Theories with multiple Higgs doublets allow Higgs couplings to significantly deviate from Standard Model values, enabling indirect probes of extra scalars. The observed couplings already place stringent limits on such theories. In this talk, I will review the situation in models with two Higgs doublets and then extend into three Higgs doublets. For more than two doublets, there are five...
I will present the collider phenomenology of a vector-like top partner (VLT) within the Type-II Two-Higgs-Doublet Model (2HDM-II) extended by a vector-like quark doublet. The study focuses on final states involving a charged Higgs boson. In this framework, the VLT predominantly decays through exotic channels, leading to signatures with high $b$-jet multiplicity and leptonic components. The...
We present a phenomenological study where an invisible scalar mediator is produced in association with a top-quark pair at the Large Hadron Collider (LHC). Using a $t\bar{t}$ experimental-like analysis, we search for light scalar particles that could be hidden in the $t\bar{t}$ final state. The signal process $pp \rightarrow t\bar{t}Y_0$ is generated within a simplified dark matter (DM) model...
Charged Higgs-pair production at hadron colliders provides an option to obtain information about the trilinear couplings involving charged Higgs states of BSM Higgs potentials. We analyze the corresponding production modes, Drell–Yan-like production, gluon fusion and vector-boson fusion at next-to-leading order with respect to the corresponding uncertainties originating from the scale...
We investigated the collider phenomenology of Vector-like Quarks (VLQs) - specifically the top ($T$) and bottom ($B$) quarks within the framework of the Two-Higgs-Doublet Model Type II (2HDM-II), considering both singlet and doublet representations. While current LHC searches constrain VLQs decaying exclusively into Standard Model (SM) final states, the presence of additional scalars in the...
ggxy is a C++ library which currently includes gg $\to$ HH up to NLO in QCD. It is able to produce differential distributions in about 30 minutes on a laptop, both for on-shell and MSbar top quark masses and including a 7-point scale variation. ggxy has been linked to Powheg and Herwig to enable the matching to parton showers. Runtime tests have shown that it is a faster a by a factor of 4-5...
After the discovery of the Higgs boson in 2012, the measurements of the Higgs self coupling is still a challenge for current and future experiments in particle physics.
Higgs-boson pair production via gluon fusion is a loop-induced process. In order to increase the accuracy of the theoretical predictions for this process, higher-order corrections are necessary to reduce theoretical...
Extended scalar sectors can significantly influence the cosmological evolution of the early universe. The additional scalar degrees of freedom allow for strong first-order phase transitions (SFOPT) into the electroweak-broken vacuum, which induce gravitational waves that, for sufficiently strong signals, might be detectable in the near future. Additionally, the universe might have undergone...
We present a fully analytic computation of the two-loop electroweak corrections to double Higgs production in gluon fusion, mediated by light quarks. The calculation is performed using the method of differential equations, employing a large mass expansion to generate boundary functions. We implement the results in the POWHEG BOX framework for phenomenological studies. The corrections to the...
Di-Higgs (HH) production provides valuable information about loosely constrained quantities of the Higgs potential, such as the Higgs trilinear self-coupling. The measurement of these properties can confirm SM predictions or point to BSM physics, where non-resonant HH production is typically described by Effective Field Theories (EFTs).
The event-level reweighting consists of parameterizing...
Many well-motivated extensions of the Standard Model predict new, entirely bosonic sources of CP violation (CPV). In these scenarios, the simultaneous observation of carefully selected bosonic processes emerges as a simple yet powerful method to unambiguously reveal the presence of CPV. The present study, which establishes a promising framework of CPV searches for the upcoming HL-LHC era,...
Higgs pair production offers the opportunity to probe correlations among the couplings of one or two Higgs bosons to fermions and gauge bosons. In this context, it serves as a powerful test of the underlying EFT framework. In this talk, we study Higgs pair production via gluon fusion within the Higgs Effective Field Theory (HEFT). We demonstrate that adopting a consistent power counting in...
We investigate the potential of future electron-positron colliders, such as FCC-ee and CEPC, to probe 2-Higgs-doublet models (2HDMs) that facilitate a strong first-order electroweak phase transition (SFOEWPT), a necessary condition for electroweak baryogenesis. Focusing on a 2HDM in the CP-conserving limit, we identify parameter regions consistent with an SFOEWPT and evaluate their...
In supersymmetric theories, the Higgs boson masses are calculated from the input parameters. Moreover, to be compatible with phenomenology, higher-order corrections have to be included in their derivation. Experimental analyses on the other hand resort to benchmarks with specific mass values. Given the large number of input parameters in the proposed supersymmetric extension, such as the...
