An attractive explanation for the flavor puzzle of the Standard Model is the multi-scale origin of the flavor hierarchies, where the size of the Standard Model Yukawas of the different families is associated to different scales. This allows to circumvent the tight flavor bounds for New Physics, and opens the possibility of interesting UV completions of the SM at the TeV scale. I will explore...
In the pursuit of physics beyond the Standard Model, a promising path is the study of exclusive B-meson decays caused by the transition b→sℓ+ℓ−. A key observable in such decays is the ratio $R_K$, which measures electron-muon universality in B→Kμ+μ−/e+e-. At first sight, the recent LHCb measurement of RK ~ 1 may seem to largely constrain deviations from universality in these decays. However,...
Precise determination of the magnitudes and phases of the elements, in particular, $V_{ub}$ and $V_{cb}$, of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is crucial for testing the unitarity of the CKM matrix, hence testing the Standard Model. The magnitudes of these elements are best measured by using $B$-meson semileptonic decays. Moreover, semileptonic $B$-meson decays provide a great...
We investigate the right handed sneutrino effect, in the framework of the $B−L$ extension of Minimal Supersymmetric Standard Model with Inverse Seesaw, on $b \to c l \bar\nu_l$ decays anomalies which has been recently measured in the lepton-universality ratios $\mathcal{R(D^{(*)})}=\mathcal{BR(B \to D^{(*)}\tau \bar\nu_{\tau})/BR(B \to D^{(*)}l \bar\nu_l)}$ ($l=e$ or $\mu$). Taking into...
Searches for new physics (NP) at particle colliders typically involve multi-variate analysis of kinematic distributions of final state particles produced in a decay o fa hypothetical NP resonance. Since the pair-production cross-sections mediated by such resonances are strongly suppressed by the NP scale, this analysis becomes less relevant for
NP searches for masses of the BSM resonance...
Muon reconstruction performance plays a crucial role in the precision and sensitivity of the Large Hadron Collider (LHC) data analysis of the ATLAS experiment. Using di-muon Resonances we are able to calibrate to per-mil accuracy the detector response for muons. Innovative techniques developed throughout the Run-2 period and during the LHC shut-down significantly improve the measurement of...
We present the first complete model of the Littlest Modular Seesaw, based on two right-handed neutrinos, within the framework of multiple modular symmetries, justifying the use of multiple moduli fields which take their values at 3 specific stabilizers of $\Gamma_4 \simeq S_4$, including a new phenomenological possibility. Using a semi-analytical approach, we perform a $\chi^2$ analysis of...
In this work, we revisit the constraints on neutrinos flavour models given by discrete symmetries. We study the solar and atmospheric sum rules and test them against the up-to-date fit of the neutrino oscillation data. We show that some models, such as a version of the Golden Ratio (GR1), are already excluded at $3\sigma$ and discuss which are the most favored models by the data. We also test...
The aim of this presentation is to introduce a dark extension of the SM that communicates to it through three portals: neutrino, vector and scalar mixing, by which it could be possible to explain the Low Energy Excess (LEE) at MiniBooNE. In the model, Heavy Neutral leptons are produced by upscattering via a dark photon, with masses around 10 MeV – 2 GeV, and subsequently decay into an...
Neutrino non-standard interactions (NSI) have been extensively explored in the context of dedicated neutrino experiments. However, the next generation of direct detection experiments is on course to observe a significant number of solar neutrino events, and the sensitivities of these experiments within the NSI landscape are yet to be determined. Due to their sensitivity to neutrino-nucleus and...
Heavy Neutral Leptons (HNLs), also known as heavy or right-handed neutrinos, are among the best motivated new particles to extend the SM and, when their masses are between the few GeV and few TeV, high-energy colliders are one of our best tools to probe their existence. Nevertheless, most of the experimental searches performed so far only consider simplified scenarios, whose connection to...
We present an updated and improved global fit analysis of current flavor and electroweak precision observables to derive bounds on unitarity deviations of the PMNS mixing matrix and the mixing of heavy neutrinos with the active flavours.
This new analysis is motivated by new and updated experimental results on key observables such as $V_{ud}$, the invisible decay width of the $Z$ boson and...
Collider-testable low scale type I seesaw models for neutrino mass generation generically feature pseudo-Dirac heavy neutrinos, composed of two Majorana states with nearly degenerate masses. These pseudo-Dirac heavy neutral leptons (HNLs) can oscillate between interaction eigenstates that couple to leptons and antileptons, and thus generate oscillations between lepton number conserving (LNC)...
We study charged lepton flavor violating processes $\mu^+\mu^+\to\ell^+\ell'^+$ at a future same-sign muon collider. Working in an effective field theory framework, we compare the potential discovery reach with existing limits from rare $\mu$ and $\tau$ decays, finding that muon colliders are the most sensitive probe of charged lepton flavor violation for a range of parameters. As a model...
I will discuss flavour non-universal gauge interactions as a generic,
and well-motivated, possibility for new physics at the TeV scale. Such
dynamics could explain the hierarchical structure of fermion masses and
mixing angles - the so-called 'flavour puzzle' - by delivering
approximate flavour symmetries as accidental. The extended gauge
interactions imply heavy gauge bosons that couple...
I will discuss a tri-hypercharge (TH) extension of the Standard Model (SM) in which a separate gauged weak hypercharge is associated with each fermion family, avoiding the family repetition of the SM. If the SM Higgs doublet only carries third family hypercharge, then only third family renormalisable Yukawa couplings are allowed, explaining the hierarchical heaviness of their masses. I will...
The Froggatt-Nielsen Mechanism is a powerful way to explain the hierarchical structure found in the masses and mixing angles of quarks and leptons.
In this mechanism, the above structure is realized by imposing different U(1) charges on each generation of fermions under a new U(1) flavor symmetry.
In this talk, I will present the results of a reconsideration of the phenomenologically valid...
We consider a minimal non-supersymmetric SO(10) Grand Unified Theory (GUT) model that can reproduce the observed fermionic masses and mixing parameters of the Standard Model. We calculate the scales of spontaneous symmetry breaking from the GUT to the Standard Model gauge group using two-loop renormalisation group equations. This procedure determines the proton decay rate and the scale of...
In the SO(10) GUTs with or without supersymmetry, the third-generation fermions' Yukawa couplings can be unified by employing renormalization group (RG) analysis, similar to the gauge couplings. In the considered models, Yukawa unification implies that different Yukawa couplings are generated from a single coupling in the UV through the decomposition of scalar and fermion representations of...
The modular symmetry provides us with an intriguing solution to the flavor mixing puzzle. In the bottom-up approach to the modular-invariant flavor models, the modulus parameter $\tau$ is usually treated as a free parameter. Interestingly, there exist some special values of $\tau$ called stabilizers at which residual symmetries can be preserved after the spontaneous breaking of the global...
The NA62 experiment at CERN took data in 2016–2018 with the main goal of measuring the $K^+ \rightarrow \pi^+ \nu \bar\nu$ decay. We report on the search for visible decays of exotic mediators from data taken in "beam-dump" mode with the NA62 experiment. The NA62 experiment can be run as a "beam-dump experiment" by removing the Kaon production target and moving the upstream collimators into a...
The NA62 experiment at CERN collected the world's largest dataset of charged kaon decays in 2016-2018, leading to the first measurement of the branching ratio of the ultra-rare $K^+ \rightarrow \pi^+ \nu \bar\nu$ decay, based on 20 candidates. In this talk the NA62 experiment reports recent results from analyses of $K^+ \rightarrow \pi^0 e^+ \nu \gamma$, $K^+ \rightarrow \pi^+ \mu^+ \mu^-$ and...
We discuss the impact of the recent LHCb update on the two lepton-flavour universality ratios $R_K$ and $R_{K^*}$, and the CMS update of $B({B_s \to \mu^+\mu^-})$ regarding the possibility of New Physics in $b\to s\ell^+\ell^-$ decays. We perform global fits of the New Physics Wilson coefficients defined in the model-independent approach of the Weak Effective Theory at the $b$-quark mass. We...
