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arXiv · 1002.0890

Equation of State at Finite Density from Imaginary Chemical Potential

Tetsuya Takaishi·Philippe de Forcrand·Atsushi Nakamura
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Abstract

We perform two flavor QCD simulations with an imaginary chemical potential and measure derivatives of the pressure up to 4th order as a function of the imaginary chemical potential and the temperature $T \in [0.83 T_c, 2 T_c]$. For temperatures $T \geq T_c$, these derivatives are fitted by a Taylor series in $μ/T$ about $μ=0$. A fit limited to 4th order describes the data poorly at all temperatures, showing that we are sensitive to 6th order contributions. Similarly, a 6th order fit fails for temperatures $T_c \leq T \leq 1.05 T_c$, showing the need for 8th order terms. Thus, our method may offer a computational advantage over the direct measurement of Taylor coefficients at $μ=0$. At temperatures $T \leq T_c$, we fit our data with a hadron resonance gas ansatz. The fit starts to fail at $T \gtrsim 0.95 T_c$. Using our fits, we also reconstruct the equation of state as a function of real quark and isospin chemical potentials.

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Tetsuya Takaishi, Philippe de Forcrand, Atsushi Nakamura. 2010-02-04. Equation of State at Finite Density from Imaginary Chemical Potential. https://arxiv.org/abs/1002.0890

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