Landau levels of cold dense quark matter in a strong magnetic field

The occupied Landau levels of strange quark matter are investigated in the framework of the SU(3) NJL model with a conventional coupling and a magnetic-field dependent coupling respectively. At lower density, the Landau levels are mainly dominated by u and d quarks. Threshold values of the chemical potential for the s quark onset are shown in the $\mu$-$B$ plane. The magnetic-field-dependent running coupling can broaden the region of three-flavor matter by decreasing the dynamical masses of $s$ quarks. Before the onset of $s$ quarks, the Landau level number of light quarks is directly dependent on the magnetic field strength $B$ by a simple inverse proportional relation $k_{i,\mathrm{max}}\approx B_i^0/B$ with $B_d^0=5\times 10^{19}$ G, which is approximately 2 times $B_u^0$ of $u$ quarks at a common chemical potential. When the magnetic field increases up to $B^0_d$, almost all three flavors are lying in the lowest Landau level.