Reinstating the 'no-lose' theorem for NMSSM Higgs discovery at the LHC

TL;DR

This paper proposes a novel detection method for NMSSM Higgs bosons at the LHC, focusing on the h -> aa -> 4 tau decay chain, using forward proton detectors to improve discovery prospects.

Contribution

It demonstrates that the h -> aa -> 4 tau decay mode can be observed at the LHC with forward detectors, enabling mass determination of Higgs bosons in the NMSSM.

Findings

The h -> aa -> 4 tau decay chain is detectable with forward proton detectors.

Masses of h and a can be reconstructed on an event-by-event basis.

Detection is feasible despite challenges with conventional channels.

Abstract

The simplest supersymmetric model that solves the mu problem and in which the GUT-scale parameters need not be finely tuned in order to predict the correct value of the Z boson mass at low scales is the Next-to-Minimal Supersymmetric Standard Model (NMSSM). However, in order that fine tuning be absent, the lightest CP-even Higgs boson h should have mass ~100 GeV and SM couplings to gauge bosons and fermions. The only way that this can be consistent with LEP limits is if h decays primarily via h->aa->4 tau or 4j but not 4b, where a is the lighter of the two pseudo-scalar Higgses that are present in the NMSSM. Interestingly, m_a < 2 m_b is natural in the NMSSM with m_a > 2 m_tau somewhat preferred. Thus, h -> 4 tau becomes a key mode of interest. Meanwhile, all other Higgs bosons of the NMSSM are typically quite heavy. Detection of any of the NMSSM Higgs bosons at the LHC in this preferred scenario will be very challenging using conventional channels. In this paper, we demonstrate that the h -> aa -> 4 tau decay chain should be visible if the Higgs is produced in the process pp -> p+h+p with the final state protons being measured using suitably installed forward detectors. Moreover, we show that the mass of both the h and the a can be determined on an event-by-event basis.