High Energy Physics - Phenomenology
We investigate the implications of spontaneous CP-violation in the general two Higgs doublet model, which leads to a non-decoupling structure of the Higgs sector. All the masses of the Higgs bosons are purely determined by the vacuum…
We summarise the physics of first-order phase transitions in the early universe, and the possible ways in which they might come about. We then focus on gravitational waves, emphasising general qualitative features of stochastic backgrounds…
The flavour puzzle remains as one of the most intriguing enigmas of particle physics. In this thesis, we propose and study theories of flavour which generically hint to a multi-scale origin of flavour. First we explore the idea of…
The tri-hypercharge proposal introduces a separate gauged weak hypercharge assigned to each fermion family as the origin of flavour. This is arguably one of the simplest setups for building "gauge non-universal theories of flavour" or…
We propose a tri-hypercharge (TH) embedding of the Standard Model (SM) in which a separate gauged weak hypercharge is associated with each fermion family. In this way, every quark and lepton multiplet carries unique gauge quantum numbers…
One of the promising dark matter (DM) candidates is a keV scale sterile neutrino. In the early universe the observed relic of the sterile neutrino DM is generated via the \textit{Dodelson-Widrow} mechanism. However, this production scenario…
Unbinned likelihood fits aim at maximizing the information one can extract from experimental data, yet their application in realistic statistical analyses is often hindered by the computational cost of profiling systematic uncertainties.…
We present the first constraints on the overlaps between an Axion-like particle (ALP) and the $\pi^0$ and $\eta$ mesons from the analysis of the distortions to the $\langle K|\overline{s}\gamma^\mu u | \pi\rangle$ form factors. We…
This paper investigates the production of non-prompt photons originating from rotating synchrotron radiation (RoSyRa), specifically the emission of photons by a rigidly rotating quark-gluon plasma in thermal equilibrium, in the presence of…
We study the Hamiltonian truncation for the two-dimensional $\lambda\phi^4$ theory within the framework of Hamiltonian truncation effective theory, where truncation artifacts are mitigated through a systematic inclusion of corrective terms…
The most precise theoretical predictions for the total cross section for the associated production of a Higgs boson with a top-antitop quark pair at the LHC, first presented in \cite{Balsach:2025tth}, are reported. The calculation combines…
We study the impact of light GeV-scale heavy neutral leptons (HNLs) on Big Bang nucleosynthesis (BBN) in the neutrino-extended Standard Model Effective Field Theory ($\nu$SMEFT). We show that, based on very general considerations, BBN…
We give an introduction to and a short overview of light meson form factors. We first discuss the classical picture and how it then fits in with amplitudes in quantum field theory. We give a short overview of the main theoretical methods…
The top-quark threshold cross section at $e^+e^-$ colliders near production threshold is investigated. We study the scale dependence of the cross section for $\sigma(e^+e^- \to ttX$) near $\sqrt{s} \simeq 2m_t$ and discuss the theoretical…
Hadronization models based on local string-breaking dynamics are typically Markovian by construction, yet the physical ensemble of final states is shaped by global constraints that couple the entire fragmentation trajectory. Recasting…
The precision program of the Large Hadron Collider (LHC) increasingly relies on the boosted regime, where top quark properties are probed at the TeV scale. However, the simultaneous presence of heavy quark mass effects and large logarithmic…
The muon has been instrumental in establishing the Standard Model of particle physics and continues to play a key role in exploring the nature of New Physics. A global program is underway to enhance the discovery potential of a wide range…
We study the decays $h \to \ell \bar{\ell} \left(Z \to \ell' \bar{\ell'}\right)$ and $h\to\ell\bar{\nu}_\ell\nu_{\ell'}\bar{\ell'}$ within the SMEFT framework and including effects up to $\mathcal O(1/\Lambda^4)$, where $\Lambda$ is the new…
In this article, we explore the use of contour deformation for the numerical evaluation of Feynman integrals after sector decomposition. In existing codes, the contour of integration is determined heuristically for each phase-space point by…
We present a compact form of the massive $1\to 3$ tree-level QCD splitting functions and discuss a decomposition of the results in terms of lower-order expressions, scalar dipole antenna functions and pure higher-order remainders. The…