E=""
 SRC="img116.svg"
 ALT="$R$"></SPAN>
(DEF(k) = <!-- MATH
 $\beta_k \times R$
 -->
<SPAN CLASS="MATH"><IMG
 STYLE=""
 SRC="img129.svg"
 ALT="$\beta_k \times R$"></SPAN> for such states).

<P>
So Mn(Ek) is the square root of <!-- MATH
 $B(Ek, 0 \rightarrow k)$
 -->
<SPAN CLASS="MATH"><IMG
 STYLE=""
 SRC="img130.svg"
 ALT="$B(Ek, 0 \rightarrow k)$"></SPAN> with some sign
within <SPAN CLASS="MATH"><IMG
 STYLE=""
 SRC="img131.svg"
 ALT="$K=0$"></SPAN> bands. Mn(Ek) always has the same sign as <SPAN CLASS="M