arXiv subjects

Akihiko Monnai

Publications and source records attributed to Akihiko Monnai.

45 records · Page 3Linked to original sources

arXiv2013

Dissipative hydrodynamic evolution of hot quark matter at finite baryon density

High-energy heavy ion collider experiments at RHIC and LHC have revealed that relativistic hydrodynamic models describe the hot and dense quark matter quantitatively. In this study, I develop a novel dissipative hydrodynamic model at finite baryon density to investigate the net baryon rapidity distribution. The results show that the distribution is widened in hydrodynamic evolution, which implies that the transparency of the collisions is effectively enhanced. This suggests that the kinetic energy loss for medium production at the initial stage could be larger. Furthermore, the net baryon distribution is found sensitive to baryon diffusion, implying that dissipative hydrodynamic modeling would be important for understanding the hot medium.

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arXiv2013

Dissipative hydrodynamic effects on the quark-gluon plasma at finite baryon density

The quark-gluon plasma behaves as a relativistic viscous fluid in high-energy heavy ion collisions. I develop a causal dissipative hydrodynamic model at finite baryon density for RHIC and LHC to estimate the net baryon rapidity distribution. The net baryon number is found to be carried to forward rapidity by the flow, effectively enhancing the transparency of the collisions. This suggests that the energy available for the production of a hot medium could be larger than that naively implied from experimental data. Also the distribution can be sensitive to baryon dissipation as much as to shear and bulk viscosity.

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arXiv2012

Dissipative Hydrodynamic Effects on Baryon Stopping

The quark-gluon plasma is considered to behave as a relativistic viscous fluid in the high-energy heavy ion collisions. In this study, I develop and estimate a second order dissipative hydrodynamic model at finite baryon density with effects of baryon dissipation together with those of shear and bulk viscosities. It is found that the hydrodynamic evolution effectively reduces baryon stopping, suggesting that the collisions are less transparent at the initial stage. Also the net baryon distribution is found sensitive to baryon dissipation as well as to viscosities. The results indicate that the dissipative hydrodynamic modeling would be important for understanding unique properties of the hot medium even in the high-energy collisions.

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arXiv2011

Viscous Hydrodynamic Evolution with Non-Boost Invariant Flow for the Color Glass Condensate

The Large Hadron Collider (LHC) experiments have revealed that the predictions of the color glass condensate (CGC) tend to underestimate the multiplicity at mid-rapidity. We develop and estimate a full second-order viscous hydrodynamic model for the longitudinal expansion to find that the CGC rapidity distributions are visibly deformed during the hydrodynamic stage due to the interplay between the entropy production and the entropy flux to forward rapidity. The results indicate the importance of viscous hydrodynamic evolution with non-boost invariant flow for understanding the CGC in terms of the heavy ion collisions.

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arXiv2011

Longitudinal Viscous Hydrodynamic Evolution for the Shattered Colour Glass Condensate

We investigate hydrodynamic evolution of the quark gluon plasma for the colour glass condensate type initial conditions. We solve full second-order viscous hydrodynamic equations in the longitudinal direction to find that non-boost invariant expansion leads to visible deformation on the initial rapidity distribution. The results indicate that hydrodynamic evolution with viscosity plays an important role in determining parameters for the initial distributions.

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arXiv2010

Relativistic Viscous Hydrodynamics for Multi-Component Systems with Multiple Conserved Currents

We would like to formulate relativistic dissipative hydrodynamics for multi-component systems with multiple conserved currents. This is important for analyses of the hot matter created in relativistic heavy ion collisions because particle creations and annihilations of various particle species are frequently taking place there. We show that consistent formulation in such systems involves many non-trivialities, and derive constitutive equations that satisfy Onsager reciprocal relations and describe the systems without ambiguity.

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arXiv2010

Relativistic Dissipative Hydrodynamic Equations at the Second Order for Multi-Component Systems with Multiple Conserved Currents

We derive the second order hydrodynamic equations for the relativistic system of multi-components with multiple conserved currents by generalizing the Israel-Stewart theory and Grad's moment method. We find that, in addition to the conventional moment equations, extra moment equations associated with conserved currents should be introduced to consistently match the number of equations with that of unknowns and to satisfy the Onsager reciprocal relations. Consistent expansion of the entropy current leads to constitutive equations which involve the terms not appearing in the original Israel-Stewart theory even in the single component limit. We also find several terms which exhibit thermal diffusion such as Soret and Dufour effects. We finally compare our results with those of other existing formalisms.

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arXiv2009

Effects of Bulk Viscosity on $p_T$-Spectra and Elliptic Flow Parameter

We estimate the effects of viscosity on the phase space distribution appearing in the Cooper-Frye formula within the framework of the Grad's fourteen moment method and find that there are non-trivialities in the discussion of a multi-component system. We calculate the viscous corrections of particle spectra and elliptic flow coefficients from the distortion of the distribution using the flow and the hypersurface taken from a (3+1)-dimensional ideal hydrodynamic simulation. We see that the bulk viscosity have visible effects on particle spectra. The results suggest we should treat both shear and bulk viscosity carefully when constraining the transport coefficients from experimental data.

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arXiv2009

Effects of Bulk Viscosity at Freezeout

We investigate particle spectra and elliptic flow coefficients in relativistic heavy ion collisions by taking into account the distortion of phase space distributions due to bulk viscosity at freezeout. We first calculate the distortion of phase space distributions in a multi-component system within the Grad's fourteen moment method. We find some subtle issues when one matches macroscopic variables with microscopic momentum distributions in a multi-component system and develop a consistent procedure to uniquely determine the corrections in the phase space distributions. Next, we calculate particle spectra by using the Cooper-Frye formula to see the effect of the bulk viscosity. In spite of the relative smallness of the bulk viscosity, we find that it is likely to have a visible effect in particle spectra and elliptic flow coefficients. This indicates the importance of bulk viscosity together with shear viscosity if one wants to constrain the transport coefficients with better accuracy from experimental data.

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