Nuclear Theory·nucl-th

Thursday·March 7, 2019

14 papers—8 primary·6 cross-listed

01
Odd-mass nuclei in the cluster shell model
R. Bijker · A.H. Santana-Valdés
In this contribution, we present the cluster shell model which is analogous to the Nilsson model, but for cluster potentials. Special attention is paid to the consequences of the discrete symmetries of three alpha-particles in an equilateral triangle configuration. This configuration is characterized by a special structure of the rotational bands which can be used as a fingerprint of the underlying geometric configuration. The cluster shell model is applied to the nucleus 13C.
nucl-thnucl-exJ.Phys.Conf.Ser.(2019)·2 citations
02
Electromagnetic couplings of pentaquarks
E. Ortiz-Pacheco🇲🇽 · R. Bijker🇲🇽
In this contribution, we discuss the electromagnetic couplings of pentaquark states with hidden charm. This work is motivated by recent experiments at CERN by the LHCb Collaboraton and current experiments at JLab to confirm the existence of hidden-charm pentaquarks in photoproduction experiments.
nucl-thhep-exhep-phnucl-exJ.Phys.Conf.Ser.(2019)·0 citations
03
The symmetry energy of the nuclear EoS: a study of collective motion and low-energy reaction dynamics in semiclassical approaches
Stefano Burrello · Maria Colonna · Hua Zheng
In the framework of mean-field based transport approaches, we discuss recent results concerning collective motion and low-energy heavy ion reactions involving neutron-rich systems. We focus on aspects which are particularly sensitive to the isovector terms of the nuclear effective interaction and the corresponding symmetry energy. As far as collective excitations are concerned, we discuss the mixed nature of dipole oscillations in neutron-rich systems. On the other hand, for reactions close to the Coulomb barrier, we investigate the structure of pre-equilibrium collective dipole oscillations, focusing on their sensitivity to the symmetry energy behavior below normal density. Nucleon emission is also considered within the same context. The possible impact of other relevant terms of the nuclear effective interaction on these mechanisms is also examined. From this analysis we expect to put further constraints on the nuclear Equation of State, of crucial importance also in the astrophysical context.
nucl-thFront.in Phys.(2019)·15 citations
04
Photoproduction of $K^{+} Λ$ with a Regge-plus-resonance model
Petr Bydžovský🇨🇿 · Dalibor Skoupil🇨🇿
Making use of the hybrid Regge-plus-resonance model, we investigate the process of kaon photoproduction off the proton target. We present a new model whose free parameters were adjusted to data in and above the resonance region and which provides an acceptable description of experimental data. The overwhelming majority of nucleon resonances selected in this analysis overlaps with those selected in our previous analyses and also with the Bayesian analysis with the Regge-plus-resonance model, which we deem to be dependable. A novel feature of our model consists in applying a different scheme for gauge-invariance restoration, which results in a need for implementing a contact current. As we further reveal, the choice of the gauge invariance restoration scheme as well as the choice of either pseudoscalar or pseudovector coupling in the strong vertex play a significant role for cross-section predictions at forward angles where data are scarce.
nucl-thPRC(2019)·13 citations
05
Volume fluctuation and multiplicity correlation on higher-order cumulants
Tetsuro Sugiura🇯🇵 · Toshihiro Nonaka🇨🇳 · ShinIchi Esumi🇯🇵
Initial volume fluctuation (VF) arising from the participant fluctuation would be the background which should be subtracted experimentally from the measured higher-order cumulants. We study the validity of the Volume Fluctuation Correction (VFC) on higher-order net-proton cumulants by using simple toy model and UrQMD model in Au+Au collisions at \sqrt s_{NN} = 200 GeV for various centrality definitions. The results are compared to the conventional data driven method called Centrality Bin Width Correction (CBWC). We find VFC works well in toy model assuming independent particle production (IPP), but does not seem to work well in UrQMD model. It is also found that cumulants are strongly affected by the multiplicity correlation effect as well as the centrality resolution effect. These results show that neither VFC nor CBWC are perfect method. Thus, both methods should be compared in the real experiment.
nucl-thhep-exhep-phPRC(2019)·25 citations
06
Effects of quantum statistics near the critical point of nuclear matter
S.N. Fedotkin · A.G. Magner · M.I. Gorenstein
Effects of quantum statistics for nuclear matter equation of state are analyzed in terms of the recently proposed quantum van der Waals model. The system pressure is expanded over a small parameter $δ \propto n (m T)^{- 3/2} [g (1 - bn)]^{- 1}$ , where $n$ and $T$ are, respectively, the particle number density and temperature, $m$ and $g$ the particle mass and degeneracy factor. The parameter $b$ corresponds to the van der Waals excluded volume. The corrections due to quantum statistics for the critical point values of $T_{c}$ , $n_{c}$ , and the critical pressure $P_{c}$ are found within the linear and quadratic orders over $δ$ . These approximate analytical results appear to be in a good agreement with exact numerical calculations in the quantum van der Waals model for interacting Fermi particles: the symmetric nuclear matter ( $g = 4$ ) and the pure neutron matter ( $g = 2$ ). They can be also applied to the system of interacting Bose particles like the matter composed of $α$ nuclei.
nucl-thPRC(2019)·8 citations
07
Influence of orthogonalization procedure on astrophysical S-factor for the direct $α + d$ $\to$ $^{6}$ Li + $γ$ capture process in a three-body model
E.M. Tursunov · A.S. Kadyrov
The astrophysical S-factor for the direct $α (d, γ)^{6} Li$ capture reaction is calculated in a three-body model based on the hyperspherical Lagrange-mesh method. A sensitivity of the E1 and E2 astrophysical S-factors to the orthogonalization method of Pauli forbidden states in the three-body system is studied. It is found that the method of orthogonalising pseudopotentials (OPP) yields larger isotriplet ( $T = 1$ ) components than the supersymmetric transformation (SUSY) procedure. The E1 astrophysical S-factor shows the same energy dependence in both cases, but strongly different absolute values. At the same time, the E2 S-factor does not depend on the orthogonalization procedure. As a result, the OPP method yields a very good description of the direct data of the LUNA collaboration at low energies, while the SUSY transformation strongly underestimates the LUNA data. \keywords{three-body model; orthogonalization method; astrophysical S factor.
nucl-thInt.J.Mod.Phys.Conf.Ser.(2019)·1 citation
08
A statistical analysis of the nuclear structure uncertainties in $μ$ D
Oscar J. Hernandez🇩🇪 · Sonia Bacca🇩🇪 · Nir Barnea🇮🇱 · Nir Nevo-Dinur🇨🇦 · Andreas Ekström🇸🇪 · Chen Ji🇨🇳
The charge radius of the deuteron (D), was recently determined to three times the precision compared with previous measurements using the measured Lamb shift in muonic deuterium (muD). However, the muD value is 5.6 $σ$ smaller than the world averaged CODATA-2014 value [1]. To shed light on this discrepancy we analyze the uncertainties of the nuclear structure calculations of the Lamb shift in muD and conclude that nuclear theory uncertainty is not likely to be the source of the discrepancy.
nucl-thSpringer Proc.Phys.(2020)·1 citation

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first authorsco-authorsvia INSPIRE