  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.
