Dorota Sokolowska

We study a new physics scenario with two inert and one active scalar doublets, hence a 3-Higgs Doublet Model (3HDM). We impose a $$ {Z}_2\times {Z}_2^{\prime } $$Z 2 × Z 2 ′ symmetry onto such a 3HDM with one inert doublet odd under the Z₂ transformation and the other odd under the $$ {Z}_2^{\prime } $$Z 2 ′ one. Such a construction leads to a two-component Dark Matter (DM) model. It has been shown that, when there is a sufficient mass difference between the two DM candidates, it is possible to probe the light DM candidate in the nuclear recoil energy in direct detection experiments and the heavy DM component in the photon flux in indirect detection experiments. With the DM masses at the electroweak scale, we show that, independently of astrophysical probes, this model feature can be tested at the Large Hadron Collider via scalar cascade decays in "Image missing" final states. We study several observable distributions whose shapes hint at the presence of the two different DM candidates.

The Inert Doublet Model is one of the simplest extensions of the Standard Model, providing a dark matter candidate. It is a two Higgs doublet model with a discrete $Z_2$ symmetry, that prevents the scalars of the second doublet (inert scalars) from coupling to the Standard Model fermions and makes the lightest of them stable. We study a large number of Inert Doublet Model scenarios, which are consistent with current constraints on direct detection, including the most recent bounds from the XENON1T experiment and relic density of dark matter, as well as collider and low-energy limits. We use a set of benchmark points with different kinematic features, that promise detectable signals at future $e^+e^-$ colliders. Two inert scalar pair-production processes are considered, $e^+e^- \to A~H $ and $e^+e^- \to H^+H^-$, followed by decays of $H^\pm$ and $A$ into the final states which include the lightest and stable neutral scalar dark matter candidate $H$. Significance of the expected observations is studied for different benchmark models and different running scenarios, for centre-of-mass energies up to 3 TeV. Numerical results are presented for the signal signatures with two muons or an electron and a muon in the final state, while the qualitative conclusions can also be drawn for the semi-leptonic signatures.

The Inert Doublet Model (IDM) is one of the simplest extensions of the Standard Model (SM), providing a dark matter candidate. It is a two Higgs doublet model with a discrete $Z_2$ symmetry, that prevents the scalars of the second doublet (inert scalars) from coupling to the SM fermions and makes the lightest of them stable. We study a large number of IDM scenarios, which are consistent with current constraints on direct detection and relic density of dark matter, as well as with all collider and low-energy limits. We propose a set of benchmark points with different kinematic features, that promise detectable signals at future $e^+e^-$ colliders. Two inert scalar pair-production processes are considered, $e^+e^- \to A~H $ and $e^+e^- \to H^+H^-$, followed by decays of $A$ and $H^\pm$ into final states which always include the lightest and stable neutral scalar dark matter candidate $H$. Significance of the expected observations is studied for different benchmark models and different running scenarios, for centre-of-mass energies from 250 GeV up to 3 TeV. For low mass scenarios, high significance can be obtained for the signal signatures with two muons or an electron and a muon in the final state. For high mass scenarios, which are only accessible at high energy stages of CLIC, the significance is too low for the leptonic signature and the semi-leptonic final state has to be used as the discovery channel. Results presented for this channel are based on the fast simulation of the CLIC detector response with the DELPHES package.

We study an extension of the Standard Model (SM) in which two copies of the SM-Higgs doublet which do not acquire a vacuum expectation value, and hence are inert, are added to the scalar sector. The lightest particle from the inert sector, which is protected from decaying to SM particles through the conservation of a $Z_2$ symmetry, is a viable dark matter candidate. We allow for $CP$ violation in this extended dark sector and evaluate the $ZZZ$ vertex and its $CP$-violating form factor in several benchmark scenarios. We provide collider signatures of this dark $CP$ violation in the form of potentially observable asymmetries and cross sections for the $f\overline{f}\to Z^{*}\to ZZ$ process at both leptonic and hadronic machines.

We study an extension of the Standard Model (SM) in which two copies of the SM Higgs doublet are added to the scalar sector. These extra doublets do not develop a vacuum expectation value, hence, they are \textit{inert}. This essentially leads to a 3-Higgs Doublet Model (3HDM) with 2 inert and 1 active scalar doublets, which we denote as I(2+1)HDM. We allow for CP-violation in the \textit{inert} sector, where the lightest \textit{inert} state is protected from decaying to SM particles through the conservation of a $Z_2$ symmetry, so that it is a Dark Matter (DM) candidate. For this scenario, we identify a smoking gun signature of dark CP-violation in the form of production thresholds of pairs of \textit{inert} neutral Higgs bosons at an $e^+e^-$ collider.

We study an extension of the Standard Model (SM) in which two copies of the SM Higgs doublet are added to the scalar sector. These extra doublets do not develop a vacuum expectation value, hence, they areinert. This essentially leads to a 3-Higgs Doublet Model (3HDM) with 2 inert and 1 active scalar doublets, which we denote as I(2+1)HDM. We allow for CP-violation in theinertsector, where the lightestinertstate is protected from decaying to SM particles through the conservation of a $$Z_2$$Z2 symmetry, so that it is a Dark Matter (DM) candidate. For this scenario, we identify a smoking gun signature of dark CP-violation in the form of production thresholds of pairs ofinertneutral Higgs bosons at an $$e^+e^-$$e+e- collider.

We study an extension of the Standard Model (SM) in which two copies of the SM-Higgs doublet which do not acquire a vacuum expectation value, and hence are {\it inert}, are added to the scalar sector. The lightest particle from the inert sector, which is protected from decaying to SM particles through the conservation of a $Z_2$ symmetry, is a viable dark matter candidate. We allow for CP-violation in this extended dark sector and evaluate the $ZZZ$ vertex and its CP-violating form factor in several benchmark scenarios. We provide collider signatures of this dark CP-violation in the form of potentially observable asymmetries and cross sections for the $f\bar f\to Z^*\to ZZ$ process at both leptonic and hadronic machines.

The Inert Doublet Model (IDM) is one of the simplest extensions of the Standard Model (SM), providing a dark matter candidate. It is a two Higgs doublet model with a discrete $Z_2$ symmetry, that prevents the scalars of the second doublet (inert scalars) from coupling to the SM fermions and makes the lightest of them stable. We study a large group of IDM scenarios, which are consistent with current constraints on direct detection, including the most recent bounds from the XENON1T experiment and relic density of dark matter, as well as with all collider and low-energy limits. We propose a set of benchmark points with different kinematic features, that promise detectable signals at future $e^+e^-$ colliders. Two inert scalar pair-production processes are considered, $e^+e^- \to H^+H^-$ and $e^+e^- \to AH$, followed by decays of $H^\pm$ and $A$ into final states which include the lightest and stable neutral scalar dark matter candidate $H$. Significance of the expected observations is studied for different benchmark models and different running scenarios, for centre-of-mass energies up to 3 TeV. Numerical results are presented for the signal signatures with two muons or an electron and a muon in the final state. For high mass scenarios, when the significance is too low for the leptonic signatures, the semi-leptonic signature can be used as the discovery channel.