lepton polarisation

p, D, A

The LHC is the rightplace for an ep/Acollider to be considered


Physics and RangeHigh mass 1-2 TeVrq few times 10-20 m

High precisionpartons in plateauof the LHC

Nuclear

Structure& dynamics

High Density Matter

Large x

Former considerations:

ECFA Study 84-10

J.Feltesse, R.Rueckl: Aachen Workshop (1990)

The THERA Book (2001)&Part IV of TESLA TDR

3 physics subjectsand working groups:

New PhysicsQCD+electroweakHigh parton densities


ECFA

Based on Dainton, Newman, Perez, Willeke, MK, JINST P10001, 2006 and many discussions with CERN accelerator experts to identify the challenges.In line with CERN Council 9/07 and CERN strategy document.


title

LHeC ‘organisation’ for the CDR

Working Groups3 technical,3 physics


If a hadron collider will be built in the LEP tunnel then ep collisions are really a mustG.Altarelli et al, Lausanne LHC workshop 1984, Proc. p549

G.Altarelli at Divonne, 2008

Divonne Workshop- Opening Lecture by G.Altarelli, chaired by J.Ellis


Brodsky


Parton Distributions in the LHC Range

Blue & red data points = NP scenario ( L = 40)Black curve = SM cross-sections [E.Perez,Divonne]NP may be accomodated by HERA DGLAP fithowever, it can not by the fit to also LHeC. (recall high Et excess at the Tevatron which disappeared when xg became modified)

Factorisation is violated in productionof high pT particles (interaction in initial and in final state). The LHeCcan be expected to be crucial forestablishing new physics at TeV scale,in itself (if eq resonant states are found)and as a complement to the LHC.

sjb, Divonne


Quark Structure of the ProtonValence quarks at low and at large x

!

xF3

"Z=x

3(2u

v+ d

v)

Extract valence quarks at low x fromy-Z interference (charge asymmetry)LHeC: high Luminosity and high Q2

→ much higher sensitivity and reach,Unknown at x below ~0.05 in DIS.With deuterons disentangle u and d

The d/u ratio is a puzzle to DIS.The LHeC reaches high x with NC and CC (+/-). It therefore allowsto measure the u and d valencedensities accurately at high x andfree of nuclear corrections (FermiMotion). This may turn out to becrucial for understanding high massparticle production at the LHC.


Quark Structure of the ProtonHeavy Quarks (s,c,b)

The strange quark density isn’t (well) known.Some information from di-muon datain neutrino scattering. Some indicationsfor s.ne.sbar. With the LHeC, for thefirst time measure e s → ν c, tag c, get s.Measure anti-strange as accurately!

First measurements of b at HERA can be turned to precision measurement of beauty.LHeC: higher fraction of b, larger rangesmaller beam spot, better Si detectors. Much of the new physics expected at the LHC proceeds with beauty, e.g. Higgs production in MSSM models. Charm becomes precision measurement as well.


Top and Top Production at the LHeC (cc)

!

e"p#$X

!

e+p"#X

!

W+s" c

!

W"s# c

!

W"b# t

!

W+b" t

LHeC is a single top andanti-top quark factory

with a CC cross sectionof O(10)pb

Top at HERA essentiallyimpossible to study. Singletop at Tevatron/LHC verychallenging


Gluon DensityThe gluon density dominates low x. It is not well constrained at large x. It yet dominates many cross sections of high interest at the LHC, as Higgs production in the Standard Model.

It is best measured from the scaling violations of F2 ,and also constrained with FL , F2

c , jets in DIS and pp

At ep colliders measure generalised parton distributionsin DVCS, with charge and polarisation asymmetries.At the LHeC accurately determine generalised gluon

xg in the proton


Amplitudes sjb


Saturation?

The dynamics at low x is not clarified withHERA. Cross sections shall saturatebecause of unitarity. The LHeC has theenergy to establish this - a new phase ofmatter in which the density is high butthe coupling is small (CGC). The cleardemonstration of this effect looks feasiblewith precision measurements with protonsup to highest energy of the LHeC.

Foreshaw, Newman, Perez, MK (DIS08/Divonne)


Kinematics

Information on nuclearparton densities is tooconfined: in range (LHeC:Q2 times 103-4 coveringfull range!) and in diversity(heavy quarks in nuclei,shadowing flavourdependent etc.). TheLHeC range accessesnew phase of matter inDIS region.

eRHIC is complementary.

Low energy collidersuggested for FAIR.

DIS eA Kinematics


?

Need eA collider data to determine nuclear parton distributions in the kinematic range of ion collisions at the LHC


title


Nuclei - gluon density amplification

p

A

pp

AA

Ag

gA

rg

rg3/1

2

2

/

/=

!

!High density

Unitarity

Striking effects predicted:

bj -> black disc limit F2 ~ Q2 ln(1/x)~50% diffractioncolour opacity, change of J/Y(A) …


Complementarity of Ap and ep

Note that DY is not DIS

LHeC

D’Enterria Divonne


Saturation - Black Hole Duality.?

Agustin Sabio Vera (Divonne)


Detector constraints from

Full (fwd) acceptanceneeded for new physics

High precision - requireL1 to be 2x as precise as H1

B.Kniehl, U.Klein,M.Khuze, E.Perez

T.Kluge, M.K.Full (bwd) acceptanceneeded for low x physics

These assumptions are used to define detector,also high jet resolution, tagging (b,c,p,n,e,y)

May determine strongcoupling to 2 per mille(QCD to NkLO),


Detector

NIKHEFT.Greenshaw


LHeC Beams

e ring: 80 GeV max., high intensity (up to 1034 ), e± , polarisation possibly, interferes with LHC

e linac: ~ 140 GeV max, lower luminosity, high polarisation, e- ok, e+ difficult for > 1032 energy recovery may lead path to high luminosity and efficient use of power

p beam energy 1TeV (synchronisation) -7 TeV (if god saves the magnets)

Pb beam: 2.76 TeV , source may handle lighter ions.

LHC upgrade: higher intensity, smaller emittance, perhaps 50ns: upgrade of injector system

For LHeC: interested in upgraded p beam. An option: use 5 GeV SPL beam, at up to 1033

an option of the option: add race track and increase e energy to 20 GeV (near to ISR)

The injection energy to PS2 is too low for ion preacceleration: if ions are desired in SLHCphase: need to foresee either another ring or extra rf in PS2

Deuterons: require EBIZ source, O(10 Mill) investment. 3.5 TeV energy

If we/you want an LHeC initially of 5-20 on 2.76-3.5-7 TeV: SLHC upgrade papers due: 1/2009

This is my understanding not CERN’s position


ring


lumiringring


bypass


Linac versions


lumilinac


1

An option: initially use SPL (e) and racetrack for perhaps 5..20 * 7000 GeV2 and eA


History

50.000 times Q2 with at most5 times the length for a Linac

ICHEP1976 Tbilissi.. Pati, Salam on GUT’s


The Future - TeV Scale [2008-2033..]

W,Z,topHiggs??

New Particles??New Symmetries?

High Precision ew+QCDHigh Density Matter

Substructure??eq-Spectroscopy??

ttbarHiggs??

Spectroscopy??

ep e+e-

pp

New Physics

LHC

ILC/CLICLHeC


Next Steps

NuPECC meeting 4.10. GlasgowICFA Seminar 28.10. StanfordECFA Interims Report 11/08 Plenary Meeting in Feb/March 2009

2nd ECFA CERN workshop 1.-3.9.09

CDR

In order to reach this the working groupswill meet in between.

The work so far and the Divonne workshophave been unique events and brought together Acc+THY+EXP in a most fruitfulstrong interaction.

Please feel invited to join.http://www.lhec.org.uk

It will be fun.


Summary

The LHeC is a unique facility of fundamental importance. Its prime motivation in terms of energy and luminosity is the exploration of eq physics at the TeV scale and its complementarity to the LHC. High s is small x=Q2 /sy.

The LHeC thus has a huge range of physics on the structureof matter and the dynamics of strong interactions, which ismuch wider than could be presented here. This potentialmay unite particle with nuclear physics around the project.

The LHeC reach in energy and beam diversity is unprecedent.In making use of the best hadron beams in the world and in adding perhaps more than one e beam to them, the LHeCwill allow to restore the symmetry of pp, ep and ee collisions,then at TeV energies.

The steering and advisory groups, ECFA and CERN encouragethe nuclear physics community to take an active part in workingout the Conceptual Design Report by the end of 2009.


backup


maldacena

H.Kowalski Divonne


wgroups


eA@LHeC

EIC

LHeC

Measurement of nuclear parton distributionsNon-linear effects (xg ‘beyond’ unitarity)50% diffraction ..

Welcome to the NuPECC study group

The LHeC extends the measurement of nuclear structure in lA by four orders of magnitude as HERA did skip the eA phase.eA in relation to ALICE programme and the EIC

a large hadron electron collider at the lhc · max klein glasgow 4.10.2008 a large hadron electron...

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