A rainbowladder truncation of QCD’s DysonSchwinger equations is used to calculate rho and phimeson valencequark (twisttwo parton) distribution amplitudes (PDAs) via a lightfront projection of their BetheSalpeter wave functions, which possess S and Dwave components of comparable size in the meson rest frame. All computed PDAs are broad concave functions, whose dilation with respect to the asymptotic distribution is an expression of dynamical chiral symmetry breaking. The PDAs can be used to define an ordering of valencequark lightfront spatialextent within mesons: this size is smallest within the pion and increases through the perppolarisation to the parallelpolarisation of the vector mesons; effects associated with the breaking of SU(3)flavour symmetry are significantly smaller than those associated with altering the polarisation of vector mesons. Notably, the predicted pointwise behaviour of the rhomeson PDAs is in quantitative agreement with that inferred recently via an analysis of diffractive vectormeson photoproduction experiments.
Category Archives: Nuclear Theory
Towards an optical potential for rareearths through coupled channels
The coupledchannel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations, defined by nuclear deformations. Proper treatment of such excitations is often essential to the accurate description of reaction experimental data. Previous works have applied different models to specific nuclei with the purpose of determining angularintegrated cross sections. In this work, we present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions in a consistent manner for neutroninduced reactions on nuclei in the rareearth region. This specific subset of the nuclide chart was chosen precisely because of a clear static deformation pattern. We analyze the convergence of the coupledchannel calculations regarding the number of states being explicitly coupled. Inspired by the work done by Dietrich \emph{et al.}, a model for deforming the spherical KoningDelaroche optical potential as function of quadrupole and hexadecupole deformations is also proposed. We demonstrate that the obtained results of calculations for total, elastic and inelastic cross sections, as well as elastic and inelastic angular distributions correspond to a remarkably good agreement with experimental data for scattering energies above around a few MeV.
3+1 dimensional viscous hydrodynamics at high baryon densities
Iu. Karpenko, M. Bleicher, P. Huovinen, H. Petersen
We apply a 3+1D viscous hydrodynamic + cascade model to the heavy ion collision reactions with √sNN=6.3…39 GeV. To accommodate the model for a given collision energy range, the initial conditions for hydrodynamic phase are taken from UrQMD, and the equation of state at finite baryon density is based on Chiral model coupled to the Polyakov loop.
We study the collision energy dependence of pion and kaon rapidity distributions and mTspectra, as well as charged hadron elliptic flow and how shear viscosity affects them. The model calculations are compared to the data for PbPb collisions at CERN SPS, as well as for AuAu collisions in the Beam Energy Scan (BES) program energies at BNL RHIC. The data favours the value of shear viscosity η/s≳0.2 for this collision energy range.
Cite as:  arXiv:1311.0133 [nuclth] 
(or arXiv:1311.0133v1 [nuclth] for this version) 
Skyrme functional from a threebody pseudopotential of secondorder in gradients. Formalism for central terms
J. Sadoudi, T. Duguet, J. Meyer, M. Bender
Description:In one way or the other, all modern parametrizations of the nuclear energy density functional (EDF) do not respect the exchange symmetry associated with Pauli’s principle. It has been recently shown that this practice jeopardizes multireference (MR) EDF calculations by contaminating the energy with spurious selfinteractions that, for example, lead to finite steps or even divergences when plotting it as a function of collective coordinates. As of today, the only viable option to bypass these pathologies is to rely on EDF kernels that enforce Pauli’s principle from the outset by strictly and exactly deriving from a genuine, i.e. densityindependent, Hamilton operator.
We wish to develop the most general Skyrmelike EDF parametrization containing linear, bilinear and trilinear terms in the density matrices with up to two gradients, under the key constraint that it derives strictly from an effective Hamilton operator. The most general threebody Skyrmelike pseudopotential containing up to two gradient operators is constructed to generate the trilinear part. The present study is limited to central terms. Spinorbit and tensor will be addressed in a forthcoming paper.
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Calculations of threenucleon reactions with N3LO chiral forces: achievements and challenges
Description:
We discuss the application of the chiral N3LO forces to threenucleon reactions and point to the challenges which will have to be addressed. Present approaches to solve threenucleon Faddeev equations are based on a partialwave decomposition. A rapid increase of the number of terms contributing to the chiral threenucleon force when increasing the order of the chiral expansion from N2LO to N3LO forced us to develop a fast and effective method of automatized partial wave decomposition. At low energies of the incoming nucleon below about 20MeV, where only a limited number of partial waves is required, this method allowed us to perform calculations of reactions in the threenucleon continuum using N3LO two and threenucleon forces. It turns out that inclusion of consistent chiral interactions, with relativistic 1/m corrections and shortrange 2picontact term omitted in the N3LO threenucleon force, does not explain the long standing low energy Aypuzzle. We discuss problems arising when chiral forces are applied at higher energies, where large threenucleon force effects are expected. It seems plausible that at higher energies, due to a rapid increase of a number of partial waves required to reach convergent results, a threedimensional formulation of the Faddeev equations which avoids partialwave decomposition is desirable.
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