Fp. Esposito et al., NEXT-TO-LEADING ORDER EFFECTIVE POTENTIAL IN THE 2-JONA-LASINIO MODELAT FINITE-TEMPERATURE - ART. NO. 065003(1 DIMENSIONAL NAMBU), Physical review. D. Particles and fields, 5806(6), 1998, pp. 5003
The finite temperature effective potential in the 2+1 dimensional Namb
u-Jona-Lasinio model is constructed up to the next to leading order in
the large N expansion, where N is the number of flavors in the model.
The distinctive feature of the analysis is an inclusion of an additio
nal scalar field, which allows us to circumvent the well known, and ot
herwise unavoidable problem with the imaginary contribution to the eff
ective potential. In accordance with the Mennin-Wagner-Coleman theorem
, applied to the dimensionally reduced subsystem of the zero Matsubara
modes of the composite boson fields, the finite temperature effective
potential reveals a global minimum at the zero of the composite order
parameter. This allows us to conclude that the continuous global symm
etry of the NJL model is not broken for any arbitrarily small, finite
temperature. [S0556-2821(98)06316-4].