<s>
The	O
Hubbard	O
–	O
Stratonovich	O
(	O
HS	O
)	O
transformation	B-Algorithm
is	O
an	O
exact	O
mathematical	O
transformation	B-Algorithm
invented	O
by	O
Russian	O
physicist	O
Ruslan	O
L	O
.	O
Stratonovich	O
and	O
popularized	O
by	O
British	O
physicist	O
John	O
Hubbard	O
.	O
</s>
<s>
The	O
basic	O
idea	O
of	O
the	O
HS	O
transformation	B-Algorithm
is	O
to	O
reformulate	O
a	O
system	O
of	O
particles	O
interacting	O
through	O
two-body	O
potentials	O
into	O
a	O
system	O
of	O
independent	O
particles	O
interacting	O
with	O
a	O
fluctuating	O
field	O
.	O
</s>
<s>
The	O
problem	O
originates	O
from	O
the	O
repulsive	O
part	O
of	O
the	O
interaction	O
potential	O
,	O
which	O
implicates	O
the	O
introduction	O
of	O
the	O
complex	O
factor	O
via	O
the	O
HS	O
transformation	B-Algorithm
.	O
</s>
