Nuclear Theory·nucl-th

Wednesday·November 22, 2017

12 papers—9 primary·3 cross-listed

01
Medium-mass hypernuclei and the nucleon-isospin dependence of the three-body hyperon-nucleon-nucleon force
Diego Lonardoni🇺🇸 · Francesco Pederiva🇮🇹
We report quantum Monte Carlo calculations of single- $Λ$ hypernuclei for $A < 50$ based on phenomenological two- and three-body hyperon-nucleon forces. We present results for the $Λ$ separation energy in different hyperon orbits, showing that the accuracy of theoretical predictions exceeds that of currently available experimental data, especially for medium-mass hypernuclei. We show the results of a sensitivity study that indicates the possibility to investigate the nucleon-isospin dependence of the three-body hyperon-nucleon-nucleon force in the medium-mass region of the hypernuclear chart, where new spectroscopy studies are currently planned. The importance of such a dependence for the description of the physics of hypernuclei, and the consequences for the prediction of neutron star properties are discussed.
nucl-th19 citations
02
Post-prior equivalence for transfer reactions with complex potentials
Jin Lei🇺🇸 · Antonio M. Moro🇪🇸
In this paper, we address the problem of the post-prior equivalence in the calculation of inclusive breakup and transfer cross sections. For that, we employ the model proposed by Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985)], conveniently generalized to include the part of the cross section corresponding the transfer to bound states. We pay particular attention to the case in which the unobserved particle is left in a bound state of the residual nucleus, in which case the theory prescribes the use of a complex potential, responsible for the spreading width of the populated single-particle states. We see that the introduction of this complex potential gives rise to an additional term in the prior cross section formula, not present in the usual case of real binding potentials. The equivalence is numerically tested for reaction induced by deuterons.
nucl-thPRC(2018)·24 citations
03
The property difference between the neutron star PSR J0348+0432 and its proto neutron star
Xian-Feng Zhao🇨🇳
The property difference between the neutron star PSR J0348+0432 and its proto neutron star is studied in the framework of the relativistic mean field theory considering neutrino trapping. We see that the central baryon number density of the proto neutron star PSR J0348+0432 is in the range $ρ_{c, P N S} = 0.539 \sim 0.698$ fm $^{- 3}$ , which is smaller than that of the neutron star PSR J0348+0432 $ρ_{c, N S} = 0.634 \sim 0.859$ fm $^{- 3}$ . Inside the neutron star PSR J0348+0432, only the neutrons, protons, $Λ$ and $Ξ^{-}$ produce, whereas the hyperons $Σ^{-}, Σ^{0}, Σ^{+}$ and $Ξ^{0}$ all do not appear. But in the proto neutron star PSR J0348+0432, hyperons $Σ^{-}$ , $Σ^{0}$ , $Σ^{+}$ and $Ξ^{0}$ all will produce, though their relative particle number density are still very small, no more than 2\%. This shows that higher temperature will be advantageous to the hyperon production.
nucl-thInt.J.Mod.Phys.D(2017)·6 citations
04
Photon Scattering off Nuclei
Hartmuth Arenhövel
The study of nuclear and subnuclear structure by means of photon scattering is outlined. Besides a brief exposition of the formalism a few illustrative examples are discussed.
nucl-th0 citations
05
Principal component analysis of the nonlinear coupling of harmonic modes in heavy-ion collisions
Piotr Bozek🇵🇱
The principal component analysis of flow correlations in heavy-ion collisions is studied. The correlation matrix of harmonic flow is generalized to correlations involving several different flow vectors. The method can be applied to study the nonlinear coupling between different harmonic modes in a double differential way in transverse momentum or pseudorapidity. The procedure is illustrated with results from the hydrodynamic model applied to Pb+Pb collisions at $s = 2760$ GeV. Three examples of generalized correlations matrices in transverse momentum are constructed corresponding to the coupling of $v_{2}^{2}$ and $v_{4}$ , of $v_{2} v_{3}$ and $v_{5}$ , or of $v_{2}^{3}$ , $v_{3}^{3}$ , and $v_{6}$ . The principal component decomposition is applied to the correlation matrices and the dominant modes are calculated.
nucl-thhep-phnucl-exPRC(2018)·22 citations
06
Event-by-event fluctuations in p+p and central A+A collisions within relativistic transport models
Anton Motornenko🇩🇪 · Katarzyna Grebieszkow🇵🇱 · Elena Bratkovskaya🇩🇪 · Mark I. Gorenstein🇺🇦 · Marcus Bleicher🇩🇪 · Klaus Werner🇫🇷
Event-by-event multiplicity fluctuations in nucleus-nucleus collisions are studied within the relativistic transport models: EPOS, PHSD, and UrQMD. As measures of particle number fluctuations we consider the scaled variances $ω [X]$ for positive, negative, and all charged hadrons, and the strongly intensive quantities $Δ [K^{+}, π^{+}],$ $Σ [K^{+}, π^{+}]$ for $K^{+}$ and $π^{+}$ yields. At the SPS energy range the fluctuation measures are calculated for proton-proton, Ar+Sc, and Pb+Pb collisions. Comparison with recent NA61/SHINE and older NA49 measurements of the multiplicity fluctuations is done. A validity of the model of independent sources, a role of the experimental acceptance, and the centrality selection procedure are studied.Event-by-event multiplicity fluctuations in nucleus-nucleus collisions are studied within the relativistic transport models: EPOS, PHSD, and UrQMD. As measures of particle number fluctuations we consider the scaled variances $ω [X]$ for positive, negative, and all charged hadrons, and the strongly intensive quantities $Δ [K^{+}, π^{+}],$ $Σ [K^{+}, π^{+}]$ for $K^{+}$ and $π^{+}$ yields. At the SPS energy range the fluctuation measures are calculated for proton-proton, Ar+Sc, and Pb+Pb collisions. Comparison with recent NA61/SHINE and older NA49 measurements of the multiplicity fluctuations is done. A validity of the model of independent sources, a role of the experimental acceptance, and the centrality selection procedure are studied.
nucl-thhep-phJ.Phys.G(2018)·11 citations
07
Single particle in a reflection-asymmetric potential
Yuanyuan Wang · Zhengxue Ren
Single particles moving in a reflection-asymmetric potential are investigated by solving the Schrödinger equation of the reflection-asymmetric Nilsson Hamiltonian with the imaginary time method in 3D lattice space and the harmonic oscillator basis expansion method. In the 3D lattice calculation, the $l^{2}$ divergence problem is avoided by introducing a damping function, and the $⟨ l^{2} ⟩_{N}$ term in the non-spherical case is calculated by introducing an equivalent $N$ -independent operator. The efficiency of these numerical techniques is demonstrated by solving the spherical Nilsson Hamiltonian in 3D lattice space. The evolution of the single-particle levels in a reflection-asymmetric potential is obtained and discussed by the above two numerical methods, and their consistency is shown in the obtained single-particle energies with the differences smaller than 10 $^{- 4} [ℏ ω_{0}]$ .
nucl-thSCPMA(2018)·13 citations
08
Finite-size effects on the Phase Structure of the Walecka Model
L. M. Abreu🇧🇷 · E. S. Nery🇧🇷
In this work we investigate the finite-size effects on the phase structure of Walecka model within the framework of generalized Zeta-function, focusing on the influence of temperature as well as the number and length of compactified spatial dimensions. Here we concentrate on the situation of larger values of the coupling between the scalar and fermion fields, in which a phase transition of first order takes place. The phase transitions are analyzed and compared with the system in the situations of one, two and three compactified spatial dimensions. Our findings suggest that the thermodynamic behavior of the system depends on the length and number of spatial dimensions, with the symmetric phase being favored as the size of the system diminishes.
nucl-thhep-phhep-thPRC(2017)·19 citations
09
Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD final State interactions (THESEUS) for FAIR-NICA-SPS-BES/RHIC energies
P. Batyuk🇷🇺 · D. Blaschke🇷🇺 · M. Bleicher🇩🇪 · Yu.B. Ivanov🇷🇺 · Iu. Karpenko🇺🇦 · L. Malinina🇷🇺 · S. Merts🇷🇺 · M. Nahrgang🇫🇷 · H. Petersen🇩🇪 · O. Rogachevsky🇷🇺
We present a new event generator based on the three-fluid hydrodynamics (3FH) approach, followed by a particlization at the hydrodynamic decoupling surface and a subsequent UrQMD afterburner stage based on the microscopic UrQMD transport model that accounts for hadronic final state interactions. First results for Au+Au collisions are presented. The following topics are addressed: the directed flow, transverse-mass spectra, as well as rapidity distributions of protons, pions and kaons for two model equations of state, one with a first-order phase transition, the other with a crossover transition. Preliminary results on the femtoscopy are also discussed. We analyze the accuracy of reproduction of the 3FH results by the new event generator and the effect of the subsequent UrQMD afterburner stage.
nucl-thhep-exhep-phnucl-exEPJ Web Conf.(2018)·18 citations
10
Relativistic particle in a box: Klein-Gordon vs Dirac Equations
Pedro Alberto🇵🇹 · Saurya Das🇨🇦 · Elias C. Vagenas🇰🇼
The problem of a particle in a box is probably the simplest problem in quantum mechanics which allows for significant insight into the nature of quantum systems and thus is a cornerstone in the teaching of quantum mechanics. In relativistic quantum mechanics this problem allows also to highlight the implications of special relativity for quantum physics, namely the effect that spin has on the quantized energy spectra. To illustrate this point, we solve the problem of a spin zero relativistic particle in a one- and three-dimensional box using the Klein-Gordon equation in the Feshbach-Villars formalism. We compare the solutions and the energy spectra obtained with the corresponding ones from the Dirac equation for a spin one-half relativistic particle. We note the similarities and differences, in particular the spin effects in the relativistic energy spectrum. As expected, the non-relativistic limit is the same for both kinds of particles, since, for a particle in a box, the spin contribution to the energy is a relativistic effect.
↳ quant-phgr-qchep-thnucl-thEur.J.Phys.(2018)·16 citations
11
Dispersive analysis tools for $π π$ and $π K$ scattering
J.R. Peláez🇪🇸 · A. Rodas (Universidad Complutense de Madrid)🇪🇸
In this talk we discuss the relevance of dispersive methods and their different applications to obtain simple but rigorous parameterizations of pion-pion and kaon-pion scattering. We show as an example our latest dispersive analysis of $π K$ scattering, where we provide simple parameterizations of data satisfying Forward Dispersion Relations up to 1.6 GeV.
↳ hep-phnucl-thPoS(2018)·2 citations
12
Isospin Breaking in Heavy-Meson Decay Constants
Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇷🇺 · Silvano Simula🇮🇹
Evaluation of Borelized QCD sum rules in the so-called local-duality limit of infinitely large Borel mass parameter provides an alternate route for extraction of the dependence of the decay constants of heavy-light mesons on the mass $m_{q}$ of the involved light quark $q$ : For appropriate choices of the two-point correlation functions of currents interpolating the hadrons under study, the local-duality limit forces all nonperturbative contributions parametrized by vacuum condensates to such kind of correlator to vanish. As a consequence, the sought $m_{q}$ dependence of the heavy-light meson decay constants proves to be controlled primarily by the correlator contributions from perturbative QCD. Our knowledge of the analytic behaviour of the latter as functions of $m_{q}$ enables us to derive the $m_{q}$ dependence of the decay constants of both pseudoscalar and vector heavy-light mesons, for which we estimate strong isospin breaking to be of the order of 1 MeV for both charm and beauty sectors.
↳ hep-phhep-latnucl-thPoS(2018)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE