Abstract
The shear viscosity of an interacting pion gas is studied using the Kubo formalism as a microscopic description of thermal systems close to global equilibrium. We implement the skeleton expansion in order to approximate the retarded correlator of the viscous part of the energy-momentum tensor. After exploring this in gφ 4 theory we show how the skeleton expansion can be consistently applied to pions in chiral perturbation theory. The shear viscosity η is determined by the spectral width, or equivalently, the mean free path of pions in the heat bath. We derive a new analytical result for the mean free path which is well conditioned for numerical evaluation and discuss the temperature and pion-mass dependence of the mean free path and the shear viscosity. The ratio η/s of the interacting pion gas exceeds the lower bound 1/4π from AdS/CFT correspondence.
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References
BRAHMS Collaboration (I. Arsene et al.), Nucl. Phys. A 757, 1 (2005).
PHENIX Collaboration (K. Adcox et al.), Nucl. Phys. A 757, 184 (2005).
PHOBOS Collaboration (B.B. Back et al.), Nucl. Phys. A 757, 28 (2005).
STAR Collaboration (J. Adams et al.), Nucl. Phys. A 757, 102 (2005).
U.W. Heinz, J. Phys. Conf. Ser. 50, 230 (2005).
P. Romatschke, U. Romatschke, Phys. Rev. Lett. 99, 172301 (2007).
M. Luzum, P. Romatschke, Phys. Rev. C 78, 034915 (2008).
N. Armesto et al., J. Phys. G: Nucl. Part. Phys. Conf. Ser. 35, 054001 (2008).
G. Kestin. U.W. Heinz, Eur. Phys. J. C 61, 545 (2008).
ALICE Collaboration (K. Aamodt et al.), Phys. Rev. Lett. 108, 252302 (2010).
ALICE Collaboration (K. Aamodt et al.), Phys. Lett. B 696, 30 (2011).
ALICE Collaboration (K. Aamodt et al.), Phys. Lett. B 708, 249 (2012).
E. Nakano, J.-W. Chen, Phys. Lett. B 347, 371 (2007).
E. Wang, U.W. Heinz, Phys. Rev. D 53, 5978 (1996).
A.B. Larionov, O. Buss, K. Gallmeister, U. Mosel, Phys. Rev. C 76, 044909 (2007).
H. Liu, D.-F. Hou, J.-R. Li, Commun. Theor. Phys. 50, 429 (2006).
M. Iwasaki, H. Ohnishi, T. Fukutome, J. Phys. G: Nucl. Part. Phys. 35, 035003 (2008).
K. Haglin, S. Pratt, Phys. Lett. B 328, 255 (1994).
R. Kubo, J. Phys. Soc. Jpn. 12, 570 (1957).
K. Yagi, T. Hatsuda, Y. Miake, Quark-Gluon Plasma (Cambridge, 2008).
S. Weinberg, Gravitation and Cosmology (John Wiley & Sons, 1972).
A. Muronga, Heavy Ion Phys. 15, 337 (2002).
J.D. Bjorken, Phys. Rev. D 27, 140 (1983).
A. Hosoya, M.A. Sakagami, M. Takao, Ann. Phys. 154, 229 (1984).
D.N. Zubarev, Nonequilibrium Statistical Thermodynamics (Plenum, NY, 1974).
P. Danielewicz, M. Gyulassy, Phys. Rev. D 31, 53 (1985).
J.L. Hung, Phys. Rev. D 45, 1217 (1992).
S. Jeon, Phys. Rev. D 52, 3591 (1995).
S. Jeon, L.G. Yaffe, Phys. Rev. D 53, 5799 (1996).
W.J. Moore, Physical Chemistry (Longmans, London, 1958).
Masaharu Iwasaki, Hiromasa Ohnishi, Takahiko Fukutome, J. Phys. G: Nucl. Part. Phys. 35, 035003 (2008).
J. Gasser, H. Leutwyler, Phys. Lett. B 188, 477 (1987).
P. Gerber, H. Leutwyler, Nucl. Phys. B 321, 387 (1989).
Y. Aoki, Z. Fodor, S.D. Katz, K.K. Szabo, Phys. Lett. B 643, 46 (2006).
A. Bazavov et al., Phys. Rev. D 80, 014504 (2009).
M. Cheng et al., Phys. Rev. D 81, 054510 (2010).
J.L. Goity, H. Leutwyler, Phys. Lett. B 228, 517 (1989).
J. Maldacena, Int. J. Theor. Phys. 38, 1113 (1999).
P.K. Kovtun, D.T. Son, A.O. Starinets, Phys. Lett. 94, 111601 (2005).
R.A. Lacey et al., Phys. Rev. Lett. 98, 092301 (2007).
T.D. Cohen, Phys. Rev. Lett. 99, 021602 (2007).
A. Rebhan, D. Steineder, Phys. Rev. Lett. 108, 021601 (2012).
D. Fernández-Fraile, A. Gómez Nicola, Eur. Phys. J. A 31, 848 (2006).
D. Fernández-Fraile, A. Gómez Nicola, Eur. Phys. J. C 62, 37 (2008).
G. Aarts, J.M.M. Resco, Phys. Rev. D 68, 085009 (2003).
G. Aarts, J.M.M. Resco, JHEP 02, 061 (2004).
D. Toublan, Phys. Rev. D 56, 5629 (1997).
N. Kaiser, Phys. Rev. C 59, 2945 (1999).
J.I. Kapusta, Ch. Gale, Finite-Temperature Field Theory (Cambridge, 2006).
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Communicated by Bo-Qiang Ma
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Lang, R., Kaiser, N. & Weise, W. Shear viscosity of a hot pion gas. Eur. Phys. J. A 48, 109 (2012). https://doi.org/10.1140/epja/i2012-12109-3
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DOI: https://doi.org/10.1140/epja/i2012-12109-3