5 dynamics and/or the chiral phase transition. However we notice that while the v 2 ( p$_{T}$ ) appears to be totally independent on the presence of the NJL-field once the η/s is kept fixed, the time evolution of 〈 v 2 〉 still shows a slightly reduced elliptic flow at t ∼ 3 − 5 fm/c . A similar difference can be observed also in the time evolution of the transverse momentum 〈 p$_{T}$ 〉 shown in Fig. 2 (right). One may ask what is the physical origin of such differences. In principle there are two parameters affecting the v 2 ( p$_{T}$ ) and the 〈 p$_{T}$ 〉 : the sound velocity c$_{s}$ and the bulk viscosity ζ . As discussed previously it is safe to discard the possibility of any significant influence of the finite ζ/s on our results considering its tiny value in the NJL, see Fig.1 (right). It is instead reasonable that the weak decrease is due to the decrease of the sound velocity for NJL at T < 1 . 1 T$_{c}$ . It is well known that c 2 s decreases from 1 / 3 that is the value of a massless free gas and that this cause already in ideal hydrodynamics a decrease of the elliptic flow [37]. On the other hand when the bulk of the system reaches this region most of the v 2 ( p$_{T}$ ) has already been built-up hence the effect of a moderate decrease of c$_{s}$ is quite weak and could explain the small difference still visible in the time evolution of 〈 v 2 〉 and 〈 p$_{T}$ 〉 . Conclusion - The novelty of the present work is to be the first study within a transport approach of a fluid at finite η/s that includes the field dynamics of the chiral phase transition. Generally we find that at fixed cross section the effect of the NJL field is to reduce the elliptic flow by about a 20%. More importantly we can state that the presence of the NJL dynamics does not change the relation between the elliptic flow and the η/s that remains the same as in the cascade models and at low p$_{T}$ is very close to the one from hydrodynamics [9–11, 33]. If such a finding is confirmed also for a more general class of interacting quasi-particle models it will make much safer and solid the determination of η/s by v 2 ( p$_{T}$ ). In fact as we have shown the relation is independent on the micro- scopic details of the interaction once the EoS and/or the c 2 $_{s}$( T ) has been fixed. This will be investigated in the next future, in fact the kinetic theory and the numerical implementation presented here can be easily extended to quasi-particle models that are fitted to reproduce the en- ergy density and pressure of lQCD results. In such a case it will be possible also to study the elliptic flow with a realistic behavior of c$_{s}$ ( T ) and the effect of a finite and sizable ζ/s on the elliptic flow complementing the study from viscous hydrodynamics that are subject to problems for not too small ζ/s and/or for p$_{T}$ > 3 T [19]. This work for V. Baran is supported in part by the Romanian Ministry for Education and Research under the CNCSIS contract PNII ID-946/2007. Acknowledgements [1] STAR, J. Adams et al. , Nucl. Phys. A757 , 102 (2005). [2] PHENIX, K. Adcox et al. , Nucl. Phys. A757 , 184 (2005). [3] E. Shuryak, Prog. Part. Nucl. Phys. 62 , 48 (2009). [4] P. Danielewicz and M. Gyulassy, Phys. Rev. D31 , 53 (1985). [5] P. Kovtun, D. T. Son, and A. O. Starinets, Phys. Rev. Lett. 94 , 111601 (2005). [6] R. A. Lacey et al. , Phys. Rev. Lett. 98 , 092301 (2007). [7] P. Romatschke and U. Romatschke, Phys. Rev. Lett. 99 , 172301 (2007). [8] H. Song and U. W. Heinz, Phys. Rev. C78 , 024902 (2008), 0805.1756. [9] Z. Xu, C. Greiner, and H. Stocker, Phys. Rev. Lett. 101 , 082302 (2008). [10] D. Molnar, (2008), nucl-th/0806.0026. [11] G. Ferini, M. Colonna, M. Di Toro, and V. Greco, Phys. Lett. B670 , 325 (2009). [12] H.-J. Drescher, A. Dumitru, C. Gombeaud, and J.-Y. Ollitrault, Phys. Rev. C76 , 024905 (2007). [13] P. Romatschke, (2009), 0902.3663. [14] P. Huovinen and D. Molnar, Phys. Rev. C79 , 014906 (2009). [15] H. Song and U. W. Heinz, (2008), 0812.4274. [16] T. Hirano, U. W. Heinz, D. Kharzeev, R. Lacey, and Y. Nara, Phys. Lett. B636 , 299 (2006). [17] V. Greco, M. Colonna, M. Di Toro, and G. Ferini, Nucl. Phys. A8** , ** (2010), nucl-th/0909.5314. [18] R. J. Fries, V. Greco, and P. Sorensen, Ann. Rev. Nucl. Part. Sci. 58 , 177 (2008). [19] H. Song and U. W. Heinz, (2009), 0909.1549. [20] Z.-w. Lin and C. M. Ko, Phys. Rev. C65 , 034904 (2002). [21] M. Buballa, Phys. Rept. 407 , 205 (2005). [22] W. M. Zhang and L. Wilets, Phys. Rev. C45 , 1900 (1992). [23] A. Dellafiore and F. Matera, Phys. Rev. C44 , 2456 (1991). [24] B. Blattel, V. Koch, , and U. Mosel, Rep. Prog. Phys. 56 , 1 (1993). [25] D. Molnar and M. Gyulassy, Nucl. Phys. A697 , 495 (2002). [26] Z. Xu and C. Greiner, Phys. Rev. C71 , 064901 (2005). [27] S. A. Bass et al. , Prog. Part. Nucl. Phys. 41 , 255 (1998). [28] C. Fuchs and H. H. Wolter, Nucl. Phys. A589 , 732 (1995). [29] A. Abada and J. Aichelin, Phys. Rev. Lett. 74 , 3130 (1995). [30] I. Mishustin and O.Scavenius, Phys. Lett. B396 , 33 (1997). [31] C. Sasaki and K. Redlich, Phys. Rev. C79 , 055207 (2009). [32] F. Karsch, D. Kharzeev, and K. Tuchin, Phys. Lett. B663 , 217 (2008). [33] V. Greco, M. Colonna, M. Di Toro, and G. Ferini, Prog. Part. Nucl. Phys. 62 , 562 (2009). [34] P. Levai and U. W. Heinz, Phys. Rev. C57 , 1879 (1998). [35] P. Castorina and M. Mannarelli, Phys. Rev. C75 , 054901 (2007). [36] Z.-W. Lin et al. , Phys. Rev. C72 , 064901 (2005). [37] R. S. Bhalerao, J.-P. Blaizot, N. Borghini, and J.-Y. Ol- litrault, Phys. Lett. B627 , 49 (2005).