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Péter Lévai

Publications and source records attributed to Péter Lévai.

14 recordsLinked to original sources
arXiv2026

Status report on long-time decay measurements of 137Cs radioisotope

The constancy of nuclear decay rates can be investigated via long-duration precision measurements. It is still an open question whether any (annual) modulation can be observed. Long-lasting nuclear decay rate measurements have been the subject of considerable research effort. A decay rate measurement with a 137Cs source is currently being conducted 30 meters below the ground at the Jánossy Underground Research Laboratory (JURLab, Csillebérc, Hungary) utilizing a High-purity Germanium (HPGe) detector. The laboratory is the low-radiation-background part of the Vesztergombi High Energy Laboratory (VLAB) on the KFKI campus, Csillebérc, Hungary. From October 2022 to April 2024, data of 18 months' worth have been collected, providing a new opportunity to look for variations in decay rates. The experimental setup, data processing method, and the first results of this measurement are presented here.

nucl-ex↗
arXiv2023

Dedicated Analysis Facility for HEP Experiments

High-energy physics (HEP) provides ever-growing amount of data. To analyse these, continuously-evolving computational power is required in parallel by extending the storage capacity. Such developments play key roles in the future of this field however, these can be achieved also by optimization of existing IT resources. One of the main computing capacity consumers in the HEP software workflow are detector simulation and data analysis. To optimize the resource requirements for these aims, the concept of a dedicated Analysis Facility (AF) for Run 3 has been suggested by the ALICE experiment at CERN. These AFs are special computing centres with a combination of CPU and fast interconnected disk storage modules, allowing for rapid turnaround of analysis tasks on a dedicated subset of data. This in turn allows for optimization of the analysis process and the codes before the analysis is performed on the large data samples on the Worldwide LHC Computing Grid. In this paper, the structure and the progress summary of the Wigner Analysis Facility (Wigner AF) is presented for the period 2020-2022.

cs.DC↗
arXiv2019

Introducing HIJING++: the Heavy Ion Monte Carlo Generator for the High-Luminosity LHC Era

Beyond 2025 we will enter the High-Luminosity era of the LHC, right after the upgrades of the third Long Shutdown of the Large Hadron Collider (LHC). The ongoing state-of-the-art experimental instrument upgrades require high-performance simulation support in the background, that is modern, robust, and comes with long term support. The original FORTRAN based HIJING (Heavy Ion Jet INteraction Generator) has been used intensively since almost three decades by the high energy physics and heavy-ion community. However, it is getting overly challenging to conform to these new requirements. Our novel Monte Carlo event generator, the HIJING++ is the successor of the old FORTRAN version containing all the physics that its predecessor have. Moreover, among others a flexible module handling layer and an analysis interface is also introduced. This latter supports the most popular event container formats such as simple ascii, ROOT and the HepMC format, together with RIVET support. In this paper we compare the pre-release results of HIJING++ with proton-proton experimental data and Pythia8 calculations.

physics.comp-ph↗
arXiv2018

HIJING++, a Heavy Ion Jet INteraction Generator for the High-luminosity Era of the LHC and Beyond

HIJING++ (Heavy Ion Jet INteraction Generator) is the successor of the widely used original HIJING, developed almost three decades ago. While the old versions (1.x and 2.x) were written in FORTRAN, HIJING++ was completely rewritten in C++. During the development we keep in mind the requirements of the high-energy heavy-ion community: the new Monte Carlo software have a well designed modular framework, therefore any future modifications are much easier to implement. It contains all the physical models that were also present in it's predecessor, but utilizing modern C++ features it also includes native thread based parallelism, an easy-to-use analysis interface and a modular plugin system, which makes room for possible future improvements. In this paper we summarize the results of our performance tests measured on 2 widely used architectures.

physics.comp-ph↗
arXiv2018

Chiral Magnetic Effect in the Dirac-Heisenberg-Wigner formalism

In this paper the emergence of the Chiral Magnetic Effect (CME) and the related anomalous current is investigated using the real time Dirac-Heisenberg-Wigner formalism. This method is widely used for describing strong field physics and QED vacuum tunneling phenomena as well as pair production in heavy-ion collisions. We extend earlier investigations of the CME in constant flux tube configuration by considering time dependent fields. In this model we can follow the formation of axial charge separation, formation of axial current and then the emergence of the anomalous electric current. Qualitative results are shown for special field configurations that help to interpret the predictions of CME related effects in heavy-ion collisions at the RHIC Beam Energy Scan program.

hep-ph↗
arXiv2018

First Results with HIJING++ on High-energy Heavy Ion Collisions

We present preliminary results with HIJING++ (3.1.1) for identified hadron production in high-energy heavy ion collisions at LHC energies. The recently developed HIJING++ version is based on the latest version of PYTHIA8 and contains all the nuclear effects that have been included in the HIJING2.552, which will be improved by a new version of the shadowing parametrization and jet quenching module. Here, we summarize the structure and the speed gain due to parallelization of the new program code, also presenting some comparison between experimental data.

hep-ph↗
arXiv2017

Chiral Magnetic Effect in the Dirac-Heisenberg-Wigner formalism

The emergence of the Chiral Magnetic Effect (CME) and the related anomalous current is investigated using the real time Dirac-Heisenberg-Wigner formalism. This method is widely used for describing strong field physics and QED vacuum tunneling phenomena as well as pair-production in heavy-ion collisions. We extend earlier investigations of the CME in constant fluxtube configuration by considering time dependent fields. In our model we can follow the formation of axial charge separation, formation of axial current and then the emergence of the anomalous electric current. Qualitative results are shown for special field configurations that help interpret the predictions of CME related effects in heavy-ion collisions in the RHIC Beam Energy Scan program.

hep-ph↗
arXiv2017

First Results with HIJING++ in High-Energy Heavy-Ion Collisions

First calculated results with the new HIJING++ are presented for identified hadron production in high-energy heavy ion collisions. The recently developed HIJING++ version is based on the latest version of PYTHIA8 and contains all the nuclear effects has been included in the HIJING2.552, which will be improved by a new version of the shadowing parametrization and jet quenching module. Here, we summarize the major changes of the new program code beside the comparison between experimental data for some specific high-energy nucleus-nucleus collisions.

hep-ph↗
arXiv2013

Pair production at the edge of the QED flux tube

We investigate the process of Abelian pair production in the presence of strong inhomogeneous and time-dependent external electric fields. The spatial dependence of the external field is motivated by a non-Abelian color flux tube in heavy-ion collisions. We show that the inhomogeneity significantly increase the particle yield compared to that in the commonly used models with a constant and homogeneous field. Moreover our results indicate that in contrast to the latter, most of the particles are produced at the interface of the field profile in accordance with Heisenberg's prediction.

hep-ph↗
arXiv2012

Anomalous baryon production in heavy ion collisions at LHC energies

In ultrarelativistic heavy ion collisions the baryon-meson ratio is not fully understood in the intermediate-to-high transverse momentum region. Although quark coalescence methods combined with jet fragmentation yield results close to the experimental data, some tendencies are not reproduced and require further investigation. We propose a new channel, namely extra quark-antiquark and diquark-antidiquark pair production from coherent gluon field created in the early stage of heavy ion collisions. This process is described quantitatively by the time-dependent Schwinger-mechanism. The extra diquark-quark coalescence yields are able to explain the measured anomalous baryon production.

hep-ph↗
arXiv2012

Simulation of Pair Production in Extreme Strong EM Fields

In this article we review a theoretical framework for pair production from strong external electromagnetic fields. We propose a numerical method to solve the resulting equations of motion and present results for both cases of spatially homogeneous and inhomogeneous electric fields.

physics.plasm-ph↗
arXiv2011

Underlying Event Studies for LHC Energies

Underlying event was originally defined by the CDF collaboration decades ago. Here we improve the original definition to extend our analysis for events with multiple-jets. We introduce a definition for surrounding rings/belts and based on this definition the jet- and surrounding-belt-excluded areas will provide a good underlying event definition. We inverstigate our definition via the multiplicity in the defined geometry. In parallel, mean transverse momenta of these areas also studied in proton-proton collisions at $\sqrt{s}=7$ TeV LHC energy.

hep-ph↗
arXiv2009

Relativistic light-on-heavy nuclear collisions and the implied rapidity asymmetry

We calculate pseudorapidity ($η$) asymmetry in $pA$ and $dA$ collisions in a pQCD-improved parton model. With the calculations tuned to describe existing spectra from $pp$ collisions and asymmetric systems at midrapidity and large rapidities at FNAL and RHIC energies, we investigate the roles of nuclear shadowing and multiple scattering on the observed asymmetry. Using this framework, we make predictions for pseudorapidity asymmetries at high $p_T$ and large $η$ in a wide range of energies up to LHC.

hep-ph↗