The purpose of this paper is to introduce and study Poincaré–Steklov (PS) operators associated to
the Dirac operator
with the so-called MIT bag boundary condition. In a domain
, for a complex
number
and for
a
solution of
,
the associated PS operator maps the value of
— the MIT bag
boundary value of
— to
, where
are projections
along the boundary
and
is the trace
operator on
.
In the first part of this paper, we show that the PS operator
is a zeroth-order pseudodifferential operator and give its principal
symbol. In the second part, we study the PS operator when the mass
is large, we prove that it fits into the framework of
-pseudodifferential
operators, and we derive some important properties, especially its
semiclassical principal symbol. Subsequently, we apply these results
to establish a Krein-type resolvent formula for the Dirac operator
for large
masses
in terms of the resolvent of the MIT bag operator on
.
With its help, the large coupling convergence with a convergence rate of
is
shown.
Keywords
Poincaré–Steklov operators, Dirac operator, the MIT bag
model, h-pseudodifferential operators, large coupling limit