  This note is to record an unsucessful idea. I tried hard to persuade myself
to write this note as I have spent a significant fraction of time during this
summer. For Higgs resonant production and decaying in the $s$ channel, $i \to H
\to f$, the cross section is proportional to $y_i^2y_f^2/\Gamma_H$. Thus there
is a multi-solution ambiguity on the couplings due to uncertain knowledge on
Higgs width. In this work, we study the process $g+q \to g+q+l^++l^-$ with the
$t$-channel Higgs boson contribution included. As Higgs boson is not on-shell,
this process can be used to measure the Higgs couplings without the ambiguity.
  Based on the performance of the ATLAS detector in Run~II, the coupling
product $y_gy_Z$ can be potentially constrained to be less than 18 times the
Standard-Model value for a $p$-$p$ dataset of 140~fb$^{-1}$ at
$\sqrt{s}=13$~TeV. Assuming the equality of on-shell couplings and off-shell
couplings and combining the on-shell measurements, the width of the Higgs boson
is constrained to be less than 1.3~GeV, which is similar to that in the direct
measurement.
  In addition, the interference effect is also analyzed.
