M. Klein H1 8. 9. 2005

Resolving the Inner Structure of Matter The H1 Experiment at HERA

Max Klein (DESY)

Workshop at Podgorica - 25 years of the Science Faculty

M. Klein H1 8. 9. 2005

Nature Vol 400 1 July 1999

M. Klein H1 8. 9. 2005

•History

•HERA

•Physics with H1

•Future Developments

M. Klein H1 8. 9. 2005

Discovery of the atomic nucleus 1909

atom

α

Ernest Rutherford (1871-1937)

H. Geiger und E. Marsden

θ

2/sin4

142

2

θEZ

ddN

∝Ω

MeV5.5=αE

m1010000rr 14atomnucleus

−≈≈

positively charged massive atomic nucleus

M. Klein H1 8. 9. 2005

Elastic electron scattering ep ep

elastic scattering off a proton with charge distribution

2Proton

232

61)()( r

QrredQf iq +≈=∫ ρr

( )rρ

Feynman diagrams 1949

Rutherfordd

d

Ω∝→

σθ 2sin14

p

e e

γ

p

QED

21, ff

photon exchange 2

1

Q∝

- incalculabe formfactors (charge, magn. moment)

Momentum transferred to p

M. Klein H1 8. 9. 2005

Protons have finite size

• 1955 R.Hofstadter and R.McAllister elastic ep scattering

m100.24)(0.74r 15Proton

−⋅±=

Mott 1929:

:Mottd

d

Ωσ

experimental curve (-) above the theoretical prediction of Mott (-)

( )2Qfd

d

d

d

Mott

⋅Ω

=Ω

σσ electron-scattering of pointlike particles

formfactor

MeV188=eE

Mott Kurve

experimental curve

Scattering angle θ

Sca

tter

ing

c ros

s s e

c tio

n

M. Klein H1 8. 9. 2005

2F

22 GeV/Q

Deep Inelastic Scattering ep eX (1969)

e e′

γp

X

GeV 20 ... 5.1=eE

°°= 26 ... 6θ

22 GeV 7 ... 1=Q

resolution m101 16−≈∝Q

( ) ( )xFQF 22

2 , →ν

quarksby carriedfraction momentum =x

Friedman, Kendall, Taylor SLAC

pointlike scattering centersinside the proton

M. Klein H1 8. 9. 2005

The function characterising the proton’s structure

0 1 x1/3

P0 1 x

2F

0 1 x1/3

−),( 22 QxF

no substructure

3 free valence quarks

3 bound quarks

x0

Valence quarks Sea quarksgluons

u

u

d

Gluon

2Q

M. Klein H1 8. 9. 2005

lowsyQx

highsxyQ

GeVE

GeVEEs

GeVEGeVE

fte

pe

pe

−=

−=

=⇔

==

==

/

100.54

3192

920,6.27

2

2

HERA - Deep inelastic scattering and searches at the energy frontier

Low x

High Q2

Q2 γZ0

M. Klein H1 8. 9. 2005

HERA: built 1985-19916.2 km ring accelerator(s)Superconducting p ringWarm magnet e ring Data delivery since 1992

M. Klein H1 8. 9. 2005

mAImAI

mAscmL

ePonpolarisati

GeVEGeVE

pe

spec

pe

100...60,50...20

102...4.0

5.0...0...5.0)(:

1000..400,30..15

21230

==

⋅≈

+−=

==

−−−

M. Klein H1 8. 9. 2005

electrons 27.6 GeV

protons 920 GeV

H1 ZEUS

M. Klein H1 8. 9. 2005

2422 10 GeVMQ ZCCNC ≈≈↔≈ ±± σσ

Neutral Current

ChargedCurrent

Xepe ++ →

Xpe ν→+

Neutral current

Charged current

HERA was built to study Rutherford backscattering and the unification of electromagnetic and weak interactions at high Q2

… its physics is much richer

M. Klein H1 8. 9. 2005

finite quark size

present limits

ZEUS r < 0.85 H1 r < 1.0 10-

18m

HERA: quarks are pointlike down to proton radius/1000

Inclusive crosssection ep eXexhibits so far no extra formfactor Limits on SUSY,leptoquarks,extra dimensions,quark radius…

Luminosity upgradeto probe deeper thesmallest dimensions

?

nucleon formfactor

M. Klein H1 8. 9. 2005

][22 qqexF q += ∑ ,...,,,, ccssduuuuu ssv ===+=

•Expectations on the density of partons before HERA

M. Klein H1 8. 9. 2005

1992 data ~30nb-1 1997 data ~30pb-1

F. Wilczek

HERA discovered high density state of matter (QCD, neutrino astrophysics, ..)

M. Klein H1 8. 9. 2005

),()(ln

222

2 QxqQQ

Fsα∝

∂∂

),()(ln

222

2 QxxgQQ

Fsα∝

∂∂

resolve correlationof coupling and gluonby accessing widerange of x and Q2

assume DGLAP evolutionthough that neglects ln(1/x)

strong coupling and the gluon

M. Klein H1 8. 9. 2005

no doubt it “runs” - BUThow large is the coupling?and is the field so simple?HERA has a fundamentalrole to answer these ?’s

The strong interaction gets larger at small distances [asymptotic freedom]and gluons carry half of proton’s momentum: QCD non Abelian qg field theory

•Nobel prize 2004: Gross, Politzer, Wilczek

quarks carry only about 1/2of the nucleon momentum:

M. Klein H1 8. 9. 2005

003.01186.0 ±=sα

)(005.0(exp)0011.01186.0)(.)( 2 thyMprelHERA Zs ±±=−α

Unification??

Next steps: higher accuracy data and NNLO

HERA may determine strong coupling best

M. Klein H1 8. 9. 2005

QCD represents ongoing exciting theory development,from hadronic interactions to a field theory of quarks and gluons

• Landau 1955:„weak coupling electrodynamics is …fundamentally logically incomplete.”

„within the limits of formal electrodynamicsa point interaction is equivalent … to no interaction at all.”

• Dyson 1960:“The correct theory will not be found within the next 100 years.”

• Feynman 1961:“I still … do not subscribe to the philosophy of renormalization.”

• Weinberg 1972, Gravitation + Cosmology:„we encounter theoretical difficulties beyond the range

of modern statistical mechanics.”

M. Klein H1 8. 9. 2005

The QCD Lagrangian

j … quark flavoursj … quark flavours a,b,c … 3 coloursa,b,c … 3 colours μμ,,νν … space-time … space-time

F.Wilczek, Physics Today, August 2000.F.Wilczek, Physics Today, August 2000.

M. Klein H1 8. 9. 2005

Physics at HERA (the expected and the unexpected)

• Inclusive ep measurements (NC, CC-inverse neutrino i.a.) pdf’s, gluon,

• Low x physics: small coupling and high density of partons “CGC, BFKL..”

• Heavy flavour physics (c and b: production and fragmentation dynamics)

• Final state physics (parton emission,,jets, y structure, dijet correlations )

• Diffraction [all related: e.g. “the structure of charm jets in diffraction”]

• Parton amplitudes (DVCS)

• Searches for exotic states (pentaquarks) and less? exotic ones (instantons)

• Searches: substructure, leptoquarks, SUSY, isolated lepton events (17/5)

• Electroweak physics (spacelike region)

•classic DIS

•QCD

•Searches

•elweak

for HERA physics see also:

• Talks at DIS05, April 2005, Madison• Ringberg Workshop (2003) Proceedings ed by G.Grindhammer, B.Kniehl, G.Kramer

M. Klein H1 8. 9. 2005

~320 authors, 40 institutes100 PhD students, 50 engineers

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

M. Klein H1 8. 9. 2005

Luminosityspectrometer

Forward tracking: Si + DC

Fast Track Trigger

ForwardProton and

NeutronSpectro-meters

e p

27.5 GeV 920 GeV

M. Klein H1 8. 9. 2005

New tracking detectors of H1 and ZEUS for HF physics in HERA II

FST BST

MVD

CST

charm and beauty

evt vtx (lo and hi y)

eID (DVCS, J/Ψ, searches)FL

Hugeinvestmentsfor high lumiphase by H1and ZEUS & fwd chambers

Online D*

M. Klein H1 8. 9. 2005

e p

LAr calorimeter

Drift chambers

Spacal

27.5 GeV 920 GeV

s=4EeEp=100000 GeV2

Silicon Strips

deep inelastic neutral current scattering event in the H1 apparatus

e+

DIS

yp

e‘

M. Klein H1 8. 9. 2005

High energy allows to take snapshots of proton structure: photon fluctuatesinto colour dipol. Its virtuality allows to scan through p’s structure.HERA measured the transition from hadronic (soft) to partonic (hard) behaviourwhich occurs at 0.3fm --> new data to come

hc/Q = 6.3 2.0 0.6 0.2 0.06 0.02 fm

F2 x- at small xrise of the parton densities

M. Klein H1 8. 9. 2005

The first ever measurement of the beauty contents of the proton F2b [lifetime tag]

Small fraction of cross section. [Beauty in pt(rel) and still above NLO QCD].

Central Silicon Tracker (CST/H1)

57 pb-1

M. Klein H1 8. 9. 2005

exp uncertainties of H1 pdfsbased on HERA I data usingLagrange method for fit:

x 0.01 0.4 0.65xU 1% 3% 7%xD 2% 10% 30%

Neutral and charged current data and heavy flavour data determine full set of pdf’s

M. Klein H1 8. 9. 2005

HERA 2 Temple

before and after

in Paestum, Italy

HERA 1: 1991-2000, HERA 2: 2003-2007 --> data analysis till 2012

the luminosity upgrade

M. Klein H1 8. 9. 2005

M. Klein H1 8. 9. 2005

New physics?

4 Fermion Contact-Term

e e

q q

HERAe p → e X

LEP _ e+ e- → q q

_FNAL_ pp → l l X

g2

M2

HERA :Standard Model ok up to = 5 TeV

•Substructure of quarks? Leptoquarks?

Symbiosis of ee, ep, pp

e

Proton

m101 18−≈∝Q

M. Klein H1 8. 9. 2005

The next huge step of accelerator based particle physics: 2007..2020

M. Klein H1 8. 9. 2005

The next huge step of collider detectors: ATLAS & CMS: 2007..2020

M. Klein H1 8. 9. 2005

F.Gianotti ly 05

The LHC is a discovery machine based on developping QCD

M. Klein H1 8. 9. 2005

•History: has been extremely rich and impressive [Einstein, Rutherford, Pauli, Gell Man]

•HERA is the highest resolution microscope of the world [a tribute to Bjoern Wiik]

•H1 is a big laboratory for particle physics [operated by 300 physicists from 39 institutes]

•“Predicting is difficult, in particular if it concerns the future” [the LHC is the next step, ILC?, ep@TeV??]

•Congratulations to the anniversary and congratulations to the many, impressive contributions by your faculty group to H1 [low x, CC/NC, trigger, Silicon, heavy quarks]

M. Klein H1 8. 9. 2005

M. Klein H1 8. 9. 2005

Deep Inelastic Electron-Proton Scattering