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D. Grunewald

Publications and source records attributed to D. Grunewald.

6 recordsLinked to original sources
arXiv2008

Transverse Momentum Broadening in Semi-inclusive DIS on Nuclei

Using a three stage model of hadron formation we calculate the change of the transverse momentum distribution of hadrons produced in semi-inclusive deep inelastic scattering (SIDIS) on nuclei. In the first stage after its interaction with the virtual photon, the struck quark propagates quasi free in the nuclear environment undergoing multiple collisions with nucleons. During this stage it can acquire transverse momentum. In the second stage a prehadron is formed which has a very small elastic cross section with the nucleons. In the third stage the prehadron turns into a hadron. For HERMES energies, prehadron elastic scatterings contribute little to $p_\perp$-broadening. The acquired extra $Δp_\perp^2$ of hadrons can therefore be deduced entirely from the first stage of quasi free quark propagation with quark-nucleon collisions. We use this model to describe $π$-production on Ne, Kr, Xe and compare with the most recent HERMES preliminary data.

hep-ph↗
arXiv2007

Formulating Light Cone QCD on the Lattice

We present the near light cone Hamiltonian $H$ in lattice QCD depending on the parameter $η$, which gives the distance to the light cone. Since the vacuum has zero momentum we can derive an effective Hamiltonian $H_{eff}$ from $H$ which is only quadratic in the momenta and therefore solvable by standard methods. An approximate ground state wave functional is determined variationally in the limit $η\to 0$.

hep-lat↗
arXiv2007

Hamiltonian Lattice QCD near the Light Cone

We give a status report of our work on light cone Hamiltonian lattice QCD. We have derived an effective Hamiltonian $H_{eff}$ which is only quadratic in the momenta and therefore can be simulated by standard methods. For this Hamiltonian we determine variationally an approximate ground state wave functional in the light cone limit.

hep-lat↗
arXiv2006

Higher Twist Effects in Deep Inelastic Scattering on Nuclei

Particle production in deep inelastic scattering on nuclei is reduced due to absorption of the produced particles in the nucleus. The photon ejects a quark from a bound nucleon which propagates through the nucleus forming a prehadron before turning into a hadron. We calculate the higher twist effect in hadronization which dominates the $z \to 1$ region of fragmentation.

hep-ph↗
arXiv2005

Atomic Mass Dependence of Hadron Production in Deep Inelastic Scattering on Nuclei

Hadron production in lepton-nucleus deep inelastic scattering is studied in an absorption model. In the proposed model, the early stage of hadronization in the nuclear medium is dominated by prehadron formation and absorption, controlled by flavor-dependent formation lengths and absorption cross sections. Computations for hadron multiplicity ratios are presented and compared with the HERMES experimental data for pions, kaons, protons and antiprotons. The mass-number dependence of hadron attenuation is shown to be sensitive to the underlying hadronization dynamics. Contrary to common expectations for absorption models, a leading term proportional to A^{2/3} is found. Deviations from the leading behavior arise at large mass-numbers and large hadron fractional momenta.

hep-ph↗