arXiv subjects

Guy Paić

Publications and source records attributed to Guy Paić.

8 recordsLinked to original sources

arXiv2026

Evolution of the underlying event and non-extensive thermodynamics in pp collisions from RHIC to LHC energies

We investigate the geometrical and thermodynamical aspects of particle production in pp collisions over a broad center-of-mass energy, ranging from $\sqrt{s}=62.4$ GeV to 13 TeV using PYTHIA8. We study the azimuthal dependence of charged-particle production relative to the leading particle. This includes the study of the Tsallis--Pareto parameters extracted from the charged-particle transverse-momentum spectra in fixed $Δϕ$ intervals relative to the leading charged particle. The simultaneous analysis of charged-particle multiplicity and event topology demonstrates that the underlying event (UE) dominated region can be extended beyond the conventional transverse side region across RHIC and LHC energies. To further disentangle effects from soft and hard particle production mechanisms, the study is performed in different transverse spherocity and charged-particle flattenicity classes. We demonstrate that the UE region extends beyond the conventional transverse region, validating an enlarged angular interval of $40^\circ\lesssim|Δϕ|\lesssim140^\circ$ from RHIC to LHC energies. Event-shape selections reveal that jetty events consistently exhibit larger $q$ and lower $T_{\rm s}$ than isotropic events. The $Δϕ$ profiles of charged-particle multiplicity and transverse spherocity remain universal in shape across collision energies despite the strong increase in overall event activity, whereas the Tsallis parameters retain a residual, leading-particle-driven energy dependence in the near- and away-side regions.

hep-ph↗

arXiv2026

Revisiting the soft-hard separation in the transverse momentum spectra of $pp$ collisions

We study the separation of soft and hard components in the transverse momentum spectra of charged particles as measured by ALICE in proton-proton collisions at $\sqrt{s}$ = 2.76, 5.02 and 13 TeV at the LHC. The soft component is described by a Boltzmann fit, while the residual spectra are identified as a hard QCD-like fragmentation contribution. After separation, the subtracted spectra show no significant evolution in shape or peak position with multiplicity, consistent with a two-component interpretation. Mean transverse momenta for both contributions remain nearly constant across multiplicity classes, while Pythia 8 Monte Carlo simulations confirm these trends. The robustness of the decomposition is demonstrated by a comparison between simulations with and without color reconnection, yielding consistent results. The terms `soft' and `hard' are used as operational labels within this framework and should not be interpreted as uniquely identified dynamical components. Our results are consistent with the two-component description as a viable and physically motivated alternative to hydrodynamical interpretations.

hep-ph↗

arXiv2025

The impact of artificial intelligence: from cognitive costs to global inequality

In this paper, we examine the wide-ranging impact of artificial intelligence on society, focusing on its potential to both help and harm global equity, cognitive abilities, and economic stability. We argue that while artificial intelligence offers significant opportunities for progress in areas like healthcare, education, and scientific research, its rapid growth -- mainly driven by private companies -- may worsen global inequalities, increase dependence on automated systems for cognitive tasks, and disrupt established economic paradigms. We emphasize the critical need for strong governance and ethical guidelines to tackle these issues, urging the academic community to actively participate in creating policies that ensure the benefits of artificial intelligence are shared fairly and its risks are managed effectively.

physics.soc-ph↗

arXiv2024

Investigating the soft and hard limits in transverse momentum spectra in pp collisions

The transverse momentum spectra and their multiplicity dependence serve as key tools for extracting parameters to be compared with theoretical models. Over the past decade, the scientific community has extensively studied the possibility of a system analogous to quark-gluon plasma, predicted in heavy nuclei collisions, also existing in collisions involving light nuclei and protons. We have reanalysed the data published by the ALICE Collaboration at the LHC. We present the dependence of the mean transverse momenta obtained in the soft and soft+hard (mixed) parts. Finally, we also discuss possible refinements of the analyses concerning the use of statistical parameters of higher order, aimed at a more detailed way of comparing the models with data.

hep-ph↗

arXiv2023

Exploring the QGP phase above the deconfinement temperature in $pp$ and $A-A$ collisions at LHC energies

In the present work we have analyzed the transverse momentum spectra of charged particles in high multiplicity ${\it pp}$ collisions at LHC energies $\sqrt s = $ 5.02 and 13 TeV published by the ALICE Collaboration using the Color String Percolation Model (CSPM). For heavy ions Pb-Pb at $\sqrt {s_{NN}} =$ 2.76 and 5.02 TeV along with Xe-Xe at $\sqrt {s_{NN}} = $ 5.44 TeV have been analyzed. The initial temperature is extracted both in low and high multiplicity events in ${\it pp}$ collisions. For $A-A$ collisions the temperature is obtained as a function of centrality. A universal scaling in the temperature from $pp$ and $A-A$ collisions is obtained when multiplicity is scaled by the transverse interaction area.From the measured energy density $\bm \varepsilon$ and the temperature the dimensionless quantity $\bm \varepsilon/T^{4}$ is obtained. Our results for Pb-Pb and Xe-Xe collisions show a sharp increase in $\bm \varepsilon/T^{4}$ above T $\sim$ 210 MeV and reaching the ideal gas of quarks and gluons value of $\bm \varepsilon/T^{4} \sim$ 16 at temperature $\sim $ 230 MeV. In case of $pp$ collisions only $\bm \varepsilon/T^{4} \sim $ 10 corresponding to $\sim$ 30 degrees of freedom.

hep-ph↗

arXiv2021

Quantifying the Underlying Event: Investigating Angular Dependence of Multiplicity Classes and Transverse-momentum Spectra in High-energy pp Collisions at LHC Energies

We present a study of the transverse momentum spectra and their evolution in function of the position of the azimuthal of the particles associated to the leading particle. Additionally, the behavior of the spherocity distribution in the same azimuthal bins is reported. The studies were made using proton-proton collisions at $\sqrt{s}$ = 13 TeV using PYTHIA8 Monte Carlo event generator. The Multiplicity and midrapidity transverse momentum spectra of charged hadrons have been analyzed in the non-extensive statistical framework. The results on the findings corresponding to the Underlying Event are reported.

hep-ph↗

arXiv2021

Deconfinement and degrees of freedom in $pp$ and $A-A$ collisions at LHC energies

We present the extraction of the temperature by analyzing the charged particle transverse momentum spectra in lead-lead (Pb-Pb) and proton-proton (${\bf pp}$) collisions at LHC energies from the ALICE Collaboration using the Color String Percolation Model (CSPM). From the measured energy density ${\bm \varepsilon}$ and the temperature T the dimensionless quantity ${\bm \varepsilon/}T^{4}$ is obtained to get the degrees of freedom (DOF), ${\bm \varepsilon}/T^{4}$ = DOF ${ π^{2}}$/30. We observe for the first time a two-step behavior in the increase of DOF, characteristic of deconfinement, above the hadronization temperature at temperature $\sim$ 210 MeV for both Pb-Pb and ${\bf pp}$ collisions and a sudden increase to the ideal gas value of $\sim $ 47 corresponding to three quark flavors in the case of Pb-Pb collisions.

hep-ph↗

arXiv2020

Parton energy loss in pp collisions at very high multiplicity

We present the results for the evolution of transverse momentum spectra for the jetty and underlying parts of events as a function of multiplicity in pp collisions at 13 TeV measured at midrapidity ($\left|η\right|<0.8$) using PYTHIA8 event generator. The main characteristic of the approach is that it reaches to extreme multiplicities not yet explored by the experiments. We demonstrate that the behavior of both the underlying and hard components are affected by the multiplicity of the events i.e. the energy density. The behavior of the spectra at very high multiplicities suggests that the partons suffer energy loss compensated by an increase in the multiplicity of events.

hep-ph↗