arXiv subjects

Alessandro Barone

Publications and source records attributed to Alessandro Barone.

17 recordsLinked to original sources

arXiv2026

The strange and flavor-singlet axial form factors of the nucleon from lattice QCD

The singlet axial form factor of the nucleon provides essential input for a complete understanding of the nucleon axial structure. Together with the isovector and isoscalar octet channels, in the forward limit it forms the basis for a full flavor decomposition of the proton spin. In this work we present a lattice QCD determination of the singlet axial form factor $G^{u+d+s}_A(Q^2)$ and related strange contribution $G^{s}_A(Q^2)$ using a set of $N_f = 2 + 1$ CLS gauge ensembles with $O(a)$-improved Wilson fermions, with a full error budget for the extrapolation to the chiral, continuum and infinite-volume limits. Particular focus is placed on the treatment of the disconnected contributions, which constitute the crucial element for the extraction of the strange component. Together with determinations of the isovector and isoscalar octet axial form factors, this work provides a comprehensive lattice QCD determination of the nucleon axial structure across different flavor channels.

hep-lat↗

arXiv2026

Study on the systematic effects on $b \to c$ inclusive semileptonic decays

We discuss the calculation of the inclusive semileptonic decay for the process $B_s \to X_c \, l \nu_l$ using lattice QCD. This calculation could be decisive in understanding the long-standing tension between inclusive and exclusive determinations of the CKM matrix element, $|V_{cb}|$. In this talk, we investigate the main sources of systematic uncertainty in these decays, including the impact of Jacobi smearing at the source and sink, variations in source-sink separation, and the intrinsic uncertainties of the inclusive reconstruction method itself. In addition, we explain how we can restrict the reconstruction of the inclusive decay rate to just the excited-state contributions. This is achieved by treating the ground-state contributions as an exclusive decay with well-controlled conventional techniques. Systematic effects from the reconstruction then only affect excited-state contributions. Where these are sub-dominant, a suppression of systematic effects is expected. We show results based on Chebyshev reconstruction, which are part of a larger effort towards a first phenomenologically relevant computation of the inclusive decay rate in the continuum and infinite-volume limits.

hep-lat↗

arXiv2026

Inclusive semileptonic $D_s\to X_s\ell\bar\nu$ decays from lattice QCD: continuum and chiral extrapolation

We present results for the inclusive semileptonic $D_s \to X_s \ell\bar\nu$ decay rate from lattice QCD. Chiral and continuum extrapolations are performed using gauge ensembles generated with 2+1 flavours of M\"obius domain-wall fermions. Systematic errors are fully addressed including those from the integral over all possible final states. Our results are in agreement with currently available experimental data, with an error at the few-percent level.

hep-lat↗

arXiv2026

Symmetry-driven layered dynamics in the Kuramoto-Sivashinsky equation

In this work, we uncover a layered organization of the state space in the Kuramoto-Sivashinsky equation with periodic boundary conditions, in which multiple invariant sets coexist at fixed system parameters and are selected by the initial condition. Within this framework, both chaotic attractors and periodic orbits (traveling waves) can be systematically generated by amplifying a single initial condition and parameterized by the initial energy. As the energy increases, the period of the periodic orbits decreases according to an inverse scaling law. In transitional parameter regions, periodic dynamics at low initial energy is found to coexist with strange attractors at higher energy levels, revealing a unique layered landscape governed by the viscosity and the initial condition. We conjecture that this behavior is linked to continuous spatial translational symmetry, which is reflected in the degeneracy of the neutral part of the Lyapunov spectrum.

nlin.CD↗

arXiv2026

Inclusive and exclusive semileptonic decays of heavy mesons on the lattice

We report the recent progress from our group in extracting observables of both inclusive and exclusive semileptonic heavy-meson decays directly from lattice QCD four-point correlators. On the inclusive side, we illustrate how to estimate the systematic uncertainties from omitted higher-order terms and non-zero smearing of the kernel approximation, building on two important features of the Chebyshev expansion. On the exclusive side, we perform BCL parameterizations of the pseudoscalar to pseudoscalar form factors and compare the fitted coefficients with those from earlier results by HPQCD. We also perform a HQET-based parameterization of the P-wave form factors to shed new light on the 1/2-vs-3/2 puzzle. This work constitutes a step toward a unified lattice treatment of inclusive and exclusive semileptonic decays, relevant for the Vcb puzzle. In this study, we use lattice ensembles from the RBC/UKQCD collaboration for numerical investigations. Future developments from our group will focus on the control of other systematic effects for inclusive decays and investigations of other techniques with reduced statistical errors to extract exclusive contributions from lattice four-point correlators.

hep-lat↗

arXiv2025

Structural Origins and Real-Time Drivers of Intermittency

In general terms, intermittency is the property for which time evolving systems alternate among two or more different regimes. Predicting the instance when the regime switch will occur is extremely challenging, often practically impossible. Intermittent processes include turbulence, convection, precipitation patterns, as well as several in plasma physics, medicine, neuroscience, and economics. Traditionally, focus has been on global statistical indicators, e.g. the average frequency of regime changes under fixed conditions, or how these vary as a function of the system's parameters. We add a local perspective: we study the causes and drivers of the regime changes in real time, with the ultimate goal of predicting them. Using five different systems, of various complexities, we identify indicators and precursors of regime transitions that are common across the different intermittency mechanisms and dynamical models. For all the systems and intermittency types under study, we find a correlation between the alignment of some Lyapunov vectors and the concomitant, or aftermath, regime change. We discovered peculiar behaviors in the Lorenz 96 and in the Kuramoto-Shivanshinki models. In Lorenz 96 we identified crisis-induced intermittency with laminar intermissions, while in the Kuramoto-Shivanshinki we detected a spatially global intermittency which follows the scaling of type-I intermittency. The identification of general mechanisms driving intermittent behaviors, and in particular the unearthing of indicators spotting the regime change, pave the way to designing prediction tools in more realistic scenarios. These include turbulent geophysical fluids, rainfall patterns, or atmospheric deep convection.

nlin.CD↗

arXiv2025

Inclusive semileptonic decays from lattice QCD: analysis of systematic effects

Lattice QCD calculations of inclusive semileptonic decay rates involve new types of systematic effects, such as truncation errors in the estimation of energy integrals, or finite-volume effects for multi-body final states. We investigate them for the lattice data of $D_s \to X_s \ell\nu$ decays, obtained using M\"obius domain-wall fermions. Separating the ground-state and excited-state contributions results in better control over these systematic effects. With the Chebyshev polynomial approximation, the truncation error is under control, while the finite-volume effects are estimated using a model to describe two-body final states.

hep-lat↗

arXiv2025

The isoscalar octet axial form factor of the nucleon from lattice QCD

The isoscalar axial-vector form factor of the nucleon plays a key role in understanding the electroweak interaction of nucleons. For the interpretation of the spin structure of the nucleon the non-singlet isoscalar axial charge is indispensable. Moreover, $G_A^{u+d-2s}(Q^2)$ together with the isovector and singlet isoscalar form factors are needed for the flavor-decomposition of the axial-vector form factor. Detailed knowledge of the flavor decomposition facilitates extractions of Standard Model (SM) parameters from low energy experiments such as the electroweak charge of the proton in the P2 experiment. Here we present a lattice determination of $G_A^{u+d-2s}(Q^2)$ on $N_f=2+1$ $\mathcal{O}(a)$ improved Wilson fermions, with a full error budget concerning extrapolations and interpolations to the continuum and infinite volume and physical quark masses.

hep-lat↗

arXiv2025

The isoscalar non-singlet axial form factor of the nucleon from lattice QCD

We present our progress on the computation of the axial form factor of the nucleon with flavour structure $u+d-2s$ from lattice QCD. We employ a set of $N_f=2+1$ CLS ensembles with $O(a)$-improved Wilson fermions and the L\"uscher-Weisz gauge action, with lattice spacings ranging from $0.05\,\text{fm}$ to $0.086\,\text{fm}$ and pion masses spanning between $130\,\text{MeV}$ and $350\,\text{MeV}$. We employ multiple source-sink separations and use the summation method to suppress the contamination from excited states. We use a $z$-expansion on each ensemble to parametrize the $Q^2$-dependence of the form factor and simultaneously fit the available source-sink separations for all $Q^2\leq 0.7 \,{\rm GeV}^2$. We outline our analysis of the stability of the fits varying the ans\"atze and different estimations of the covariance matrix and report on our strategy for a comprehensive determination of the physical form factor.

hep-lat↗

arXiv2024

Systematic effects in the lattice calculation of inclusive semileptonic decays

We report on the calculation of the inclusive semileptonic decay of the $D_s$ meson on the lattice. We simulate the $D_s \rightarrow X_s\ell\nu_\ell$ process with M\"obius domain-wall charm and strange quarks, whose masses are approximately tuned to their physical values. Our simulations cover the whole kinematical region. The focus of this work is to present updates on our strategies towards estimating the systematic uncertainties in the determination of the inclusive decay rate. We specifically focus on the systematic errors due to the choice of our approximation strategy and finite-volume effects.

hep-lat↗

arXiv2024

Updates on inclusive charmed and bottomed meson decays from the lattice

With the development of lattice QCD in recent years, a determination of decay rates for inclusive semileptonic decays from lattice correlators now seems viable. We report on the calculation of the inclusive semileptonic decay of the $D_s$ meson on the lattice. We simulate the $D_s \rightarrow X_s\ell\nu_\ell$ process with M\"obius domain-wall charm and strange quarks, whose masses were approximately tuned to the physical values. We cover the whole kinematical region. We present a general overview on how the inclusive decays are treated on the lattice and discuss ongoing challenges, such as the estimation of systematic errors and future prospects of the project.

hep-lat↗

arXiv2023

Chebyshev and Backus-Gilbert reconstruction for inclusive semileptonic $B_{(s)}$-meson decays from Lattice QCD

We present a study on the nonperturbative calculation of observables for inclusive semileptonic decays of $B_{(s)}$ mesons using lattice QCD. We focus on the comparison of two different methods to analyse the lattice data of Euclidean correlation functions, specifically Chebyshev and Backus-Gilbert approaches. This type of computation may eventually provide new insight into the long-standing tension between the inclusive and exclusive determinations of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements $|V_{cb}|$ and $|V_{ub}|$. We report the results from a pilot lattice computation for the decay $B_s \rightarrow X_c \, l\nu_l$, where the valence quark masses are approximately tuned to their physical values using the relativistic-heavy quark action for the $b$ quark and the domain-wall formalism for the other valence quarks. We address the computation of the total decay rate as well as leptonic and hadronic moments, discussing similarities and differences between the two analysis techniques.

hep-lat↗

arXiv2023

Studies on finite-volume effects in the inclusive semileptonic decays of charmed mesons

We report on the calculation of the inclusive semileptonic decay of the $D_s$ meson on the lattice. We simulate the $D_s \rightarrow X_s\ell\nu_\ell$ process with M\"obius domain-wall charm and strange quarks, whose masses were approximately tuned to the physical values. We cover the whole kinematical region. The focus of this work is on the systematic error due to finite-volume effects. We construct a model of two-body final states to describe the data on a finite volume lattice of $L \simeq 0.055 \, \text{fm}$ to investigate the extrapolation to the infinite-volume limit.

hep-lat↗

arXiv2023

Approaches to inclusive semileptonic $B_{(s)}$-meson decays from Lattice QCD

We address the nonperturbative calculation of the inclusive decay rate of semileptonic $B_{(s)}$-meson decays from lattice QCD. Precise Standard-Model predictions are key ingredients in searches for new physics, and this type of computation may eventually provide new insight into the long-standing tension between the inclusive and exclusive determinations of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements $|V_{cb}|$ and $|V_{ub}|$. We present results from a pilot lattice computation for $B_s \rightarrow X_c\, l \nu_l$, where the initial $b$ quark described by the relativistic-heavy-quark (RHQ) formalism on the lattice and the other valence quarks discretised with domain-wall fermions are simulated approximately at their physical quark masses. We compare two different methods for computing the decay rate from lattice data of Euclidean $n$-point functions, namely Chebyshev and Backus-Gilbert approaches. We further study how much the ground-state meson dominates the inclusive decay rate and indicate our strategy towards a computation with a more comprehensive systematic error budget.

hep-lat↗

arXiv2022

Inclusive semi-leptonic decays of charmed mesons with M\"obius domain wall fermions

We perform a non-perturbative lattice calculation of the decay rates for inclusive semi-leptonic decays of charmed mesons. In view of the long-standing tension in the determination of the CKM matrix elements $|V_{ub}|$ and $|V_{cb}|$ from exclusive and inclusive processes, recently, the use of lattice QCD has been extended towards the description of inclusive decays. Since the determination of hadronic input parameters from QCD based methods require independent tests, we focus on the charm sector, since it not only offers experimental data, but also well determined CKM parameters. We carry out a pilot lattice simulation for the $D_s \rightarrow X_s \ell\nu$ and explore the improvement of existing techniques. Our simulation employs M\"obius domain-wall charm and strange quarks whose masses are tuned to be approximately physical and we cover the whole kinematical region. We report on our progress in analyzing different sources of systematic effects, such as the extrapolation of the kernel function chosen for the Chebsyhev approximation as well as the influence on the analysis in the region close to the kinematical limit.

hep-lat↗

arXiv2022

Inclusive semi-leptonic $B_{(s)}$ mesons decay at the physical $b$ quark mass

We address the non-perturbative calculation of the decay rate of inclusive semi-leptonic $B_{(s)}$ mesons decays from lattice QCD. Precise theoretical Standard Model predictions are key ingredients in searches for new physics. This type of computation may eventually provide new insight into the long-standing tension between the inclusive and exclusive determinations of the CKM matrix elements $|V_{cb}|$ and $|V_{ub}|$. We perform a pilot lattice computation for $B_s \rightarrow X_c \, l \nu_l$ and improve on existing techniques. The valence-quark masses in our simulations are approximately physical for the domain-wall strange and charm quarks as well as for the bottom quark, for which we use a relativistic heavy quark effective action. We report on our progress and discuss future plans towards a first study with fully controlled systematic effects.

hep-lat↗

arXiv2021

A variance reduction technique for hadronic correlators with partially twisted boundary conditions

Partially twisted boundary conditions are widely used for improving the momentum resolution in lattice computations of hadronic correlation functions. The method is however expensive since every additional twist requires computing additional propagators. We propose a novel variance reduction technique that exploits statistical correlations to reduce the overall cost for computing correlators with additional twist angles. We explain and demonstrate the method for meson 2pt and 3pt functions.

hep-lat↗