DIS from EMC to H1 T.Sloan, University of Lancaster. QCDN-06 Rome 2006

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DIS from EMC to H1T.Sloan, University of
Lancaster.QCDN-06 Rome 2006
DIS discovered at SLAC in 1960s 1990 Nobel Prize
This led to - later generations of ?N and µ(e)N
experiments

• EMC proposal 72-74
• Build 1974-1978
• Run 1978-1985
• NMC (3rd generation)
• SMC (4th generation)
• Compass (5th gen)

• H1 proposal 1985 Build 1985-1992 Run 1992 -
  2007

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The Crowning Glory of the Work
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EMC Spin Effect.
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Proved that only a small fraction of nucleons
spin is carried by the quarks. Incredible we
all thought we understood the quark-parton
model. Is it ?G or is the nucleon a Skyrmion ?
Or is it something else ?
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Unexpected Effect (EMC Effect)
NMC
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H1 How long will F2 Rise ?
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EMC BSM

• Search for free quarks
• Search for D?µµ

Observe J/? peak Charm cross section order of
magnitude bigger
Set limit on BR D?µµ of lt 3.4 10-4 (A.
Staianos thesis - 1984)
Sociology one senior physicist commented on the
draft paper Why have you done this analysis ?
This is a very quiet paper.
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Was he correct ? There are 8 citations for the
paper on Spires.

• Look at quality of the citations
• 1. Particle data group (paper still there)
• 2. The experiment which copied us using a pion
  beam (bigger luminosity)
• 3. Others

If we had found a signal for D?µµ the standard
model would have needed modification
Conclusion We were right to do the analysis.
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The Collaborations

• EMC and H1 Work divided into several sub groups
• Structure Functions, Heavy flavour, hadronic
  final states (EMC and H1)
• Diffraction, BSM (H1) diffraction and the
  standard model not part of vocabulary in EMC days

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Heavy Flavour Physics

• EMC discovered via multimuons that boson gluon
  fusion was responsible for charm production
  among first evidence for gluons

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Contribution of b and c to F2 - F2cc and F2 bb
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Hadronic Final States

• Programme in EMC (NA2, NA9)
• Lund Model developed for ee- and µp data
  (ca1980). Much
• work was done to tune up the parameters of
  the model.
• H1 works in Breit frame, studies jets etc. Jets
  give insight into
• production of primary quarks and gluons.

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EMC Inclusive Identified Hadrons - 1983
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EMC Seagull plot gluon radiation (1983)
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H1 Scaling violations in fragmentation functions
in Breit Frame compared to ee- data.
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as versus Q from event shapes

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Using dijets to constrain gluon distribution
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EW Physics
First BCDMS measurement from µp µ-p differences
BCDMS data
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H1 from ep e-p differences
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Are there right handed currents ?
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Diffraction

• Not known in EMC days except for exclusive ?, f,
  J/?
• Discovered in rapidity gap data at HERA.
• Now also being studied in forward leading proton
  and neutron data.
• Diffraction important for cosmic ray shower
  generation.

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Cosmic Ray shower simulation

• Energy flow into forward region is very important
  for simulation of cosmic ray air showers.
• Estimate x of events have a leading proton and
  y have a leading neutron.
• Hence diffraction is important.

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ZEUS Leading neutrons
Zeus Leading protons
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ISR leading photons
ISR leading Neutrons (Flauger and Monnig
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Leading neutron data ISR Is the bump at high
x one pion exchange ?
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Holtmann,Szczurek,Speth
Dashed ps meson exch Dotted vec meson exch Solid
total
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Conclusions

• EMC and H1 have been great places to work.
• Plenty of outstanding questions where is the
  spin of the proton ?
• What will limit the rise of F2 ?
• Is diffraction telling us something about the
  nuclear force ?
• Many questions for the workshop

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F2 Accuracy Now and 1996 Expected

• Projected final accuracy is much better at x0.65
  than we actually have now.

• Wider x range expected to be covered
• (down to 1.4 10-5 compared to 6.510-5)
• Improved systematic errors expected in 1996
  compared to now. Eg 0.5 electron energy
  calibration backward and 1 central and forward
  (compared to 1 backward and 0.7-3
  central-forward).
• Some work is needed here.

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PDF Accuracy
1996 Suggested to use jets to determine PDF by
G.Lobo fit made by ZEUS
The ZEUS fit already approaches the accuracy
expected in 1996.
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Measurement of xF3 from e e- differences
Based on 16 pb-1 of e- data so improvement
expected.
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FL - 1996
Black points from extrapolation Measurement
.Open from 4 proton Energies 10pb-1 at each
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Diffraction

• In 1995/6 rapidity gaps had not been known for
  too long so plans at workshop were primitive.
• We have done much more than was considered at the
  workshop.
• E.g.F2D3,F2D4, diffractive charm, vector meson
  production, dijets, DVCS

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Correlations between quarks studied by DVCS i.e.
scatter highly virtual photon and detect a real
one (NB e,?, proton in final state).
Several new structure functions are needed to
describe such correlations. It is not yet known
how to measure them hence can only compare with
models.
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Jets and High ET Group

• I could not find anything on this topic in the
  1995-96 workshop that we have not done.
• Some things extra odderon searches,
  anti-deuterons
• However, we still have not published the
  fragmentation functions for identified particles
  (except p0).

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Flagship Plot
aS0.11980.0013(exp) 0.0056-0.0043(theor)
L106pb-1
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EW Plot Status with 21 pb-1 L and 27 pb-1 R
Classic plot demonstrating directly the left
handedness of the W this plot will end up in
the text books. Must check with e- which should
have negative slope.
Poor fit to SM New physics ?
Current limit on ?sR/sL is 7
In 1996 projected to achieve 0.4 With L500pb-1
and 70 polarisation. Use this to set limit on
mass of WR
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Conclusions

• Not much in the 1996 workshop to help us today
• H1 has done great work I have shown my ideas of
  the flagship plots which we should leave for
  future generations.
• Each sub-group should identify its flagship
  plots.
• These should be made before we stop analysing
  HERA data with the smallest errors possible.