In strong magnetic fields the transport coefficients of strange quark matter become anisotropic. We determine the general form of the complete set of transport coefficients in the presence of a strong magnetic field. By using a local linear response method, we calculate explicitly the bulk viscosities $\zeta${}$\perp${} and $\zeta${}$\parallel${} transverse and parallel to the B field, respectively, which arise due to the nonleptonic weak processes u+s$\leftrightarrow${}u+d. We find that for magnetic fields B1018\,\,G, the dependence of both $\zeta${}$\perp${} and $\zeta${}$\parallel${} on the field is strong, and they exhibit de~Haas\char21{}van~Alphen\char21{}type oscillations. With increasing magnetic field, the amplitude of these oscillations increases, which eventually leads to negative $\zeta${}$\perp${} in some regions of parameter space. We show that the change of sign of $\zeta${}$\perp${} signals a hydrodynamic instability. As an application, we discuss the effects of the new bulk viscosities on the r-mode instability in rotating strange quark stars. We find that the instability region in strange quark stars is affected when the magnetic fields exceed the value B=1017\,\,G. For fields which are larger by an order of magnitude, the instability region is significantly enlarged, making magnetized strange stars more susceptible to r-mode instability than their unmagnetized counterparts.

We investigate rotating effect on deconfinement phase transition in an Einstein-Maxwell-Dilaton (EMD) model in bottom-up holographic QCD approach. By constructing a rotating black hole, which is supposed to be dual to rotating strongly coupled nuclear matter, we investigate the thermodynamic quantities, including entropy density, pressure, energy density, trace anomaly, sound speed and specific heat for both pure gluon system and two-flavor system under rotation. It is shown that those thermodynamic quantities would be enhanced by large angular velocity. Also, we extract the information of phase transition from those thermodynamic quantities, as well as the order parameter of deconfinement phase transition, i.e. the loop operators. It is shown that, in the T − ω plane, for two-flavor case with small chemical potential, the phase transition is always crossover. The transition temperature decreases slowly with angular velocity and chemical potential. For pure gluon system with zero chemical potential, the phase transition is always first order, while at finite chemical potential a critical end point (CEP) will present in the T − ω plane.

The recently discovered inverse magnetic catalysis around the critical temperature indicates that some important information is missing in our current understanding of conventional chiral dynamics of QCD, which is enhanced by the magnetic field. In this work, we provide a mechanism to explain that the inverse magnetic catalysis around $T_c$ is induced by sphalerons. At high temperatures, sphaleron transitions between distinct classical vacua cause an asymmetry in the chiral number density due to the axial anomaly of QCD. In the presence of a strong magnetic field, the chiral imbalance is enhanced and destroys the pairings between the different chiralities, which naturally lowers the critical temperature of the chiral phase transition for increasing magnetic field. The inverse magnetic catalysis at finite baryon density and the critical end point in the presence of a strong magnetic field is also explored in this work.

We study the chiral phase transition of quark matter under rotation in two-flavor Nambu–Jona-Lasinio (NJL) model. It is found that, in the rotating frame, the angular velocity plays the similar role as the baryon chemical potential and suppresses the chiral condensate, thus the chiral phase transition shows a critical end point not only in the temperature-chemical potential $T\text{−}\mu$ plane, but also in the temperature-angular momentum $T\text{−}\omega$ plane. One interesting observation is that in the $T\text{−}\mu$ plane, the presence of the angular momentum only shifts down the critical temperature $T^E$ of the CEP and does not shift the critical chemical potential ${\mu }^E$, and in the $T\text{−}\omega$ plane, the increase of the chemical potential only shifts down the critical temperature $T^E$ and does not change the critical angular momentum ${\omega }^E$. The phase structure in the $T\text{−}\mu$ plane is sensitive to the coupling strength in the vector channel, while the phase structure in $T\text{−}\omega$ plane is not. It is also observed that the rotating angular velocity suppresses the kurtosis of the baryon number fluctuations, while it enhances the pressure density, energy density, the specific heat, and the sound velocity.