A persistent issue in electroweak baryogenesis calculations is the significant disparity in predictions yielded by different approaches, with variations spanning several orders of magnitude. In this study, we examine a system comprising two fermion flavours, proposing the existence of two sources of CP-violating. The semiclassical force and a new resonantly enhanced mixing source can be...
Rare kaon decays are among the most sensitive probes of both heavy and light new physics beyond the Standard Model description thanks to high precision of the Standard Model predictions, availability of very large datasets, and the relatively simple decay topologies. The NA62 experiment at CERN is a multi-purpose high-intensity kaon decay experiment, and carries out a broad rare-decay and...
Heavy Neutral Leptons (HNLs) are hypothetical particles that are able to explain neutrino oscillations. The presence of HNLs induces charged lepton flavor violating (cLFV) processes. Non-observations of these processes puts the strongest limits on parameters of HNL much heavier than the electroweak scale.
We demonstrate that for such HNLs, the branching ratio of cLFV processes is actually...
In modern experiments on flavour physics it is possible to search for the decays of $B$’s, $D$’s, or $\tau$’s into final states with heavy neutrinos $N$ (a.k.a. heavy neutral leptons). I present a common study of theorists and experimentalists from Belle II on constraints on $B-> D^{*} \ell N$. Next I discuss the status of the theory predictions of the various $N$ decay rates. In scenarios in...
The magnetic moment anomaly of the muon, that relates the cyclotron and spin precession frequency, provides one of the most stringent tests of the Standard Model of Particle Physics since it is measured and theoretically predicted to very high precision. Deviations between theoretical prediction and experimental measurements can be used to investigate tensions in the methods or can be...
We present a Dirac leptogenesis model in which the only out-of-equilibrium particles are right-handed neutrinos undergoing asymmetric scatterings. They are produced from a negligible initial abundance and their density freezes in soon after reheating. Even though the asymmetry source term vanishes, we demonstrate that opposite asymmetries of right-handed neutrinos and standard model leptons...
We show that the process of non-instantaneous reheating during the post-inflationary period can have a sizable impact on the charged lepton Yukawa equilibration temperature in the early Universe. This suggests relooking the effects of lepton flavors in the leptogenesis scenario where the production and decay of right-handed neutrinos take place within this prolonged era of reheating. We find...
A derivative coupling of an axion-like particle (ALP) with a B-L current can lead to the baryon asymmetry of the universe through spontaneous leptogenesis, provided there is a lepton number-breaking interaction in thermal equilibrium. Typically, this requires heavy ALPs and a high reheating temperature, as the lepton number-breaking is also linked to neutrino mass generation. In this study, we...
Primordial neutrinos are important messengers from the Early Universe, affecting several key observables such as primordial nuclear abundances and cosmic microwave background. If some new physics existed at the time around neutrino decoupling, it would have left imprints on the neutrino distribution function, which requires solving the neutrino Boltzmann equation. Existing approaches have...
At the Deep Underground Neutrino Experiment (DUNE), a proton beam hits a fixed target leading to large production rates of mesons. These mesons can decay and potentially provide a source of long-lived neutral fermions. Examples of such long-lived fermions are heavy neutral leptons which can mix with the standard-model active neutrinos, and the bino-like lightest neutralino in...
We discuss a simple theory for physics beyond the Standard Model where a Majorana dark matter is predicted from anomaly cancellation. We discuss in detail the minimal theory where the baryon number is a local symmetry spontaneously broken at the low scale. The correlation between the cosmological constraints on the dark matter relic density, the direct detection and collider bounds is...
Models of inelastic (or pseudo-Dirac) Dark Matter (DM) commonly assume an accidental symmetry between the left-handed and right-handed mass terms in order to suppress diagonal couplings. We point out that this symmetry is unnecessary, because for Majorana fermions the diagonal couplings are not strongly constrained. Removing the requirement of such an accidental ad-hoc symmetry instead relaxes...
A quasi-Dirac pair of Heavy Neutral Leptons possesses a number of features that make it an appealing target for search in the GeV mass scale at future collider experiments. This scenario is studied in the Left-Right Symmetric Model. Predictions for the HNL couplings to different lepton flavors are derived, and the possible probes of the model based on the LNV signature are considered.
An investigation of relatively light (GeV-scale), long-lived right-handed neutrinos is performed within minimal left-right symmetric models using the neutrino-extended Standard Model Effective Field Theory framework. Light sterile neutrinos can be produced through rare decays of kaons, $D$-mesons, and $B$-mesons at the Large Hadron Collider (LHC) and the Long-Baseline Neutrino Facility (LBNF)...
In this talk, we discuss tree-level UV completions for dimension 6 and 7 operators in the Standard Model Effective Field Theory extended with right-handed neutrinos ($N_R$SMEFT). We reveal that every model generating lepton number violating (LNV) operators with right-handed neutrinos also leads to the formation of active neutrino masses. This intrinsic connection between LNV processes and the...
We investigate the possibility of disentangling different new physics contributions to the rare meson decays $K\rightarrow\pi+$invisible and $B\rightarrow K(K^*)+$invisible through kinematic distributions in the missing invariant mass squared. We employ dimension-$6$ operators within the Low-Energy Effective Field Theory (LEFT), identifying the invisible part of the final state as either...
We discuss a class of theories that predict a fermionic dark matter candidate from gauge anomaly cancellation.
As an explicit example, we study the predictions in theories where the global symmetry associated with baryon number is promoted to a local gauge symmetry.
In this context the symmetry-breaking scale has to be below the multi-TeV scale in order to be in agreement with the...
