arXiv subjects

P. Lévai

Publications and source records attributed to P. Lévai.

15 recordsLinked to original sources

arXiv2022

Report on a pre-earthquake signal detection by enhanced Eötvös torsion balance

More than 30 minutes before the earthquake event in Florina, Greece at 21:43:47(UTC) on 9th January 2022 an enhanced Eötvös torsion balance registered unidentified signals in the Jánossy Underground Research Laboratory in Budapest, Hungary. These signals were not visible on the seismograms, although seismic noises are continuously recorded by a side-by-side broadband seismometer. Moreover, seismological stations did not detect anything unusual, they presented a negative confirmation of the events. Our observation suggests that torsion balances might effectively detect precursory earthquake signals from a considerable distance. Such a finding could trigger the development of new observational devices and networks and can provide novel knowledge about the origin and mechanism of earthquake phenomena.

physics.geo-ph↗

arXiv2018

Long term measurements from the Mátra Gravitational and Geophysical Laboratory

Summary of the long term data taking, related to one of the proposed next generation ground-based gravitational detector's location is presented here. Results of seismic and infrasound noise, electromagnetic attenuation and cosmic muon radiation measurements are reported in the underground Matra Gravitational and Geophysical Laboratory near Gyöngyösoroszi, Hungary. The collected seismic data of more than two years is evaluated from the point of view of the Einstein Telescope, a proposed third generation underground gravitational wave observatory. Applying our results for the site selection will significantly improve the signal to nose ratio of the multi-messenger astrophysics era, especially at the low frequency regime.

astro-ph.IM↗

arXiv2018

Seismic noise measures for underground gravitational wave detectors

The selection of sites for underground gravitational wave detectors based on spectral and cumulative characterisation of the low frequency seismic noise. The evaluation of the collected long term seismological data in the Mátra Gravitational and Geophysical Laboratory revealed several drawbacks of the previously established characteristics. Here we demonstrate the problematic aspects of the recent measures and suggest more robust and more reliable methodology. In particular, we show, that the mode of the data is noisy, sensitive to the discretization and intrinsic averaging, and the $rms_{2Hz}$ is burdened by irrelevant information and not adapted to the technological changes. Therefore the use of median of the data instead of the mode and also the modification of the frequency limits of the $rms$ is preferable.

astro-ph.IM↗

arXiv2017

Predictions for Cold Nuclear Matter Effects in $p+$Pb Collisions at $\sqrt{s_{_{NN}}} = 8.16$ TeV

Predictions for cold nuclear matter effects on charged hadrons, identified light hadrons, quarkonium and heavy flavor hadrons, Drell-Yan dileptons, jets, photons, gauge bosons and top quarks produced in $p+$Pb collisions at $\sqrt{s_{_{NN}}} = 8.16$ TeV are compiled and, where possible, compared to each other. Predictions of the normalized ratios of $p+$Pb to $p+p$ cross sections are also presented for most of the observables, providing new insights into the expected role of cold nuclear matter effects. In particular, the role of nuclear parton distribution functions on particle production can now be probed over a wider range of phase space than ever before.

hep-ph↗

arXiv2017

First report of long term measurements of the {MGGL} laboratory in the {M}átra mountain range

Matra Gravitational and Geophysical Laboratory (MGGL) has been established near Gyöngyösoroszi, Hungary in 2015, in the cavern system of an unused ore mine. The Laboratory is located at 88~m below the surface, with the aim to measure and analyse the advantages of the underground installation of third generation gravitational wave detectors. Specialized instruments have been installed to measure seismic, infrasound, electromagnetic noise, and the variation of the cosmic muon flux. In the preliminary (RUN-0) test period, March-August 2016, data collection has been accomplished. In this paper we describe the research potential of the MGGL, list the installed equipments and summarize the experimental results of RUN-0. Here we report RUN-0 data, that prepares systematic and synchronized data collection of the next run period.

physics.ins-det↗

arXiv2013

Pre-Excitation Studies for Rubidium-Plasma Generation

The key element in the Proton-Driven-Plasma-Wake-Field-Accelerator (AWAKE) project is the generation of highly uniform plasma from Rubidium vapor. The standard way to achieve full ionization is to use high power laser which can assure the over-barrier-ionization (OBI) along the 10 meters long active region. The Wigner-team in Budapest is investigating an alternative way of uniform plasma generation. The proposed Resonance Enhanced Multi Photon Ionization (REMPI) scheme probably can be realized by much less laser power. In the following the resonant pre-excitations of the Rb atoms are investigated, theoretically and the status report about the preparatory work on the experiment are presented.

physics.plasm-ph↗

arXiv2011

Underlying Event in pp Collisions at LHC Energies

Hadron production is investigated in proton-proton (pp) collisions at \surds = 7 TeV LHC energy - especially outside the cones of identified jets. We improved the original CDF definition of underlying event and introduce surrounding rings/belts (SB) around the cone of identified jets. We compare the characteristics of hadron production using the original CDF-based and the new SB-based via analysing PYTHIA generated fluxes of these hadrons within the geometrical regions of pp collisions.

hep-ph↗

arXiv2011

Underlying events in p+p collisions at LHC energies

General properties of hadron production are investigated in proton-proton collisions at LHC energies. We are interested in the characteristics of hadron production outside the identified jet cones. We improve earlier definitions and introduce surrounding rings/belts around the cone of identified jets. In this way even multiple jet events can be studied in details. We define the underlying event as collected hadrons from outside jet cones and outside surrounding belts, and investigate the features of these hadrons. We use a PYTHIA generated data sample of proton-proton collisions at s = (7 TeV)^2. This data sample is analysed by our new method and the widely applied CDF method. Angular correlations and momentum distributions have been studied and the obtained results are compared and discussed.

hep-ph↗

arXiv2011

VHMPID: a new detector for the ALICE experiment at LHC

This article presents the basic idea of VHMPID, an upgrade detector for the ALICE experiment at LHC, CERN. The main goal of this detector is to extend the particle identification capabilities of ALICE to give more insight into the evolution of the hot and dense matter created in Pb-Pb collisions. Starting from the physics motivations and working principles the challenges and current status of development is detailed.

hep-ex↗

arXiv2010

Jets and Underlying Events at LHC Energies

Jet-matter interaction remains a central question and a theoretical challenge in heavy-ion physics and might become important in high-multiplicity events in proton-proton collisions at LHC energies. Full jet measurement at LHC offer the proper tool to investigate energy loss process and fragmentation of hard parton in the medium. Since jet reconstruction will be constrained to small cone sizes, then study of the connection between jets and surrounding environment provides a further possibility to extend our exploration. We study jets at s = (14 TeV)^2 and pp collisions at s = (7 TeV)^2. We analyze the flavor components in jet-like environments. We introduce a definition for surrounding cones/belts and investigate flavor dependence and correlation of different hadron species produced in jets. Here, we focus on proton-triggered correlations. Our analysis can be extended for heavy ion collisions.

hep-ph↗

arXiv2008

Prospect of Rapidity Asymmetry and Nuclear Modifications

In asymmetric heavy ion collisions like dA or pA, particle production yields are different in the forward (d- or p-side) and backward (A-side) rapidity directions. The rapidity distribution reflects the geometry and phase-space distribution of nuclear matter. These properties may depend on the time evolution of the collision. Due to the smallness of the backward-forward differences, the rapidity asymmetry factor can be useful to quantify nuclear modification effects, like e.g. shadowing and the EMC effect. Our work is a survey of the nuclear modification factor and the rapidity asymmetries at RHIC energies. We analyze the rapidity dependence and the strength of the nuclear effects. We focus on the high transverse momentum region, and make predictions for the role of nuclear modifications and rapidity asymmetries for future experimental measurements at increasing absolute values of rapidity.

hep-ph↗

arXiv2008

Cold Nuclear Modifications at RHIC and LHC

We use recent nuclear parton distributions, among them the Hirai--Kumano--Nagai (HKN) and Eskola--Paukkunen--Salgado (EPS08) parameterizations, in our pQCD-improved parton model to calculate the nuclear modification factor, R_{AA'}(p_T), at RHIC and at the LHC. At RHIC, the deuteron-gold nuclear modification factor for pions, measured at p_T > 10 GeV/c in central collisions, appears to deviate more from unity than the model results. The slopes of the calculated R_{dAu}(p_T) are similar to the slopes of the PHENIX pion and photon data. At LHC, without final-state effects we see a small enhancement of R_{dPb}(p_T) in the transverse momentum range 10 GeV/c < p_T < 100 GeV/c for most parameterizations. The inclusion of final-state energy loss will reduce the R_{dPb}(p_T) values.

hep-ph↗

arXiv2008

Event-by-event transverse momentum fluctuations in nuclear collisions at CERN SPS

The latest NA49 results on event-by-event transverse momentum fluctuations are presented for central Pb+Pb interactions over the whole SPS energy range (20A - 158A GeV). Two different methods are applied: evaluating the $Φ_{p_{T}}$ fluctuation measure and studying two-particle transverse momentum correlations. The obtained results are compared to predictions of the UrQMD model. The results on the energy dependence are compared to the NA49 data on the system size dependence. The NA61 (SHINE, NA49-future) strategy of searching of the QCD critical end-point is also discussed.

nucl-ex↗

arXiv2006

Jet Tomography in the Forward Direction at RHIC

Hadron production at high-$p_T$ displays a strong suppression pattern in a wide rapidity region in heavy ion collisions at RHIC energies. This finding indicates the presence of strong final state effects for both transversally and longitudinally traveling partons, namely induced energy loss. We have developed a perturbative QCD based model to describe hadron production in $pp$ collision, which can be combined with the Glauber -- Gribov model to describe hadron production in heavy ion collisions. Investigating $AuAu$ and $CuCu$ collisions at energy $\sqrt{s}=200$ $A$GeV at mid-rapidity, we find the opacity of the strongly interacting hot matter to be proportional to the participant nucleon number. Considering forward rapidities, the suppression pattern indicates the formation of a longitudinally contracted dense deconfined zone in central heavy ion collisions. We determine parameters for the initial geometry from the existing data.

hep-ph↗

arXiv2003

Parton coalescence and antiproton/pion anomaly at RHIC

Coalescence of minijet partons with the partons from the quark-gluon plasma formed in relativistic heavy ion collisions is suggested as the mechanism for production of hadrons with intermediate transverse momentum. The resulting enhanced antiproton and pion yields at intermediate transverse momentum gives a plausible explanation for the observed large antiproton to pion ratio. With further increasing momentum, the ratio is predicted to decrease and approach the small value given by independent fragmentations of minijet partons after their energy loss in the quark-gluon plasma.

nucl-th↗