K. Rabbertz

HERAFitter is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton and for many different kinds of analyses in Quantum Chromodynamics (QCD). It encodes results from a wide range of experimental measurements in lepton–proton deep inelastic scattering and proton–proton (proton–antiproton) collisions at hadron colliders. These are complemented with a variety of theoretical options for calculating PDF-dependent cross section predictions corresponding to the measurements. The framework covers a large number of the existing methods and schemes used for PDF determination. The data and theoretical predictions are brought together through numerous methodological options for carrying out PDF fits and plotting tools to help to visualise the results. While primarily based on the approach of collinear factorisation, HERAFitter also provides facilities for fits of dipole models and transverse-momentum dependent PDFs. The package can be used to study the impact of new precise measurements from hadron colliders. This paper describes the general structure of HERAFitter and its wide choice of options.

Abstract Quantum Chromodynamics, the theory of quarks and gluons, whose interactions can be described by a local SU(3) gauge symmetry with charges called “color quantum numbers”, is reviewed; the goal of this review is to provide advanced Ph.D. students a comprehensive handbook, helpful for their research. When QCD was “discovered” 50 years ago, the idea that quarks could exist, but not be observed, left most physicists unconvinced. Then, with the discovery of charmonium in 1974 and the explanation of its excited states using the Cornell potential, consisting of the sum of a Coulomb-like attraction and a long range linear confining potential, the theory was suddenly widely accepted. This paradigm shift is now referred to as the November revolution . It had been anticipated by the observation of scaling in deep inelastic scattering, and was followed by the discovery of gluons in three-jet events. The parameters of QCD include the running coupling constant, $$\alpha _s(Q^2)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> </mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:msup> <mml:mi>Q</mml:mi> <mml:mn>2</mml:mn> </mml:msup> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> , that varies with the energy scale $$Q^2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>Q</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:math> characterising the interaction, and six quark masses. QCD cannot be solved analytically, at least not yet, and the large value of $$\alpha _s$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> at low momentum transfers limits perturbative calculations to the high-energy region where $$Q^2\gg \varLambda _{{\textrm{QCD}}} ^2\simeq $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>Q</mml:mi> <mml:mn>2</mml:mn> </mml:msup> <mml:mo>≫</mml:mo> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mrow> <mml:mtext>QCD</mml:mtext> </mml:mrow> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo>≃</mml:mo> </mml:mrow> </mml:math> (250 MeV) $$^2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mn>2</mml:mn> </mml:msup> </mml:math> . Lattice QCD (LQCD), numerical calculations on a discretized space-time lattice, is discussed in detail, the dynamics of the QCD vacuum is visualized, and the expected spectra of mesons and baryons are displayed. Progress in lattice calculations of the structure of nucleons and of quantities related to the phase diagram of dense and hot (or cold) hadronic matter are reviewed. Methods and examples of how to calculate hadronic corrections to weak matrix elements on a lattice are outlined. The wide variety of analytical approximations currently in use, and the accuracy of these approximations, are reviewed. These methods range from the Bethe–Salpeter, Dyson–Schwinger coupled relativistic equations, which are formulated in both Minkowski or Euclidean spaces, to expansions of multi-quark states in a set of basis functions using light-front coordinates, to the AdS/QCD method that imbeds 4-dimensional QCD in a 5-dimensional deSitter space, allowing confinement and spontaneous chiral symmetry breaking to be described in a novel way. Models that assume the number of colors is very large, i.e. make use of the large $$N_c$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>N</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> -limit, give unique insights. Many other techniques that are tailored to specific problems, such as perturbative expansions for high energy scattering or approximate calculations using the operator product expansion are discussed. The very powerful effective field theory techniques that are successful for low energy nuclear systems (chiral effective theory), or for non-relativistic systems involving heavy quarks, or the treatment of gluon exchanges between energetic, collinear partons encountered in jets, are discussed. The spectroscopy of mesons and baryons has played an important historical role in the development of QCD. The famous X,Y,Z states – and the discovery of pentaquarks – have revolutionized hadron spectroscopy; their status and interpretation are reviewed as well as recent progress in the identification of glueballs and hybrids in light-meson spectroscopy. These exotic states add to the spectrum of expected $$q{{\bar{q}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>q</mml:mi> <mml:mover> <mml:mrow> <mml:mi>q</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> </mml:math> mesons and qqq baryons. The progress in understanding excitations of light and heavy baryons is discussed. The nucleon as the lightest baryon is discussed extensively, its form factors, its partonic structure and the status of the attempt to determine a three-dimensional picture of the parton distribution. An experimental program to study the phase diagram of QCD at high temperature and density started with fixed target experiments in various laboratories in the second half of the 1980s, and then, in this century, with colliders. QCD thermodynamics at high temperature became accessible to LQCD, and numerical results on chiral and deconfinement transitions and properties of the deconfined and chirally restored form of strongly interacting matter, called the Quark–Gluon Plasma (QGP), have become very precise by now. These results can now be confronted with experimental data that are sensitive to the nature of the phase transition. There is clear evidence that the QGP phase is created. This phase of QCD matter can already be characterized by some properties that indicate, within a temperature range of a few times the pseudocritical temperature, the medium behaves like a near ideal liquid. Experimental observables are presented that demonstrate deconfinement. High and ultrahigh density QCD matter at moderate and low temperatures shows interesting features and new phases that are of astrophysical relevance. They are reviewed here and some of the astrophysical implications are discussed. Perturbative QCD and methods to describe the different aspects of scattering processes are discussed. The primary parton–parton scattering in a collision is calculated in perturbative QCD with increasing complexity. The radiation of soft gluons can spoil the perturbative convergence, this can be cured by resummation techniques, which are also described here. Realistic descriptions of QCD scattering events need to model the cascade of quark and gluon splittings until hadron formation sets in, which is done by parton showers. The full event simulation can be performed with Monte Carlo event generators, which simulate the full chain from the hard interaction to the hadronic final states, including the modelling of non-perturbative components. The contribution of the LEP experiments (and of earlier collider experiments) to the study of jets is reviewed. Correlations between jets and the shape of jets had allowed the collaborations to determine the “color factors” – invariants of the SU(3) color group governing the strength of quark–gluon and gluon–gluon interactions. The calculated jet production rates (using perturbative QCD) are shown to agree precisely with data, for jet energies spanning more than five orders of magnitude. The production of jets recoiling against a vector boson, $$W^\pm $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>W</mml:mi> <mml:mo>±</mml:mo> </mml:msup> </mml:math> or Z , is shown to be well understood. The discovery of the Higgs boson was certainly an important milestone in the development of high-energy physics. The couplings of the Higgs boson to massive vector bosons and fermions that have been measured so far support its interpretation as mass-generating boson as predicted by the Standard Model. The study of the Higgs boson recoiling against hadronic jets (without or with heavy flavors) or against vector bosons is also highlighted. Apart from the description of hard interactions taking place at high energies, the understanding of “soft QCD” is also very important. In this respect, Pomeron – and Odderon – exchange, soft and hard diffraction are discussed. Weak decays of quarks and leptons, the quark mixing matrix and the anomalous magnetic moment of the muon are processes which are governed by weak interactions. However, corrections by strong interactions are important, and these are reviewed. As the measured values are incompatible with (most of) the predictions, the question arises: are these discrepancies first hints for New Physics beyond the Standard Model? This volume concludes with a description of future facilities or important upgrades of existing facilities which improve their luminosity by orders of magnitude. The best is yet to come!

The impact of recent measurements of heavy-flavour production in deep inelastic $ep$ scattering and in $pp$ collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions $x$ of the proton momentum, down to $x \sim 5 \times 10^{-6}$. This kinematic range is currently not covered by other experimental data in perturbative QCD fits.

This Report summarizes the proceedings of the 2015 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) the new PDF4LHC parton distributions, (III) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (IV) a host of phenomenological studies essential for comparing LHC data from Run I with theoretical predictions and projections for future measurements in Run II, and (V) new developments in Monte Carlo event generators.

Standard methods for higher-order calculations of QCD cross sections in hadron-induced collisions are time-consuming. The fastNLO project uses multi-dimensional interpolation techniques to convert the convolutions of perturbative coefficients with parton distribution functions and the strong coupling into simple products. By integrating the perturbative coefficients for a given observable with interpolation kernels, fastNLO can store the results of the time-consuming folding integrals in tables, which subsequently are used for very fast rederivations of the same observable for arbitrary parton distribution functions, different scale choices, or alpha_s(M_Z). Various tables with code for their evaluation are available for numerous jet measurements at the LHC, the TeVatron, and HERA. FastNLO is used in publications of experimental results by the ATLAS, CMS, CDF, D0, and H1 collaborations, and in all recent global PDF analyses by MSTW, CTEQ, and NNPDF. This article focuses on developments implemented in the new version 2 of fastNLO, enhancing and broadening its functionality.

Deep Inelastic Scattering DIS 2006, pp. 483-486 (2007) No AccessFAST pQCD CALCULATIONS FOR PDF FITST. KLUGE, K. RABBERTZ, and M. WOBISCHT. KLUGEDESY, Hamburg, Germany, K. RABBERTZUniversity of Karlsruhe, Karlsruhe, Germany, and M. WOBISCHFermi National Accelerator Laboratory, Batavia, Illinois, USAhttps://doi.org/10.1142/9789812706706_0110Cited by:25 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: We present a method for very fast repeated computations of higher-order cross sections in hadron-induced processes for arbitrary parton density functions. A full implementation of the method for computations of jet cross sections in Deep-Inelastic Scattering and in Hadron-Hadron Collisions is offered by the "fastNLO" project at http://hepforge.cedar.ac.uk/fastnlo/. FiguresReferencesRelatedDetailsCited By 25NNLO interpolation grids for jet production at the LHCD. Britzger, A. Gehrmann-De Ridder, T. Gehrmann, E. W. N. Glover and C. Gwenlan et al.19 October 2022 | The European Physical Journal C, Vol. 82, No. 10The Linear Template FitDaniel Britzger22 August 2022 | The European Physical Journal C, Vol. 82, No. 8Higgs boson production at the LHC: fast and precise predictions in QCD at higher ordersStefano Camarda, Leandro Cieri, Giancarlo Ferrera and Jesús Urtasun-Elizari27 May 2022 | The European Physical Journal C, Vol. 82, No. 5Accelerating Monte Carlo event generation -- rejection sampling using neural network event-weight estimatesKatharina Danziger, Timo Janßen, Steffen Schumann and Frank Siegert18 May 2022 | SciPost Physics, Vol. 12, No. 5PineAPPL: NLO EW corrections for PDF processesChristopher Schwan13 July 2022 | SciPost Physics Proceedings, No. 8The Large Hadron–Electron Collider at the HL-LHCP Agostini, H Aksakal, S Alekhin, P P Allport and N Andari et al.20 December 2021 | Journal of Physics G: Nuclear and Particle Physics, Vol. 48, No. 11An exploratory study of the impact of CMS double-differential top distributions on the gluon parton distribution functionMichał Czakon, Sayipjamal Dulat, Tie-Jiun Hou, Joey Huston and Alexander Mitov et al.28 November 2020 | Journal of Physics G: Nuclear and Particle Physics, Vol. 48, No. 1Dependence of inclusive jet production on the anti-kT distance parameter in pp collisions at $$ \sqrt{\mathrm{s}} $$ = 13 TeVA. M. Sirunyan, A. Tumasyan, W. Adam, F. Ambrogi and T. Bergauer et al.11 December 2020 | Journal of High Energy Physics, Vol. 2020, No. 12Theoretical OverviewSvenja Karen Pflitsch19 August 2020Differential top quark pair production at the LHC: Challenges for PDF fitsS. Bailey and L. A. Harland-Lang25 January 2020 | The European Physical Journal C, Vol. 80, No. 1Precision phenomenology with MCFMJohn Campbell and Tobias Neumann4 December 2019 | Journal of High Energy Physics, Vol. 2019, No. 12Single-jet inclusive rates with exact color at $$ \mathcal{O} $$ ($$ {\alpha}_s^4 $$)Michał Czakon, Andreas van Hameren, Alexander Mitov and Rene Poncelet29 October 2019 | Journal of High Energy Physics, Vol. 2019, No. 10Calculations for deep inelastic scattering using fast interpolation grid techniques at NNLO in QCD and the extraction of $$\alpha _{\mathrm {s}}$$ from HERA dataD. Britzger, J. Currie, A. Gehrmann-De Ridder, T. Gehrmann and E. W. N. Glover et al.14 October 2019 | The European Physical Journal C, Vol. 79, No. 10Resummation for rapidity distributions in top-quark pair productionBenjamin D. Pecjak, Darren J. Scott, Xing Wang and Li Lin Yang12 March 2019 | Journal of High Energy Physics, Vol. 2019, No. 3Reweighting a parton shower using a neural network: the final-state caseEnrico Bothmann and Luigi Del Debbio4 January 2019 | Journal of High Energy Physics, Vol. 2019, No. 1Determination of the strong coupling constant using inclusive jet cross section data from multiple experimentsDaniel Britzger, Klaus Rabbertz, Daniel Savoiu, Georg Sieber and Markus Wobisch28 January 2019 | The European Physical Journal C, Vol. 79, No. 1Event generation with Sherpa 2.2Enrico Bothmann, Gurpreet Singh Chahal, Stefan Höche, Johannes Krause and Frank Krauss et al.18 September 2019 | SciPost Physics, Vol. 7, No. 3Machine learning challenges in theoretical HEPStefano Carrazza18 October 2018 | Journal of Physics: Conference Series, Vol. 1085Search for new physics in dijet angular distributions using proton–proton collisions at $$\sqrt{s}=13\hbox {TeV}$$ and constraints on dark matter and other modelsA. M. Sirunyan, A. Tumasyan, W. Adam, F. Ambrogi and E. Asilar et al.28 September 2018 | The European Physical Journal C, Vol. 78, No. 9Measurement of the triple-differential dijet cross section in proton-proton collisions at $$\sqrt{s}=8\,\text {TeV} $$ s = 8 TeV and constraints on parton distribution functionsA. M. Sirunyan, A. Tumasyan, W. Adam, E. Asilar and T. Bergauer et al.7 November 2017 | The European Physical Journal C, Vol. 77, No. 11Top-pair production at the LHC through NNLO QCD and NLO EWMichał Czakon, David Heymes, Alexander Mitov, Davide Pagani and Ioannis Tsinikos et al.26 October 2017 | Journal of High Energy Physics, Vol. 2017, No. 10Theoretical FrameworkKlaus Rabbertz12 October 2016Forward Physics − a new window on high energy interactions. Results from Large Hadron Collider Run 1 data taking obtained with Compact Muon Solenoid experimentGrzegorz Brona1 January 2017Measurement of dijet production in diffractive deep-inelastic ep scattering at HERAV. Andreev, A. Baghdasaryan, K. Begzsuren, A. Belousov and V. Boudry et al.18 March 2015 | Journal of High Energy Physics, Vol. 2015, No. 3Measurement of the inclusive production cross sections for forward jets and for dijet events with one forward and one central jet in pp collisions at $ \sqrt {s} = 7 $ TeVS. Chatrchyan, V. Khachatryan, A. M. Sirunyan, A. Tumasyan and W. Adam et al.5 June 2012 | Journal of High Energy Physics, Vol. 2012, No. 6 Recommended Deep Inelastic Scattering DIS 2006Metrics History PDF download

This report summarizes the proceedings of the 2014 Mainz Institute for Theoretical Physics (MITP) scientific program on "High precision fundamental constants at the TeV scale". The two outstanding parameters in the Standard Model dealt with during the MITP scientific program are the strong coupling constant $α_s$ and the top-quark mass $m_t$. Lacking knowledge on the value of those fundamental constants is often the limiting factor in the accuracy of theoretical predictions. The current status on $α_s$ and $m_t$ has been reviewed and directions for future research have been identified.

These are the proceedings of the "Workshop on Precision Measurements of alphas" held at the Max-Planck-Institute for Physics, Munich, February 9-11, 2011. The workshop explored in depth the determination of alphas(mZ) in the MS-bar scheme from the key categories where high precision measurements are currently being made, including DIS and global PDF fits, tau-decays, electroweak precision observables and Z-decays, event-shapes, and lattice QCD. These proceedings contain a short summary contribution from the speakers, as well as the lists of authors, conveners, participants, and talks.

HERAFitter is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton and for many different kinds of analyses in Quantum Chromodynamics (QCD). It encodes results from a wide range of experimental measurements in lepton-proton deep inelastic scattering and proton-proton (proton-antiproton) collisions at hadron colliders. These are complemented with a variety of theoretical options for calculating PDF-dependent cross section predictions corresponding to the measurements. The framework covers a large number of the existing methods and schemes used for PDF determination. The data and theoretical predictions are brought together through numerous methodological options for carrying out PDF fits and plotting tools to help visualise the results. While primarily based on the approach of collinear factorisation, HERAFitter also provides facilities for fits of dipole models and transverse-momentum dependent PDFs. The package can be used to study the impact of new precise measurements from hadron colliders. This paper describes the general structure of HERAFitter and its wide choice of options.

This report summarizes the activity on comparisons of existings tools for the standard model and on issues in jet physics by the SMHC working group during and subsequent to the Workshop "Physics at TeV Colliders", Les Houches, France, 11-29 June, 2007.

Combined HERA data on charm production in deep-inelastic scattering have previously been used to determine the charm-quark running mass mc(mc) in the MS‾ renormalisation scheme. Here, the same data are used as a function of the photon virtuality Q2 to evaluate the charm-quark running mass at different scales to one-loop order, in the context of a next-to-leading order QCD analysis. The scale dependence of the mass is found to be consistent with QCD expectations.

The extension of interpolation-grid frameworks for perturbative QCD calculations at next-to-next-to-leading order (NNLO) is presented for deep inelastic scattering (DIS) processes. A fast and flexible evaluation of higher-order predictions for any a posteriori choice of parton distribution functions (PDFs) or value of the strong coupling constant is essential in iterative fitting procedures to extract PDFs and Standard Model parameters as well as for a detailed study of the scale dependence. The APPLfast project, described here, provides a generic interface between the parton-level Monte Carlo program NNLOjet and both the APPLgrid and fastNLO libraries for the production of interpolation grids at NNLO accuracy. Details of the interface for DIS processes are presented together with the required interpolation grids at NNLO, which are made available. They cover numerous inclusive jet measurements by the H1 and ZEUS experiments at HERA. An extraction of the strong coupling constant is performed as an application of the use of such grids and a best-fit value of αs(MZ)=0.1170(15)exp(25)th is obtained using the HERA inclusive jet cross section data.

This document provides a writeup of all contributions to the workshop on "High precision measurements of $α_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $α_s$ from 15 methods where high precision measurements are (or will be) available. Those include low-energy observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv) $τ$ decays, (v) soft parton-to-hadron fragmentation functions, as well as high-energy observables: (vi) global fits of parton distribution functions, (vii) hard parton-to-hadron fragmentation functions, (viii) jets in $e^\pm$p DIS and $γ$-p photoproduction, (ix) photon structure function in $γ$-$γ$, (x) event shapes and (xi) jet cross sections in $e^+e^-$ collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv) top-quark cross sections in proton-(anti)proton collisions. The current status of the theoretical and experimental uncertainties associated to each extraction method, the improvements expected from LHC data in the coming years, and future perspectives achievable in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) with $\cal{O}$(1--100 ab$^{-1}$) integrated luminosities yielding 10$^{12}$ Z bosons and jets, and 10$^{8}$ W bosons and $τ$ leptons, are thoroughly reviewed. The current uncertainty of the (preliminary) 2015 strong coupling world-average value, $α_s(m_Z)$ = 0.1177 $\pm$ 0.0013, is about 1\%. Some participants believed this may be reduced by a factor of three in the near future by including novel high-precision observables, although this opinion was not universally shared. At the FCC-ee facility, a factor of ten reduction in the $α_s$ uncertainty should be possible, mostly thanks to the huge Z and W data samples available.

This Report summarizes the proceedings of the 2019 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments for high precision Standard Model calculations, (II) the sensitivity of parton distribution functions to the experimental inputs, (III) new developments in jet substructure techniques and a detailed examination of gluon fragmentation at the LHC, (IV) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, and (V) Monte Carlo event generator studies relating to PDF evolution and comparisons of important processes at the LHC.

We present a comprehensive overview of theory-data comparisons for inclusive jet production. Theory predictions are derived for recent parton distribution functions and compared with jet data from different hadron-induced processes at various center-of-mass energies sqrt(s). The comparisons are presented as a function of jet transverse momentum pT or, alternatively, of the scaling variable xT = 2pT/sqrt(s).

The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse femtobarn of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focussed on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.

Sets of parton distribution functions (PDFs) of the proton are reported for the leading (LO), next-to-leading (NLO) and next-to-next-to-leading-order (NNLO) QCD calculations. The parton distribution functions are determined with the HERAFitter program using the data from the HERA experiments and preserving correlations between uncertainties for the LO, NLO and NNLO PDF sets. The sets are used to study cross-section ratios and their uncertainties when calculated at different orders in QCD. A reduction of the overall theoretical uncertainty is observed if correlations between the PDF sets are taken into account for the ratio of $$WW$$ di-boson to $$Z$$ boson production cross sections at the LHC.

The charm quark mass is one of the fundamental parameters of the Standard Model Lagrangian. In this work we present a determination of the $$ \overline{\mathrm{MS}} $$ charm mass from a fit to the inclusive and charm HERA deep-inelastic structure function data. The analysis is performed within the xFitter framework, with structure functions computed in the FONLL general-mass scheme as implemented in APFEL. In the case of the FONLL-C scheme, we obtain m c (m c ) = 1.335 ± 0.043(exp) − 0.000 + 0.019 (param) − 0.008 + 0.011 (mod) − 0.008 + 0.003 (th) GeV. We also perform an analogous determination in the fixed-flavor-number scheme at next-to-leading order, finding m c (m c ) = 1.318 ± 0.054(exp) − 0.010 + 0.011 (param) − 0.004 + 0.015 (mod) − 0.004 + 0.045 (th) GeV, compatible with the FONLL-C value. Our results are consistent with previous determinations from DIS data as well as with the PDG world average.

Inclusive jet cross section measurements from the ATLAS, CDF, CMS, D0, H1, STAR, and ZEUS experiments are explored for determinations of the strong coupling constant $$\alpha _{\text {s}} (M_{\text {Z}})$$ . Various jet cross section data sets are reviewed, their consistency is examined, and the benefit of their simultaneous inclusion in the $$\alpha _{\text {s}} (M_{\text {Z}})$$ determination is demonstrated. Different methods for the statistical analysis of these data are compared and one method is proposed for a coherent treatment of all data sets. While the presented studies are based on next-to-leading order in perturbative quantum chromodynamics (pQCD), they lay the groundwork for determinations of $$\alpha _{\text {s}} (M_{\text {Z}})$$ at next-to-next-to-leading order.

Fast interpolation-grid frameworks facilitate an efficient and flexible evaluation of higher-order predictions for any choice of parton distribution functions or value of the strong coupling αs . They constitute an essential tool for the extraction of parton distribution functions and Standard Model parameters, as well as studies of the dependence of cross sections on the renormalisation and factorisation scales. The APPLfast project provides a generic interface between the parton-level Monte Carlo generator and both the APPLgrid and the fastNLO libraries for the grid interpolation. The extension of the project to include hadron-hadron collider processes at next-to-next-to-leading order in perturbative QCD is presented, together with an application for jet production at the LHC.

This Report summarizes the proceedings of the 2017 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) theoretical uncertainties and dataset dependence of parton distribution functions, (III) new developments in jet substructure techniques, (IV) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (V) phenomenological studies essential for comparing LHC data from Run II with theoretical predictions and projections for future measurements, and (VI) new developments in Monte Carlo event generators.

Correlations among hadrons with the same electric charge produced in Z0 decays are studied using the high statistics data collected from 1991 through 1995 with the OPAL detector at LEP. Normalized factorial cumulants up to fourth order are used to measure genuine particle correlations as a function of the size of phase space domains in rapidity, azimuthal angle and transverse momentum. Both all-charge and like-sign particle combinations show strong positive genuine correlations. One-dimensional cumulants initially increase rapidly with decreasing size of the phase space cells but saturate quickly. In contrast, cumulants in two- and three-dimensional domains continue to increase. The strong rise of the cumulants for all-charge multiplets is increasingly driven by that of like-sign multiplets. This points to the likely influence of Bose–Einstein correlations. Some of the recently proposed algorithms to simulate Bose–Einstein effects, implemented in the Monte Carlo model Pythia, are found to reproduce reasonably well the measured second- and higher-order correlations between particles with the same charge as well as those in all-charge particle multiplets.

We present a method for very fast repeated computations of higher-order cross sections in hadron-induced processes for arbitrary parton density functions. A full implementation of the method for computations of jet cross sections in Deep-Inelastic Scattering and in Hadron-Hadron Collisions is offered by the ''fastNLO'' project.

The experiments at Run 2 of the Tevatron have each accumulated over 1 fb{sup -1} of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focused on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.

We point out an inconsistency in perturbative QCD predictions previously used for dijet azimuthal decorrelations for azimuthal angles of Δϕ dijet < 2π/3 between the two jets. We show how the inconsistency arises and how the calculations can be modified to provide more accurate results that exhibit a smaller scale dependence and give a better description of the data than the inconsistent results. We also explain how the quality of the predictions strongly depends on a perceivedly minor detail in the definition of the dijet phase space and give recommendations for future measurements.

This book reviews the latest experimental results on jet physics from proton-proton collisons at the LHC. Jets allow to determine the strong coupling constant over a wide range of energies up the high

A successful description of hadron-hadron collision data demands a profound understanding of quantum chromodynamics. Inevitably, the complexity of strong-interaction phenomena requires the use of a large variety of theoretical techniques -- from perturbative cross-section calculations up to the modelling of exclusive hadronic final states. Together with the unprecedented precision of the data provided by the experiments in the first running period of the LHC, a solid foundation of hadron-hadron collision physics at the TeV scale could be established that allowed the discovery of the Higgs boson and that is vital for estimating the background in searches for new phenomena. This chapter on studies of quantum chromodynamics at the LHC is part of a recent book on the results of LHC Run 1 and presents the advances in theoretical methods side-by-side with related key measurements in an integrated approach.

The charm quark mass is one of the fundamental parameters of the Standard Model Lagrangian. In this work we present a determination of the MSbar charm mass from a fit to the inclusive and charm HERA deep-inelastic structure function data. The analysis is performed within the xFitter framework, with structure functions computed in the FONLL general-mass scheme as implemented in APFEL. In the case of the FONLL-C scheme, we obtain mc(mc) = 1.335 +- 0.043(exp) +0.019 -0.000(param) +0.011 -0.008(mod) +0.033 -0.008(th) GeV. We also perform an analogous determination in the fixed-flavor-number scheme at next-to-leading order, finding mc(mc) = 1.318 +- 0.054(exp) +0.011 -0.010(param) +0.015 -0.019(mod) +0.045 -0.004(th) GeV, compatible with the FONLL-C value. Our results are consistent with previous determinations from DIS data as well as with the PDG world average.

This article is part of the "Review of Particle Physics" by the Particle Data Group and reviews the current status of quantum chromodynamics and the strong coupling constant $\alpha_s$. The latest updates as of August 2023 are included.

PAX (Physics Analysis Expert) is a novel, C++ based toolkit designed to assist teams in particle physics data analysis issues. The core of PAX are event interpretation containers, holding relevant information about and possible interpretations of a physics event. Providing this new level of abstraction beyond the results of the detector reconstruction programs, PAX facilitates the buildup and use of modern analysis factories. Class structure and user command syntax of PAX are set up to support expert teams as well as newcomers in preparing for the challenges expected to arise in the data analysis at future hadron colliders.

This document collects a written summary of all contributions presented at the workshop $\alpha_s$(2019): Precision measurements of the strong held at ECT* (Trento) in Feb. 11--15, 2019. The workshop explored in depth the latest developments on the determination of the QCD coupling $\alpha_s$ from the key categories where high precision measurements are available: (i) lattice QCD, (ii) hadronic $\tau$ decays, (iii) deep-inelastic scattering and parton distribution functions, (iv) event shapes, jet cross sections, and other hadronic final-states in $e^+e^-$ collisions, (v) Z boson and W boson hadronic decays, and (vi) hadronic final states in p-p collisions. The status of the current theoretical and experimental uncertainties associated to each extraction method, and future perspectives were thoroughly reviewed. Novel $\alpha_s$ determination approaches were discussed, as well as the combination method used to obtain a world-average value of the QCD coupling at the Z mass pole.

A summary of the main points of discussion raised during the talks and their follow-up questions,as well as in the round table of the last day of the $α_s$ (2019) workshop, is presented. The discussions not only focused on particular issues affecting each one of the individual $α_s$ extractions, but also on the current PDG categorization of $α_s$ measurements and on the methods used to average them into a single $α_s$ ($m_Z$) value. Most of the listed points are open and sources of potential controversies, which we highlight here as one might expect that ongoing progress in the field will lead to their clarification and resolution.

The restart of the Large Hadron Collider (LHC) at CERN, Geneva, in 2015 at a new record centre-of-mass energy of 13 TeV is a good occasion to collect, discuss, and summarise the experience gained with jet analyses in Run 1.

Sets of parton distribution functions (PDFs) of the proton are reported for the leading (LO), next-to-leading (NLO) and next-to-next-to leading order (NNLO) QCD calculations. The parton distribution functions are determined with the HERAFitter program using the data from the HERA experiments and preserving correlations between uncertainties for the LO, NLO and NNLO PDF sets. The sets are used to study cross-section ratios and their uncertainties when calculated at different orders in QCD. A reduction of the overall theoretical uncertainty is observed if correlations between the PDF sets are taken into account for the ratio of $WW$ di-boson to $Z$ boson production cross sections at the LHC.

Inclusive jet cross section measurements from the ATLAS, CDF, CMS, D0, H1, STAR, and ZEUS experiments are explored for determinations of the strong coupling constant $α_{\text{s}}(M_{\text{Z}})$. Various jet cross section data sets are reviewed, their consistency is examined, and the benefit of their simultaneous inclusion in the $α_{\text{s}}(M_{\text{Z}})$ determination is demonstrated. Different methods for the statistical analysis of these data are compared and one method is proposed for a coherent treatment of all data sets. While the presented studies are based on next-to-leading order in perturbative quantum chromodynamics (pQCD), they lay the groundwork for determinations of $α_{\text{s}}(M_{\text{Z}})$ at next-to-next-to-leading order.

First LHC data have been collected and collisions at a center-of-mass energy of 7TeV are anticipated for the next months. The commissioning of the detectors and the re-establishment of the Standard Model in the new energy regime will be the main tasks for the experimental collaborations in the year to come. This report summarizes the measurement plans and performance expectations of the ATLAS and CMS experiments for a selected number of QCD and electroweak analyses with an emphasis on the early data taking phase. Some longer term prospects are pointed out.

Deep-inelastic ep scattering data, taken with the H1 detector at HERA, are used to study event shape variables over a large range of "relevant energy" Q between 7 GeV and 100 GeV. Previously published analysis on thrust, jet broadening, jet mass and C parameter are substantially refined and updated; differential two-jet rates treated as event shapes are presented for the first time. The Q dependence of the mean values is fit to second order calculations of perturbative QCD applying power law corrections proportional to 1/Q^p to account for hadronization effects. The concept of these power corrections is tested by a systematic investigation in terms of a non-perturbative parameter \bar{alpha}_{p-1} and the strong coupling constant.

This document summarises the status of the existing grid infrastructure and functionality for the high-energy physics experiment CMS and the expertise in operation attained during the so-called ”Computing, Software and Analysis Challenge” performed in 2006 (CSA06). This report is especially focused on the role of the participating computing centres in Germany located at Karlsruhe, Hamburg and Aachen. In preparation for the enormous amounts of data expected from the future large hadron collider (LHC) presently under construction at the European laboratory for particle physics, CERN, a grid infrastructure is being set up by the physics communities in the participating countries. The world-wide LHC Computing Grid (WLCG) is based on tier-structured layers of one Tier0 at CERN and several Tier1, Tier2 and Tier3 centres distributed all around the globe. The German part of the CMS grid infrastructure relies heavily on the two Helmholtz centres Forschungszentrum Karlsruhe as Tier1 and DESY Hamburg as well as on installations at the universities Karlsruhe and Aachen. The emphasis of this report lies on so-called service challenges performed in 2006 where the full functionality of the whole chain from data processing at the Tier0, data distribution to the Tier1 and Tier2 centres up to organised data re-processing and more chaotic physics analyses by single users was exercised.

The CMS 2004 Data Challenge (DC04) was devised to test several key aspects of the CMS Computing Model in three ways: by trying to sustain a 25 Hz reconstruction rate at the Tier-0; by distributing the reconstructed data to six Tier-1 Regional Centres (CNAF in Italy, FNAL in US, GridKA in Germany, IN2P3 in France, PIC in Spain, RAL in UK) and handling catalogue issues; by granting data accessibility at remote centres for analysis. Simulated events, up to the digitization step, were produced prior to the DC as input for the reconstruction in the Pre-Challenge Production (PCP04). In this paper, the model of the Tier-0 implementation used in DC04 is described, as well as the experience gained in using the newly developed data distribution management layer, which allowed CMS to successfully direct the distribution of data from Tier-0 to Tier-1 sites by loosely integrating a number of available Grid components. While developing and testing this system, CMS explored the overall functionality and limits of each component, in any of the different implementations that were deployed within DC04. The role of Tier-1's is presented and discussed, from the import of reconstructed data from Tier-0, to the archiving on to the local Mass Storage System (MSS) and the data distribution management to Tier-2's for analysis. Participating Tier-1's differed in available resources, setup and configuration. A critical evaluation of the results and performances achieved adopting different strategies in the organization and management of each Tier-1 centre to support CMS DC04 is presented.

We point out an inconsistency in perturbative QCD predictions previously used for dijet azimuthal decorrelations for azimuthal angles of $\Delta\phi_{\rm dijet} < 2\pi/3$ between the two jets. We show how the inconsistency arises and how the calculations can be modified to provide more accurate results that exhibit a smaller scale dependence and give a better description of the data than the inconsistent results. We also explain how the quality of the predictions strongly depends on a perceivedly minor detail in the definition of the dijet phase space and give recommendations for future measurements.

Absolute cross sections are the most fundamental measurements to be made in collision experiments. They represent the proportionality constant between the luminosity characterising the performance of a particle accelerator and event count rates in an experiment. After introducing some basic terminology, measurements of inclusive jet, dijet, and 3-jet cross sections and their use in determining SM parameters are presented.

As demonstrated in the previous chapter, valuable insights can be gained from the measurement of absolute cross sections. However, they are subject to the totality of experimental and theoretical uncertainties. Therefore, it is worthwhile to contemplate alternative observables that are either insensitive or sensitive at a reduced level to the dominant sources of uncertainty. The possibility discussed in this chapter deals with cross section ratios.

A second possibility to reduce uncertainties caused by systematic effects consists in performing shape comparisons only. In this case the measured and the predicted distributions are normalised to the integral over the whole or a part of the investigated phase space. Luminosity uncertainties are irrelevant in this case and JEC, JER, QCD scale, or PDF effects cancel at least partially.

Jet physics, in particular at a hadron collider such as the LHC, cannot be understood without being thoroughly familiar with the theory of the strong interaction: quantum chromodynamics or short QCD. The material presented in this chapter is intended to provide the required proficiency to comprehend experimental and phenomenological publications on the subject of jet physics, some of which will be discussed in detail in the later chapters of this book.

On June 3rd, 2015, the LHC resumed operations after a 2-years break for consolidation and upgrades. Most notably, the centre-of-mass energy was raised from 8 to 13 $$\,\text {TeV}$$ . In the following two sections, first results will be presented on new phenomena from dijets and on inclusive jet measurements that were released by the LHC experiments at or before the so-called end-of-year jamboree on December 15th, 2015. This is complemented with an outlook on determinations of the strong coupling constant.

Jets are versatile tools that are produced abundantly in high- $$p_{\mathrm {T}}$$ hadron-hadron collisions. When energy frontiers are probed they enable searches for new phenomena at the highest scales achievable. Owing to the unprecedented experimental precision reached with the new detectors at the LHC, jet measurements have evolved into precision tests of QCD.

This chapter introduces the necessary experimental concepts and tools needed for a generic jet analysis at the LHC. The sections are ordered in a similar way as they would typically appear in an experimental publication and start with a synopsis of the measuring apparatus.

The charm quark mass is one of the fundamental parameters of the Standard Model Lagrangian. In this work we present a determination of the MSbar charm mass from a fit to the inclusive and charm HERA deep-inelastic structure function data. The analysis is performed within the xFitter framework, with structure functions computed in the FONLL general-mass scheme as implemented in APFEL. In the case of the FONLL-C scheme, we obtain mc(mc) = 1.335 +- 0.043(exp) +0.019 -0.000(param) +0.011 -0.008(mod) +0.033 -0.008(th) GeV. We also perform an analogous determination in the fixed-flavor-number scheme at next-to-leading order, finding mc(mc) = 1.318 +- 0.054(exp) +0.011 -0.010(param) +0.015 -0.019(mod) +0.045 -0.004(th) GeV, compatible with the FONLL-C value. Our results are consistent with previous determinations from DIS data as well as with the PDG world average.

This chapter contains sections titled: Introduction The Strong Coupling Perturbative QCD at Colliders Hard Parton Scattering Parton Luminosity Fragmentation Functions and Event Shapes Jet Production Gauge-Boson Production Jet Shapes Tests of the QCD Gauge Structure Outlook References

Abstract Wissenschaftler des CMS‐Experiments am Large Hadron Collider (LHC) in Genf haben im Laufe dieses Jahres neue Ergebnisse zur Bestimmung der Kopplungskonstanten α S der starken Wechselwirkung bekannt gegeben. Die Messungen bei bisher unerreichten Energien bestätigen die Vorhersage des Standardmodells und liefern keinen Hinweis auf neue Phänomene.

The first very successful LHC running period has been finished. At 7 TeV centre-of-mass energy about 5/fb of data have been collected and at 8 TeV even 20/fb. Many detailed analyses of these data are still going on. The latest measurements on photon, weak boson plus jet, and jet production are compared against the most recent theory predictions. They are complemented by new results reported by the experiments at the Tevatron and HERA colliders. Finally, several new determinations of the strong coupling constant from jet data are presented.

A fundamental characteristic of hadron colliders is the abundant production of jets, which then are studied to learn about hard QCD, the proton structure, or nonperturbative effects. In the following the latest results and developments from the LHC experiments on jet cross sections, event shapes, flavour and rapidity dependence, and cross section ratios are presented. The ratio of the inclusive 3-jet to the inclusive 2-jet event cross section is used for a first determination of the strong coupling constant at the TeV scale.

The first very successful LHC running period has been finished. At 7 TeV centre-of-mass energy about 5/fb of data have been collected and at 8 TeV even 20/fb. Many detailed analyses of these data are still going on. The latest measurements on photon, weak boson plus jet, and jet production are compared against the most recent theory predictions. They are complemented by new results reported by the experiments at the Tevatron and HERA colliders. Finally, several new determinations of the strong coupling constant from jet data are presented.

Standard methods for higher-order calculations of QCD cross sections in hadron-induced collisions are time-consuming. The fastNLO project uses multi-dimensional interpolation techniques to convert the convolutions of perturbative coefficients with parton distribution functions and the strong coupling into simple products. By integrating the perturbative coefficients for a given observable with interpolation kernels, fastNLO can store the results of the time-consuming folding integrals in tables, which subsequently are used for very fast rederivations of the same observable for arbitrary parton distribution functions, different scale choices, or alpha_s(M_Z). Various tables with code for their evaluation are available for numerous jet measurements at the LHC, the TeVatron, and HERA. FastNLO is used in publications of experimental results by the ATLAS, CMS, CDF, D0, and H1 collaborations, and in all recent global PDF analyses by MSTW, CTEQ, and NNPDF. This article focuses on developments implemented in the new version 2 of fastNLO, enhancing and broadening its functionality.

From 1996 up to 2000 the LEP collider at CERN has operated at center of mass energies above the production threshold for W boson pairs of approximately 160 GeV. The obtained data are used to extract a preliminary W mass value of (80.450 +- 0.039) GeV by direct reconstruction. To a large extent the uncertainty is due to systematic effects especially in the fully hadronic decay channel W+W- --&gt; qq' qq' that suffers most from ambiguities in modelling the hadronic final state. Methods to assess and reduce these uncertainties are the current main concern of the four LEP experiments.

Deep-inelastic ep scattering data, taken with the H1 and ZEUS detectors at HERA, are used to study the means and distributions of the event shape variables thrust, jet broadening, jet mass, C-parameter and two kinds of differential two-jet rate. The data cover a range of the four-momentum transfer Q, taken to be the relevant energy scale, between 7 GeV and 141 GeV. The Q dependences are compared with second-order calculations of perturbative QCD. Power law corrections are applied to account for hadronization effects.

First LHC data have been collected and collisions at a center-of-mass energy of 7 TeV are anticipated for the next months. The commissioning of the detectors and the re-establishment of the Standard Model in the new energy regime will be the main tasks for the experimental collaborations in the year to come. This report summarizes the measurement plans and performance expectations of the ATLAS and CMS experiments for a selected number of QCD and electroweak analyses with an emphasis on the early data taking phase. Some longer term prospects are pointed out.

First LHC data have been collected and collisions at a center-of-mass energy of 7 TeV are anticipated for the next months. The commissioning of the detectors and the re-establishment of the Standard Model in the new energy regime will be the main tasks for the experimental collaborations in the year to come. This report summarizes the measurement plans and performance expectations of the ATLAS and CMS experiments for a selected number of QCD and electroweak analyses with an emphasis on the early data taking phase. Some longer term prospects are pointed out.

In view of the approaching LHC operation the feasibility and accuracy of QCD measurements with the CMS experiment at the Large Hadron Collider (LHC) involving hadrons and jets are discussed. This summary is based on analyses performed at CMS for center-of-mass energies of 10 as well as 14 TeV assuming event numbers ranging from some days of data taking up to 100/pb of integrated luminosity with proton-proton collisions.

The event shape variables thrust, jet broadening and jet mass, defined in the current hemisphere of the Breit frame, are studied for the first time in deep-inelastic ep scattering using data of the H1 experiment at HERA in a range of momentum transfer Q from 7 GeV to 100 GeV. Applying power corrections to account for hadronisation effects the Q dependence of the event shape means corrected for detector deficiencies is fit to second order pQCD calculations. The determined fit parameters α0¯ and αs(MZ2) are compatible with a 1/Q behaviour of all investigated shape variables.

Significant progress in experimental and theoretical techniques allow a determination of the strong coupling constant αsfrom proton-proton collisions with much improved precision. Results of the CMS experiment [1] at the LHC are reviewed, which are based on measurements of jet and of top-quark pair production.

This Report summarizes the proceedings of the 2017 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) theoretical uncertainties and dataset dependence of parton distribution functions, (III) new developments in jet substructure techniques, (IV) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (V) phenomenological studies essential for comparing LHC data from Run II with theoretical predictions and projections for future measurements, and (VI) new developments in Monte Carlo event generators.

This Report summarizes the proceedings of the 2017 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) theoretical uncertainties and dataset dependence of parton distribution functions, (III) new developments in jet substructure techniques, (IV) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (V) phenomenological studies essential for comparing LHC data from Run II with theoretical predictions and projections for future measurements, and (VI) new developments in Monte Carlo event generators.

This document collects a written summary of all contributions presented at the workshop "$α_s$(2019): Precision measurements of the strong coupling" held at ECT* (Trento) in Feb. 11--15, 2019. The workshop explored in depth the latest developments on the determination of the QCD coupling $α_s$ from the key categories where high precision measurements are available: (i) lattice QCD, (ii) hadronic $τ$ decays, (iii) deep-inelastic scattering and parton distribution functions, (iv) event shapes, jet cross sections, and other hadronic final-states in $e^+e^-$ collisions, (v) Z boson and W boson hadronic decays, and (vi) hadronic final states in p-p collisions. The status of the current theoretical and experimental uncertainties associated to each extraction method, and future perspectives were thoroughly reviewed. Novel $α_s$ determination approaches were discussed, as well as the combination method used to obtain a world-average value of the QCD coupling at the Z mass pole.

The efficient exploitation of worldwide distributed storage and computing resources available in the grids require a robust, transparent and fast deployment of experiment specific software. The approach followed by the CMS experiment at CERN in order to enable Monte-Carlo simulations, data analysis and software development in an international collaboration is presented. The current status and future improvement plans are described.

The efficient exploitation of worldwide distributed storage and computing resources available in the grids require a robust, transparent and fast deployment of experiment specific software. The approach followed by the CMS experiment at CERN in order to enable Monte-Carlo simulations, data analysis and software development in an international collaboration is presented. The current status and future improvement plans are described.

Deep-inelastic ep scattering data, taken with the H1 detector at HERA, are used to study the event shape variables thrust, jet broadening, jet mass, C parameter, and two kinds of differential two-jet rates over a large range of “relevant energy” Q between 7 GeV and 100 GeV. The Q dependence of the mean values is fit to second order calculations of perturbative QCD applying power law corrections proportional to 1Qp to account for hadronization effects. The concept of these power corrections is tested by a systematic investigation in terms of a non-perturbative parameter αp−1 and the strong coupling constant.