Publications (45)
Exploring Effective Three-body Forces
Alexander Volya
Topics related to the construction, phenomenological determination, and effects of the effective three-body forces within the traditional nuclear shell model approach are discussed…
Solving the pairing problem with exact particle number conservation
Alexander Volya, Vladimir Zelevinsky
This paper has been withdrawn by the authors
Nuclear pairing and Coriolis effects in proton emitters
Alexander Volya, Cary Davids
We introduce a Hartree-Fock-Bogoliubov mean-field approach to treat the problem of proton emission from a deformed nucleus. By substituting a rigid rotor in a particle-rotor-model…
Motivations for Early High-Profile FRIB Experiments
B. Alex Brown, Alexandra Gade, S. Ragnar Stroberg +39
This white paper is the result of a collaboration by those that attended a workshop at the Facility for Rare Isotope Beams (FRIB), organized by the FRIB Theory Alliance (FRIB-TA),…
Discrete and continuum spectra in the unified shell model approach
Alexander Volya, Vladimir Zelevinsky
A new version of the nuclear shell model unifies the consideration of the discrete spectrum, where the results agree with the standard shell model, and continuum. The ingredients o…
Exact solution of the nuclear pairing problem
Alexander Volya, B. Alex Brown, Vladimir Zelevinsky
In many applications to finite Fermi-systems, the pairing problem has to be treated exactly. We suggest a numerical method of exact solution based on SU(2) quasispin algebras and d…
Emergence of symmetry from random n-body interactions
Alexander Volya
An ensemble with random n-body interactions is investigated in the presence of symmetries. A striking emergence of regularities in spectra, ground state spins and isospins is disco…
Multiple pion production from an oriented chiral condensate
Alexander Volya, Scott Pratt, Vladimir Zelevinsky
We consider an ``oriented'' chiral condensate produced in the squeezed states of the effective field theory with time- and space-dependent pion mass parameter. We discuss the gener…
Modeling Pionic Fusion
Alexander Volya, Scott Pratt, Vladimir Zelevinsky
Recently observed rare heavy ion fusion processes, where the entire available energy is carried away by a single pion, is an example of extreme collectivity in nuclear reactions. W…
Nuclear Schiff moment and soft vibrational modes
Vladimir Zelevinsky, Alexander Volya, Naftali Auerbach
The atomic electric dipole moment (EDM) currently searched by a number of experimental groups requires that both parity and time-reversal invariance be violated. According to curre…
Theoretical Studies of alpha Clustering in Nuclei and Beyond
Takaharu Otsuka, Alexander Volya, Naoyuki Itagaki
This article comprises three sections. Section 2 starts with a review of ab initio no-core shell model calculations by Monte Carlo Shell Model. Alpha clustering arises for 8,10,12B…
Porter-Thomas distribution in unstable many-body systems
Alexander Volya
We use the continuum shell model approach to explore the resonance width distribution in unstable many-body systems. The single-particle nature of a decay, the few-body character o…
Exploring quantum dynamics in an open many-body system: Transition to superradiance
Alexander Volya, Vladimir Zelevinsky
We study the dynamics of a complex open quantum many-body system. The coupling to external degrees of freedom can be viewed as a coupling to a radiation field, to continuum states…
Continuum Shell Model
Alexander Volya, Vladimir Zelevinsky
The Continuum Shell Model is an old but recently revived method that traverses the boundary between nuclear many-body structure and nuclear reactions. The method is based on the no…
The role of E1-E2 interplay in multiphonon Coulomb excitation
Alexander Volya, Henning Esbensen
In this work we study the problem of a charged particle, bound in a harmonic-oscillator potential, being excited by the Coulomb field from a fast charged projectile. Based on a cla…
A soft mode in a finite Fermi-system: anharmonic effects near the instability point
Vladimir Zelevinsky, Alexander Volya
We consider a finite Fermi-system where the residual interactions create a soft mode of the excitation spectrum. Because of the large vibrational amplitude, the standard random pha…
Many-Body Physics on the Border of Nuclear Stability
Alexander Volya, Vladimir Zelevinsky
A brief overview is given of the Continuum Shell Model, a novel approach that extends the traditional nuclear shell model into the domain of unstable nuclei and nuclear reactions.…
Coherent and chaotic properties of nuclear pairing
Alexander Volya, Vladimir Zelevinsky, B. Alex Brown
The properties of the pairing interaction in the shell model framework are considered with the aid of the exact numerical solution utilizing the quasispin symmetry. We emphasize th…
Non-exponential and oscillatory decays in quantum mechanics
Murray Peshkin, Alexander Volya, Vladimir Zelevinsky
The quantum-mechanical theory of the decay of unstable states is revisited. We show that the decay is non-exponential both in the short-time and long-time limits using a more physi…
Measurement of the reaction and impact on the reaction rate
Eli Temanson, Jessica Baker, Sean Kuvin +6
The reaction is part of a reaction network with impact on the observed galactic Al abundance. A new determination of the proton strength of t…
Applications of Continuum Shell Model
Alexander Volya
The nuclear many-body problem at the limits of stability is considered in the framework of the Continuum Shell Model that allows a unified description of intrinsic structure and re…
Neutron Resonance Widths and the Porter-Thomas Distribution
Alexander Volya, Hans A. Weidenmüller, Vladimir Zelevinsky
Experimental evidence has recently put the validity of the Porter-Thomas distribution (PTD) for partial neutron widths into question. We identify two terms in the effective Hamilto…
Super-Radiance: From Nuclear Physics to Pentaquarks
Vladimir Zelevinsky, Alexander Volya
The phenomenon of super-radiance in quantum optics predicted by Dicke 50 years ago and observed experimentally has its counterparts in many-body systems on the borderline between d…
Assessment of the beta-delayed proton decay rate of Be
Alexander Volya
The Be neutron halo nucleus appears to decay into Be with a rate that exceeds expectations. Neutron disappearance into dark matter, beta decay of a halo neutron, or b…
Chaotic wave functions and exponential convergence of low-lying energy eigenvalues
Mihai Horoi, Alexander Volya, Vladimir Zelevinsky
We suggest that low-lying eigenvalues of realistic quantum many-body hamiltonians, given, as in the nuclear shell model, by large matrices, can be calculated, instead of the full d…
Randomness and collectivity in nuclear structure: Three theoretical puzzles
Vladimir Zelevinsky, Alexander Volya
We show and interpret three examples of nontrivial results obtained in numerical simulations of many-body systems: exponential convergence of low-lying energy eigenvalues in the pr…
Nuclear Many-Body Physics Where Structure And Reactions Meet
Naureen Ahsan, Alexander Volya
The path from understanding a simple reaction problem of scattering or tunneling to contemplating the quantum nuclear many-body system, where structure and continuum of reaction-st…
Time-dependent relaxation of observables in complex quantum systems
Alexander Volya, Vladimir Zelevinsky
We consider time-dependent relaxation of observables in quantum systems of chaotic and regular type. We show that the spread of the wave function in the Hilbert space is determined…
Quadrupole collectivity in random two-body ensembles
Volha Abramkina, Alexander Volya
We conduct a systematic investigation of the nuclear collective dynamics that emerges in systems with random two-body interactions. We explore the development of the mean field and…
Nuclear Structure, Random Interactions and Mesoscopic Physics
Vladimir Zelevinsky, Alexander Volya
Standard concepts of nuclear physics explaining the systematics of ground state spins in nuclei by the presence of specific coherent terms in the nucleon-nucleon interaction were p…
Quantum Tunneling and Scattering of a Composite Object: Revisited and Reassessed
Naureen Ahsan, Alexander Volya
This work presents an extensive exploration of scattering and tunneling involving composite objects with intrinsic degrees of freedom. We aim at exact solutions to such scattering…
Manifestation of three-body forces in f7/2-shell nuclei
Alexander Volya
The traditional nuclear shell model approach is extended to include many-body forces. The empirical Hamiltonian with a three-body force is constructed for the identical nucleons on…
Nuclear pairing: new perspectives
Vladimir Zelevinsky, Alexander Volya
Nuclear pairing correlations are known to play an important role in various single-particle and collective aspects of nuclear structure. After the first idea by A. Bohr, B. Mottels…
Thermodynamics of pairing in mesoscopic systems
Tony Sumaryada, Alexander Volya
Using numerical and analytical methods implemented for different models we conduct a systematic study of thermodynamic properties of pairing correlation in mesoscopic nuclear syste…
Study of nuclear pairing with Configuration-Space Monte-Carlo approach
Mark Lingle, Alexander Volya
Pairing correlations in nuclei play a decisive role in determining nuclear drip-lines, binding energies, and many collective properties. In this work a new Configuration-Space Mont…
From bound states to the continuum
Calvin W. Johnson, Kristina D. Launey, Naftali Auerbach +35
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 bo…
Are the ground states of randomly interacting bosons random?
Charles White, Alexander Volya, Declan Mulhall +1
Bosonic degrees of freedom and their emergence as a part of complex quantum many-body dynamics, symmetries, collective behavior, clustering and phase transitions play an important…
Order generated by random many-body dynamics
Alexander Volya, Vladimir Zelevinsky
New features related to collective properties generated in the systems driven by random dynamics are observed and their implications for further understanding of interplay between…
Invariant correlational entropy as a signature of quantum phase transitions in nuclei
Alexander Volya, Vladimir Zelevinsky
We study phase transformations in finite nuclei as a function of interaction parameters. The signature of a transition is given by invariant correlational entropy that reflects the…
Constructing realistic alpha cluster channels
Konstantinos Kravvaris, Alexander Volya
We present techniques that allow for -cluster channels with realistic -particle wave functions from No Core Shell Model calculations to be constructed. We compare results o…
The nuclear pairing problem: new perspectives
Vladimir Zelevinsky, Alexander Volya
The overview of the Exact Pairing technique based on the quasispin symmetry is presented. Extensions of this method are discussed in relation to mean field, quadrupole collectivity…
Computational approaches to many-body dynamics of unstable nuclear systems
Alexander Volya
The goal of this presentation is to highlight various computational techniques used to study dynamics of quantum many-body systems. We examine the projection and variable phase met…
Exploring the nuclear pion dispersion relation through the anomalous coupling of photon to photon and neutral pion
Alexander Volya, Kevin Haglin, Scott Pratt +1
We investigate the possibility of measuring the pion dispersion relation in nuclear matter through the anomalous coupling in the reaction γ- γ' Ï_0. It is shown that this reacti…
Effective non-Hermitian Hamiltonian and continuum shell model
Alexander Volya, Vladimir Zelevinsky
The intrinsic dynamics of a system with open decay channels is described by an effective non-Hermitian Hamiltonian which at the same time allows one to find the external dynamics,…
Interplay of pairing and multipole interactions in a simple model
Alexander Volya
The interplay of pairing and other interactions is addressed in this work using a simple single-j model. We show that enhancements in pairing correlations observed through studies…