arXiv subjects

Francesco Giuli

Publications and source records attributed to Francesco Giuli.

At least 19 recordsLinked to original sources

arXiv2026

QCD studies and precision physics at the LHeC

The Large Hadron electron Collider (LHeC) would add a high-current Energy Recovery Linac to the HL-LHC, delivering electron-proton collisions at centre-of-mass energies around the TeV scale. This contribution summarises the QCD and parton-distribution-function (PDF) aspects of the recent LHeC bridge-project study. The combination of high luminosity, a very large lever arm in Bjorken $x$ and $Q^2$, and clean neutral- and charged-current deep-inelastic scattering measurements would enable a coherent determination of all proton PDFs in a single experiment. The resulting constraints would substantially reduce uncertainties in the gluon, valence, strange and heavy-flavour distributions, provide stringent tests of perturbative and small-$x$ QCD, and improve the parton luminosities that enter precision and discovery measurements at the HL-LHC and at future hadron colliders. The same programme gives competitive and complementary determinations of the strong coupling and weak mixing angle, including measurements of its running over a wide range of scales.

hep-ex↗

arXiv2026

High-$p_{\rm T}$ physics and jet production

Jet production is the dominant high-$p_{\rm T}$ process at hadron colliders and provides a central testing ground for perturbative QCD, parton distribution functions and determinations of the strong coupling. This contribution summarises recent measurements of inclusive-jet, dijet and jet-multiplicity observables presented at DIS2026, with emphasis on the interplay between experimental precision, next-to-next-to-leading-order predictions, non-perturbative and electroweak corrections, and the treatment of correlated systematic uncertainties. Inclusive jet measurements from CMS and ATLAS constrain the gluon distribution at large Bjorken $x$ and enable extractions of $\alpha_s(m_Z)$ compatible with the world average. Dijet measurements provide complementary sensitivity through the dijet invariant mass, rapidity separation and longitudinal boost, while ratios of inclusive jet multiplicities reduce several experimental and PDF uncertainties and directly probe additional QCD radiation. Recent progress in jet-energy calibration, together with new results from RHIC, ALICE and CMS on jet substructure and heavy-quark radiation, illustrates the breadth of current high-$p_{\rm T}$ jet physics and its relevance for Run~3 and future global PDF analyses.

hep-ex↗

arXiv2025

Precision and rare ElectroWeak processes

This proceeding summarizes recent measurements of electroweak boson and diboson production. The results, based on data from LHC Run 2 at $\sqrt{s}=13\,\mathrm{TeV}$ and Run 3 at $\sqrt{s}=13.6\,\mathrm{TeV}$, probe the Standard Model with unprecedented precision. These include inclusive and differential cross-section measurements of $W$, $Z$, $WZ$, $WW$, and $ZZ$ final states, constraints on Parton Distribution Functions, and interpretations within Effective Field Theories. A consistent picture with theory predictions emerges, laying the groundwork for future precision studies.

hep-ex↗

arXiv2025

Flavoured jet algorithms: a comparative study

The accurate identification of heavy-flavour jets, those which originate from bottom or charm quarks, is crucial for precision studies of the Standard Model and searches for new physics. However, assigning flavour to jets presents significant challenges, primarily due to issues with infrared and collinear (IRC) safety. This paper aims to address these challenges by evaluating recently-proposed jet algorithms designed to be IRC-safe and applicable in high-precision measurements. We compare these algorithms across benchmark heavy-flavour production processes and kinematic regimes that are relevant for LHC phenomenology. Exploiting both fixed-order calculations in QCD as well as parton shower simulations, we analyse the infrared sensitivity of these new algorithms at different stages of the event evolution and compare to flavour-labelling strategies currently adopted by LHC collaborations. The results highlight that, while all algorithms lead to more robust flavour-assignments compared to current techniques, they vary in performance depending on the observable and energy regime. The study lays groundwork for robust, flavour-aware jet analyses in current and future collider experiments to maximise the physics potential of experimental data by reducing discrepancies between theoretical and experimental methods.

hep-ph↗

arXiv2025

Early Career Researcher Input to the European Strategy for Particle Physics Update: White Paper

This document, written by early career researchers (ECRs) in particle physics, aims to represent the perspectives of the European ECR community and serves as input for the 2025--2026 update of the European Strategy for Particle Physics. With input from a community-wide survey, it highlights key challenges faced by ECRs -- career stability, funding access and long-term research opportunities -- while proposing policy recommendations and targeted initiatives. It underscores the importance of practices fostering diverse, equitable, inclusive and healthy workplaces, as well as of stronger ECR communities, and highlights how effective communication and interdisciplinary collaborations reinforce the societal relevance of particle physics and promote continued support for large-scale and long-term projects. Finally, the future of both collider and beyond-collider experiments is addressed, emphasising the critical role of ECRs in shaping future projects. The ECR contribution is formed of two parts: the ten-page executive summary submitted as input to the European Strategy for Particle Physics Update and, as backup document, this extended white paper providing additional context.

hep-ex↗

arXiv2023

Analysis of HERA data with a PDF parametrization inspired by quantum statistical mechanics

We present a determination of the parton distribution functions (PDFs) of the proton from HERA data using a PDF parametrization inspired by a quantum statistical model of the proton dynamics. This parametrization is characterised by a very small number of parameters, yet it leads to a reasonably good description of the data, comparable with other parametrizations on the market. It may thus provide an alternative to standard parametrizations, useful for studying parametrization bias and to possibly simplify the fit procedure thanks to the small number of parameters. Interestingly, the model reproduces key physical features, such as a $\bar d$ distribution larger than $\bar u$, that HERA data alone are not able to constrain when using more flexible parametrizations. Moreover, polarized distributions are described in the model by the same parameters of the unpolarized ones, giving us the possibility of extracting both types of distributions within the same fit.

hep-ph↗

arXiv2023

Exploring SMEFT Couplings Using the Forward-Backward Asymmetry in Neutral Current Drell-Yan Production at the LHC

Neutral current Drell-Yan (DY) lepton-pair production is considered in the framework of the Standard Model Effective Field Theory (SMEFT). Using the open-source fit platform xFitter, we investigate the impact of high-statistics measurements of the neutral current DY (NCDY) forward-backward asymmetry $A_{\rm{FB}}$ near the weak boson mass scale in the present and forthcoming stages of the Large Hadron Collider (LHC). Besides recovering earlier results on the $A_{\rm{FB}}$ sensitivity to parton distribution functions, we analyze the precision determination of $Z$-boson couplings to left-handed and right-handed $u$-quarks and $d$-quarks, and explore Beyond-Standard-Model contributions using the SMEFT framework. We perform a sensitivity study and comment on the role of the $A_{\rm{FB}}$ asymmetry for the electroweak SMEFT fit and precision $Z$-boson physics at the LHC and high-luminosity HL-LHC.

hep-ph↗

arXiv2023

High-$x$ quark density and their impact on $Z'$-boson dilepton searches

In this proceeding, we study the influence of theoretical systematic uncertainties due to the quark density on LHC experimental searches for $Z'$-bosons. Using an approach originally proposed in the context of the ABMP16 PDF set for the high-$x$ behaviour of the quark density, we presents results on differential cross section and Forward-Backward asymmetry observables commonly used to study $Z'$ signals in dilepton channels.

hep-ph↗

arXiv2023

Impact of Inclusive Electron Ion Collider Data on Collinear Parton Distributions

A study is presented of the impact of simulated inclusive Electron Ion Collider Deep Inelastic Scattering data on the determination of the proton and nuclear parton distribution functions (PDFs) at next-to-next-to-leading and next-to-leading order in QCD, respectively. The influence on the proton PDFs is evaluated relative to the HERAPDF2.0 set, which uses inclusive HERA data only, and also relative to the global fitting approach of the MSHT20 PDFs. The impact on nuclear PDFs is assessed relative to the EPPS21 global fit and is presented in terms of nuclear modification ratios. For all cases studied, significant improvements in the PDF uncertainties are observed for several parton species. The most striking impact occurs for the nuclear PDFs in general and for the region of high Bjorken $x$ in the proton PDFs, particularly for the valence quark distributions.

hep-ph↗

arXiv2023

Measurements of $W$ boson production in association with heavy flavour at ATLAS

The production of $W/Z$ bosons in association with heavy flavour jets or hadrons at the LHC is sensitive to the flavour content of the proton and provides an important test of perturbative QCD. The production of a $W$ boson in association with $D^{+}$ and $D^{*+}$ mesons will be discussed. This precision measurement provides information about the strange content of the proton. Measurements are compared to the state-of-the art next-to-next-to-leading order theoretical calculations.

hep-ex↗

arXiv2023

Quantifying the interplay of experimental constraints in analyses of parton distributions

Parton distribution functions (PDFs) play a central role in calculations for the Large Hadron Collider (LHC). To gain a deeper understanding of the emergence and interplay of constraints on the PDFs in the global QCD analyses, it is important to examine the relative significance and mutual compatibility of the experimental data sets included in the PDF fits. Toward this goal, we discuss the L2 sensitivity, a convenient statistical indicator for exploring the statistical pulls of individual data sets on the best-fit PDFs and identifying tensions between competing data sets. Unlike the Lagrange Multiplier method, the L2 sensitivity can be quickly computed for a range of PDFs and momentum fractions using the published Hessian error sets. We employ the L2 sensitivity as a common metric to study the relative importance of data sets in the recent ATLAS, CTEQ-TEA, MSHT, and reduced PDF4LHC21 PDF analyses at NNLO and approximate N3LO. We illustrate how this method can aid the users of PDFs to identify data sets that are important for a PDF at a given kinematic point, to study quark flavor composition and other detailed features of the PDFs, and to compare the data pulls on the PDFs for various perturbative orders and functional forms. We also address the feasibility of computing the sensitivities using Monte Carlo error PDFs. Together with the article, we present a companion interactive website with a large collection of plotted L2 sensitivities for eight recent PDF releases.

hep-ph↗

arXiv2023

PDFs determination from the LHeC

Deep Inelastic Scattering would be brought into the unexplored TeV regime by the the proposed Large Hadron Electron Collider at CERN. Its rich physics program, includes both precision Standard Model measurements to complement LHC physics as well as studies of QCD in the high energy limit. The present proceeding reports on studies included in the updated LHeC Conceptual Design Report. We study the impact of LHeC simulated data on Parton Distribution Functions uncertainties. We also assess the LHeC potential to allow the determination of the strong coupling constant $α_{S}$, at per-mille level as well as to disentangle between various scenarios of small-$x$ QCD.

hep-ph↗

arXiv2022

High-precision QCD physics at FCC-ee

The Future Circular Collider (FCC) is a post-LHC project aiming at direct and indirect searches for physics beyond the SM in a new 100 km tunnel at CERN. In addition, the FCC-ee offers unique possibilities for high-precision studies of the strong interaction in the clean environment provided by $e^{+}e^{-}$ collisions, thanks to its broad span of center-of-mass energies ranging from the Z pole to the top-pair threshold, and its huge integrated luminosities yielding $10^{12}$ and $10^8$ jets from Z and W bosons decays, respectively, as well as $10^5$ pure gluon jets from Higgs boson decays. In this contribution, we will summarize studies on the impact the FCC-ee will have on our knowledge of the strong force including: (i) QCD coupling extractions with per-mille uncertainties, (ii) parton radiation and parton-to-hadron fragmentation functions, (iii) jet properties (ligh-quark-gluon discrimination, $e^{+}e^{-}$ event shapes and multijet rates, jet substructure, etc.), (iv) heavy-quark jets (dead cone effect, charm-bottom separation, gluon $\rightarrow c\bar{c}$, $b\bar{b}$ splitting, etc.); and (v) non-perturbative QCD phenomena (color reconnection, baryon and strangeness production, Bose-Einstein and Fermi-Dirac final-state correlations, etc.).

hep-ex↗

arXiv2022

The ATLASpdf21 fit: a novel determination of proton Parton Distribution Functions using ATLAS data

We present fits to determine Parton Distribution Functions using a diverse set of measurements from the ATLAS experiment at the LHC, including inclusive $W$ and $Z$ boson production, $t\bar{t}$ production, $W$+jets and $Z$+jets production, inclusive jet production and direct photon production. These ATLAS measurements are used in combination with deep-inelastic scattering data from the electron-proton collider HERA. Particular attention is paid to the correlation of systematic uncertainties within and between the various ATLAS data sets and to the impact of model, theoretical and parameterisation uncertainties.

hep-ex↗

arXiv2022

Proceedings of the Low-$x$ 2021 International Workshop

The purpose of the Low-$x$ Workshop series is to stimulate discussions between experimentalists and theorists in diffractive hadronic physics, QCD dynamics at low $x$, parton saturation, and exciting problems in QCD at HERA, Tevatron, LHC, RHIC, and the future EIC. The central topics of the workshop, summarized in the current Proceedings, were: Diffraction in ep and e-ion collisions (including EIC physics); Diffraction and photon-exchange in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions; Spin Physics; Low-$x$ PDFs, forward physics, and hadronic final states. This Workshop has been the XXVIII edition in the series of the workshop.

hep-ph↗

arXiv2022

Recent developments and latest results from the xFitter project

In this proceeding, the xFitter project is presented. xFitter is an open-source package that provides a framework for the determination of the parton distribution and fragmentation functions for many different kinds of analyses in Quantum Chromodynamics. xFitter version 2.2.0 has recently been released and offers an expanded set of tools and options. xFitter has been used for a number of analyses performed recently. An emphasis is given on the recently published study performed by the xFitter Developers' team of the pion fragmentation functions.

hep-ph↗

arXiv2022

The Forward Physics Facility: Sites, Experiments, and Physics Potential

The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF's physics potential. We then review the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.

hep-ph↗

arXiv2022

Precision measurements of the Lepton-Charge and Forward-Backward Drell-Yan Asymmetries to Enhance the Sensitivity to Broad Resonances of New Gauge Sectors

We study the impact of future measurements of lepton-charge and forward-backward asymmetries in Drell-Yan processes in regions of transverse and invariant masses near the Standard Model gauge bosons peaks to improve the Parton Distribution Functions uncertainties. We study the implications on $W^{'}$ and $Z^{'}$ searches following the reduction of these uncertainties. We find that the sensitivity to the Beyond the Standard Model states is greatly increased with respect to the case of base Parton Distribution Functions sets, thereby enabling one to set more stringent limits on (or indeed discover) such new particles.

hep-ph↗