Higgs Signal for h to aa at Hadron Colliders

TL;DR

This paper investigates the prospect of discovering a light SM-like Higgs in extended Higgs sectors where h→aa decays dominate, by studying Higgs-strahlung (Wh/Zh) with h→aa and a→bb or a→ττ at the Tevatron and LHC. It introduces a C^2 parameterization to capture deviations from SM Higgs production and decays, and analyzes two primary channels, 2b2τ and 4b, across collider environments. The Tevatron can yield a few events in favorable 2b2τ or 4b channels, while the LHC—with higher cross sections and luminosities—finds the 4b channel particularly promising for discovery, contingent on maintaining low-p_T b-tagging efficiency and accurate background modeling. The study also emphasizes the interplay of m_h and m_a relations, and suggests combining Wh and Zh channels to enhance sensitivity, though it notes the need for more realistic detector simulations and background estimates.

Abstract

We assess the prospect of observing a neutral Higgs boson at hadron colliders in its decay to two spin-zero states, a, for a Higgs mass of 90-130 GeV, when produced in association with a W or Z boson. Such a decay is allowed in extensions of the MSSM with CP-violating interactions and in the NMSSM, and can dominate Higgs boson final states, thereby evading the LEP constraints on standard Higgs boson production. The light spin-zero state decays primarily via a to bb and tau+tau-, so this signal channel retains features distinct from the main backgrounds. Our study shows that at the Tevatron, there may be potential to observe a few events in the bb tau+tau- or bbbb channels with relatively small background, although this observation would be statistically limited. At the LHC, the background problem is more severe, but with cross sections and integrated luminosities orders of magnitude larger than at the Tevatron, the observation of a Higgs boson in this decay mode would be possible. The channel h to aa to bbbb would provide a large statistical significance, with a signal-to-background ratio on the order of 1:2. In these searches, the main challenge would be to retain the adequate tagging efficiency of b's and tau's in the low p_T region.