  To investigate the mass generating problem without Higgs mechanism we present
a model in which a new scalar gauge coupling is naturally introduced. Because
of the existence of production and annihilation for particles in quantum field
theory, we extend the number of independent variables from conventional four
space-time dimensions to five ones in order to describe all degrees of freedom
for field functions while the conventional space-time is still retained to be
the background. The potential fifth variable is nothing but the proper time of
particles. In response, a mass operator $(\hat{m}=-i\hbar
\frac{\partial}{\partial\tau})$ should be introduced. After that, the
lagrangian for free fermion fields in terms of five independent variables and
mass operator is written down. By applying the gauge principle, three kinds of
vector gauge couplings and one kind of scalar gauge coupling are naturally
introduced. In the current scenario, the mass spectrum for all fundamental
particles is accounted for in principle by solving the eigenvalue of mass
operator under the function of all kinds of interactions. Moreover, there no
any auxiliary mechanism including spontaneous symmetry breaking get involved in
the model. Therefore, traditional problems in the standard model such as the
vacuum energy problem are removed from our model, as well as the hierarchy
problem on the mass spectrum for fundamental particles.
