Background and Aim:

The impact of measurements made at HERA, present and future, on the physics of the LHC is potentially large. However, this potential is currently not as well explored as e.g. the more obvious connection between the Tevatron and the LHC.

The most obvious area of impact is in the determination of proton structure from very low to very high x, which is measured precisely at HERA. Others topics include QCD production of heavy flavors and the study of multi-jet final states, energy flows and structure of underlying events. A unique feature of HERA is the photon, which, depending upon its virtuality, can be hadronic or point-like, enabling to effectively turn on and off the internal structure of one of the beam particles. Finally, the area of diffractive and forward physics, where HERA data have made a large impact in the last decade, is of growing interest to LHC experimentalists as a window on high density and low x QCD and as a search channel for new physics.

• To identify and prioritize those measurements to be made at HERA which have an impact on the physics reach of the LHC.

• To encourage and stimulate transfer of knowledge between the HERA and LHC communities and establish an ongoing interaction.

• To encourage and stimulate theory and phenomenological efforts related to the above goals.

• To examine and improve theoretical and experimental tools related to the above goals.

• To increase the quantitative understanding of the implication of HERA measurements on LHC physics.

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  Information on the expected capacity and reach of HERA-II can be found here

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  Topics to be studied:

• Parton density functions

  • Topics:
    high x and low x gluon and quarks from HERA fits, un-integrated pdfs (kt factorization), parton luminosities and precision cross section measurements at LHC

• Conveners:
  Theory: S. Forte (Milan U.) , S. Moch (DESY, Zeuthen)
  Exp: M. Dittmar (CMS), A. Glazov (H1)
  Contactpersons: M. Botje (Alice), J. Butterworth (ATLAS)

• Multi-jet final states and energy flows

  • Topics:
    Underlying event and minimum bias, Rapidity gaps and survival probabilities, Multi-jet topologies and multi-scale QCD, Parton shower/ME matching

• Conveners:
  Theory: L. Lönnblad (Lund), V. Khoze (Durham)
  Exp: N. Tuning (LHCb), C. Buttar (ATLAS), J. Butterworth (ZEUS)
  Contactpersons: S. Banerjee (CMS)
  

• Heavy quarks (charm and beauty)

  • Topics:
    production cross sections, fragmentation, charm and beauty in the proton distributions.

• Conveners:
  Theory: M Cacciari (Parma U. )
  Exp: U. Uwer (LHCb) , M. Smizanska (ATLAS), M. Corradi (ZEUS)
  Contactpersons: A. Dainese (ALICE) C. Weiser (CMS) A. Meyer (H1)

• Diffraction

  • Topics:
    Diffractive pdfs and (non)factorization, Rapidity gaps and physics with forward proton tagging, Forward physics and low-x dynamics, Heavy Ions and high density QCD

• Conveners:
  Theory: J. Forshaw (Manchester U.), M. Diehl (DESY)
  Exp: K. Piotrzkowski (CMS) , R. Orava (Totem), H. Kowalski (ZEUS), P. van Mechelen (H1)
  Contactpersons: M. Rijssenbeek (ATLAS), B. Cox (ATLAS)

• MC - tools:

  • Topics:
    General Monte Carlos (Pythia, Herwig, Phojet), New Monte Carlos with kt factorisation, NLO calculation (MC@NLO, NLOLIB...), MC Validiation & tuning (JetWeb, HZTOOL)

• Conveners:
  Theory: M Seymour (Manchester U.)
  Exp: A. Nikitenko (CMS) , E. Richter-Was (ATLAS) , P. Robbe (LHCb), V. Lendermann (H1)

Time plan and organization:

Real progress in terms of improved or new programs cannot be achieved in a single meeting, but require substantial work and thereby time. Therefore, we plan a plenary starting meeting March 26 - 27, 2004 to discuss the problems, set priorities and form study groups. These groups will then have informal meetings as necessary over a rather long period. We will avoid having a big organization with many formal groups and conveners, but some coordination will be needed for different topics. A mid-term plenary meeting is planned for late September or early October 2004 and the final meeting at DESY in January 2005. Those interested are welcome to spend some time at DESY, not only for these meetings, but also for more extensive collaborative work.

Presentation of results:

Final meeting at DESY with presentation of results. The main outcome should be identify and prioritize those measurements to be made at HERA which have an impact on the physics reach of the LHC. We will have proceedings, with a summary report from each working group and individual contributions. The proceedings will be printed and published electronically.