Higher-order surface FEM for incompressible Navier-Stokes flows on manifolds

Stationary and instationary Stokes and Navier-Stokes flows are considered on two-dimensional manifolds, i.e., on curved surfaces in three dimensions. The higher-order surface FEM is used for the approximation of the geometry, velocities, pressure, and Lagrange multiplier to enforce tangential velocities. Individual element orders are employed for these various fields. Stream-line upwind stabilization is employed for flows at high Reynolds numbers. Applications are presented which extend classical benchmark test cases from flat domains to general manifolds. Highly accurate solutions are obtained and higher-order convergence rates are confirmed.Comment: Submitted to International Journal for Numerical Methods in Fluids V1: Initial submission V2: Corrected errors in strong forms, revised discussion of the result

Hybrid Hadronization

We discuss Hybrid Hadronization, a hadronization model which interpolates between string fragmentation in dilute parton systems and quark recombination in dense parton systems. We lay out the basic principles, discuss some details of the implementation, and show some prelimiary results. Hybrid Hadronization is realized as a software package which works with PYTHIA 8 and will be released publicly in the near future.Comment: 4 pages, 2 figures; Contribution to Hard Probes 201

The Skyrme Model piNN Form Factor and the Sea Quark Distribution of the Nucleon

We calculate the sea quark distribution of the nucleon in a meson cloud model. The novel feature of our calculation is the implementation of a special piNN form factor recently obtained by Holzwarth and Machleidt. This form factor is hard for small and soft for large momentum transfers. We show that this feature leads to a substantial improvement.Comment: 9 pages, 5 figures; v2: some typos corrected, including eq. (9

Global Flow of Glasma in High Energy Nuclear Collisions

We discuss the energy flow of the classical gluon fields created in collisions of heavy nuclei at collider energies. We show how the Yang-Mills analoga of Faraday's Law and Gauss' Law predict the initial gluon flux tubes to expand or bend. The resulting transverse and longitudinal structure of the Poynting vector field has a rich phenomenology. Besides the well known radial and elliptic flow in transverse direction, classical quantum chromodynamics predicts a rapidity-odd transverse flow that tilts the fireball for non-central collisions, and it implies a characteristic flow pattern for collisions of non-symmetric systems $A+B$. The rapidity-odd transverse flow translates into a directed particle flow $v_1$ which has been observed at RHIC and LHC. The global flow fields in heavy ion collisions could be a powerful check for the validity of classical Yang-Mill dynamics in high energy collisions.Comment: 7 figure

Rapidity Profile of the Initial Energy Density in Heavy-Ion Collisions

The rapidity dependence of the initial energy density in heavy-ion collisions is calculated from a three-dimensional McLerran-Venugopalan model (3dMVn) introduced by Lam and Mahlon. This model is infrared safe since global color neutrality is enforced. In this non-boost-invariant framework, the nuclei have non-zero thickness in the longitudinal direction. This results in Bjorken-x dependent unintegrated gluon distribution functions which lead to a rapidity-dependent initial energy density after the collision. The initial energy density and its rapidity dependence are important initial conditions for the quark gluon plasma and its hydrodynamic evolution.Comment: 7 pages, 2 figures. Matches the published versio