Nonlinear evolution of density and flow perturbations on a Bjorken background

Brouzakis, N.; Floerchinger, Stefan; Tetradis, N.; Wiedemann, Urs Achim

doi:10.1103/physrevd.91.065007

Cited by 4 publications

(6 citation statements)

References 85 publications

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“…(4.16). Similar strategy has also been applied in analyses of perturbations on top of solvable hydro models [29][30][31]. To recover quantities in the original (τ, r, φ, ξ) coordinate system, one is additionally required to do a coordinate transformation according to Eqs.…”

Section: Solving Gubser Flow With Hydrodynamical Noisementioning

confidence: 99%

Hydrodynamical noise and Gubser flow

Yan

Grönqvist

2016

J. High Energ. Phys.

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Hydrodynamical noise is introduced on top of Gubser's analytical solution to viscous hydrodynamics. With respect to the ultra-central collision events of Pb-Pb, p-Pb and p-p at the LHC energies, we solve the evolution of noisy fluid systems and calculate the radial flow velocity correlations. We show that the absolute amplitude of the hydrodynamical noise is determined by the multiplicity of the collision event. The evolution of azimuthal anisotropies, which is related to the generation of harmonic flow, receives finite enhancements from hydrodynamical noise. Although it is strongest in the p-p systems, the effect of hydrodynamical noise on flow harmonics is found to be negligible, especially in the ultra-central Pb-Pb collisions. For the short-range correlations, hydrodynamical noise contributes to the formation of a near-side peak on top of the correlation structure originated from initial state fluctuations. The shape of the peak is affected by the strength of hydrodynamical noise, whose height and width grow from the Pb-Pb system to the p-Pb and p-p systems.

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Section: Solving Gubser Flow With Hydrodynamical Noisementioning

confidence: 99%

Hydrodynamical noise and Gubser flow

Yan

Grönqvist

2016

J. High Energ. Phys.

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“…[30]. One can in fact formulate a systematic perturbative expansion for deviations from a symmetric situation, with favorable convergence properties [31,32]. What is missing until today is an efficient numerical algorithm to solve fluid evolution equations for the symmetric background as well azimuthal and rapidity dependent perturbations in an accurate way.…”

Section: Contentsmentioning

confidence: 99%

Fluid dynamics of heavy ion collisions with mode expansion

2019

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The fluid dynamics of a relativistic fireball with longitudinal and transverse expansion is described using a background-fluctuation splitting. Symmetry representations of azimuthal rotations and longitudinal boosts are used for a classification of initial state configurations and their fluid dynamic propagation in terms of a mode expansion. We develop an accurate and efficient numerical scheme based on the pseudo-spectral method to solve the resulting hyperbolic partial differential equations. Comparison to the analytically known Gubser solution underlines the high accuracy of this technique. We also present first applications of FluiduM to central heavy ion collisions at the LHC energies featuring a realistic thermodynamic equations of state as well as shear and bulk viscous dissipation. arXiv:1811.01870v1 [nucl-th] 5 Nov 2018 8 Conclusions 30 A Discrete cosine and sine transform 31

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“…For the fluid dynamics of heavy ions, in contrast, no such late time instability is expected and the relative amplitude of perturbations decreases due to viscous effects. Numerical investigations for realistic viscosities indicate that non-linear effects remain within reach of a perturbative treatment during the time-and length scales of a heavy ion collision [10,11]. Developing a perturbative description of anisotropies in heavy ion collisions in detail seems to be a well motivated goal for theory in the coming years.…”

Section: Theory Of Inhomogeneities and Anisotropiesmentioning

confidence: 99%

“…Although there is no general consensus, most people believe now that gravitational backreaction is a rather small effect. In a recent work comparing fluid evolution equations describing heavy ion collisions to those describing the evolution of the universe [11,31], we became aware of an additional backreaction effect that is due to dissipative terms, more specific shear and bulk viscosity.…”

Section: The Backreactionmentioning

confidence: 99%

Heavy ion collisions and cosmology

Floerchinger

2016

Nuclear Physics A

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There are interesting parallels between the physics of heavy ion collisions and cosmology. Both systems are out-ofequilibrium and relativistic fluid dynamics plays an important role for their theoretical description. From a comparison one can draw interesting conclusions for both sides. For heavy ion physics it could be rewarding to attempt a theoretical description of fluid perturbations similar to cosmological perturbation theory. In the context of late time cosmology, it could be interesting to study dissipative properties such as shear and bulk viscosity and corresponding relaxation times in more detail. Knowledge and experience from heavy ion physics could help to constrain the microscopic properties of dark matter from observational knowledge of the cosmological fluid properties.Keywords: Relativistic fluid dynamics, Cosmological perturbation theory, Dissipation, Backreaction The analogyThe analogy between ultra-relativistic heavy ion collisions and cosmology has often been emphasized. What distinguishes the physics there from typical situations in condensed matter physics is the aspect of history or dynamical evolution. Experimentally, one cannot probe a static quark gluon plasma with external probes as it is possible for solid state systems. All information must be reconstructed from the final state, which contains essentially the decay products of the quark-gluon plasma. In cosmology, this is very similar. The cosmic microwave background allows to see back in time until photon decoupling but information about earlier times is not directly available. Similarly, one can observe the large scale structure today and, by looking at more distant galaxies, in the recent past, but large parts of the history of structure formation are not accessible.On first sight there are big differences: cosmological and nuclear scales differ by many orders of magnitude, late time cosmology is dominated by gravity, QED and the still rather poorly understood physics of dark matter and dark energy, while heavy ion collisions are governed by QCD. Another difference is that only a single event can be studied in cosmology, in contrast to very many heavy ion collisions. However, from a more abstract viewpoint, there are many interesting parallels. In the theoretical description, a particularly nice one is that many aspects of the dynamics can be described in both cases by relativistic fluid dynamics.While the fluid produced in high energy nuclear collisions consists initially of a quark-gluon plasma which then expands and cools down and eventually undergoes a transition to hadronic degrees of freedom, the cosmological fluid has many more different stages. Very shortly after the big bang, there is also one

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Nonlinear evolution of density and flow perturbations on a Bjorken background

Cited by 4 publications

References 85 publications

Hydrodynamical noise and Gubser flow

Hydrodynamical noise and Gubser flow

Fluid dynamics of heavy ion collisions with mode expansion

Heavy ion collisions and cosmology

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