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Hydrodynamics of charge fluctuations and balance functions

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journal contribution
posted on 27.01.2016, 00:00 by B. Ling, T. Springer, M. Stephanov
We apply stochastic hydrodynamics to the study of charge-density fluctuations in QCD matter undergoing Bjorken expansion. We find that the charge-density correlations are given by a time integral over the history of the system, with the dominant contribution coming from the QCD crossover region where the change of susceptibility per entropy, χT /s, is most significant. We study the rapidity and azimuthal angle dependence of the resulting charge balance function using a simple analytic model of heavy-ion collision evolution. Our results are in agreement with experimental measurements, indicating that hydrodynamic fluctuations contribute significantly to the measured charge correlations in high-energy heavy-ion collisions. The sensitivity of the balance function to the value of the charge diffusion coefficient D allows us to estimate the typical value of this coefficient in the crossover region to be rather small, of the order of (2πT ) −1, characteristic of a strongly coupled plasma


This work is supported by the U.S. Department of Energy under Grant No. DE-FG0201ER41195.


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This is a copy of an article published in the Physical Review C © 2014 American Physical Society Publications.


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