Resolving the Inner Structure of Matter The H1 Experiment at HERA

transcript

M. Klein H1 8. 9. 2005

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

Ernest Rutherford (1871-1937)

H. Geiger und E. Marsden

2/sin4

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

61)()( r

QrredQf iq +≈=∫ ρr

( )rρ

Feynman diagrams 1949

Rutherfordd

Ω∝→

σθ 2sin14

21, ff

photon exchange 2

- 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

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

( )2Qfd

σσ electron-scattering of pointlike particles

formfactor

MeV188=eE

Mott Kurve

experimental curve

Scattering angle θ

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22 GeV/Q

Deep Inelastic Scattering ep eX (1969)

e e′

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

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The function characterising the proton’s structure

0 1 x1/3

P0 1 x

0 1 x1/3

−),( 22 QxF

no substructure

3 free valence quarks

3 bound quarks

Valence quarks Sea quarksgluons

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lowsyQx

highsxyQ

GeVEEs

GeVEGeVE

100.54

920,6.27

HERA - Deep inelastic scattering and searches at the energy frontier

High Q2

Q2 γZ0

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

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mAImAI

mAscmL

ePonpolarisati

GeVEGeVE

100...60,50...20

102...4.0

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

1000..400,30..15

⋅≈

−−−

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electrons 27.6 GeV

protons 920 GeV

H1 ZEUS

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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-

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

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

•Expectations on the density of partons before HERA

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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

2 QxqQQ

Fsα∝

∂∂

),()(ln

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

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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.”

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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

27.5 GeV 920 GeV

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

FST BST

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*

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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

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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

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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

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New physics?

4 Fermion Contact-Term

HERAe p → e X

LEP _ e+ e- → q q

_FNAL_ pp → l l X

HERA :Standard Model ok up to = 5 TeV

•Substructure of quarks? Leptoquarks?

Symbiosis of ee, ep, pp

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

Deep Inelastic Electron-Proton Scattering

Resolving the Inner Structure of Matter The H1 Experiment at HERA

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