Signals of an invisibly decaying Higgs in a scalar dark matter scenario: a study for the Large Hadron Collider

TL;DR

This paper investigates the collider signatures of an invisibly decaying Higgs boson within a singlet Majoron model featuring dark matter candidates, emphasizing the importance of invisible decay channels for Higgs detection at the LHC.

Contribution

It introduces a model where the Higgs can decay invisibly into pseudo-Majorons, affecting Higgs search strategies and bounds at colliders.

Findings

Higgs predominantly decays into pseudo-Majorons, leading to missing energy signals.

Invisible decay channels weaken existing Higgs mass bounds from LEP and Tevatron.

Invisible decays are crucial for low-mass Higgs discovery at the LHC.

Abstract

We consider the collider phenomenology of a singlet Majoron model with softly broken lepton number. Lepton number is spontaneously broken when the real part of a new singlet scalar develops vacuum expectation value. With the additional soft terms violating lepton numbers, the imaginary part of this singlet scalar becomes a massive pseudo-Majoron which can account for the dark matter. In presence of the coupling of the pseudo-Majoron with the Standard Model (SM) Higgs, the SM Higgs mostly decays into a pair of pseudo-Majorons, giving rise to missing transverse energy signals at a hadron collider. Since the Higgs visible decay branching fractions get reduced in presence of this invisible decay mode, the bounds on the SM Higgs mass from the LEP and Tevatron experiments get diluted and the invisible decay channel of the Higgs become important for the discovery of low mass Higgs at the Large Hadron Collider.