Search results for "Two-Higgs-doublet model"
showing 6 items of 26 documents
Exclusive radiative B-meson decays within the aligned two-Higgs-doublet model
2012
In the aligned two-Higgs-doublet model, the alignment of Yukawa matrices in flavour space guarantees the absence of tree-level flavour-changing neutral currents, while allowing at the same time for new sources of CP violation, implying potentially large effects in many low-energy processes. In this work we study the constraints from exclusive radiative $B\to V\gamma$ decays, where $V$ denotes a light vector meson. The current experimental data on the CP-averaged branching ratios and the direct CP and isospin asymmetries are analyzed. It is found that, while the branching ratios and direct CP asymmetries do not constrain the parameter space much further compared to the inclusive $B\to X_{s,d…
Charged Higgs signals in tt¯H searches
2017
New scalars from an extended Higgs sector could have weak scale masses and still have escaped detection. In a type I two Higgs doublet model, for instance, even the charged Higgs can be lighter than the top quark. Because electroweak production of these scalars is modest, the greatest opportunity for their detection might come from rare top decays. For mass hierarchies of the type ${m}_{t}g{m}_{{H}^{+}}g{m}_{{A}^{0},{H}^{0}}$, the natural signal can arise from top quark pair production, followed by the decay chain $t\ensuremath{\rightarrow}b{H}^{+}$, ${H}^{+}\ensuremath{\rightarrow}{W}^{+(*)}{\ensuremath{\phi}}^{0}$, ${\ensuremath{\phi}}^{0}\ensuremath{\rightarrow}b\overline{b},{\ensuremath…
Explaining 750 GeV diphoton excess from top/bottom partner cascade decay in two-Higgs-doublet model extension
2016
In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu extension of the two-Higgs-doublet model by introducing a top partner ($T$)/bottom partner ($B$). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson ($H$), which can be sizably produced via the QCD process $pp \to T\bar{T}$ or $pp \to B\bar{B}$ followed by the decay $T\to Ht$ or $B \to Hb$. The diphoton decay rate of $H$ is greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of $H$ can be as large as 7 GeV. Under the current LHC constraints, we scan the parameter space and find that such an extension can account for the observe…
Vacuum Induced CP Violation Generating a Complex CKM Matrix with Controlled Scalar FCNC
2018
We propose a viable minimal model with spontaneous CP violation in the framework of a two Higgs doublet model. The model is based on a generalised Branco–Grimus–Lavoura model with a flavoured Z2 symmetry, under which two of the quark families are even and the third one is odd. The lagrangian respects CP invariance, but the vacuum has a CP violating phase, which is able to generate a complex CKM matrix, with the rephasing invariant strength of CP violation compatible with experiment. The question of scalar mediated flavour changing neutral couplings is carefully studied. In particular we point out a deep connection between the generation of a complex CKM matrix from a vacuum phase and the ap…
New signatures of flavor violating Higgs couplings
2016
We explore several novel LHC signatures arising from quark or lepton flavor violating couplings in the Higgs sector, and we constrain such couplings using LHC data. Since the largest signals are possible in channels involving top quarks or tau leptons, we consider in particular the following flavor violating processes: (1) $pp \to thh$ (top plus di-Higgs final state) arising from a dimension six coupling of up-type quarks to three insertions of the Higgs field. We develop a search strategy for this final state and demonstrate that detection is possible at the high luminosity LHC if flavor violating top--up--Higgs couplings are not too far below the current limit. (2) $pp \to tH^0$, where $H…
Extensions of the standard model scalar sector and constraints from ccolliders and cosmology
2013
In this thesis we study the Higgs sector of the Standard Model and compare it to the latest data from the LHC and Tevatron experiments. Then we consider two extensions of the Higgs sector. First we extend the Standard Model Higgs sector with one real SU(2) singlet and then we consider two-Higgs- doublet model and extend also it with one real singlet. In both extensions the singlet scalar is considered as a potential dark matter candidate. We find that the parameter space of the so called two-Higgs-doublet-inert-singlet model includes regions which could provide a dark matter candidate which constitutes significant amount of the total dark matter mass density.