M. Stratmann

University of Tübingen

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Werner Vogelsang

University of Tübingen

R. Sassot

University of Buenos Aires

Daniel de Florian

National University of General San Martín

Felix Ringer

Old Dominion University

Pía Zurita

University of Regensburg

Ignacio Borsa

University of Tübingen

Daniele Paolo Anderle

South China Normal University

E. Reya

TU Dortmund University

Barbara Jäger

University of Tübingen

Tom Kaufmann

University of Tübingen

Cooperative Institutions

European Organization for Nuclear Research

147

Brookhaven National Laboratory

138

Centre National de la Recherche Scientifique

Thomas Jefferson National Accelerator Facility

Deutsches Elektronen-Synchrotron DESY

University of Adelaide

A. Alikhanyan National Laboratory

Stony Brook University

Institut National de Physique Nucléaire et de Physique des Particules

Universität Hamburg

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Photoproduction of heavy quarks in next-to-leading order QCD with longitudinally polarized initial states

Nuclear Physics B (1999)

Ingo Bojak M. Stratmann

Charm quark

Charm (quantum number)

Perturbative QCD

10.1016/s0550-3213(98)00751-2

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Citations (36)

Global analysis of helicity PDFs: past - present - future

arXiv (Cornell University) (2011)

Daniel de Florian M. Stratmann R. Sassot Werner Vogelsang

We discuss the current status of the DSSV global analysis of helicity-dependent parton densities. A comparison with recent semi-inclusive DIS data from COMPASS is presented, and constraints on the polarized strangeness density are examined in some detail.

Helicity

Compass

10.48550/arxiv.1108.3955

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Parton content of virtual photons

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields (1995)

M. Glück E. Reya M. Stratmann

The parton content of virtual transverse photons \ensuremath{\gamma}(${\mathit{P}}^{2}$) is expressed in terms of perturbative pointlike and nonperturbative hadronic (VMD) components. The resulting LO and NLO parton distributions ${\mathit{f}}^{\ensuremath{\gamma}(\mathit{P}2}$)(x,${\mathit{Q}}^{2}$) are smooth in ${\mathit{P}}^{2}$. They apply uniformly to all ${\mathit{P}}^{2}$\ensuremath{\ge}0 whenever \ensuremath{\gamma}(${\mathit{P}}^{2}$) is probed at a scale ${\mathit{Q}}^{2}$\ensuremath{\gg}${\mathit{P}}^{2}$ where the transverse photons furthermore also dominate physically relevant cross sections. Predictions are given for ${\mathit{F}}_{2}^{\ensuremath{\gamma}(\mathit{P}2}$)(x,${\mathit{Q}}^{2}$) and ${\mathrm{\ensuremath{\mu}}}^{\ensuremath{\gamma}(\mathit{P}2}$)(x,${\mathit{Q}}^{2}$), ${\mathit{g}}^{\ensuremath{\gamma}(\mathit{P}2}$)(x,${\mathit{Q}}^{2}$) relevant for future CERN LEP and present DESY HERA measurements, respectively. Except for certain kinematic regions, these virtual structure functions and parton distributions at ${\mathrm{\ensuremath{\Lambda}}}^{2}$\ensuremath{\ll}${\mathit{P}}^{2}$\ensuremath{\ll}${\mathit{Q}}^{2}$ are not solely described by purely perturbative contributions, in contrast with ``naive'' expectations; these remaining nonperturbative components, although being based on VMD-inspired simplicity, represent the largest uncertainty in our quantitative results and eventually have to be tested by future experiments.

Virtual particle

Content (measure theory)

10.1103/physrevd.51.3220

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Citations (50)

Next-to-leading order QCD corrections to spin-dependent hadron-pair photoproduction

arXiv (Cornell University) (2008)

Christof Hendlmeier Andreas Schäfer M. Stratmann

We compute the next-to-leading order QCD corrections to the ``direct'' part of the spin-dependent cross section for hadron-pair photoproduction. The calculation is performed using largely analytical methods. We present a brief phenomenological study of our results focussing on the $K$-factors and scale dependence of the next-to-leading order cross sections. This process is relevant for the extraction of the gluon polarization in present and future spin-dependent lepton-nucleon scattering experiments.

10.48550/arxiv.0803.1940

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Verleihung der Adolf-Martens-Medaille an Herrn Prof. Dr. rer. nat. Hans Jürgen Grabke

HTM Journal of Heat Treatment and Materials (2002)

Helmut Mallener M. Stratmann

10.1515/htm-2002-570103

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High-tech und Stahl - Neue Ansätze zur Oberflächenveredelung von Stahl

M. Stratmann Guido Grundmeier

Source

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Evidence for Polarization of Gluons in the Proton

Physical Review Letters (2014)

Daniel de Florian R. Sassot M. Stratmann Werner Vogelsang

We discuss the impact of recent high-statistics RHIC data on the determination of the gluon polarization in the proton in the context of a global QCD analysis of polarized parton distributions. We find clear evidence for a non-vanishing polarization of gluons in the region of momentum fraction and at the scales mostly probed by the data. Although information from low momentum fractions is presently lacking, this finding is suggestive of a significant contribution of gluon spin to the proton spin, thereby limiting the amount of orbital angular momentum required to balance the proton spin budget.

10.1103/physrevlett.113.012001

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Citations (296)

Global analysis of nuclear parton distributions

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology (2012)

Daniel de Florian R. Sassot Pía Zurita M. Stratmann

We present a new global QCD analysis of nuclear parton distribution functions and their uncertainties. In addition to the most commonly analyzed data sets for the deep-inelastic scattering of charged leptons off nuclei and Drell-Yan di-lepton production, we include also measurements for neutrino-nucleus scattering and inclusive pion production in deuteron-gold collisions. The analysis is performed at next-to-leading order accuracy in perturbative QCD in a general mass variable flavor number scheme, adopting a current set of free nucleon parton distribution functions, defined accordingly, as reference. The emerging picture is one of consistency, where universal nuclear modification factors for each parton flavor reproduce the main features of all data without any significant tension among the different sets. We use the Hessian method to estimate the uncertainties of the obtained nuclear modification factors and examine critically their range of validity in view of the sparse kinematic coverage of the present data. We briefly present several applications of our nuclear parton densities in hard nuclear reactions at BNL-RHIC, CERN-LHC, and a future electron-ion collider.

10.1103/physrevd.85.074028

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Citations (256)

Photoproduction Processes in Polarized ep - Collisions at HERA

arXiv (Cornell University) (1997)

J. M. Butterworth Nadine Goodman M. Stratmann Werner Vogelsang

We study various conceivable photoproduction reactions in a polarized ep collider mode of HERA with respect to their sensitivity to the proton's polarized gluon distribution. A special emphasis is put on the `resolved' part of the cross sections which in principle opens the possibility to determine for the first time also the completely unknown parton content of longitudinally polarized photons. In the very promising case of dijet production we also investigate the impact of parton showering, hadronization and jet finding on the parton level results.

Hadronization

10.48550/arxiv.hep-ph/9711250

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Next-to-leading order QCD corrections to inclusive heavy-flavor production in polarized deep-inelastic scattering

Physical review. D/Physical review. D. (2018)

Felix Hekhorn M. Stratmann

We provide a first calculation of the complete next-to-leading order QCD corrections for heavy flavor contributions to the inclusive structure function ${g}_{1}$ in longitudinally polarized deep-inelastic scattering. The results are derived with largely analytical methods and retain the full dependence on the heavy quark's mass. We discuss all relevant technical details of the calculation and present numerical results for the heavy quark scaling functions. We perform important crosschecks to verify our results in the known limit of photoproduction and for the unpolarized electroproduction of heavy quarks. We also compare our calculations to the available, partial results in the polarized case, in particular, in the limit of asymptotically large photon virtualities, and analyze the behavior of the scaling functions near threshold. First steps towards phenomenological applications are taken by providing some estimates for inclusive charm production in polarized deep-inelastic scattering at a future electron-ion collider and studying their sensitivity to the polarized gluon distribution. The residual dependence of heavy quark electroproduction on unphysical factorization and renormalization scales and on the heavy quark mass is investigated.

10.1103/physrevd.98.014018

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Citations (20)