arXiv subjects

Maria Vittoria Garzelli

Publications and source records attributed to Maria Vittoria Garzelli.

At least 19 recordsLinked to original sources

arXiv2026

The role of charm and unflavored mesons in prompt atmospheric lepton fluxes

The all-sky very-high-energy ($10^4-10^6$ GeV) atmospheric muon flux measured by IceCube shows a spectral hardening at the highest energies, indicating the presence of a prompt component. IceCube has also measured the atmospheric muon neutrino flux at high energy. However, since this flux is dominated by astrophysical neutrinos, only an upper bound can be placed on the prompt atmospheric $ν_μ+\barν_μ$ contribution. In this work, we provide a new evaluation of the prompt atmospheric muon flux including an intrinsic charm component in the cosmic ray-air interactions. The latter enhances the forward production of $\bar{D}^0$, $D^-$, and $Λ_c$, which subsequently decay into final states containing muons and muon neutrinos. We show how the increase in the prompt muon flux due to intrinsic charm is accompanied by a corresponding enhancement in the prompt muon neutrino flux. We implement different intrinsic charm production models in \texttt{MCEq} to calculate the resulting lepton fluxes. We discuss the challenges of achieving predictions that are simultaneously consistent with both IceCube's high-energy atmospheric muon flux measurements and IceCube upper bounds on the prompt muon neutrino flux, and we quantify the resulting discrepancies. As possible solutions, we explore scaling of the unflavored meson contributions to the prompt atmospheric muon flux to assess how such adjustments can reconcile these differences. The tensions emphasized in our work call for a refinement of the hadronic interaction models, especially the production of unflavored mesons, and for new experimental data sensitive to unflavored meson and heavy flavor production with reliable estimates of the associated uncertainties. We suggest that the energy and zenith angle dependence of muon and neutrino flux ratios from future neutrino telescope measurements may help to disentangle different scenarios.

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arXiv2026

Threshold Top-Quark Pair-Production: Cross Sections and Key Uncertainties

We study theoretical uncertainties in predicting top-quark pair-production near threshold at the LHC using the non-relativistic QCD framework. We include variations in the top-quark mass and width, the strong coupling $α_s$, renormalization and factorization scales, and parton distribution functions, as well as uncertainties from the color-singlet and octet Green's functions that describe quasi-bound toponium formation. These uncertainties are compared with those from standard fixed-order QCD predictions, and implications for ATLAS and CMS analyses are discussed. For the LHC at 13 TeV center-of-mass energy, the integral of the top-quark pair invariant-mass distribution from 340 to 350 GeV is 11.67 pb with ${}^{+1.43}_{-1.47}$ pb uncertainty. The corresponding excess after subtracting the POWHEG-BOX result is 4.15 pb with the same uncertainties.

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arXiv2026

Update of the nonlocal sub-leading ${O}_1$-${O}_7$ contribution to $\bar B \to X_s γ$ at LO

In all previous calculations of the non-local sub-leading contribution to the inclusive penguin decay $\bar B \to X_s γ$ due to the interference of the electroweak operators ${O}_1^c$ - ${O}_{7γ}$ the local Voloshin term was subtracted. In view of the ongoing analysis at order $α_s$, we present a calculation of the complete non-local contribution which takes into account the high correlation between the uncertainties of the local Voloshin and the non-local term of the previous analyses. The new calculation has a high impact on the range of the non-local contribution.

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arXiv2025

Prompt atmospheric leptons and the potential role of intrinsic charm

The all-sky very-high energy ($10^4-10^6$ GeV) atmospheric muon flux is most recently measured by IceCube, where in the higher energy range, the spectrum hardens indicating a prompt component. IceCube also measures the atmospheric muon neutrino flux at high energy. Since this is dominated by the astrophysical flux, they are only able to set an upper bound on the prompt atmospheric muon neutrino flux contribution. We provide a new evaluation of the prompt atmospheric muon flux including for the first time an intrinsic charm component to colliding nucleons. This increases forward production of $\bar{D}^{0}$, $D^-$ and $Λ_c$ which decay into final states that can contain muons and muon neutrinos. We show how the increase in the prompt muon flux due to intrinsic charm has an associated increase in the prompt muon neutrino flux. We consider the Regge ansatz for intrinsic charm production that we implement in MCEq used for the calculation of the lepton fluxes. We discuss the challenges of obtaining predictions that are simultaneously consistent with both IceCube's high energy atmospheric muon flux measurements and their upper bound on the prompt muon neutrino flux. We quantify the discrepancies.

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arXiv2025

Ideas and Requirements for the Global Cosmic-Ray Observatory (GCOS)

After a successful kick-off meeting in 2021. two workshops in 2022 and 2023 on the future Global Cosmic-Ray Observatory (GCOS) focused mainly on a straw man design of the detector and science possibilities for astro- and particle physics. About 100 participants gathered for in-person and hybrid panel discussions. In this report, we summarize these discussions, present a preliminary straw-man design for GCOS and collect short write-ups of the flash talks given during the focus sessions.

astro-ph.IM↗

arXiv2024

UHECR measurements and physics at man-made accelerators: mutual constraints

Measurements of the products of UHECR interactions with the Earth's atmosphere, as obtained in Extended Air Shower experiments, offer important information concerning hadronic interactions, which for some aspects overlaps and for many others complements the information extracted by measurements of collisions at human-made accelerators. In this contribution I discuss some of the constraints that the UHE astroparticle and accelerator fields exercise one over each other, emphasizing the importance of further new measurements, through new experiments or observations, in both fields.

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arXiv2023

Compatibility between theoretical predictions and experimental data for top-antitop hadroproduction at NNLO QCD accuracy

We compare double-differential normalized production cross sections for top-antitop $+ X$ hadroproduction at NNLO QCD accuracy, as obtained through a customized version of the MATRIX framework interfaced to PineAPPL, with recent data by the ATLAS and CMS collaborations. We take into account theory uncertainties due to scale variation and we see how predictions vary as a function of parton distribution function (PDF) choice and top-quark pole mass value, considering different state-of-the-art PDF fits with their uncertainties. Notwithstanding the overall reasonable good agreement, we observe discrepancies at the level of a few $σ$'s between data and theoretical predictions in some kinematical regions, which can be alleviated by refitting the top-quark mass value, and/or the PDFs and/or $α_s(M_Z)$, considering the correlations between these three quantities. In a fit of top-quark mass standalone, we notice that, for all considered PDF + $α_s(M_Z)$ sets used as input, some datasets point towards top-quark pole mass values lower by about $2\,σ$'s than those emerging from fitting other datasets, suggesting a possible tension between experimental measurements using different decay channels, and/or the need of better estimating uncertainties on the latter.

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arXiv2023

Prompt neutrinos from the atmosphere to the forward region of LHC

We investigate the kinematical regions that are important for producing prompt neutrinos in the atmosphere and in the forward region of the LHC, as probed by different experiments. We illustrate the results as a function of the center-of-mass nucleon-nucleon collision energies and rapidities of neutrinos and of the parent heavy-flavoured hadrons. We find overlap in part of the kinematic space.

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arXiv2023

Forward production of prompt neutrinos from charm in the atmosphere and at high energy colliders

The high-energy atmospheric neutrino flux is dominated by neutrinos from the decays of charmed hadrons produced in the forward direction by cosmic ray interactions with air nuclei. We evaluate the charm contributions to the prompt atmospheric neutrino flux as a function of the center-of-mass energy $\sqrt{s}$ of the hadronic collision and of the center-of-mass rapidity $y$ of the produced charm hadron. Uncertainties associated with parton distribution functions are also evaluated as a function of $y$. We find that the $y$ coverage of LHCb for forward heavy-flavour production, complemented by the angular coverage of present and future forward neutrino experiments at the LHC, bracket the most interesting $y$ regions for the prompt atmospheric neutrino flux. At $\sqrt{s}=14$ TeV foreseen for the HL-LHC phase, nucleon collisions in air contribute to the prompt neutrino flux prominently below $E_ν\sim 10^7$~GeV. Measurements of forward charm and/or forward neutrinos produced in hadron collisions up to $\sqrt{s}=100$ TeV, which might become possible at the FCC, are relevant for the prompt atmospheric neutrino flux up to $E_ν=10^8$ GeV and beyond.

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arXiv2023

Forward production of prompt neutrinos in the atmosphere and at high-energy colliders

The atmospheric neutrino flux at very high energies is dominated by prompt neutrinos, mostly contributed by the decays of charmed hadrons produced in the forward direction by cosmic ray interactions with air nuclei. Theoretical predictions of the prompt atmospheric neutrino flux have large uncertainties mainly related to charm hadron production. Prompt neutrinos can also be studied through high-energy colliders. In particular, two ongoing forward experiments and the proposed Forward Physics Facility at the LHC can detect forward prompt neutrinos. We will present the kinematic regions relevant to the prompt atmospheric neutrino flux in terms of collider kinematic variables, the collision energy $\sqrt{s}$ and the center-of-mass rapidity of charm hadrons $y$, and discuss implications of the forward experiments at the LHC on the theoretical predictions of the prompt atmospheric neutrino flux.

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arXiv2023

The case for an EIC Theory Alliance: Theoretical Challenges of the EIC

We outline the physics opportunities provided by the Electron Ion Collider (EIC). These include the study of the parton structure of the nucleon and nuclei, the onset of gluon saturation, the production of jets and heavy flavor, hadron spectroscopy and tests of fundamental symmetries. We review the present status and future challenges in EIC theory that have to be addressed in order to realize this ambitious and impactful physics program, including how to engage a diverse and inclusive workforce. In order to address these many-fold challenges, we propose a coordinated effort involving theory groups with differing expertise is needed. We discuss the scientific goals and scope of such an EIC Theory Alliance.

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arXiv2022

On the prompt contribution to the atmospheric neutrino flux

The prompt contribution to the atmospheric neutrino flux is analyzed. It is demonstrated that the corresponding theoretical uncertainties related to perturbative treatment of charm production, notably, the ones stemming from the low and high $x$ behavior of parton distribution functions, can be conveniently studied at the level of charm quark production. Additionally, we discuss the non-perturbative contribution to the prompt neutrino flux, related to the intrinsic charm content of the proton, and analyze its main features.

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arXiv2022

Report of the Topical Group on Top quark physics and heavy flavor production for Snowmass 2021

This report summarizes the work of the Energy Frontier Topical Group on EW Physics: Heavy flavor and top quark physics (EF03) of the 2021 Community Summer Study (Snowmass). It aims to highlight the physics potential of top-quark studies and heavy-flavor production processes (bottom and charm) at the HL-LHC and possible future hadron and lepton colliders and running scenarios.

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arXiv2022

Tau Neutrinos in the Next Decade: from GeV to EeV

Tau neutrinos are the least studied particle in the Standard Model. This whitepaper discusses the current and expected upcoming status of tau neutrino physics with attention to the broad experimental and theoretical landscape spanning long-baseline, beam-dump, collider, and astrophysical experiments. This whitepaper was prepared as a part of the NuTau2021 Workshop.

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arXiv2022

Report of the Topical Group on Cosmic Probes of Fundamental Physics for for Snowmass 2021

Cosmic Probes of Fundamental Physics take two primary forms: Very high energy particles (cosmic rays, neutrinos, and gamma rays) and gravitational waves. Already today, these probes give access to fundamental physics not available by any other means, helping elucidate the underlying theory that completes the Standard Model. The last decade has witnessed a revolution of exciting discoveries such as the detection of high-energy neutrinos and gravitational waves. The scope for major developments in the next decades is dramatic, as we detail in this report.

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arXiv2022

High-Energy and Ultra-High-Energy Neutrinos

Astrophysical neutrinos are excellent probes of astroparticle physics and high-energy physics. With energies far beyond solar, supernovae, atmospheric, and accelerator neutrinos, high-energy and ultra-high-energy neutrinos probe fundamental physics from the TeV scale to the EeV scale and beyond. They are sensitive to physics both within and beyond the Standard Model through their production mechanisms and in their propagation over cosmological distances. They carry unique information about their extreme non-thermal sources by giving insight into regions that are opaque to electromagnetic radiation. This white paper describes the opportunities astrophysical neutrino observations offer for astrophysics and high-energy physics, today and in coming years.

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arXiv2022

One-loop soft anomalous dimension matrices for $t\bar t j$ hadroproduction

We calculate the one-loop corrections to the soft anomalous dimension matrices for the production of a top-antitop quark pair in association with a jet at hadron colliders. This is a step forward towards implementing a procedure for the resummation of soft-gluon emission logarithms for the $t\bar{t}j + X$ hadroproduction process, that will enable the improvement of the accuracy of the $t\bar{t} j + X$ cross sections, beyond the current degree of knowledge. The latter, so far, has reached the next-to-leading order (NLO) level, complemented by the accuracy of the Shower Monte Carlo approaches used in matching the NLO computations to parton showers (PS) and by merging with matrix elements with a different number of light jets.

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arXiv2022

Parton distribution function uncertainties in theoretical predictions for far-forward tau neutrinos at the Large Hadron Collider

New experiments to measure neutrinos in the far-forward region at the Large Hadron Collider (LHC) are under design or already in preparation. Two of them, FASER$ν$ and SND@LHC, are expected to be active during Run 3 and have the potential to detect neutrinos that come from high-energy collisions in one of the LHC interaction points, extracted along the direction tangent to the beam line. Tau neutrinos and antineutrinos come predominantly from $D_s^\pm$ production in $pp$ collisions, followed by the leptonic decay of these mesons. Neutrino pseudorapidities in the range of $η>6.9$ and $η>8.9$ are relevant to these future experiments. At such pseudorapidities at high energies, theoretical predictions for the flux of tau neutrinos rely on parton distribution functions (PDFs) in a combination of very small and large parton$-x$ values. We evaluate PDF uncertainties in a next-to-leading order (NLO) QCD calculation of the flux of $ν_τ$ + $\barν_τ$ produced by $D_s^\pm$ decay in the far forward region at the LHC. The theoretical uncertainty associated with the 40 PDF sets of the PROSA19 group amounts to $\pm (20-30)$\% for the ($ν_τ$ + $\barν_τ$) number of charged-current (CC) events. Scale uncertainties are much larger, resulting in a range of CC event predictions from $\sim 70\%$ lower to $\sim 90\%$ higher than the central prediction. A comparison of the predictions with those obtained using as input the central PDFs from the 3-flavour NLO PDF sets of the CT14, ABMP16 and NNPDF3.1 collaborations show that far-forward neutrino energy distributions vary by as much as a factor of $\sim 2-4$ relative to the PROSA19 predictions at TeV neutrino energies. The Forward Physics Facility in the high luminosity LHC era will provide data capable of constraining NLO QCD evaluations with these PDF sets.

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