Hydrodynamics with parametric slowing down and fluctuations near the critical point
The search for the QCD critical point in heavy-ion collision experiments requires dynamical simulations of the bulk evolution of QCD matter as well as of fluctuations. We consider two essential ingredients of such a simulation: a generic extension of hydrodynamics by a parametrically slow mode or mo...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
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American Physical Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/117343 |
| _version_ | 1826194318374731776 |
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| author | Stephanov, M. Yin, Yi |
| author2 | Massachusetts Institute of Technology. Center for Theoretical Physics |
| author_facet | Massachusetts Institute of Technology. Center for Theoretical Physics Stephanov, M. Yin, Yi |
| author_sort | Stephanov, M. |
| collection | MIT |
| description | The search for the QCD critical point in heavy-ion collision experiments requires dynamical simulations of the bulk evolution of QCD matter as well as of fluctuations. We consider two essential ingredients of such a simulation: a generic extension of hydrodynamics by a parametrically slow mode or modes (“Hydro+”) and a description of fluctuations out of equilibrium. By combining the two ingredients, we are able to describe the bulk evolution and the fluctuations within the same framework. Critical slowing-down means that equilibration of fluctuations could be as slow as hydrodynamic evolution, and thus fluctuations could significantly deviate from equilibrium near the critical point. We generalize hydrodynamics to partial-equilibrium conditions where the state of the system is characterized by the off-equilibrium magnitude of fluctuations in addition to the usual hydrodynamic variables—conserved densities. We find that the key element of the new formalism—the extended entropy taking into account the off-equilibrium fluctuations—is remarkably similar to the 2PI action in the quantum field theory. We show how the new Hydro+ formalism reproduces two major effects of critical fluctuations on the bulk evolution: the strong frequency dependence of the anomalously large bulk viscosity as well as the stiffening of the equation of state with an increasing frequency or wave number. While the agreement with known results confirms its validity, the fact that Hydro+ achieves this within a local and deterministic framework gives it significant advantages for dynamical simulations. |
| first_indexed | 2024-09-23T09:53:52Z |
| format | Article |
| id | mit-1721.1/117343 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T09:53:52Z |
| publishDate | 2018 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/1173432022-09-30T17:35:13Z Hydrodynamics with parametric slowing down and fluctuations near the critical point Stephanov, M. Yin, Yi Massachusetts Institute of Technology. Center for Theoretical Physics Massachusetts Institute of Technology. Department of Nuclear Science and Engineering Yin, Yi The search for the QCD critical point in heavy-ion collision experiments requires dynamical simulations of the bulk evolution of QCD matter as well as of fluctuations. We consider two essential ingredients of such a simulation: a generic extension of hydrodynamics by a parametrically slow mode or modes (“Hydro+”) and a description of fluctuations out of equilibrium. By combining the two ingredients, we are able to describe the bulk evolution and the fluctuations within the same framework. Critical slowing-down means that equilibration of fluctuations could be as slow as hydrodynamic evolution, and thus fluctuations could significantly deviate from equilibrium near the critical point. We generalize hydrodynamics to partial-equilibrium conditions where the state of the system is characterized by the off-equilibrium magnitude of fluctuations in addition to the usual hydrodynamic variables—conserved densities. We find that the key element of the new formalism—the extended entropy taking into account the off-equilibrium fluctuations—is remarkably similar to the 2PI action in the quantum field theory. We show how the new Hydro+ formalism reproduces two major effects of critical fluctuations on the bulk evolution: the strong frequency dependence of the anomalously large bulk viscosity as well as the stiffening of the equation of state with an increasing frequency or wave number. While the agreement with known results confirms its validity, the fact that Hydro+ achieves this within a local and deterministic framework gives it significant advantages for dynamical simulations. United States. Department of Energy (Grant DE-SC0011090) 2018-08-13T19:26:06Z 2018-08-13T19:26:06Z 2018-08 2018-01 2018-08-08T18:00:30Z Article http://purl.org/eprint/type/JournalArticle 2470-0010 2470-0029 http://hdl.handle.net/1721.1/117343 Stephanov, M. and Y. Yin. "Hydrodynamics with parametric slowing down and fluctuations near the critical point." Physical Review D 98, 3 (August 2018): 036006 © 2018 American Physical Society en http://dx.doi.org/10.1103/PhysRevD.98.036006 Physical Review D Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Physical Society application/pdf American Physical Society American Physical Society |
| spellingShingle | Stephanov, M. Yin, Yi Hydrodynamics with parametric slowing down and fluctuations near the critical point |
| title | Hydrodynamics with parametric slowing down and fluctuations near the critical point |
| title_full | Hydrodynamics with parametric slowing down and fluctuations near the critical point |
| title_fullStr | Hydrodynamics with parametric slowing down and fluctuations near the critical point |
| title_full_unstemmed | Hydrodynamics with parametric slowing down and fluctuations near the critical point |
| title_short | Hydrodynamics with parametric slowing down and fluctuations near the critical point |
| title_sort | hydrodynamics with parametric slowing down and fluctuations near the critical point |
| url | http://hdl.handle.net/1721.1/117343 |
| work_keys_str_mv | AT stephanovm hydrodynamicswithparametricslowingdownandfluctuationsnearthecriticalpoint AT yinyi hydrodynamicswithparametricslowingdownandfluctuationsnearthecriticalpoint |