Summary of the HERA-LHC workshop

I present a summary of the last in the series of HERA-LHC workshops, CERN, 26-30th May 2008.Comment: To appear in the proceedings of the Ringberg Workshop on New Trends in HERA Physics, October 2008. 12 pages, 14 figures included as .ps or .eps file

Observation of Scaling Violations in Scaled Momentum Distributions at HERA

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of $x$ and $Q^2$ using the ZEUS detector. The evolution of the scaled momentum, $x_p$, with $Q^2,$ in the range 10 to 1280 $GeV^2$, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of $Q^2$.Comment: 21 pages including 4 figures, to be published in Physics Letters B. Two references adde

Multi-hadron Final States

This summary aims to highlight major results and insights gained from recent studies of hadronic final states in ep, ppbar, e+e-, as well as relevant theoretical developments, presented in the Multi-hadron final states parallel sessions of the DIS2002 workshop held in Krakow, Poland in May 2002.Comment: Contributed to the X International Workshop on Deep Inelastic Scattering (DIS2002), Krakow, Poland, 30 April - 4 May, 200

CEDAR: tools for event generator tuning

I describe the work of the CEDAR collaboration in developing tools for tuning and validating Monte Carlo event generator programs. The core CEDAR task is to interface the Durham HepData database of experimental measurements to event generator validation tools such as the UCL JetWeb system - this has necessitated the migration of HepData to a new relational database system and a Java-based interaction model. The "number crunching" part of JetWeb is also being upgraded, from the Fortran HZTool library to the new C++ Rivet system and a generator interfacing layer named RivetGun. Finally, I describe how Rivet is already being used as a central part of a new generator tuning system, and summarise two other CEDAR activities, HepML and HepForge.Comment: 13 pages, prepared for XI International Workshop on Advanced Computing and Analysis Techniques in Physics Research, Amsterdam, April 23-27 200

Zooming-in on Instantons at HERA

In view of the intriguing, preliminary search results for instanton-induced events at HERA from the H1 collaboration, some important remaining theoretical issues are discussed. Notably, the question is addressed, to which extent the H1 analysis may be directly compared to our original predictions from instanton-perturbation theory, since certain fiducial cuts are lacking in the H1 data. Various theoretical uncertainties are evaluated and their impact on the observed excess is discussed. An improved understanding of the experimental findings along with an encouraging over-all agreement with our original predictions seems to emerge.Comment: 13 pages, 12 figure

RunMC - an object-oriented analysis framework for Monte Carlo simulation of high-energy particle collisions

RunMC is an object-oriented framework aimed to generate and to analyse high-energy collisions of elementary particles using Monte Carlo simulations. This package, being based on C++ adopted by CERN as the main programming language for the LHC experiments, provides a common interface to different Monte Carlo models using modern physics libraries. Physics calculations (projects) can easily be loaded and saved as external modules. This simplifies the development of complicated calculations for high energy physics in large collaborations.This desktop program is open-source licensed and is available on the LINUX and Windows/Cygwin platforms.Comment: 15 pages, 1 eps figure, accepted by Comp. Phys. Commu

Survey of present data on photon structure functions and resolved photon processes

Present data on the partonic content of the photon from LEP, TRISTAN and HERA accelerators are reviewed and the essential aspects of the underlying ideas and methods are pointed out. Results of the unpolarized photon structure function F_2 from DIS_{e gamma} experiments and on large p_T jet production processes in the resolved gamma-gamma collisions are presented for both real and virtual photons. The results of analysis of the hadronic final state accompanying the DIS_{e gamma} measurements, showing some discrepancies with the Monte Carlo models, are collected together and presented as a separate issue. Also results on the DIS_{e gamma} with leptonic final states are shown. The results from resolved real and virtual photon processes at HERA collider based on the single and double jet events, also charged particles and prompt photons, are presented. In the context of virtual photon processes the data for forward jet and forward particle production are included. In addition a short presentation of the recent data on the heavy quark content of the photon is given. Related topics - the polarized (spin dependent) structure functions for the real and virtual photon, the structure function of the electron and the photonic content of the proton are also shortly mentioned.Comment: latex, 220 pages, 195 ps figures; extended and updated version of hep-ph/9806291; to appear in Physics Report

Discussion session on diffractive Higgs production

This note summarizes the discussion session on diffractive Higgs production at the DIS2002 workshop.Comment: Discussion session at DIS 2002, Cracow, May 200