Detecting a Higgs Pseudoscalar with a Z Boson Produced in Bottom Quark Fusion

We investigate the prospects of detecting a Higgs pseudoscalar ($A^0$) in association with a $Z$ gauge boson produced from bottom quark fusion ($b\bar{b} \to ZA^0$) at the CERN Large Hadron Collider (LHC). A general two Higgs doublet model and the minimal supersymmetric standard model are adopted to study the discovery potential of $pp \to ZA^0 \to \ell \bar{\ell} b\bar{b} +X (\ell = e, \mu)$, via $b\bar{b} \to ZA^0$ with physics backgrounds and realistic cuts. Promising results are found for $m_A \alt 400$ GeV in a general two Higgs doublet model when the heavier Higgs scalar ($H^0$) can decay into a $Z$ boson and a Higgs pseudoscalar ($H^0 \to ZA^0$). We compare the production rates from bottom quark fusion ($b\bar{b} \to ZA^0$) and gluon fusion ($gg \to ZA^0$) and find that they are complementary processes to produce $ZA^0$ in hadron collisions. While gluon fusion is the major source for producing a Higgs pseudoscalar associated with a $Z$ boson at the LHC for $\tan\beta \alt 10$, bottom quark fusion can make dominant contributions for $\tan\beta \agt 10$.