Searcharxiv⌕ Search

arXiv subjects

Giulia Ricciardi

Publications and source records attributed to Giulia Ricciardi.

At least 19 recordsLinked to original sources
arXiv2026

A High-Precision Statistical Analysis of the SN1987A Neutrino Temporal Distribution

The interpretation of the SN1987A neutrino data remains limited by significant absolute timing uncertainties across independent detectors and a long-standing tension in the angular distributions. This work presents a high-precision statistical framework that resolves these issues by formalizing the mathematical distinction between intrinsic and relative timing offsets (ITOs and RTOs). By performing a simultaneous $χ^2$-alignment of the Kamiokande-II and Baksan data with the IMB clock, we systematically incorporate non-Gaussian statistical correlations, reducing the temporal uncertainty by two orders of magnitude to the sub-second level. The $χ^2$-analysis shows that Baksan's absolute timestamps require an advancement of $30.4\,$s, while those of Kamiokande-II require a delay of about $6.4\,$s. Establishing this unified, high-precision timeline is critical to test the physical nature of the first Kamiokande-II event (K1), specifically whether its distinct angular features signal the onset of the prompt neutronization burst. Previous literature often assumes that K1 originated from inverse beta decay (IBD) on qualitative grounds. By contrast, our multidimensional likelihood analysis incorporates energy, direction, and MSW flavor-conversion effects to provide the first quantitative constraint on its origin. We find a likelihood ratio of 3-6 in favor of an accretion-phase $\barν_e$ origin over a neutronization-burst origin, thereby turning a traditional assumption into a statistically bounded physical inference. This framework provides the most stringent constraints to date on the chronology of SN1987A and establishes a precise methodology for future multimessenger observations of Galactic supernovae.

hep-ph↗
arXiv2026

Compact CO emission and no evidence of radial drift. ALMA observations of the faintest planet-forming disks in Lupus

A large fraction of planet-forming disks observed with ALMA show faint CO emission, often interpreted as strong CO depletion. However, faint emission may also arise from spatially unresolved disks, whose sizes are overestimated, making them appear intrinsically faint. The limited sensitivity of previous observations has prevented testing this scenario, hindering our understanding of disk evolution and planet formation. We present new ALMA Band 7 observations of 12CO (J=3-2) and 13CO (J=3-2) in 17 of the faintest disks in Lupus, aiming to assess whether compact disk structure can explain their weak CO emission. The data reach an angular resolution of 0.25arcsec (about 20 au at 160 pc) and are an order of magnitude deeper than archival observations. We apply line stacking to enhance sensitivity and compare the derived CO luminosities with physical-chemical models of compact and extended disks, also estimating gas and dust sizes. We detect both isotopologues in 10 disks, only 12CO in 4, and neither in 3. Several disks are consistent with being intrinsically compact and optically thick in both lines, providing an alternative to the CO depletion scenario. The inferred gas radii (Rco less than 40 au) support this interpretation and suggest that a significant fraction of disks may be born compact, in line with recent Class 0/I results. Gas-to-dust size ratios show no clear evidence for dust evolution, indicating these disks are not drift-dominated.

astro-ph.EP↗
arXiv2025

Rescuing 331 bileptons from the Landau pole

Among the particles being searched for at the LHC beyond the Standard Model are bileptons, which are doubly charged gauge bosons. Bileptons are predicted by several Standard Model extensions, including the so-called 331 models with $β= \sqrt 3$. The minimal formulation of these models is generally plagued by a "low energy" Landau pole, which can undermine current predictions for TeV-scale bileptons. We analyze this issue and investigate the possibility to shift the Landau pole at higher energy scales by extending the troublesome minimal 331 models.

hep-ph↗
arXiv2025

Survey of Orion Disks with ALMA (SODA) III: Disks in wide binary systems in L1641 and L1647

Aims. The goal of this work is to comprehensively characterize the impact of stellar multiplicity on Class II disks in the L1641 and L1647 regions of Orion A (~1-3 Myr), part of the Survey of Orion Disks with ALMA (SODA). We characterize the protostellar multiplicity using the Atacama Large Millimeter/submillimeter Array (ALMA), the ESO-VISTA, and Hubble Space telescopes. The resulting sample of 65 multiple systems represents the largest catalogue of wide binary systems to date (projected separation >1000 AU), allowing a more robust statistical characterization of the evolution and properties of protoplanetary disks. Methods. The disk population was observed in continuum with ALMA at 225 GHz, with a median rms of 1.5 Mearth. Combining these data (resolution ~1.1arcsec ) with the ESO-VISTA near-infrared survey of the Orion A cloud (resolution ~0.7arcsec ), multiple systems are assembled and selected by an iterative inside-out search in projected separation (>1000 AU). Results. We identify 61 binary systems, 3 triple systems, and one quadruple system. The separation range is between 1000 and 10^4 AU. The dust mass distributions inferred with the Kaplan-Meier estimator yield a median mass of 3.23+0.6-0.4 Mearth for primary disks and 3.88+0.3-0.3 Mearth for secondary disks.

astro-ph.EP↗
arXiv2025

Improved precision in inverse beta decay cross section

We analyze the cross section for inverse beta decay, focusing on the moderate energies (a few MeV to hundreds of MeV) relevant for reactor and supernova neutrinos. We discuss the updated evaluations of values and uncertainties in the cross section, and the effect of second-class currents. The estimate of theoretical precision is important for current and future experiments, when large data samples are or become available.

hep-ph↗
arXiv2025

The flux of electron antineutrinos from supernova SN1987A data

By adopting a state-of-the-art parameterized model of electron antineutrino emission, we have made some steps forward in the analysis of the thermodynamical properties and temporal structure of neutrino emission from core collapse SN1987A. Our analysis, unlike similar previous ones, takes into account the times, energies and angles of arrival of the detected events in a reliable framework which includes a finite ramp in the initial stage of the neutrino emission. The existence of the accretion phase is confirmed with a confidence level of about 99%, and the neutrons involved in the emission during accretion, for the first time, do not show significant tensions with expectations, being about 0.02 $M_\odot$. We determine the parameters of the cooling emission and discuss its duration, that compares well with theoretical expectations. We estimate the delay times between the first neutrino and the first event in the detectors. The goodness of fit checks, performed on the temporal, energy and angular distributions, show that the flux resulting from the best-fit analysis is compatible with the observed data.

hep-ph↗
arXiv2025

Are there critical aspects in the time, energy and angular distributions of SN1987A?

Supernova neutrinos are of considerable importance for ongoing research in astrophysics, nuclear and particle physics. Existing simulations of this complex event are increasingly sophisticated, but the accuracy with which they describe the emission is unknown. The only event observed so far with neutrino telescopes, SN1987A, still plays a crucial role and deserves to be studied meticulously. With this in mind, we have undertaken a refined analysis of the observations, taking into account the knowledge gained over the past decades. In this work, we consider a new parameterised model of electron antineutrino emission and test its adequacy in describing the observed distributions of energy, time and angle. The values of the model parameters derived from the data and their uncertainty intervals are presented and their significance is discussed.

hep-ph↗
arXiv2024

The cross section of inverse beta decay

We discuss the accuracy of the evaluation of the cross section for inverse beta decay at low energies and its relevance in the current experimental framework.

hep-ph↗
arXiv2024

331 Models and Bilepton Searches at LHC

Despite being remarkable predictive, the Standard Model leaves unanswered several important issues, which motivate an ongoing search for its extensions. One fashionable possibility are the so-called 331 models, where the electroweak gauge group is extended to $SU_L(3)\times U(1)$. We focus on a minimal extension which includes vector-like quarks (VLQs) and new gauge bosons, performing a consistent analysis of the production at LHC of a pair of doubly-charged bileptons. We include for the first time all the relevant processes where VLQs contribute, and in particular the associate production VLQ-bilepton. Finally, we extract the bound on the bilepton mass, $m_Y>$ 1300 GeV, from a reinterpretation of a recent ATLAS search for doubly-charged Higgs bosons in multi-lepton final states.

hep-ph↗
arXiv2023

A discussion of the cross section $\barν_e+p\to e^+ + n$

We discuss the interaction cross section $\barν_e-p$ due to charged currents, of major importance for neutrino detection. We present the history of its understanding and highlight the aspects necessary for its precise evaluation. We examine the three most recent determinations and, on the basis of the most recent one, tabulate its updated values and assess its uncertainty.

hep-ph↗
arXiv2022

Anomalies in the heavy sector

Heavy flavour physics is well described by the Standard Model with the exception of some measurements which could be pointing to new physics. We briefly review status and prospects of $R(D^{(\ast)})$ and $R(K^{(\ast)})$ anomalies and also address the long standing tension in the $|V_{cb}|$ and $|V_{ub}|$ exclusive/inclusive determinations.

hep-ph↗
arXiv2022

Interpreting B-anomalies within an extended 331 gauge theory

In light of the recent $R_{K^{(*)}}$ data on neutral current flavour anomalies in $B \to K^{(*)} \ell^+ \ell^-$ decays, we re-examine their quantitative interpretation in terms of an extended 331 gauge theory framework. We achieve this by adding two extra lepton species with novel 331 charges, while ensuring that the model remains anomaly free. In contrast to the canonical 331 models, the gauge charges of the first and second lepton families differ from each other, allowing lepton flavour universality violation. We further expand the model by adding the neutral fermions required to provide an adequate description for small neutrino masses.

hep-ph↗
arXiv2022

An accurate evaluation of electron (anti-)neutrino scattering on nucleons

We discuss as accurately as possible the cross section of quasi-elastic scattering of electron (anti-)neutrinos on nucleons, also known as inverse beta decay in the case of antineutrinos. We focus on the moderate energy range from a few MeV up to hundreds of MeV, which includes neutrinos from reactors and supernovae. We assess the uncertainty on the cross section, which is relevant to experimental advances and increasingly large statistical samples. We estimate the effects of second-class currents, showing that they are small and negligible for current applications.

hep-ph↗
arXiv2020

Determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$

In this review we present and discuss the determination of the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameter $V_{cb}$. The CKM matrix parametrizes the weak charged current interactions of quarks in the Standard Model (SM), and a precise determination of its elements has always been one of the most important targets of particle physics. The precise knowledge of the $|V_{cb}|$ value plays a pivotal role in testing the flavour sector of the SM and in the analyses of the unitarity of the CKM matrix. The SM does not predict the values of the CKM matrix elements, which have to be extracted by experimental data. Given the variety of channels that allow the extraction of $|V_{cb}|$, different theoretical and experimental techniques are mustered for the $|V_{cb}|$ determination. The exertion toward precision represents not only a significant test of our theoretical procedures but a stimulus towards better detection performances. The most precise measurements of $|V_{cb}|$ come from semileptonic decays, that being tree level at the lowest order in the SM are generally considered unaffected by physics beyond the SM. After summarizing the characteristics of the SM that set the frame for the determination of $|V_{cb}|$, we discuss inclusive and exclusive semileptonic $B$ decays. We analyze the $|V_{cb}|$ extraction methods and recent results, detailing both the theoretical and experimental techniques, and, finally, outline future prospects. We also comment on exclusive decays into heavy leptons, on the observables $R(D)$ and $R(D^\ast)$, on decays to excited $D$ meson states and on baryon decays.

hep-ph↗
arXiv2019

Research and Development for Near Detector Systems Towards Long Term Evolution of Ultra-precise Long-baseline Neutrino Experiments

With the discovery of non-zero value of $θ_{13}$ mixing angle, the next generation of long-baseline neutrino (LBN) experiments offers the possibility of obtaining statistically significant samples of muon and electron neutrinos and anti-neutrinos with large oscillation effects. In this document we intend to highlight the importance of Near Detector facilities in LBN experiments to both constrain the systematic uncertainties affecting oscillation analyses but also to perform, thanks to their close location, measurements of broad benefit for LBN physics goals. A strong European contribution to these efforts is possible.

physics.ins-det↗
arXiv2019

Non-minimal $331$ model for Lepton Flavour Universality Violation in $b\to s\ell\ell$ decays

331 models constitute an extension of the Standard Model (SM) obtained by enlarging the SM gauge group $SU(3)_\text{C}\times SU(2)_\text{L}\times U(1)_Y$ to the group $SU(3)_\text{C}\times SU(3)_\text{L}\times U(1)_X$. We investigate how a non-minimal 331 model may embed lepton flavour universality violating contributions to $b\to s\ell\ell$ processes without introducing lepton flavour violation, as suggested by the recent LHCb measurements of the ratios $R_K$ and $R_{K^*}$. We discuss the model-independent scenarios of New Physics in $b\to s\ell\ell$ currently favoured by the data that could be accommodated by this model and consider a few phenomenological constraints on this model.

hep-ph↗