Nuclear Theory·nucl-th

Tuesday·March 30, 2021

15 papers—7 primary·8 cross-listed

01
Emergent four-body parameter in universal two-species bosonic systems
Lorenzo Contessi🇫🇷 · Johannes Kirscher🇬🇧 · Manuel Pavon Valderrama🇨🇳
The description of unitary few-boson systems is conceptually simple: only one parameter -- the three-body binding energy -- is required to predict the binding energies of clusters with an arbitrary number of bosons. Whether this correlation between the three- and many-boson systems still holds for two species of bosons for which only the inter-species interaction is resonant depends on how many particles of each species are in the system. For few-body clusters with species $A$ and $B$ and a resonant $A B$ interaction, it is known that the emergent $AA B$ and $A B B$ three-body scales are correlated to the ground-state binding energies of the $AAA B$ and $A B B B$ systems, respectively. We find that this link between three and four bodies is broken for the $AA B B$ tetramer whose binding energy is neither constrained by the $AA B$ nor by the $A B B$ trimer. From this de-correlation, we predict the existence of a scale unique to the $AA B B$ tetramer. In our explanation of this phenomenon, we understand the $AA B B$ and $AAA B$ / $A B B B$ tetramers as representatives of two different universal classes of $N$ -body systems with distinct renormalization-group and discrete-scaling properties.
nucl-thcond-mat.quant-gasphysics.atm-clusquant-phPLA(2021)·3 citations
02
Effects of Strong Magnetic Fields on the Hadron-Quark Deconfinement Transition
Betânia C. T. Backes🇧🇷 · Kauan D. Marquez🇧🇷 · Débora P. Menezes🇧🇷
The aim of the present work is to investigate the effects of strong magnetic fields on the hadron-quark phase transition point at zero temperature. To describe the hadronic phase, a relativistic mean field (RMF) model is used and to describe the quark phase a density dependent quark mass model (DDQM) is employed. As compared with the results obtained with non-magnetised matter, we observe a shift of the transition point towards higher pressures and, generally also towards higher chemical potentials. An investigation of the phase transitions that could sustain hybrid stars is also performed.
nucl-thastro-ph.HEhep-thEPJA(2021)·17 citations
03
Generation of fragment angular momentum in fission
J. Randrup🇺🇸 · R. Vogt🇺🇸
A recent analysis of experimental data [J. Wilson $e t . a l$ , Nature $590$ , 566 (2021)] found that the angular momenta of nuclear fission fragments are uncorrelated. Based on this finding, the authors concluded that the spins are therefore determined only $a f t er$ scission has occurred. We show here that the nucleon-exchange mechanism, as implemented in the well-established event-by-event fission model $FREYA$ , while agitating collective rotational modes in which the two spins are highly correlated, nevertheless leads to fragment spins that are largely uncorrelated. This fact invalidates the reasoning of those authors. Furthermore, it was reported [J. Wilson $e t . a l$ , Nature $590$ , 566 (2021)] that the mass dependence of the average fragment spin has a sawtooth structure. We demonstrate that such a behavior naturally emerges when shell and deformation effects are included in the moments of inertia of the fragments at scission.
nucl-thPRL(2021)·69 citations
04
Higher order cumulants of transverse momentum and harmonic flow in relativistic heavy ion collisions
Piotr Bozek🇵🇱 · Rupam Samanta🇵🇱
Higher order symmetric cumulants of global collective observables in heavy ion collisions are studied. The symmetric cumulants can be straightforwardly constructed for scalar observables: the average transverse momentum, the multiplicity, and the squares of harmonic flow vectors. Third and fourth order cumulants are calculated in the hydrodynamic model. A linear predictor of the average transverse momentum and harmonic flow coefficients in a collision is used to predict the value of the cumulants from the moments of the initial distribution. The symmetric cumulants divided by the averages (or the standard deviations) of the considered observables can be used as a fine tool to study correlations present in the initial state of the collision.
nucl-thnucl-exPRC(2021)·17 citations
05
QCD at finite chemical potential in and out-of equilibrium
Olga Soloveva🇩🇪 · Pierre Moreau🇺🇸 · Elena Bratkovskaya🇩🇪
We review the transport properties of the strongly interacting quark-gluon plasma (QGP) created in heavy-ion collisions at ultrarelativistic energies, i.e. out-of equilibrium, and compare them to the equilibrium properties. The description of the strongly interacting (non-perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_{c}$ from lattice QCD. We study the transport coefficients such as the ratio of shear viscosity and bulk viscosity over entropy density, diffusion coefficients, electric conductivity etc. versus temperature and baryon chemical potential. Based on a microscopic transport description of heavy-ion collisions we, furthermore, discuss which observables are sensitive to the QGP formation and its properties.
nucl-thhep-phPhys.Scripta(2021)·4 citations
06
Nuclear Fermi Momenta of $^{2}$ H, $^{27}$ Al and $^{56}$ Fe from an Analysis of CLAS data
Hui Liu🇨🇳 · Na-Na Ma🇨🇳 · Rong Wang🇨🇳
Nuclear Fermi momentum is a basic property of a nucleus where many nucleons dwell. However, in experiments only the nuclear Fermi momenta of just a few nuclei are measured using quasielastic electron scattering on the nuclear targets so far. Particularly, we still do not know experimentally the Fermi momentum of the lightest nucleon composite -- the deuteron. In this paper, we apply both gaussian distribution and Cauchy distribution to describe the quasielastic peak in the cross section of electron-nucleus scattering. The dip of the cross-section ratio at about $x_{B} = 1$ is explained with the nuclear Fermi momentum. By performing the least-square fits to the published CLAS data in the narrow kinematic region of quasielastic scattering, we obtain the nuclear Fermi momenta of $^{2}$ H, $^{27}$ Al and $^{56}$ Fe, which are $116 \pm 7$ MeV/c, $232 \pm 27$ MeV/c, and $244 \pm 28$ MeV/c respectively. The extracted nuclear Fermi momenta are compared to the simple calculations based on Fermi gas model, and the consistencies are found.
nucl-thnucl-exNPA(2022)·1 citation
07
Deuteron-Deuteron Correlation Function in Nucleus-Nucleus Collisions
Stanislaw Mrowczynski🇵🇱 · Patrycja Slon🇵🇱
A formula of the $D$ - $D$ correlation function is derived. The deuterons are treated either as elementary particles or as neutron-proton bound states. In the first case the deuterons are directly emitted from a source and in the second one the deuteron formation is a final-state process simultaneous with a generation of $D$ - $D$ correlation. The source radius of deuterons formed due to final-state interactions is bigger by the factor of $2$ than that of directly emitted deuterons. To check how sizable is the effect we compute the $D$ - $D$ correlation function taking into the Bose-Einstein statistics of deuterons, the $s$ -wave scattering due to strong interaction and the Coulomb repulsion. The correlation function is shown to be sensitive to the source radius for sources which are sufficiently small with RMS radii smaller than 3.5 fm. Otherwise the correlation function is dominated by the Coulomb repulsion and weakly depends on the source radius. Measurements which can make use of our finding are discussed.
nucl-thhep-phPRC(2021)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE

Emergent four-body parameter in universal two-species bosonic systems

Effects of Strong Magnetic Fields on the Hadron-Quark Deconfinement Transition

Generation of fragment angular momentum in fission

Higher order cumulants of transverse momentum and harmonic flow in relativistic heavy ion collisions

QCD at finite chemical potential in and out-of equilibrium

Nuclear Fermi Momenta of 2H, 27Al and 56Fe from an Analysis of CLAS data

Deuteron-Deuteron Correlation Function in Nucleus-Nucleus Collisions

Affiliations

Nuclear Fermi Momenta of $^{2}$ H, $^{27}$ Al and $^{56}$ Fe from an Analysis of CLAS data