In recent years, hints for "multi-lepton anomalies" have been accumulated by the analysis of Large Hadron Collider (LHC) data, pointing towards the existence of beyond the Standard Model (SM) Higgs bosons: a new scalar particle S with a mass mS in the range between 130 GeV and 160 GeV, produced from the decay of a heavier new scalar particle, H. Motivated by this observation, we perform a search for the signatures of S within this mass region, which has been studied by CMS and ATLAS as a by-product of the SM Higgs searches in the side-bands of the kinematic regions. Combining the γγ and Zγ channels, with associated leptons, di-jets, bottom quarks and missing energy, we obtain a local (global) significance of 5.1σ (4.8σ) for a mass of mS = 151.5 GeV and provide the preferred ranges for the corresponding (fiducial) cross sections. This is a strong indication for a scalar resonance S decaying into photons, and, to a lesser extent to Zγ, in association with missing energy, jets or leptons. Hints for the decays into, or production in association with, bottom quarks are statistically less significant. In order to test this hypothesis, we propose a search for H → γγbb, τ + τ − bb in asymmetric configurations that has not yet been performed by ATLAS and CMS.

Multi-lepton anomalies at the Large Hadron Collider are reasonably well described by a two Higgs doublet model with an additional singlet scalar. Here, we demonstrate that using this model we are also able to describe the excesses in gamma-ray flux from the galactic centre and the cosmic-ray spectra from AMS-02. This is achieved through Dark Matter (DM) annihilation via the singlet scalar. Of great interest is the flux of synchrotron emissions which results from annihilation of DM in Milky-Way satellites. We make predictions for MeerKAT observations of the nearby dwarf galaxy Reticulum II and we demonstrate the power of this instrument as a new frontier in indirect dark matter searches.

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The proposed future Large Hadron electron collider provides sufficient center of mass energies, $$\sqrt{s}$$ s , to probe heavy particles decaying into $$W^\pm (Z)-$$ W ± ( Z ) - boson of mass $$>2m_W$$ > 2 m W $$(2m_Z)$$ ( 2 m Z ) . In this work we present a study to produce one such heavy CP even scalar H of mass $$2m_h< m_H < 2 m_t$$ 2 m h < m H < 2 m t through charged-current production mode where $$H \rightarrow W^+W^-$$ H → W + W - , where hadronic decay of $$W^\pm -$$ W ± - boson is considered to reconstruct $$m_H$$ m H . Due to the presence of missing energy and forward jet in this channel, it is challenging to reconstruct $$m_H$$ m H with above final state and thus we employed three different reconstruction methods and discuss the significance of each one. For this analysis we consider a benchmark value of $$m_H = 270$$ m H = 270 GeV and $$\sqrt{s} \approx 1.3$$ s ≈ 1.3 TeV with an assumed luminosity of 1 ab$$^{-1}$$ - 1 .

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