DIS from EMC to H1T.Sloan, University of Lancaster.

QCDN-06 Rome 2006

• 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

DIS discovered at SLAC in 1960s – 1990 Nobel Prize

This led to - later generations of νN and μ(e)N experiments

The Crowning Glory of the Work

EMC Spin Effect.

Proved that only a small fraction of nucleon’s spin is carried by the quarks.

Incredible – we all thought we understood the quark-parton model.

Is it ΔG or is the nucleon a Skyrmion ? Or is it something else ?

NMC

Unexpected Effect (EMC Effect)

H1 How long will F2 Rise ?

EMC BSMSearch for free quarks

Search for D→μμObserve J/ψ peakCharm cross section order of magnitude bigger

Set limit on BR D→μμ of < 3.4 10-4 (A. Staiano’s thesis - 1984)

Sociology – one senior physicist commentedon the draft paper Why have you done this analysis ? This is a very quiet paper.

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.

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

Heavy Flavour Physics• EMC discovered via multimuons that boson gluon fusion was

responsible for charm production – among first evidence for gluons

Contribution of b and c to F2 - F2cc and F2 bb

Hadronic Final States• Programme in EMC (NA2, NA9)

• Lund Model developed for e+e- 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.

EMC Inclusive Identified Hadrons - 1983

EMC Seagull plot – gluon radiation (1983)

H1 Scaling violations in fragmentation functions

in Breit Frame compared to e+e- data.

αs versus Q from event shapes

Using dijets to constrain gluon distribution

EW PhysicsFirst BCDMS measurement from μ+p μ-p differences

BCDMS data

H1 from e+p e-p differences

Are there right handed currents ?

Diffraction

• Not known in EMC days except for exclusive ρ, φ, J/ψ …

• 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.

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.

ZEUS Leading neutrons

Zeus Leading protons

ISR leadingphotons

ISR leading Neutrons(Flauger and Monnig

Leading neutron data – ISRIs the bump at high x one pion exchange ?

Holtmann,Szczurek,Speth

Dashed ps meson exch

Dotted vec meson exch

Solid total

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

F2 Accuracy Now and 1996 Expected

• 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.

–Projected final accuracy is much better at x=0.65 than we actually have now.

PDF Accuracy

1996 Suggested to use jets to determinePDF by G.Lobo – fit made by ZEUS

The ZEUS fit already approaches the accuracy expected in 1996.

Measurement of xF3 from e+ e- differences

Based on 16 pb-1 of e- data – so improvement expected.

FL - 1996

Black points from extrapolation Measurement .Open from 4 protonEnergies 10pb-1 at each

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,F2

D4, diffractive charm, vector meson production, dijets, DVCS…

Correlations between quarks studied by DVCS i.e. scatter highly virtual photon and detect a real one (NB e,γ, 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.

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 π0).

Flagship Plot

αS=0.1198±0.0013(exp) +0.0056-0.0043(theor) L=106pb-1

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 ΔσR/σL is 7%

In 1996 projected to achieve 0.4%With L=500pb-1 and 70% polarisation.Use this to set limit on mass of WR

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.