The unique dimension-$5$ effective operator, $LLHH$, known as the Weinberg operator, generates tiny Majorana masses for neutrinos after electroweak spontaneous symmetry breaking. If there are new scalar multiplets that take vacuum expectation values (VEVs), they should not be far from the electroweak scale. Consequently, they may generate new dimension-$5$ Weinberg-like operators which in turn...
Constraints on dark sector particles decaying into neutrinos typically focus on their impact on the effective number of relativistic species, $N_{eff}$, in the early Universe. However, for heavy relics with longer lifetimes, constraints mainly arise from the photo-disintegration of primordial abundances. The high-energy neutrinos injected by the decay can interact with both the thermal...
The relic $\nu$ background (R$\nu$B) is the `holy grail’ of neutrino physics and it is also the only known Dark Matter subcomponent. Yet, it has so far escaped detection attempts, mainly due to the very low energies and very weak cross-sections involved in the detection channels. In this talk, I will describe the mechanism by which ultra high energy (UHE) cosmic rays, stored in cosmic...
Neutrinos are among the most fascinating particles of the standard model (SM). We know very little about their nature and unveiling their secrets might be the key to broadening our understanding of nature. Despite being extremely elusive particles, they can undergo a process where their interaction cross-section with matter is enhanced by orders of magnitudes: this is Coherent Elastic...
We investigate IceCube's ability to constrain the neutrino relic abundance using events from the recently identified neutrino source NGC1068. Since these neutrinos have large energies $\gtrsim$1 TeV and have propagated through large distances, they make a great probe for overabundances of the cosmic neutrino background.
The propagation of neutrinos from NGC1068 was simulated by solving a...
Neutrino oscillations are a nature given interferometer and as such is a door to better explore the quantum realm. In this work we address the question of how to compute the neutrino wavepacket width from first principles based on decoherence models. We show how the relevant parameters end up fixed solely by the mother particle interactions.
CMB and LSS measurements are placing the best upper bounds on the sum of the neutrino masses. Even more, a detection is currently promised by experiments such as EUCLID, which is already taking data. However, these results are model dependent and are relaxed if new physics in the neutrino sector exists. In this context, we present a framework to disentangle the different effects on neutrino...
We explore the potential of neutrinoless double-beta ($0\nu\beta\beta$) decays to probe scalar leptoquark models that dynamically generate Majorana masses at the one-loop level. By relying on Effective Field Theories, we perform a detailed study of the correlation between neutrino masses and the $0\nu\beta\beta$ half-life in these models. We describe the additional tree-level leptoquark...
Abstract: This study delves into how quantum decoherence in neutrinos could influence the precision of standard oscillation parameter measurements in the DUNE and T2HK experiments. Our analysis suggests that the measurements of $\delta_\text{CP}$, $\sin^2\theta_{13}$, and $\sin^2\theta_{23}$ are notably affected in DUNE, more so than in T2HK. Conversely, DUNE exhibits a higher sensitivity to...
The neutrino has a lifetime that is significantly longer than the Age of the Universe as it can only decay radiatively via loops with gauge bosons. However the presence of physics Beyond the Standard Model could induce 'visible' neutrino decay between neutrino mass eigenstates. This decay process could be identified in laboratory experiments as well as from astrophysical or cosmological...
We study the impact of the presence of heavy neutral leptons (HNL) on lepton flavour universality and electroweak precision observables (EWPO). In view of the increasing experimental sensitivity, we consider the one-loop contributions of the HNL to the several observables under scrutiny. We show the significance of next-to-leading order corrections to lepton flavour universality in $Z\to...
We consider the scattering of low-mass halo dark-matter particles in the hot plasma of the Sun, focusing on dark matter that interact with ordinary matter through a dark-photon mediator. The resulting "solar-reflected" dark matter (SRDM) component contains high-velocity particles, which significantly extend the sensitivity of terrestrial direct-detection experiments to sub-MeV dark-matter...
We propose a topological portal between quantum chromodynamics (QCD) and a dark QCD-like sector. Such a portal is present only for a unique coset structure after QCD confinement and it connects three QCD to two dark pions. When gauged, it is the leading portal between the two sectors, providing an elegant self-consistent scenario of light thermal inelastic dark matter. The inherent...
Conversion-driven freeze-out is an appealing mechanism to explain the observed relic density while naturally accommodating the null-results from direct and indirect detection due to a very weak dark matter coupling. Interestingly, the scenario predicts long-lived particles decaying into dark matter with lifetimes favorably coinciding with the range that can be resolved at the LHC. However, the...
Models of inelastic (or pseudo-Dirac) dark matter commonly assume an accidental symmetry between the left-handed and right-handed mass terms in order to suppress diagonal couplings. Here we point out that this symmetry is unnecessary, because for Majorana fermions the diagonal couplings are in fact not strongly constrained. Removing the requirement of such an accidental symmetry in fact...
Direct detection experiments lose sensitivity to light dark matter because of the small energy deposition in nuclear recoil events. Scenarios where dark matter is boosted to relativistic velocities thus provide a promising means to constrain sub-GeV dark matter particles. Cosmic-ray upscattering is a particularly appealing boosting mechanism as it does not require any assumptions beyond dark...
We compute the one-loop contribution to the $\bar \theta$-parameter of an axion-like particle (ALP) with CP-odd derivative couplings. Its contribution to the neutron electric dipole moment is shown to be orders of magnitude larger than that stemming from the one-loop ALP contributions to the up- and down-quark electric and chromoelectric dipolemoments. This strongly improves existing bounds on...
The standard reheating process after inflation can be preceded by preheating, a phase where the oscillations of the inflaton field at the bottom of its potential lead to explosive production of particles via parametric resonance, potentially altering the history of the universe.
I will discuss an inflating modulus, coupled to an axion via a typical potential coupling coming from type iib...
CP-violating probes are among the most promising and yet relatively unexplored ways to look for Axion-Like Particles (ALPs) and to investigate their phenomenology. With this work we construct the most general effective Chiral Lagrangian describing the interactions of a light CP-violating ALP $\phi$ with mesons, baryons, leptons and photons at energies below the QCD confinement scale ($m_\phi <...
After discovering dark matter (DM) axions in a haloscope, follow-up experiments will be required to break the degeneracy between the axion coupling to photons and its local DM abundance. Since a discovery would justify more significant investments, I assess the ability of ambitious light-shining-through-a-wall (LSW) experimental designs to target the QCD axion band. The measurement of the...
In this talk we present a theoretical analysis of the $\theta$-dependence of $\alpha$-decay half-lives for heavy isotopes, which provides a method to explore axion dark matter. To test such effect, a setup has recently been constructed and installed at the Gran Sasso Laboratory, based on the $\alpha$-decay of Americium-241. This prototype experiment will allow us to explore a broad range of...
We study the role of an ultra-light primordial black hole (PBH) dominated phase on the generation of baryon asymmetry of the Universe (BAU) and dark matter (DM) in a type-I seesaw framework augmented by Peccei-Quinn (PQ) symmetry which solves the strong CP problem. While the BAU is generated via leptogenesis from the decay of heavy right-handed neutrino (RHN) at the seesaw scale dictated by...
We will discuss vorticity as an intrinsic property of highly-spinning black holes. The connection between vorticity and limiting spin represents a universal feature shared by objects of maximal microstate entropy, so-called saturons. Using Q-ball-like saturons as a laboratory for black holes, we study the collision of two such objects and find that vorticity can have a large impact on the...
Last year pulsar timing arrays unveiled the first detection of a stochastic gravitational wave background at nano-Hertz frequencies. The background could potentially arise from a population of merging supermassive black holes or – arguably even more exciting – an event in the early cosmos. In this talk, I will discuss the possibility that the recently measured signal stems from a phase...
I will start by explaining why it is interesting and how one can quantise from first principles field theories living on the background of a bubble wall in the planar limit, i.e. a domain wall, with a particular focus on the case of spontaneous breaking of gauge symmetry. Using the tools I introduced, we can compute the average momentum transfer from transition radiation, which denotes the...
High-Frequency Gravitational Waves (HFGWs) constitute a unique window on the early Universe as well as exotic astrophysical objects. If the current gravitational wave experiments are more dedicated to the low frequency regime, the graviton conversion into photons in a strong magnetic field constitutes a powerful tool to probe HFGWs. In this paper, we show that neutron stars, due to their...
Radiative quarkonia decays offer an ideal setup for probing Axion-Like Particle (ALP) interactions. In this talk, we will present the results of our recent analysis of this type of processes including an updated set of new experimental searches. This analysis consists of a comprehensive study of the production channels in the process $e^+ e^- \to a \, \gamma$ in $B$- and Charm-factories, as...
We propose a novel realisation of leptogenesis that relies on the out-of-equilibrium decay of an axion-like particle (ALP) into right-handed Majorana neutrinos (RHN) in the Early Universe. With respect to thermal leptogenesis and for any RHN mass down to a TeV, our mechanism improves by a factor of $\sim100$ the tuning in the RHN mass splittings needed to reproduce the baryon asymmetry of the...
The generation of a mass for an axion-like-particle is a long-standing open issue. We propose a model where a GeV mass for this pseudo-scalar particle is predicted in a large portion of the parameter space due to the presence of explicit Peccei-Quinn symmetry-breaking terms in an exotic leptonic sector. The latter provides a solution to the muon $g-2$ anomaly, within the framework of the...
Hot white dwarfs lose energy mainly in the form of neutrinos through plasmon decay from the inner part of the star. BSM physics can have visible contributions to the cooling of these compact objects. The aim of this study is to show how hot white dwarf cooling could be altered by a dark photon from the L_mu - L_tau model and explore these effects from ultra-light to heavy intermediators. This...
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 “flavour deconstructed theories”, which are receiving increasing attention in recent years. Firstly, I will breafly introduce the tri-hypercharge proposal and...
The QCD axion is one of the most promising solutions to the Strong CP Problem. In Standard QCD axion models, axion solutions lie around a straight line, the so-called canonical QCD axion band. Recently, there have been numerous attempts to find QCD axion solutions away from the canonical band. In this talk, we show how such solutions naturally arise in a variety of UV models.
Option 1 for Talk / Poster: In this talk, we present a family-non-universal extension of the Standard Model where the first two families feature both quark-lepton and electroweak-flavour unification, via the $SU (4)\times Sp(4)_L \times Sp(4)_R \,$ gauge group, whereas quark-lepton unification for the third family is realised `a la Pati-Salam.
Via staggered symmetry breaking steps, this...
We studied the Time reversal symmetry violation in a model-independent way for the long baseline experiments T2HK and DUNE. The theoretical framework allows us to find the energy bins that provide sensitivity for T-violation test. We then perform extensive numerical simulations on the appearance probabilities to testify our theoretical calculations. The measurement accuracy at the near...
The topic of this talk will be a new inflationary model called ‘Loop Blow-Up Inflation’, first presented in 2403.04831. This model originates from string theory, by including string loop corrections in the potential of a blow-up Kähler modulus, a scalar field playing the role of the inflaton. The loop effects become dominant as soon as the inflaton is displaced from its post-inflationary...
We introduce a minimal setup to achieve dynamical inflection point inflation, utilizing a minimal framework. Our approach examines collider constraints on inflationary parameters using the same field composition. Specifically, we incorporate a dark SU(2)D gauge sector featuring a dark scalar doublet as the inflaton, accompanied by particle content akin to the Standard Model but with degenerate...
Simplified t-channel dark matter models serve as a versatile and well-motivated framework for rich dark sectors that are widely studied by ongoing experimental and theoretical efforts. In this work,
we investigate the impact of non-perturbative effects on the dark matter relic abundance for two representative models of this kind of models, focusing on regions of parameter space where...
Majoron-like particle $J$ in the mass range between 1MeV to 10 GeV, which dominantly decays into the standard model (SM) neutrinos, can be constrained from the big-bang nucleosynthesis (BBN). For majoron lifetime ($\tau_J$) smaller than 1sec, the injected neutrinos from the majoron decay heat up the background plasma and it results in the deficit of Helium-4 abundance and enhancement of...
We consider the possibility for Dark Matter (DM) freeze-in occurring at high values of the couplings between the DM and the SM states. Such a possibility requires a reheating temperature of the Universe below the value of the DM mass. Contrary to conventional freeze-in scenarios, the values of the DM couplings required by the correct relic density are within the reach of Direct Detection...
We study the stochastic gravitational wave (GW) background resulting from the strong first-order phase transition (SFOPT) associated with $SU(2)_R\times U(1)_{B-L}$-breaking in the doublet left-right symmetric model (DLRSM). For different values of the symmetry-breaking scale $v_R =20,~30$, and $50$ TeV, we construct the one-loop finite temperature effective potential to explore the parameter...
$U(1)$ extension of the Standard Model (SM) is well motivated, where the charges of SM fermions are fixed by gauge anomaly cancellations and Yukawa interactions. The scientific literature extensively covers the study of vector solutions in which SM fermions are vector-like under new $U(1)_X $ symmetry, allowing the Yukawa structure to remain invariant. On the other hand, chiral solutions in...
Tidal Disruption Event (TDE) is an astrophysical event where stars are tidally disrupted as they pass near a black hole. This event results in a flux of high-energy neutrinos. IceCube data suggests the presence of these neutrinos in TDEs. The emitting region of neutrinos and photons is likely to be located near the central black hole, where the dark matter density may be significantly higher...
