  Constrained Instanton and Baryon Number Non--Conservation at High Energies,
P.G.Silvestrov, BUDKERINP 92--92. The total cross-section for baryon number
violating processes at high energies is usually parametrized as
$\sigma_{total}\propto\exp(\frac{4\pi}{\alpha} F(\varepsilon))$, where
$\varepsilon =\sqrt{s}/E_0 , \,\, E_0 = \sqrt{6} \pi m_w/\alpha$. In the
present paper the third nontrivial term of the expansion \[ F(\varepsilon)=
-1+\frac{9}{8}\varepsilon^{4/3} -\frac{9}{16}\varepsilon^2 -\frac{9}{32} \left(
\frac{m_h}{m_w}\right)^2 \varepsilon^{8/3}\log\left(
\frac{1}{3\varepsilon}\left( \frac{2m_w}{\gamma m_h}\right)^2 \right) +
O(\varepsilon^{8/3}) \] is obtained.The unknown corrections to $F(\varepsilon)$
are expected to be of the order of $\varepsilon^{8/3}$, but have neither
$(m_h/m_w)^2$, nor $\log(\varepsilon)$ enhancement. The total cross-section is
extremely sensitive to the value of single Instanton action. The correction to
Instanton action $\triangle S\sim (m\rho)^4 \log(m\rho)/g^2$ is found ($\rho$
is the Instanton radius). For sufficiently heavy Higgs boson the $\rho$
-dependent part of the Instanton action is changed drastically. In this case
even the leading contribution to $F(\varepsilon)$, responsible for a growth of
cross-section due to the multiple production of classical W-bosons, is changed:
\[ F(\varepsilon)=-1+ \frac{9}{8}\left( \frac{2}{3} \right)^{2/3}
\varepsilon^{4/3} +\ldots \,\, , \,\, \varepsilon\ll 1\ll \varepsilon \left(
\frac{m_h}{m_w} \right)^{3/2} \,\, . \]
