# 56. International Winter Meeting on Nuclear Physics

22-26 January 2018
Bormio, Italy
Europe/Berlin timezone

## Diffusion of conserved charges in relativistic heavy ion collisions

22 Jan 2018, 17:24
3m
Bormio, Italy

#### Bormio, Italy

Poster Relativistic Heavy Ion Physics

### Speaker

Mr Moritz Greif (Goethe University Frankfurt)

### Description

We calculate all diffusion constants of the conserved baryon, electric and strangeness charge in hot relativistic multi-component systems using kinetic theory. Applying the algorithm for massive pions, kaons, nucleons, lambda- and sigma-baryons, with resonance cross sections when possible, we present for the first time realistic values for the hadronic diffusion coefficient matrix. These values can readily be used in dissipative hydrodynamic calculations for baryon rich systems and serve as benchmark for other theoretical approaches. In order to put the hadronic results in context, we compute the diffusion matrix for the quark-gluon plasma (QGP). To this end we use massless quarks and gluons, fixing the shear viscosity to the lower bound of $1/4\pi$. For all but the baryon-electric cross diffusion coefficient, we find that the QGP result matches the hadronic result around the phase transition temperature. All results fulfill the Onsager theorem and the qualitative similarity to the relaxation time approximation. We find that the baryon diffusion current depends strongly on baryon chemical potential, and, we see a comparable strength of the baryon-strange cross diffusion to baryon diffusion. Electric current is equally strongly affected from baryon, electric and strangeness gradients, whereas strangeness currents depend mostly on strange and baryon gradients. These results imply, that calculations involving only the diagonal diffusion effects are incomplete.

### Summary

We calculate all diffusion constants of the conserved baryon, electric and strangeness charge in
hot relativistic multi-component systems using kinetic theory. Applying the algorithm for massive
pions, kaons, nucleons, lambda- and sigma-baryons, with resonance cross sections when possible, we
present for the first time realistic values for the hadronic diffusion coefficient matrix. These values
can readily be used in dissipative hydrodynamic calculations for baryon rich systems and serve
as benchmark for other theoretical approaches. In order to put the hadronic results in context, we
compute the diffusion matrix for the quark-gluon plasma (QGP). To this end we use massless quarks
and gluons, fixing the shear viscosity to the lower bound of $1/4\pi$. For all but the baryon-electric
cross diffusion coefficient, we find that the QGP result matches the hadronic result around the phase
transition temperature. All results fulfill the Onsager theorem and the qualitative similarity to the
relaxation time approximation.
We find that the baryon diffusion current depends strongly on baryon chemical potential, and, we
see a comparable strength of the baryon-strange cross diffusion to baryon diffusion. Electric current
is equally strongly affected from baryon, electric and strangeness gradients, whereas strangeness
currents depend mostly on strange and baryon gradients. These results imply, that calculations
involving only the diagonal diffusion effects are incomplete.

### Primary author

Mr Moritz Greif (Goethe University Frankfurt)

### Co-authors

Prof. Carsten Greiner (Goethe University Frankfurt) Prof. Gabriel Denicol (Universidade Federal Fluminense, Brazil) Mr Jan Fotakis (Goethe University Frankfurt)

 Slides