  The search for the heavy charged Higgs (mH+ > mtop) has been mainly based on
the off-shell top pair production process. However, resonance production in
s-channel single top events is an important channel to search for this
particle. In a previous work, it was shown that this process, i.e., qq' -> H+
-> tb + h.c., can lead to comparable results to what is already obtained from
LHC searches through gb -> tH- process. What was obtained was, however, based
on diagonal Yukawa couplings between incoming quarks assuming cs as the main
incoming pair due to the CKM matrix element being close to unity. The aim of
this paper is to show that off-diagonal couplings, like cb, may lead to
substantial contributions to the cross section, even if the corresponding CKM
matrix element is two orders of magnitude smaller. For this reason, the cross
section is calculated for each initial state including all diagonal and
off-diagonal terms, and all is finally added together to get the total cross
section which is observed to be ~ 2.7 times larger than what is obtained from
cs initial state. Results are eventually reflected into 95% C.L. exclusion and
$5\sigma$ discovery contours at different integrated luminosities of LHC. A
reasonable coverage of the parameter space is obtained by the 95% C.L.
exclusion contour.
