arXiv subjects

Gyula Bencédi

Publications and source records attributed to Gyula Bencédi.

8 recordsLinked to original sources

arXiv2024

Characterisation of plastic scintillator paddles and lightweight MWPCs for the MID subsystem of ALICE 3

The ALICE collaboration is proposing a completely new detector, ALICE 3, for operation during the LHC Runs 5 and 6. One of the ALICE~3 subsystems is the Muon IDentifier detector (MID), which has to be optimised to be efficient for the reconstruction of $J/ψ$ at rest (muons down to $p_{\rm T}\approx1.5$ GeV/$c$) for $|η|<1.3$. Given the modest particle flux expected in the MID of a few Hz/cm$^2$, technologies like plastic scintillator bars ($\approx1$ m length) equipped with wavelength-shifting fibers and silicon photomultiplier readout, and lightweight Multi-Wire Proportional Chambers (MWPCs) are under investigation. To this end, different plastic scintillator paddles and MWPCs were studied at the CERN T10 test beam facility. This paper reports on the performance of the scintillator prototypes tested at different beam momenta (from 0.5 GeV/$c$ up to 6 GeV/$c$) and positions (horizontal, vertical, and angular scans). The MWPCs were tested at different momenta (from 0.5 GeV/$c$ to 10 GeV/$c$) and beam intensities, their efficiency and position resolutions were verified beyond the particle rates expected with the MID in ALICE 3.

physics.ins-det↗

arXiv2023

Multi-parton interactions in pp collisions using charged-particle flattenicity with ALICE

Event classifiers based either on the charged-particle multiplicity or on event topologies, such as spherocity and underlying event, became very useful tools to study collective-like behaviors in small collision systems. However, multiplicity-based event classifiers were shown to bias the data sample in a way that can obscure the effects of multi-parton interactions, and, this way, make it difficult to pin down the origins of small-system collectivity. In this proceedings, the measurement of the transverse momentum ($p_{\mathrm{T}}$) spectra of primary charged pions, kaons, (anti)protons and unidentified hadrons in inelastic pp collisions at $\sqrt{s}=13~\mathrm{TeV}$ are reported. Events are classified using a novel event shape observable, flattenicity, that was proposed to select minijet-enhanced pp collisions. Particle production is studied as a function of flattenicity and double-differentially as a function of flattenicity and charged-particle multiplicity. The results are compared with theoretical predictions from the PYTHIA 8 and EPOS LHC Monte Carlo models.

hep-ex↗

arXiv2021

Particle production as a function of the underlying event in pp collisions simulated with PYTHIA 8

In this work we present the production of charged particles associated with high-$p_{\rm T}$ trigger particles ($8<p_{\rm T}^{\rm trig.}<15$ GeV /$c$) at mid-pseudorapidity in proton-proton collisions at $\sqrt{s}=5.02$\,TeV simulated with the \textsc{PYTHIA 8} Monte Carlo model. The study is performed as a function of the relative transverse activity classifier, $R_{\rm T}$, which is the relative charged-particle multiplicity in the transverse region ($π/3 <|Δϕ| <2π/3$) of the di-hadron correlations, and it is sensitive to the Multi-Parton Interactions. The evolution of the yield of associated particles on both the toward and the away regions with $3\leq p_{\rm T}^{\rm assoc.}<8$ GeV/$c$ as a function of $R_{\rm T}$ is investigated. We propose a strategy which allows for the modelling and subtraction of the Underlying Event (UE) contribution from the toward and the away regions in challenging environments like those characterised by large $R_{\rm T}$. We found that the signal in the away region becomes broader with increasing $R_{\rm T}$. Contrarily, the yield increases with $R_{\rm T}$ in the toward region. This effect is reminiscent of that seen in heavy-ion collisions, where an enhancement of the yield in the toward region for $0-5\%$ central Pb--Pb collisions at $\sqrt{s}_{\rm NN}=2.76$\,TeV was reported. To further understand the role of the UE and additional jet activity, the transverse region is divided into two one-sided sectors, "trans-max" and "trans-min" selected in each event according to which region has larger or smaller charged particle multiplicity. Based on this selection criterion, the observables are studied as a function of $R_{\rm T}^{\rm max}$ and $R_{\rm T}^{\rm min}$, respectively. The presented results have been published in J. Phys. G 48, no.1, 015007 (2020) and Phys. Rev. D 104, no.1, 016017 (2021).

hep-ph↗

arXiv2021

Probing the interaction of semi-hard quarks and gluons with the underlying event in light- and heavy-flavor triggered proton-proton collisions

We study underlying-event observables in inelastic proton-proton (pp) collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV with identified light and heavy-flavor triggers using the PYTHIA 8 event generator. The study is performed as a function of the transverse momentum of the leading particle ($p_\mathrm{T}^{\rm trigger}$). While at high $p_\mathrm{T}^{\rm trigger}$ ($>10$ GeV/$c$) the underlying-event activity is independent of the leading particle species, at intermediate $p_\mathrm{T}^{\rm trigger}$ ($2<p_\mathrm{T}^{\rm trigger}<8$ GeV/$c$) it is larger in pion-triggered events than in events triggered with B mesons. Moreover, the underlying event in pion-triggered events, the majority of which are initiated by gluons, shows a stronger effect of color reconnection than events triggered with B-hadrons, that are mostly initiated by quark jets. The effect is observed at both hadronic and partonic level. Given that color reconnection affects the interaction among final partons before the hadronization, and that in the string model quarks (gluons) are connected to one (two) string piece(s), we conclude that the observed effect can be attributed to differences in the interactions of gluon and quark jets with the underlying event.

hep-ph↗

arXiv2020

Apparent modification of the jet-like yield in proton-proton collisions with large underlying event

This paper presents the production of charged particles associated with high-$p_{\rm T}$ trigger particles ($8<p_{\rm T}^{\rm trig.}<15$ GeV/$c$) in proton-proton collisions at $\sqrt{s}=5.02$ TeV simulated with PYTHIA 8.244. The study is performed as a function of the relative transverse activity classifier, $R_{\rm T}$, which is the relative charged-particle multiplicity in the transverse region ($π/3<|ϕ^{\rm trig.}-ϕ^{\rm assoc.}|<2π/3$) of the di-hadron correlations, and it is sensitive to the Multi-Parton Interactions. The evolution of both the near and the away-side yield of associated particles ($3\leq p_{\rm T}^{\rm assoc.}< 8$ GeV/$c$) as a function of $R_{\rm T}$ is investigated. We propose a strategy which allows for the modelling and subtraction of the underlying event contribution from the near and the away side in challenging environments like those characterised by large $R_{\rm T}$. We found that the away-side signal becomes broader with increasing $R_{\rm T}$, while its corresponding yield is independent of $R_{\rm T}$. Contrarily, the near-side yield increases with $R_{\rm T}$. This effect is reminiscent of that seen in heavy-ion collisions, where an enhancement in the near-side yield for 0-5% central Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV was reported. A discussion on the origin of these effects in PYTHIA, as well as their implications for the interpretation of recent LHC results for pp collisions, is presented.

hep-ph↗

arXiv2017

Revealing the source of the radial flow patterns in proton--proton collisions using hard probes

In this work, we propose a tool to reveal the origin of the collective-like phenomena observed in proton--proton collisions. We exploit the fundamental difference between the underlying mechanisms, color reconnection (CR) and hydrodynamics, which produce radial flow patterns in \textsc{Pythia}~8 and \textsc{Epos}~3, respectively. Specifically, we proceed by examining the strength of the coupling between the soft and hard components which, by construction, is larger in \textsc{Pythia}~8 than in \textsc{Epos}~3. We study the transverse momentum ($p_{\rm T}$) distributions of charged pions, kaons and (anti)protons in inelastic pp collisions at $\sqrt{s}=$ 7\,TeV produced at mid-rapidity. Specific selections are made on an event-by-event basis as a function of the charged particle multiplicity and the transverse momentum of the leading jet ($p_{\rm T}^{\rm jet}$) reconstructed using the \textsc{FastJet} algorithm at mid-pseudorapidity ($|η|<1$). From our studies, quantitative and qualitative differences between \textsc{Pythia}~8 and \textsc{Epos}~3 are found in the $p_{\rm T}$ spectra when (for a given multiplicity class) the leading jet $p_{\rm T}$ is increased. In addition, we show that for low-multiplicity events the presence of jets can produce radial flow-like behavior. Motivated by our findings, we propose to perform a similar analysis using experimental data from RHIC and LHC.

hep-ph↗

arXiv2016

Jet effects in high-multiplicity pp events

The study of the high-multiplicity pp events has become important because we need to understand the origin of the fluid-like features which have been found in such small systems. In this work we concentrate on the radial flow signatures. To this end, the role of jets in high-multiplicity pp collisions is investigated using PYTHIA 8.

hep-ph↗

arXiv2015

Identified Two-particle Correlations and Quantum Number Conservations in p-p and Pb-Pb Collisions at LHC Energies

In this paper we continue the investigation of the effect of quantum number conservations of pions, kaons, and protons, with very high transverse momenta (up to 25 GeV/c), during parton fragmentation and hadronization in p-p and Pb-Pb collisions at LHC energies. The strength of the conservation effects are studied by identified two-particle correlations in Monte Carlo generated events in the mid-rapidity region ($|η| < 1$). The simulated p-p events were generated with PYTHIA 8, using its main default settings, at $\sqrt{s}=200$~GeV, $\sqrt{s}=2.76$~TeV, $\sqrt{s}=7$~TeV, and $\sqrt{s}=14$~TeV. In parallel to this, HIJING 1.36 was used to generate Pb-Pb events at $\sqrt{s_{\rm NN}}=2.76$~TeV with centralities $0-10\%$, $30-40\%$ and $80-90\%$. The extracted identified associated hadron spectra for charged pion, kaon, and proton show identified trigger-hadron dependent splitting between oppositely charged associated particle species in any nucleus-nucleus collisions. The Pb-Pb data exhibits a peculiar splitting pattern as a function of the transverse momentum of the associated particle $p_{T,assoc}$ both on the near and away side that is different from the patterns observed in p-p collisions. The splitting shows smooth evolution with collision energy and event multiplicity in p-p collisions while in Pb-Pb collisions different trend were observed for kaons and protons.

hep-ex↗