Direct production of a light CP-odd Higgs boson at the Tevatron and LHC

Abstract

We show that the existing CDF $L=630p{b}^{-1}$ Tevatron data on $pp\to {\mu }^{+}{\mu }^{-}+X$ places substantial limits on a light CP-odd Higgs boson $a$ with $m_a<2m_B$ produced via $gg\to a$, even for $m_a>2m_{\tau }$ for which $BR(a\to {\mu }^{+}{\mu }^{-})$ is relatively small. Extrapolation of this existing CDF analysis to $L=10f{b}^{-1}$ suggests that Tevatron limits on the $ab\text{anti}b$ coupling strength in the region $m_a>8\text{gev}$ could be comparable to or better than limits from Upsilon decays in the $m_a<7\text{gev}$ region. We also give rough estimates of future prospects at the LHC, demonstrating that early running will substantially improve limits on a light $a$ (or perhaps discover a signal). In particular, outside the Upsilon peak region, integrated luminosity of only $5-20f{b}^{-1}$ (depending on $m_a$ and $\sqrt{s}$) could reveal a peak in $M_{{\mu }^{+}{\mu }^{-}}$ and will certainly place important new limits on a light $a$. The importance of such limits in the context of NMSSM Higgs discovery and $(g-2{)}_{\mu }$ are outlined.

Comments: 25 pages, 12 figures, updated LHC estimates and table based on ATLAS-related input now included (v4 and v5). In addition, comments regarding final ALEPH limits in the Z+4\tau channel are included in v5.