arXiv subjects

P. Kovács

Publications and source records attributed to P. Kovács.

11 recordsLinked to original sources

arXiv2022

Observation of large scale precursor correlations between cosmic rays and earthquakes

The search for correlations between secondary cosmic ray detection rates and seismic effects has long been a subject of investigation motivated by the hope of identifying a new precursor type that could feed a global early warning system against earthquakes. Here we show for the first time that the average variation of the cosmic ray detection rates correlates with the global seismic activity to be observed with a time lag of approximately two weeks, and that the significance of the effect varies with a periodicity resembling the undecenal solar cycle, with a shift in phase of around three years, exceeding 6 sigma at local maxima. The precursor characteristics of the observed correlations point to a pioneer perspective of an early warning system against earthquakes.

physics.geo-ph↗

arXiv2017

Mass shift of charmonium states in $\bar p A$ collision

The masses of the low lying charmonium states, namely, the $J/Ψ$, $Ψ(3686)$, and $Ψ(3770)$ are shifted downwards due to the second order Stark effect. In $\bar p + \text{Au}$ collisions at $6-10$ GeV we study their in\,-\,medium propagation. The time evolution of the spectral functions of these charmonium states is studied with a Boltzmann\,-\,Uehling\,-\,Uhlenbeck (BUU) type transport model. We show that their in\,-\,medium mass shift can be observed in the dilepton spectrum. Therefore, by observing the dileptonic decay channel of these low lying charmonium states, especially for $Ψ(3686)$, we can gain information about the magnitude of the gluon condensate in nuclear matter. This measurement could be performed at the upcoming PANDA experiment at FAIR.

hep-ph↗

arXiv2017

The phase diagram in the vector meson extended linear sigma model

We investigate the chiral phase transition of the strongly interacting matter at nonzero temperature and baryon chemical potential $μ_B$ within an extended (2+1) flavor Polyakov constituent quark-meson model which incorporates the effect of the vector and axial vector mesons. The parameters of the model are determined by comparing masses and tree-level decay widths with experimental values. We examine the restoration of the chiral symmetry by monitoring the temperature evolution of condensates. We study the $T-ρ_B$ phase diagram of the model and find that a critical end point exists, although at very low density.

hep-ph↗

arXiv2017

Charmonium spectral functions in $\bar p A$ collision

We study the in-medium propagation of low-lying charmonium states: $J/Ψ$, $Ψ$(3686), and $Ψ$(3770) in a $\bar p$ Au $10$ GeV collision. This energy regime will be available for the PANDA experiment. The time evolution of the spectral functions of the charmonium states is studied with a BUU type transport model. We observe a substantial effect of the medium in the dilepton spectrum.

nucl-th↗

arXiv2015

Probability density functions for the variable solar wind near the solar cycle minimum

Unconditional and conditional statistics is used for studying the histograms of magnetic field multi-scale fluctuations in the solar wind near the solar cycle minimum in 2008. The unconditional statistics involves the magnetic data during the whole year 2008. The conditional statistics involves the magnetic field time series splitted into concatenated subsets of data according to a threshold in dynamic pressure. The threshold separates fast stream leading edge compressional and trailing edge uncompressional fluctuations. The histograms obtained from these data sets are associated with both large-scale (B) and small-scale (δB) magnetic fluctuations, the latter corresponding to time-delayed differences. It is shown here that, by keeping flexibility but avoiding the unnecessary redundancy in modeling, the histograms can be effectively described by a limited set of theoretical probability distribution functions (PDFs), such as the normal, log-normal, kappa and logkappa functions. In a statistical sense the model PDFs correspond to additive and multiplicative processes exhibiting correlations. It is demonstrated here that the skewed small-scale histograms inherent in turbulent cascades are better described by the skewed log-kappa than by the symmetric kappa model. Nevertheless, the observed skewness is rather small, resulting in potential difficulties of estimation of the third-order moments. This paper also investigates the dependence of the statistical convergence of PDF model parameters, goodness of fit and skewness on the data sample size. It is shown that the minimum lengths of data intervals required for the robust estimation of parameters is scale, process and model dependent.

physics.space-ph↗

arXiv2014

Chiral phase transition in an extended linear sigma model: initial results

We investigate the scalar meson mass dependence on the chiral phase transition in the framework of an SU(3), (axial)vector meson extended linear sigma model with additional constituent quarks and Polyakov loops. We determine the parameters of the Lagrangian at zero temperature in a hybrid approach, where we treat the mesons at tree-level, while the constituent quarks at 1-loop level. We assume two nonzero scalar condensates and together with the Polyakov-loop variables we determine their temperature dependence according to the 1-loop level field equations.

hep-ph↗

arXiv2012

Efficient implementations of minimum-cost flow algorithms

This paper presents efficient implementations of several algorithms for solving the minimum-cost network flow problem. Various practical heuristics and other important implementation aspects are also discussed. A novel result of this work is the application of Goldberg's recent partial augment-relabel method in the cost-scaling algorithm. The presented implementations are available as part of the LEMON open source C++ optimization library (\url{http://lemon.cs.elte.hu/}). The performance of these codes is compared to well-known and efficient minimum-cost flow solvers, namely CS2, RelaxIV, MCF, and the corresponding method of the LEDA library. According to thorough experimental analysis, the presented cost-scaling and network simplex implementations turned out to be more efficient than LEDA and MCF. Furthermore, the cost-scaling implementation is competitive with CS2. The RelaxIV algorithm is often much slower than the other codes, although it is quite efficient on particular problem instances.

cs.DM↗

arXiv2012

Comment on "Finite Size Corrections to the Radiation Reaction Force in Classical Electrodynamics" [arXiv:1005.2617]

In [1, arXiv:1005.2617] effective field theory methods have been employed to compute the equations of motion of a spherically symmetric charged shell of radius R, taking into account the radiation reaction force exerted by the shell's own electromagnetic field up to O(R^2). The authors of Ref. [1] have stated that the known result for the self force of the shell as can be found from Eq. (16.28) of the textbook of Jackson [2] (see also Chap. 4 in the review of Pearle [3]) is incorrect, in that the term linear in R should be absent. We claim that this conclusion of Ref. [1] is incorrect, and that the textbook result, Eq. (1) does hold.

gr-qc↗

arXiv2008

Pion condensation in the two--flavor chiral quark model at finite baryochemical potential

Pion condensation is studied at one--loop level and nonzero baryochemical potential in the framework of two flavor constituent quark model using the one--loop level optimized perturbation theory for the resummation of the perturbative series. A Landau type of analysis is presented for the investigation of the phase boundary between the pion condensed/non-condensed phases. The statement that the condensation starts at $\muI = m_π$ is slightly modified by one--loop corrections. The second order critical surface is determined and analysed in the $\muI-\muB-T$ space. The $\muI$ dependence of the one--loop level charged pion pole masses is also studied.

hep-ph↗

arXiv2004

Scaling and singularity characteristics of solar wind and magnetospheric fluctuations

Preliminary results are presented which suggest that scaling and singularity characteristics of solar wind and ground based magnetic fluctuations appear to be a significant component in the solar wind - magnetosphere interaction processes. Of key importance is the intermittence of the "magnetic turbulence" as seen in ground based and solar wind magnetic data. The methods used in this paper (estimation of flatness and multifractal spectra) are commonly used in the studies of fluid or MHD turbulence. The results show that single observatory characteristics of magnetic fluctuations are different from those of the multi-observatory AE-index. In both data sets, however, the influence of the solar wind fluctuations is recognizable. The correlation between the scaling/singularity features of solar wind magnetic fluctuations and the corresponding geomagnetic response is demonstrated in a number of cases. The results are also discussed in terms of patchy reconnection processes in magnetopause and forced or/and self-organized criticality (F/SOC) of internal magnetosphere dynamics.

physics.space-ph↗

arXiv2002

Lattice study of the Coleman--Weinberg mass in the SU(2)-Higgs model

Radiative symmetry breaking is a well known phenomenon in perturbation theory. We study the problem in a non-perturbative framework, i.e. lattice simulations. The example of the bosonic sector of the SU(2)-Higgs model is considered. We determine the minimal scalar mass which turns out to be higher than the mass value given by 1-loop continuum perturbation theory.

hep-lat↗