arXiv subjects

Marek Ploszajczak

Publications and source records attributed to Marek Ploszajczak.

7 recordsLinked to original sources

arXiv2024

B(E2) strength in $^{36,38}$Ca and in mirror nuclei 36S, 38Ar

Recently, $B(E2, 0^+_1 \to 2^+_1)$ transition strength have been measured in $^{36}$Ca and $^{38}$Ca. Surprisingly, the measured value in $^{36}$Ca: $B(E2\ \uparrow) = 131(20)$ e$^2$fm$^4$, is significantly larger than in $^{38}$Ca, where $B(E2\ \uparrow) = 101(11)$ e$^2$fm$^4$, whereas an opposite tendency of $B(E2)$ values is seen in the mirror nuclei $^{36}$S and $^{38}$Ar. The resonance $2^+_1$ in $^{36}$Ca lies 465 keV above the proton emission threshold and its description requires inclusion of the coupling to the continuum. In this work, we are analyzing $B(E2\ \uparrow)$ values in $^{36}$Ca, $^{36}$S, $^{38}$Ca, and $^{38}$Ar using the real-energy continuum shell model, the so-called shell model embedded in the continuum, in the $(1s_{1/2}\, 0d_{3/2}\, 0f_{7/2}\, 1p_{3/2})$ model space with the monopole adjusted effective interaction ZBM-IO.

nucl-th↗

arXiv2020

From bound states to the continuum

This white paper reports on the discussions of the 2018 Facility for Rare Isotope Beams Theory Alliance (FRIB-TA) topical program "From bound states to the continuum: Connecting bound state calculations with scattering and reaction theory". One of the biggest and most important frontiers in nuclear theory today is to construct better and stronger bridges between bound state calculations and calculations in the continuum, especially scattering and reaction theory, as well as teasing out the influence of the continuum on states near threshold. This is particularly challenging as many-body structure calculations typically use a bound state basis, while reaction calculations more commonly utilize few-body continuum approaches. The many-body bound state and few-body continuum methods use different language and emphasize different properties. To build better foundations for these bridges, we present an overview of several bound state and continuum methods and, where possible, point to current and possible future connections.

nucl-th↗

arXiv2008

Two-proton radioactivity

In the first part of the present review paper, experimental results which lead to the discovery of two-proton radioactivity are reviewed. Beyond two-proton emission from nuclear ground states, we also discuss experimental studies of two-proton emission from excited states populated either by nuclear beta decay or by inelastic reactions. In the second part, we review the modern theory of two-proton radioactivity. An outlook to future experimental studies and theoretical developments will conclude this review.

nucl-ex↗

arXiv2001

Phase Transitions in Non-extensive Spin Systems

The spherical spin model with infinite-range ferromagnetic interactions is investigated analytically in the framework of non-extensive thermostatics generalizing the Boltzmann-Gibbs statistical mechanics. We show that for repulsive correlations, a new weak-ferromagnetic phase develops. There is a tricritical point separating para, weak-ferro and ferro regimes. The transition from paramagnetic to weak-ferromagnetic phase is an unusual first order phase transition in which a discontinuity of the averaged order parameter appears, even for finite number of spins. This result puts in a new way the question of the stability of critical phenomena with respect to the long-ranged correlations.

cond-mat.stat-mech↗

arXiv2000

Universal features of fluctuations

Universal scaling laws of fluctuations (the $Δ$-scaling laws) can be derived for equilibrium and off-equilibrium systems when combined with the finite-size scaling analysis. In any system in which the second-order critical behavior can be identified, the relation between order parameter, criticality and scaling law of fluctuations has been established and the relation between the scaling function and the critical exponents has been found.

hep-ph↗

arXiv1999

Universal features of the off-equilibrium fragmentation with the Gaussian dissipation

We investigate universal features of the off-equilibrium sequential and conservative fragmentation processes with the dissipative effects which are simulated by the Gaussian random inactivation process. The relation between the fragment multiplicity scaling law and the fragment size distribution is studied and a dependence of scaling exponents on the parameters of fragmentation and inactivation rate functions is established.

cond-mat.stat-mech↗

arXiv1995

Scaling and universality in binary fragmenting with inhibition

We investigate a new model of binary fragmentation with inhibition, driven by the white noise. In a broad range of fragmentation probabilities, the power-law spatiotemporal correlations are found to arise due to self-organized criticality (SOC). We find in the SOC phase a non-trivial power spectrum of the temporal sequence of the fragmentation events. The $1/f$~ behaviour is recovered in the irreversible, near-equilibrium part of this phase.

adap-org↗