OPUS 4 | Search

Ion stopping in dense plasma target for high energy density physics (2010)

Claude Deutsch Gilles Maynard Marin Chabot Daniel Gardes Serge Della-Negra René Bimbot Marie-France Rivet Claude Fleurier Christophe Couillaud Dieter H. H. Hoffmann H Wahl Karin Weyrich Olga N. Rosmej Naeem Ahmad Tahir Joachim Jacoby Masao Ogawa Yoshiyuki Oguri Jun Hasegawa Boris Y. Sharkov Alexey A. Golubev Alexander Fertman Vladimir E. Fortov Victor Mintsev

The basic physics of nonrelativistic and electromagnetic ion stopping in hot and ionized plasma targets is thoroughly updated. Corresponding projectile-target interactions involve enhanced projectile ionization and coupling with target free electrons leading to significantly larger energy losses in hot targets when contrasted to their cold homologues. Standard stoppping formalism is framed around the most economical extrapolation of high velocity stopping in cold matter. Further elaborations pay attention to target electron coupling and nonlinearities due to enhanced projectile charge state, as well. Scaling rules are then used to optimize the enhanced stopping of MeV/amu ions in plasmas with electron linear densities nel ~ 10 18 -10 20 cm -2 . The synchronous firing of dense and strongly ionized plasmas with the time structure of bunched and energetic multicharged ion beam then allow to probe, for the first time, the long searched enhanced plasma stopping and projectile charge at target exit. Laser ablated plasmas (SPQR1) and dense linear plasma columns (SPQR2) show up as targets of choice in providing accurate and on line measurements of plasma parameters. Corresponding stopping results are of a central significance in asserting the validity of intense ion beam scenarios for driving thermonuclear pellets. Other applications of note feature thorium induced fission, novel ion sources and specific material processing through low energy ion beams. Last but not least, the given ion beam-plasma target interaction physics is likely to pave a way to the production and diagnostics of warm dense matter (WDM).

Direct photon emission in heavy ion collisions from microscopic transport theory and fluid dynamics : XLVIII International Winter Meeting on Nuclear Physics, BORMIO2010, January 25 - 29, 2010, Bormio, Italy (2010)

Björn Bäuchle Marcus Bleicher

Direct photon emission in heavy-ion collisions is calculated within a relativistic micro+macro hybrid model and compared to the microscopic transport model UrQMD. In the hybrid approach, the high-density part of the collision is calculated by an ideal 3+1-dimensional hydrodynamic calculation, while the early (pre-equilibrium-) and late (rescattering-) phase are calculated with the transport model. Different scenarios of the transition from the macroscopic description to the transport model description and their effects are studied. The calculations are compared to measurements by the WA98-collaboration and predictions for the future CBM-experiment are made.

Towards the Nf = 2 deconfinement transition temperature with O(a) improved Wilson fermions (2010)

Bastian B. Brandt Hartmut Wittig Owe Philipsen Lars Zeidlewicz

A lot of effort in lattice simulations over the last years has been devoted to studies of the QCD deconfinement transition. Most state-of-the-art simulations use rooted staggered fermions, while Wilson fermions are affected by large systematic uncertainties, such as coarse lattices or heavy sea quarks. Here we report on an ongoing study of the transition, using two degenerate flavours of nonperturbatively O(a) improved Wilson fermions. We start with Nt = 12 and 16 lattices and pion masses of 600 to 450 MeV, aiming at chiral and continuum limits with light quarks.

Thermal transition temperature from twisted mass QCD (2010)

Florian Burger Malik Kirchner Michael Müller-Preussker Ernst-Michael Ilgenfritz Maria Paola Lombardo Owe Philipsen Lars Zeidlewicz Carsten Urbach

We present the current status of lattice simulations with Nf = 2 maximally twisted mass Wilson fermions at finite temperature. In particular, the determination of the thermal transition tempera- ture is discussed.

The spectrum of static-light baryons in twisted mass lattice QCD (2010)

Marc Wagner Christian Wiese

We compute the static-light baryon spectrum with Nf = 2 flavors of sea quarks using Wilson twisted mass lattice QCD. As light valence quarks we consider quarks, which have the same mass as the sea quarks with corresponding pion masses in the range 340MeV<∼ mPS<∼ 525MeV, as well as partially quenched quarks, which have the mass of the physical s quark. We extract masses of states with isospin I = 0,1/2,1, with strangeness S = 0,−1,−2, with angular momentum of the light degrees of freedom j = 0,1 and with parity P = +,−. We present a preliminary extrapolation in the light u/d and an interpolation in the heavy b quark mass to the physical point and compare with available experimental results.

Constraints for the QCD phase diagram from imaginary chemical potential (2010)

Owe Philipsen Philippe de Forcrand

We present unambiguous evidence from lattice simulations of Nf = 3 QCD for two tricritical points in the (T;m) phase diagram at fixed imaginary m=T = ip=3 mod. 2p=3, one in the light and one in the heavy quark regime. Together with similar results in the literature for Nf = 2 this implies the existence of a chiral and of a deconfinement tricritical line at those values of imaginary chemical potentials. These tricritical lines represent the boundaries of the analytically continued chiral and deconfinement critical surfaces, respectively, which delimit the parameter space with first order phase transitions. It is demonstrated that the shape of the deconfinement critical surface is dictated by tricritical scaling and implies the weakening of the deconfinement transition with real chemical potential. A qualitatively similar effect holds for the chiral critical surface.

Light hadrons from Nf = 2+1+1 dynamical twisted mass fermions (2010)

Rémi Baron Benoit Blossier Philippe Boucaud Jaume Carbonell Albert Deuzeman Vincent Drach Federico Farchioni Federico Farchioni Vicent Gimenez Gregorio Herdoiza Karl Jansen Chris Michael István Montvay Elisabetta Pallante Olivier Pène Siebren Reker Carsten Urbach Marc Wagner Urs Wenger

We present results of lattice QCD simulations with mass-degenerate up and down and mass-split strange and charm (Nf = 2+1+1) dynamical quarks using Wilson twisted mass fermions at maximal twist. The tuning of the strange and charm quark masses is performed at three values of the lattice spacing a ~ 0:06 fm, a ~ 0:08 fm and a ~ 0:09 fm with lattice sizes ranging from L ~ 1:9 fm to L ~ 3:9 fm. We perform a preliminary study of SU(2) chiral perturbation theory by combining our lattice data from these three values of the lattice spacing.

Kaon and D meson masses with Nf = 2+1+1 twisted mass lattice QCD (2010)

Rémi Baron Philippe Boucaud Jaume Carbonell Vincent Drach Federico Farchioni Gregorio Herdoiza Karl Jansen Chris Michael István Montvay Elisabetta Pallante Siebren Reker Carsten Urbach Marc Wagner Urs Wenger

We discuss the computation of the kaon and D meson masses in the Nf = 2+1+1 twisted mass lattice QCD setup, where explicit heavy flavor and parity breaking occurs at finite lattice spacing. We present three methods suitable in this context and verify their consistency.

Forces between static-light mesons (2010)

Marc Wagner

The isospin, spin and parity dependent potential of a pair of static-light mesons is computed using Wilson twisted mass lattice QCD with two flavors of degenerate dynamical quarks. From the results a simple rule can be deduced stating, which isospin, spin and parity combinations correspond to attractive and which to repulsive forces.

The QCD phase diagram at low baryon density from lattice simulations (2010)

Owe Philipsen

The QCD phase diagram as a function of temperature, T, and chemical potential for baryon number, mB, is still unknown today, due to the sign problem, which prohibits direct Monte Carlo simulations for non-vanishing baryon density. Investigations in models sharing chiral symmetry with QCD predict a phase diagram, in which the transition corresponds to a smooth crossover at zero density, but which is strengthened by chemical potential to turn into a first order transition beyond some second order critical point. This contribution reviews the lattice evidence in favour and against the existence of a critical point.

Refine

Author

Year of publication

Document Type

Language

Keywords

Institute

58 search hits