Quark matter under strong magnetic fields in the su(3) Nambu–Jona-Lasinio model

Abstract

In the present work we use the mean-field approximation to investigate quark matter described by the su(3) Nambu--Jona-Lasinio (NJL) model subject to a strong magnetic field. We consider two cases: pure quark matter and quark matter in $\ensuremath{\beta}$ equilibrium possibly present in magnetars. The results are compared with the ones obtained with the su(2) version of the model. The energy per baryon of magnetized quark matter becomes more bound than nuclear matter made of iron nuclei, for $B$ around $2\ifmmode\times\else\texttimes\fi{}{10}^{19}$ G. When the su(3) NJL model is applied to stellar matter, the maximum mass configurations are always above $1.45{M}_{\ensuremath{\bigodot}}$ and may be as high as $1.86{M}_{\ensuremath{\bigodot}}$ for a central magnetic field of $5\ifmmode\times\else\texttimes\fi{}{10}^{18}$ G. These numbers are within the masses of observed neutron stars.