arXiv subjects

Valentina Zaccolo

Publications and source records attributed to Valentina Zaccolo.

14 recordsLinked to original sources

arXiv2026

Strangeness enhancement in pp collisions from string closepacking in Pythia 8.3

Measurements at LHC show an increased production of strange hadrons with charged multiplicity in pp collisions, which is not described by the Lund String Model (with the Monash tune) implemented in PYTHIA. This work investigates string closepacking, a mechanism invoked during hadronization where overlapping strings create a background field that increases the effective string tension. This reduces strangeness suppression, effectively enhancing production. The model also incorporates an option for "popcorn destructive interference", which suppresses baryon production, to address the non-strange $p/π$ ratio, utilizing color algebra arguments; and an option for "strange junctions", which enhances strangeness specifically within the baryon sector. The Trieste tunes of this model to LHC data are presented. The closepacking model is in qualitative agreement with many of the salient particle ratios, although the $Ξ_c/D$ ratio and the shape of $p_\perp$ spectra remain challenging to account for. Overall, the closepacking model with the Trieste tunes provides a competitive description of enhanced strangeness production in pp collisions, improving upon existing PYTHIA models while avoiding excessive proton yields.

hep-ph↗

arXiv2026

Closepacking effects on strangeness and baryon production at the LHC

Data from the LHC show a rise in strange-hadron production with charged-particle multiplicity in pp collisions. The Monte-Carlo event generator PYTHIA, using its default Monash tune, instead predicts constant strangeness. We investigate a mechanism invoked during hadronization called string closepacking, where overlapping strings generate a background field, here assumed to be predominantly aligned with the beam axis. This increases the effective string tension, reducing strangeness suppression and thus enhancing strangeness production. We tune this model to LHC data and contrast it with several alternatives. We comment specifically on the challenge of simultaneously describing the non-strange p/pi ratio, and introduce a mechanism which may act to suppress it. Many of the salient particle-production ratios can be qualitatively described by this model, although the XiC/D ratio and the shape of pT spectra remain challenging to account for.

hep-ph↗

arXiv2024

The ECFA Early-Career Researchers Panel: Report for the year 2023

The European Committee for Future Accelerators (ECFA) Early-Career Researcher (ECR) panel, which represents the interests of the ECR community to ECFA, presents in this document its initiatives and activities in the year 2023. This report summarises the process of the first big turnover in the panel composition at the start of 2023 and reports on the activities of the active working groups - either pursued from before or newly established. The overarching goal of the ECFA-ECR panel is to better understand and support the diverse interests of early-career researchers in the ECFA community and beyond.

physics.acc-ph↗

arXiv2024

A test of strangeness quantum number conservation in proton-proton collisions

The study delves into the production of (multi-)strange hadrons in proton-proton collisions at LHC. Novel observables are proposed to distinguish between EPOS4, based on core-corona separation between a thermalised QGP phase and a vacuum phase with global strangeness conservation, and PYTHIA8.3, based on microscopic interactions between Lund strings that conserve strangeness locally. Correlations between a $ϕ$ meson and (multi-)strange hadrons are shown to be an excellent discriminator between the two types of models.

hep-ph↗

arXiv2024

QCD challenges from pp to AA collisions -- 4th edition

This paper is a write-up of the ideas that were presented, developed and discussed at the fourth International Workshop on QCD Challenges from pp to AA, which took place in February 2023 in Padua, Italy. The goal of the workshop was to focus on some of the open questions in the field of high-energy heavy-ion physics and to stimulate the formulation of concrete suggestions for making progresses on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results.

hep-ex↗

arXiv2022

The ECFA Early Career Researcher's Panel: composition, structure, and activities, 2021 -- 2022

The European Committee for Future Accelerators (ECFA) Early Career Researcher's (ECR) panel, which represents the interests of the ECR community to ECFA, officially began its activities in January 2021. In the first two years, the panel has defined its own internal structure, responded to ECFA requests for feedback, and launched its own initiatives to better understand and support the diverse interests of early career researchers. This report summarises the panel composition and structure, as well as the different activities the panel has been involved with during the first two years of its existence.

physics.acc-ph↗

arXiv2021

Results of the 2021 ECFA Early-Career Researcher Survey on Training in Instrumentation

The European Committee for Future Accelerators (ECFA) Early-Career Researchers (ECR) Panel was invited by the ECFA Detector R&D Roadmap conveners to collect feedback from the European ECR community. A working group within the ECFA ECR panel held a Townhall Meeting to get first input, and then designed and broadly circulated a detailed survey to gather feedback from the larger ECR community. A total of 473 responses to this survey were received, providing a useful overview of the experiences of ECRs in instrumentation training and related topics. This report summarises the feedback received, and is intended to serve as an input to the ECFA Detector R&D Roadmap process.

physics.ins-det↗

arXiv2019

Particle production as a function of underlying-event activity measured with ALICE at the LHC

ALICE has performed several measurements aimed at understanding the collective-like effects observed in small collision systems. New approaches may be needed to clarify particle-production mechanisms in high-multiplicity pp collisions. Transverse momentum ($p_{\rm T}$) spectra as a function of charged-particle multiplicity show intriguing features. For example, data exhibit a stronger-than-linear increase of the self-normalised high-$p_{\rm T}$ particle yields versus multiplicity. In order to understand the role of auto-correlations on these effects, it has been proposed to use the underlying event as a multiplicity estimator to factorise the hardest and the softest components of the events. This approach can also be used to study collective effects in events with exceptionally large activity in the underlying-event region with respect to the event-averaged mean. In these proceedings, $p_{\rm T}$ spectra as a function of underlying-event activity in pp collisions measured with the ALICE detector are presented. Results are compared with PYTHIA 8.2 event generator.

hep-ex↗

arXiv2019

INDIGO-DataCloud:A data and computing platform to facilitate seamless access to e-infrastructures

This paper describes the achievements of the H2020 project INDIGO-DataCloud. The project has provided e-infrastructures with tools, applications and cloud framework enhancements to manage the demanding requirements of scientific communities, either locally or through enhanced interfaces. The middleware developed allows to federate hybrid resources, to easily write, port and run scientific applications to the cloud. In particular, we have extended existing PaaS (Platform as a Service) solutions, allowing public and private e-infrastructures, including those provided by EGI, EUDAT, and Helix Nebula, to integrate their existing services and make them available through AAI services compliant with GEANT interfederation policies, thus guaranteeing transparency and trust in the provisioning of such services. Our middleware facilitates the execution of applications using containers on Cloud and Grid based infrastructures, as well as on HPC clusters. Our developments are freely downloadable as open source components, and are already being integrated into many scientific applications.

cs.DC↗

arXiv2018

Multiplicity and Underlying Event in ALICE: as measurements and as tools to probe QCD

With the high collision energies at the LHC, the contributions to particle production from hard-QCD processes increase, but it remains dominated by soft-QCD processes. Such processes challenge the theoretical models, since they are described by non-perturbative phenomenology. A selection of the most recent ALICE measurements of charged-particle multiplicities and the Underlying Event will be presented, focusing on model comparisons. A summary of the current understanding of soft-QCD processes will be discussed, evaluating possible ways to further constrain theory.

nucl-ex↗

arXiv2017

Improved Cloud resource allocation: how INDIGO-DataCloud is overcoming the current limitations in Cloud schedulers

Performing efficient resource provisioning is a fundamental aspect for any resource provider. Local Resource Management Systems (LRMS) have been used in data centers for decades in order to obtain the best usage of the resources, providing their fair usage and partitioning for the users. In contrast, current cloud schedulers are normally based on the immediate allocation of resources on a first-come, first-served basis, meaning that a request will fail if there are no resources (e.g. OpenStack) or it will be trivially queued ordered by entry time (e.g. OpenNebula). Moreover, these scheduling strategies are based on a static partitioning of the resources, meaning that existing quotas cannot be exceeded, even if there are idle resources allocated to other projects. This is a consequence of the fact that cloud instances are not associated with a maximum execution time and leads to a situation where the resources are under-utilized. These facts have been identified by the INDIGO-DataCloud project as being too simplistic for accommodating scientific workloads in an efficient way, leading to an underutilization of the resources, a non desirable situation in scientific data centers. In this work, we will present the work done in the scheduling area during the first year of the INDIGO project and the foreseen evolutions.

cs.DC↗

arXiv2017

Soft-QCD physics in pp and p-Pb with ALICE

At high collision energies as achieved at the LHC there are increasing contributions from hard processes, which can be computed with perturbative QCD. Nevertheless, particle production is still dominated by soft QCD with transferred momentum of a few GeV. These phenomena are described by non-perturbative phenomenology and challenge the theoretical models. ALICE has measured several observables which target soft QCD, both in Run 1 and 2 proton-proton and proton-lead collisions at the LHC. A selection of results will be presented in these proceedings, focusing on the model comparisons and summarising the understanding of soft QCD after almost 8 years of data taking.

nucl-ex↗

arXiv2017

Study of charged-particle multiplicities with ALICE

The multiplicity measurements include the pseudorapidity density, $\rm{d}N_{\rm ch}/\rm{d}η$, and the probability distribution as a function of the number of charged particles, $\rm{P}(N_{\rm ch})$. ALICE has measured the multiplicities for three collision systems, for proton-proton, proton-lead and lead-lead collisions at Run 1 and 2 at the Large Hadron Collider. A selection of these results will be presented in these proceedings, concluding with an overview of new measurements planned.

nucl-ex↗

arXiv2015

Charged-Particle Multiplicity Distributions over a Wide Pseudorapidity Range in Proton-Proton Collisions with ALICE

Multiplicity distributions of charged particles for pp collisions at LHC Run 1 energies, from $\sqrt{s}=$ 0.9 to 8 TeV are measured over a wide pseudorapidity range ($-3.4<η<5.0$) for the first time. The results are obtained using the Forward Multiplicity Detector and the Silicon Pixel Detector within ALICE. The results are compared to Monte Carlo simulations, and to the IP-Glasma model.

hep-ex↗