268 citations · 3k across the 94 of their papers we have counts for
18 papers · 1 filter
How to extract the scattering length from production reactions
A. Gasparyan, J. Haidenbauer, C. Hanhart +1
A dispersion integral is derived that allows one to relate directly (spin dependent) invariant mass spectra, measured in a large-momentum transfer reaction such as $pp\to K^+p…
Meson model for f_0(980) production in peripheral pion-nucleon reactions
F. P. Sassen, S. Krewald, J. Speth
The Juelich model for pion-pion-scattering, based on an effective meson-meson Lagrangian is applied to the analysis of the S-wave production amplitudes derived from the BNL E852 ex…
Perturbative QCD versus pion exchange and hadronic FSI effects in the gamma gamma --> pi^+ pi^- reaction
A. Szczurek, J. Speth
The interplay of pQCD, pion exchange and FSI effects is studied for the gamma gamma --> pi^+ pi^- reaction in the region of 2 GeV < W_{gamma gamma} < 6 GeV. We find strong interfer…
From soft to hard regime in elastic pion-pion scattering above resonances
A. Szczurek, N. N. Nikolaev, J. Speth
We discuss the onset of the dominance of the Glauber-Gribov-Landshoff (GGL) component of pQCD hard two-gluon (2G) exchange contribution to hard elastic scattering at moderate…
The reaction revisited: the scattering length
C. Hanhart, A. Sibirtsev, J. Speth
We reinvestigate the experimental data on --meson production in pion-nucleon collisions based on both an analytical approach and a Monte Carlo simulation. Our analysis allows us…
Towards mapping the proton unintegrated gluon distribution in dijets correlations in real and virtual photoproduction at HERA
A. Szczurek
It is discussed how the dijet azimuthal correlations in DIS and real photoproduction at HERA probe the unintegrated gluon distribution in the proton. The correlation function shows…
Mapping the proton unintegrated gluon distribution in dijets correlations in real and virtual photoproduction at HERA
A. Szczurek, N. N. Nikolaev, W. Schäfer +1
We discuss how the dijet azimuthal correlations in DIS and real photoproduction at HERA probe the differential (unintegrated) gluon distribution in the proton. We find a strong dep…
asymmetry and semi-inclusive production of pions in DIS
A. Szczurek, V. Uleshchenko, J. Speth
We investigate unambiguities in the extraction of the asymmetry from semi-inclusive production of pions in DIS. The role of several effects beyond the quark-parto…
Nuclear-Medium Modification of the Rho(1S)- and Rhoprim(2S)-Mesons in Coherent Photo- and Electroproduction: Coupled Channel Analysis
N. N. Nikolaev, J. Speth, B. G. Zakharov
We study medium modifications of the dilepton mass spectrum in coherent photo- and electroproduction of the Rho(1S)- and Rhoprim(2S)-meson resonances on nuclear targets. The analys…
Do the E866 Drell Yan data change our picture of the chiral structure of the nucleon ?
N. N. Nikolaev, W. Schäfer, A. Szczurek +1
We revisit the evaluation of the pionic mechanism of the -asymmetry in the proton structure function. Our analysis is based on the extended AGK unitarity relation…
Semi-inclusive Pion Production and the d/u Ratio
W. Melnitchouk, J. Speth, A. W. Thomas
We explore the feasibility of directly extracting the large-x valence d/u ratio through a measurement of pions in the current fragmentation region of semi-inclusive deep-inelastic…
Dynamics of Light Antiquarks in the Proton
W. Melnitchouk, J. Speth, A. W. Thomas
We present a comprehensive analysis of the recent data from the E866 experiment at Fermilab on Drell-Yan production in pD and pp collisions, which indicates a non-trivial x-depende…
Leading proton spectrum from DIS at HERA
A. Szczurek, N. N. Nikolaev, J. Speth
The QCD hardness scale for secondary particles () production in semi-inclusive deep inelastic scattering (DIS), , gradually decreases from , the photon vi…
Strange vector currents and the OZI-rule
Ulf-G. Meißner, V. Mull, J. Speth +1
We investigate the role of correlated exchange in the extraction of matrix elements of the strange vector current in the proton. We show that a realistic isoscalar spectral fu…
How to measure the pion structure function at HERA
H. Holtmann, G. Levman, N. N. Nikolaev +2
We suggest a method of determination of the pion structure function down to x \simeq 10^{-4} based on semi-exclusive deep inelastic scattering off protons. The idea is to exploit t…
Testing the meson cloud in the nucleon in Drell-Yan processes
A. Szczurek, M. Ericson, H. Holtmann +1
We discuss the present status of the \bar u-\bar d asymmetry in the nucleon and analize the quantities which are best suited to verify the asymmetry. We find that the Drell-Yan asy…
Flavour and Spin of the Proton and the Meson Cloud
H. Holtmann, A. Szczurek, J. Speth
We present a complete set of formulas for longitudinal momentum distribution functions (splitting functions) of mesons in the nucleon. It can be applied in the framework of convolu…
Pion Content of the Nucleon as seen in the NA51 Drell-Yan experiment
H. Holtmann, N. N. Nikolaev, J. Speth +1
In a recent CERN Drell-Yan experiment the NA51 group found a strong asymmetry of and densities in the proton at . We interpret this result as a decis…