M. Klein H1 27. 3. 2007

Resolving the Inner Structure of Matter The H1 Experiment at HERA

Max Klein (University of Liverpool)

Talk at Plovdiv - Bulgaria

M. Klein H1 27. 3. 2007

•History

•HERA

•H1 and its physics

•Completing H1

•Outlook

M. Klein H1 27. 3. 2007

Discovery of the atomic nucleus 1909

atom

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 27. 3. 2007

p

e e

γ

p

QED

21, ff

photon exchange 2

1

Q∝

- incalculabe formfactors (charge, magn. moment)

Elastic electron scattering ep -> ep

elastic scattering off a proton with charge distribution

2Proton

232

61)()( r

QrredQf iq +≈=∫ ρr

Feynman diagrams 1949

Rutherfordd

d

Ω∝→

σθ 2sin14

Momentum transferred to p

M. Klein H1 27. 3. 2007

Protons have finite size

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

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

Mott Kurve

experimental curve

Scattering angle θ

Sca

tter

ing

c ros

s s e

c tio

n

M. Klein H1 27. 3. 2007

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

( ) ( )xFQF 22

2 , →ν

quarksby carriedfraction momentum =x

Friedman, Kendall, Taylor SLAC

pointlike scattering centersinside the proton

M. Klein H1 27. 3. 2007

Deep Inelastic Electron-Proton Scattering

M. Klein H1 27. 3. 2007

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 27. 3. 2007

HERA

Hoch-Energie Ring Anlage - High Energy Ring Accelerator

M. Klein H1 27. 3. 2007

Nature Vol 400 1 July 1999

M. Klein H1 27. 3. 2007

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

M. Klein H1 27. 3. 2007

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 27. 3. 2007

electrons 27.6 GeV

protons 920 GeV

H1 ZEUS

M. Klein H1 27. 3. 2007

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 27. 3. 2007

The function characterising the proton’s structure

0 1 x1/3

P0 1 x

2F

0 1 x1/3

no substructure

3 free valence quarks

3 bound quarks

x0

Valence quarks Sea quarksgluons

u

u

d

Gluon

M. Klein H1 27. 3. 2007

•Expectations on the density of partons before HERA

M. Klein H1 27. 3. 2007

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

F. Wilczek

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

M. Klein H1 27. 3. 2007

H1 and its physics

M. Klein H1 27. 3. 2007

~320 authors, 40 institutes100 PhD students, 50 engineers

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

M. Klein H1 27. 3. 2007

Luminosityspectrometer

Forward tracking: Si + DC

Fast Track Trigger

ForwardProton and

NeutronSpectro-meters

e p

27.5 GeV 920 GeV

M. Klein H1 27. 3. 2007

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

• Electroweak physics (spacelike region)

•classic DIS•QCD

•Searches

•elweak for HERA physics see also:

• Talks at DIS05, April 2005, Madison• 4/06, Tsukuba and 4/07, Munich

M. Klein H1 27. 3. 2007Q2/GeV2

M. Klein H1 27. 3. 2007

Asymptotic Freedom

€

μ dg(μ)

dμ= β (g(μ))

β (g) = −g[α s

4πβ1 + (

α s

4π)2β 2 + ...]

β1 = (11Nc − 2n f ) /3

β 2 =102 − 38n f /3

α s

4π=

1

β1 ln(μ 2 /Λ2)−β 2 ln(lnμ 2 /Λ2)

β13 ln2(μ 2 /Λ2)

+ ...

RGE

gluon & quark loops

leading and next-to-leading order (NLO)

Prediction confirmed in many reactions Nobel price 2004 ( Gross, Politzer, Wilczek)

At small distances < fm quarks are freeQPM restored in the limit of perturbative QCD

At large distances, quarks are confined.(?)Lattice, string theories, nonperturbative regime

There is a 3rd region discovered at HERA,where the coupling is small BUT the densitiesare large (low x physics, AA, superhigh energyneutrino physics, forward physics at the LHC)

M. Klein H1 27. 3. 2007

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

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

Central Silicon Tracker (CST/H1)

57 pb-1

M. Klein H1 27. 3. 2007

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 27. 3. 2007

The end of HERA operation at high energies (1992-2007)

•27.6 GeV * 920 GeV --> 460 GeV 4-6/2007

M. Klein H1 27. 3. 2007

M. Klein H1 27. 3. 2007

Polarisation asymmetries

establish parity violation~vqae at small distances

M. Klein H1 27. 3. 2007

Completing H1’s Physics Programme

2007-2010+

• Take low proton beam energy data (until 2.7.2007)• Use all data available for final measurements• Analyses in high order QCD (NNLO in inclusive case)• Combination with ZEUS data where appropriate• Highest possible accuracy in testing QCD and predictions for LHC

M. Klein H1 27. 3. 2007

Two independent structure functionscharacterise inclusive DIScompletelyF2 : quarks

FL : gluons

Measurement of FL

just starting at HERA

M. Klein H1 27. 3. 2007

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 27. 3. 2007

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 27. 3. 2007

M. Klein H1 27. 3. 2007

HERA 2 Temple

before and after

in Paestum, Italy

HERA 1: 1991-2000, HERA 2: 2003-2007 --> data analysis till 2010+

the luminosity upgrade

M. Klein H1 27. 3. 2007

Outlook

M. Klein H1 27. 3. 2007

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

M. Klein H1 27. 3. 2007

F.Gianotti ly 05

The LHC is a discovery machine based on developping QCD

M. Klein H1 27. 3. 2007

M. Klein H1 27. 3. 2007

A possible future - ep Scattering at TeV Energies

-New Physics in the eq Sector leptoquarks, RP violating SUSY,..-Quark-Gluon Dynamics and the Origin of Mass confinement and diffraction, the gluon-The Structure of Quantum Chromodynamics high density (CGC, instantons, odderons..), resumm’s-The Structure of the Proton substructure, parton correlations, transverse, uPDF’s-Precision for the LHC heavy flavour (b), strong coupling, partons-The Origin of the Quark Gluon Plasma partons in nuclei, deconfinement phase, CGC

Design study for e ring in the LHC tunnel (LHeC) by 2009/10.70 on 7000 GeV2 , 100 times HERA luminosity

JINST 1 2006 P10001

M. Klein H1 27. 3. 2007

•The H1 (+ ZEUS) experiment at HERA has been a major success

•Its results have revolutionised the way we understandthe structure of the proton and the underlying field theory

•Many new fields were opened up such as the physics of high parton densities or the phenomenon of hard diffraction

•Many unique measuremnets are being done at HERA, on theparton distributions, light, heavy quarks and gluons, withunprecedent precision and kinematic reach

•Thus the results of HERA are of vital importance forunderstanding the data at the LHC which are imminent

•A future DIS scattering experiment at TeV energy scalesmay be of fundamental importance, yet, the findings at the LHC will direct particle physics further

•Within 100 years we went from the atomic nucleus at 10-14 mto pointlike quarks at 10-18 m, who knows what is ‘next door’?

M. Klein H1 27. 3. 2007

M. Klein H1 27. 3. 2007

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 27. 3. 2007

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

M. Klein H1 27. 3. 2007

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 27. 3. 2007

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 27. 3. 2007

M. Klein H1 27. 3. 2007

M. Klein H1 27. 3. 2007

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 luminosityphase by H1[and ZEUS] & fwd chambers

Online D*

M. Klein H1 27. 3. 2007

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.