Periodic maser flares in high-mass star-forming regions provide a sensitive probe of the physical conditions in these environments. The methanol maser source G9.62+0.20E is a benchmark object, exhibiting multiple long-lived periodicities and a rich variety of flare morphologies, from highly asymmetric to nearly symmetric profiles across different velocity components. In previous work, we showed that the Maxwell-Bloch equations operating in the fast-transient superradiance regime, driven by narrow periodic pump excitations, can reproduce the asymmetric flares in this source while yielding consistent environmental parameters for the masing gas.

We recently extended that framework by demonstrating that the same Maxwell–Bloch equations can also accounts for the symmetric flares observed in maser-hosting regions such as G9.62+0.20E. Using a common set of physical conditions (e.g. temperature, collisional timescales) across components, we fit representative symmetric and assymetric flares and show that modest changes in the pump modulation and coherence history are sufficient to explain the full range of observed light-curve shapes, without invoking distinct environments for each periodicity. This consistent modelling of both symmetric and asymmetric flares in a single benchmark source strengthens the case for superradiance as a general framework for flaring in maser-hosting regions and motivates its application to other flaring systems.

The redshifted 21 cm line signal is a unique probe for the Epoch of Reionisation (EoR)—it enables tomographic studies, which track the evolution of the averaged intergalactic medium (IGM) properties and their fluctuations. Accurate modelling of the 21 cm global and power spectrum signals is crucial for interpreting measurements from current and forthcoming 21 cm experiments. Theoretical predictions usually post-process reionisation simulations with optical depth approximation, which treats local line broadening and peculiar velocities approximately and often leads to divergences due to its velocity gradient term. I will present our cosmological 21 cm line radiative transfer (C21LRT) formulation, which explicitly accounts for local 21 cm line emission and absorption, Doppler shifts by peculiar velocity, broadening of the line, and the radiation transfer effects. We will adopt the IGM properties from reionisation simulations as inputs and assess the accuracy of the optical depth approximation for predicting 21 cm global signals and power spectra. I will demonstrate how our C21LRT delivers robust results for the redshift-space distortion (RSD) effects in the 21 cm power spectrum. I will show where the optical depth approach remains valid (for length scales of 1 -10 cMpc at mid-reionisation) and highlight the need to fully quantify the uncertainties with further exploration across a wider EoR parameter space using our C21LRT code.

In this contribution, I will present a novel detection technique for low-energy antideuterons in cosmic rays, a promising signature of dark matter annihilation. Sub-GeV antideuterons represent an exceptionally clean channel for dark matter searches: their secondary production through conventional astrophysical processes (inelastic collisions of primary cosmic rays with interstellar medium) is extremely rare at low energies, making the expected background essentially negligible. Consequently, even a few detected events would constitute a significant signal potentially attributable to dark matter annihilation or decay in the Galactic halo. Current dark matter models predict antideuteron fluxes several orders of magnitude above the astrophysical background in the sub-GeV range, motivating the development of novel detection techniques optimized for this energy window.

PLASTICAMI is a segmented plastic tracker designed to identify a distinctive "double pion-star" topology characteristic of antideuteron annihilation: when an antideuteron stops in hydrogen-rich plastic, one antinucleon annihilates promptly, while the second survives with kinetic energy, travels several centimeters, and annihilates after nanoseconds. This spatial separation and timing delay between two annihilation vertices creates a unique double-vertex signature. The detector consists of 30 segmented plastic scintillator layers (3×3 m²) stacked with gaps to resolve these displaced vertices, combined with external Cherenkov veto layers based on the newly characterized FB118 wavelength-shifting plastic for efficient background rejection. Geant4 simulations demonstrate 90% efficiency for identifying antideuterons while rejecting 99% of proton background. Considering atmospheric and geomagnetic effects for Antarctic balloon flights, two missions could achieve sensitivity of ~2×10⁻⁶ (m²sr s GeV/n)⁻¹ in the 100-600 MeV/n range, enabling exploration of theoretically motivated dark matter scenarios. Construction of a prototype detector subsystem is ongoing at INFN-TIFPA, utilizing SiPM photodetectors from FBK and custom front-end electronics.

In this talk, a closed isotropic universe with scalar and spinor fields is considered within the framework of the extended phase space approach. This approach implies the derivation of the Schrödinger equation for the wave function of the universe from the path integral with the Faddeev–Popov effective action, including gauge fixing and ghost terms, instead of the Wheeler–DeWitt equation. In the path integral, we use a mixed representation: a coordinate representation for gravitational variables (the lapse function and scale factor) and the so-called holomorphic representation for scalar and spinor fields. In the first step, the scalar field is assumed to be conformal. It enables us to find exact solutions to the Schrödinger equation for special gauge conditions. We consider a set of supersymmetric multiplets of scalar and spinor fields to cancel vacuum divergences and to determine vacuum energy in a closed universe. In the next step, the scalar field is slightly non-conformal. In a time-dependent gravitational field, it gives rise to scalar particle production. In its turn, it acts as a perturbation and results in transitions between quantum states in the Early Universe. Making use of the perturbation theory technique, it is possible to compute probabilities of transitions between states with different energy values.

We investigate the generation of the matter–antimatter asymmetry in the early Universe, prior to the electroweak phase transition, by extending the Standard Model with three right-handed neutrinos that complete Dirac mass terms and two heavy scalar fields. This constitutes a minimal and well-motivated Beyond-the-Standard-Model framework, since the Standard Model alone cannot account for neutrino masses or produce the observed baryon asymmetry due to insufficient CP violation. Using the Closed Time Path (CTP) formalism, we analyze 2→2 scattering processes mediated by the heavy off-shell scalars. Since these scalars remain off-shell throughout, the post-inflationary temperature of the Universe does not need to be high enough to produce them on-shell.

In this setup, right-handed neutrinos depart from thermal equilibrium, generating a lepton asymmetry that is subsequently converted into the observed baryon asymmetry via sphaleron processes. We compute the resulting baryon-to-photon ratio and compare it with the observational value reported by the Planck mission. We also compare the predicted contribution of the right-handed neutrinos to the effective number of relativistic species N_{eff}​ with current cosmological bounds, confirming the model’s consistency with observations.

The use of the CTP formalism eliminates the need for Real Intermediate State (RIS) subtraction, leading to a more consistent and elegant treatment. Furthermore, by incorporating quantum statistical factors, we demonstrate that viable asymmetry generation is achievable even with only two right-handed neutrino flavours. Consequently, the mechanism is generic and does not rely on specific particle species such as leptoquarks or other particular Standard Model extensions.

Atom interferometry provides a unique platform for testing fundamental physics. Building on the successful realization of the gravitational Aharonov-Bohm (gAB) effect in a large-baseline atom interferometer, I propose a next-generation experiment adapting this precise setup by adding a controllable electric potential. This experiment enables a background-free search for Beyond Standard Model (BSM) physics manifesting as a phenomenological composition-dependent coupling to both a gravitational and an electric potential ($\mathcal{L}_{BSM} \propto q \varphi_g \varphi_e$). I show that the analogous Standard Model (SM) effect, a gravitationally-modified Stark shift, vanishes identically due to parity conservation; as the atomic ground state has even parity, the expectation value of this interaction is zero. To detect the target microradian-scale signal beneath milliradian-scale technical noise and gigaradian-scale inertial backgrounds, the experimental design integrates three crucial solutions: (1) a simultaneous dual-isotope ($^{85}$Rb/$^{87}$Rb) interferometer to reject technical common-mode noise, (2) optimal spin-squeezed states providing N$^{-2/3}$ sensitivity scaling to surpass the Standard Quantum Limit, and (3) a four-point differential quadrature ($\pm V_0, \pm k_{\text{eff}}$) to algebraically cancel the dominant inertial phase and all k-odd systematics. A Monte Carlo analysis validates this complete protocol's robustness against systematics and projects a realistic path to a 5-sigma discovery within a 3-month integration time. This model-independent search, particularly sensitive to neutron-coupled forces like U(1)$_{B-L}$ gauge bosons, constitutes a high-precision null test that further solidifies the Aharonov–Bohm intuition that potentials are more fundamental than fields.

This work presents a comprehensive investigation of the formation and cosmological implications of domain walls within the framework of Einstein–Gauss–Bonnet (EGB) gravity. A pivotal feature of this model is the capacity for the scalar field Lagrangian to undergo a spontaneous process of Z₂ symmetry breaking and restoration. This phase transition is a fundamental prerequisite for the formation of topological defects, specifically domain walls, which arise as solitonic solutions interpolating between the distinct vacua of the theory. We perform a detailed numerical analysis of the dynamics of a neutral scalar field non-minimally coupled to the Gauss–Bonnet invariant, exploring its behavior across different cosmological backgrounds. Our findings demonstrate that the coupling to the Gauss–Bonnet term facilitates the formation of the static domain wall in terms of proper distance in a de Sitter (inflationary) background. Furthermore, we extend our analysis to a radiation-dominated epoch, where we identify that expansion leads to the "melting" of these walls. To assess the potential observational signatures of this scenario, we calculate the predicted spectrum of stochastic gravitational waves generated by the network dynamics using the CosmoLattice package. Additionally, we study the production of primordial black holes, which could be associated with the collapse of domain wall structures. Regrettably, our calculations indicate that the direct observational detection of such domain walls from this model lies beyond the reach of foreseeable experiments.

We present a framework in which the origin of the baryon asymmetry of the universe is linked to the dynamics of an asymmetric and self-interacting dark sector, while neutrinos remain Dirac fermions. The model extends the Standard Model by introducing three right-handed neutrinos, a pair of dark fermions, and two heavy scalar doublets that mediate interactions between the visible and dark sectors. A global U(1)_B-L symmetry, consistent with a possible ultraviolet gauged completion, ensures the Dirac nature of neutrinos at the renormalisable level. The out-of-equilibrium and CP-violating decays of the heavy scalar doublets generate equal and opposite asymmetries in left-handed and right-handed neutrinos. Because the Yukawa couplings of Dirac neutrinos are tiny, the left–right equilibration occurs only after sphaleron freeze-out, allowing the asymmetry stored in left-handed neutrinos to be partially converted into baryon asymmetry. The same heavy-scalar decays that generate the lepton asymmetry also induce a dark-sector asymmetry, naturally linking the cosmic abundances of visible and dark matter. The dark sector contains a light MeV-scale gauge boson associated with a secluded U(1)_D symmetry. This mediator efficiently depletes the symmetric dark matter component and provides the self-interactions required to address small-scale structure anomalies, while interacting only feebly with the Standard Model through a highly suppressed kinetic portal. The framework offers a coherent and testable connection between Dirac leptogenesis, asymmetric dark matter, and self-interacting dark-sector dynamics.

The Standard Model (SM) of particle physics, despite its tremendous success, fails to explain two key observations: the nonzero masses of neutrinos and the existence of dark matter. These fundamental shortcomings clearly indicate the need for new physics beyond the Standard Model (BSM). Among the viable frameworks addressing these challenges, the Scotogenic mechanism proposed by Ernest Ma in 2006 provides a compelling setup in which neutrino masses are generated radiatively at one loop, while a discrete Z₂ symmetry simultaneously guarantees the stability of a dark matter candidate. This framework naturally links neutrino mass generation and dark matter within a unified setup. This idea has since been generalised to the Dirac scotogenic framework, where small Dirac neutrino masses are generated radiatively through the introduction of new fields together with the additional discrete symmetries or the global U(1)_B-L symmetry already present in the SM. The Dirac scotogenic model offers an elegant framework for generating small Dirac neutrino masses radiatively at the one-loop level. A single abelian discrete symmetry, Z_6, simultaneously preserves the Dirac nature of neutrinos and ensures the stability of the dark matter candidate, emerging as an unbroken subgroup of the 445 U(1)_B-L symmetry. In this work, we present a comprehensive study of the phenomenological consequences of this construction, focusing on electroweak vacuum stability, charged lepton flavor violation, and dark matter constraints. After incorporating current theoretical and experimental bounds, we find that the model not only remains viable but also permits novel low-mass scalar and fermionic dark matter regimes—distinct from those in the canonical Majorana scotogenic scenario. These features position the framework as a compelling bridge between neutrino physics, dark matter, and BSM cosmology.

Long-lived or stable heavy multiply-charged particles X, predicted in various Beyond-the-Standard-Model (BSM) scenarios, can significantly affect Big Bang Nucleosynthesis (BBN). The neutralization process of such states via the capture of light primordial nuclei N (e.g., p, d, t, 3He, 4He) leads to the formation of bound states XN (electrically neutral dark atoms, negatively charged dark ions or positively charged anomalous isotopes) and a shift in the ratios of the primordial abundances of ordinary light elements. The dependence of reaction rates on the charge of the heavy particle and the deviations from the standard BBN predictions are studied using a combination of analytic and numerical estimates. The cross-section of the first stage of the dark recombination may be calculated numerically in the dipole approximation. The finite size of the nucleus in the shell of the dark atom is taken into account. The rates of further reactions are strongly affected by strong nuclear forces and can be estimated by scaling the experimental data for the corresponding ordinary nuclear fusion processes. The reduced Coulomb barrier and modified reduced masses are considered. Changes in the reaction network are predicted for high charges. To avoid contradictions with the observed ratios of the primordial abundances, the fine-tuning of the model parameters (charge, mass, and baryon-to-photon ratio) may be required.