Quark droplets stability induced by external magnetic field

The influence of a constant homogeneous external magnetic field H on the formation and stability of quark droplets is investigated within a simple Nambu-Jona-Lasinio model by using a thermodynamic approach. For a vanishing magnetic field stable quark droplets, which are schematically the bags of massless quarks, are allowed to exist only at G > G(bag), where G is the quark coupling constant, G(bag) = 1.37G(crit), and G(crit) is the value of the coupling constant above which chiral symmetry is spontaneously broken down. On the other hand, a nonvanishing external magnetic field can induce the stability of quark droplets so that they may exist even at G < G(bag). In this case, depending on the value of H, quark droplets are composed either of massive or massless quarks. (C) 2003 Elsevier B.V. All rights reserved.