Nuclear Theory·nucl-th

Tuesday·September 11, 2018

14 papers—9 primary·5 cross-listed

01
Study of various few-body systems using Gaussian expansion method (GEM)
Emiko Hiyama🇯🇵 · Masayasu Kamimura🇯🇵
We review our calculation method, Gaussian expansion method (GEM), and its applications to various few-body (3- to 5-body) systems such as 1) few-nucleon systems, 2) few-body structure of hypernuclei, 3) clustering structure of light nuclei and unstable nuclei, 4) exotic atoms/molecules, 5) cold atoms, 6) nuclear astrophysics and 7) structure of exotic hadrons. Showing examples in our published papers, we explain i) high accuracy of GEM calculations and its reason, ii) wide applicability of GEM and iii) successful predictions by GEM calculations before measurements. GEM was proposed 30 years ago and has been applied to a variety of subjects. To solve few-body Schroedinger equations accurately, use is made of the Rayleigh-Ritz variational method for bound states, the complex-scaling method for resonant states and the Kohn-type variational principle to S-matrix for scattering states. The total wave function is expanded in terms of few-body Gaussian basis functions spanned over all the sets of rearrangement Jacobi coordinates. Gaussians with ranges in geometric progression work very well both for short-range and long-range behavior of the few-body wave functions. Use of Gaussians with complex ranges gives much more accurate solution when the wave function has many oscillations.
nucl-thnucl-exphysics.atom-phphysics.chem-phFront.Phys.(Beijing)(2018)·39 citations
02
Evaluation of particle--anti-particle scaled correlation within effective models
Andre Garcia🇧🇷 · Volker Koch🇺🇸 · Marcus Benghi Pinto🇧🇷
Correlations and fluctuations of physical quantities are known to play an important role in phase transitions and critical phenomena. In recent years some experimental attempts were made in the scope of the Beam Energy Scan program to locate a possible critical point in the QCD phase diagram. In this work we use the Nambu--Jona-Lasinio model to investigate the off-diagonal quark susceptibility, which is related to the quark--anti-quark scaled correlation at the mean field level. We show that this correlation has a significant peak near the critical point and, therefore, may be a useful quantity to measure in experiment. We further study the effects of a repulsive vector coupling, which reduces the strength of the scaled correlation near the critical point.
nucl-thhep-phnucl-exNPA(2020)·3 citations
03
Calculation Energy levels and charge radius for odd $^{41 - 49}$ Ca Isotopes by using the analytical approach
Mohsen Mousavi · Mohammad Reza Shojaei
In the present study, some static properties of odd isotopes of Ca were investigated in the non-relativistic shell model. We also suggested a novel suitable local potential model for the non-microscopic investigation of the mentioned nuclei. We modeled the odd $^{41 - 49}$ Ca nuclei as doubly-magic isotopes, with further nucleons (valence) in the lf7/2 and 2p3/2 levels. Then the modified Eckart potential as well as Hulthen potential were chosen for the interaction between core and nucleons. We also used the Parametric Nikiforov Uvarov method to calculate the values of energy, the radius of charge and wave function. The obtained results showed a good agreement with the experimental data, so this model is applicable for the similar nuclei.
nucl-thMod.Phys.Lett.A(2019)·4 citations
04
Squeezed back-to-back correlations of $K^{+}$ $K^{-}$ in d+Au collisions at $s_{N N} = 200$ GeV and Au+Au collisions at $s_{N N} = 62.4$ GeV
Yong Zhang🇨🇳 · Jing Yang🇨🇳 · WeiHua Wu
We investigate the squeezed back-to-back correlations (BBC) of $K^{+}$ $K^{-}$ , caused by the mass modification of the particle in the dense medium formed in d+Au collisions at $s_{N N} = 200$ GeV and Au+Au collisions at $s_{N N} = 62.4$ GeV. Considering some kaons may be not affected by the medium, we further study the BBC functions of $K^{+}$ $K^{-}$ when parts of all kaons have a mass-shift. Our results indicate that the BBC functions of $K^{+}$ $K^{-}$ can be observed when only about 10 $%$ of all kaons have a mass-shift in d+Au collisions at $s_{N N} = 200$ GeV and the peripheral collisions of Au+Au at $s_{N N} = 62.4$ GeV. Since the BBC function is caused by the mass-shift due to the interaction between the particle and the medium, the successful detection of the BBC function indirectly marks that the dense medium has formed in these collision systems. We suggest to measure the BBC function of $K^{+}$ $K^{-}$ experimentally in d+Au collisions at $s_{N N} = 200$ GeV and peripheral collisions of Au+Au at $s_{N N} = 62.4$ GeV.
nucl-thnucl-exCPC(2019)·1 citation
05
Spectator partons contribution in the rapidity width of lamda in p+p collisions at various SPS and LHC energies
Nur Hussain🇮🇳 · Banajit Barman · Buddhadeb Bhattacharjee🇮🇳
Pseudorapidity distributions of all primary charged particles produced in p+p collisions at various Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies using UrQMD-3.4 and PYTHIA8.2-generated events are estimated and compared with the existing results of UA5 and ALICE collaborations. With both the sets of generated data, the variation of rapidity widths with the rest masses of different mesons and baryons of p+p collisions at various Super Proton Synchrotron (SPS) and LHC energies are presented. An increase in the width of the rapidity distribution of lambda, similar to heavy-ion data, could be seen in p+p collisions as well from SPS to the LHC energies (up to {sqrt_s} =13 TeV) when the entire rapidity space is considered, indicating its universal feature both in p+p and A+A collisions. The genesis of the increased width of rapidity distribution of Lambda in p+p collision is found to be in the production of light flavored quarks and diquarks from the spectator partons of the colliding hadrons resulting {lambda}/{anti_lambda}>1 at the extreme rapidities of the studied p+p collisions. At the LHC energies for central p+p collision, when there is no spectator partons, the rapidity width of {lambda} is found to take the same Gaussian shape as that of lambda and the widths of both the distributions become the same confirming no non-trivial contribution to the rapidity width of {lambda} as seen in heavy-ion and non-central p+p collisions.
nucl-thnucl-ex2 citations
06
Strangeness $S = - 2$ baryon-baryon interactions in relativistic chiral effective field theory
Kai-Wen Li🇨🇳 · Tetsuo Hyodo🇯🇵 · Li-Sheng Geng🇨🇳
We study the strangeness $S = - 2$ baryon-baryon interactions in relativistic chiral effective field theory at leading order. Among the 15 relevant low energy constants, eight of them are determined by fitting to the state of the art lattice QCD data of the HAL QCD Collaboration (with $m_{π} = 146$ MeV), and the rest are either taken from the study of the $S = - 1$ hyperon-nucleon systems, assuming strict SU(3) flavor symmetry, or temporarily set equal to zero. Using the so-obtained low energy constants, we extrapolate the results to the physical point, and show that they are consistent with the available experimental scattering data. Furthermore, we demonstrate that the $ΛΛ$ and $Ξ N$ phase shifts near the $Ξ N$ threshold are very sensitive to the lattice QCD data fitted, to the pion mass, and to isospin symmetry breaking effects. As a result, any conclusion drawn from lattice QCD data at unphysical pion masses (even close to the physical point) should be taken with caution. Our results at the physical point, similar to the lattice QCD data, show that a resonance/quasi-bound state may appear in the $I = 0$ $ΛΛ$ / $Ξ N$ channel.
nucl-thhep-lathep-phPRC(2018)·46 citations
07
On the contribution of the P and D partial-wave states to the binding energy of the triton in the Bethe-Salpeter-Faddeev approach
S. G. Bondarenko · V. V. Burov · S. A. Yurev
The influence of the partial-wave states with nonzero orbital moment of the nucleon pair on the binding energy of the triton in the relativistic case is considered. The relativistic generalization of the Faddeev equation in the Bethe-Salpeter formalism is applied. Two-nucleon t matrix is obtained from the Bethe-Salpeter equation with separable kernel of nucleon-nucleon interaction of the rank one. The kernel form factors are the relativistic type of the Yamaguchi functions. The following two-nucleon partial-wave states are considered: $^{1} S_{0}$ , $^{3} S_{1}$ , $^{3} D_{1}$ , $^{3} P_{0}$ , $^{1} P_{1}$ , $^{3} P_{1}$ . The system of the integral equations are solved by using the iteration method. The binding energy of the triton and three-nucleon amplitudes are found. The contribution of the P and D states to the binding energy of triton is given.
nucl-thPhys.Atom.Nucl.(2019)·3 citations
08
Symmetry energy in neutron star matter
Claudio O. Dorso · Guillermo A. Frank · Jorge A. Lopez
We investigate the structure attained by neutron star matter with proton to neutron ratios ranging from x=0.1 to 0.5, densities in the range of 0.02 fm-3 to 0.085 fm-3, and temperatures T<4 MeV. In particular we study the pasta shapes and the phase changes previously observed in nuclear matter, as well as the behavior of the symmetry energy. We corroborate the existence of homogeneous to non-homogeneous phase transitions, and the different values of the symmetry energy at different densities and temperatures.
nucl-thNPA(2019)·9 citations
09
Influence of the interactions of scalar mesons on the behavior of the symmetry energy
Noemi Zabari🇵🇱 · Sebastian Kubis🇵🇱 · Włodzimierz Wójcik🇵🇱
Symmetry energy behavior of scalar mesons interactions is analyzed within the framework of the standard relativistic mean field model. Whereas the presence of the $δ$ meson itself makes the symmetry energy stiffer, the crossing term $δ - σ$ allows its slope to decrease to the suggested experimental value. Moreover, such controlling of the symmetry energy does not significantly affect the stiffness of the equation of state and acceptable neutron star masses result. Interestingly, for the most plausible value of the symmetry energy slope, the phase transition occurs in the neutron star core.
nucl-thPRC(2019)·25 citations
10
Measuring the Weizsaecker-Williams distribution of linearly polarized gluons at an EIC through dijet azimuthal asymmetries
Adrian Dumitru🇺🇸 · Vladimir Skokov🇺🇸 · Thomas Ullrich🇺🇸
The production of a hard dijet with small transverse momentum imbalance in semi-inclusive DIS probes the conventional and linearly polarized Weizsaecker-Williams (WW) Transverse Momentum Dependent (TMD) gluon distributions. The latter, in particular, gives rise to an azimuthal dependence of the dijet cross-section. In this paper we analyze the feasibility of a measurement of these TMDs through dijet production in DIS on a nucleus at an Electron-Ion Collider. We introduce the MCDijet Monte-Carlo generator to sample quark-antiquark dijet configurations based on leading order parton level cross-sections with WW gluon distributions that solve the non-linear small-x QCD evolution equations. These configurations are fragmented to hadrons using PYTHIA, and final state jets are reconstructed. We report on background studies and on the effect of kinematic cuts introduced to remove beam jet remnants. We estimate that with an integrated luminosity of 20 fb^{-1}/A one can determine the distribution of linearly polarized gluons with a statistical accuracy of approximately 5%.
↳ hep-phnucl-thPRC(2019)·79 citations
11
Consistent account of deuteron-induced reactions on Cr up to 60 MeV
E. Simeckova · M. Avrigeanu · U. Fischer · J. Mrazek · J. Novak · M. Stefanik · C. Costache · V. Avrigeanu
Purpose: Accurate new measurements of low-energy deuteron-induced reaction cross sections for natural Cr target can enhance the related database and the opportunity for an unitary and consistent account of the involved reaction mechanisms. Methods: The activation cross sections of $^{51, 52, 54}$ Mn, $^{51}$ Cr, and $^{48}$ V nuclei for deuterons incident on natural Cr at energies up to 20 MeV, were measured by the stacked-foil technique and high resolution gamma spectrometry using U-120M cyclotron of the Center of Accelerators and Nuclear Analytical Methods (CANAM) of the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS). They as well as formerly available data for deuteron interactions with Cr isotopes up to 60 MeV are the object of an extended analysis of all processes from elastic scattering until the evaporation from fully equilibrated compound system, but with a particular attention given to the BU and DR mechanisms. Results: The new measured activation excitation functions proved essential for the enrichment of the deuteron database, while the theoretical analysis of all available data strengthens for the first time their consistent account provided that (i) a suitable BU and DR assessment is completed by (ii) the assumption of PE and CN contributions corrected for decrease of the total-reaction cross section due to the leakage of the initial deuteron flux towards BU and DR processes. Conclusions: The suitable description of nuclear mechanisms involved within deuteron-induced reactions on chromium, taking into account especially the BU and DR direct processes, is validated by an overall agreement of the calculated and measured cross sections including particularly the new experimental data at low energies.
↳ nucl-exnucl-thPRC(2018)·11 citations
12
Augmenting the Gauge-Gravity Correspondence to include Hadron Polarizabilities
Pervez Hoodbhoy🇵🇰
ADS/CFT models have achieved considerable success in describing hadronic properties such as masses and Regge trajectories. Even if the minimal vertex that couples photons to structureless spin-zero fields is used, one still ends up with electromagnetic form factors of hadrons that are in fair to good agreement with experiment. However, contradicting both experiment and intuition, this minimal model gives zero for hadronic electric and magnetic polarizabilities. We show here that if effective vertices are used, and axial and vector mesons are allowed to propagate as intermediate states, then the static polarizabilities can in principle be computed from ADS/CFT.
↳ hep-phnucl-thPRD(2018)·0 citations
13
Fractal structure of hadrons and non-extensive statistics
Eugenio Megias🇪🇸 · Airton Deppman🇧🇷 · Tobias Frederico🇧🇷 · Debora P. Menezes🇧🇷
The role played by non-extensive thermodynamics in physical systems has been under intense debate for the last decades. Some possible mechanisms that could give rise to non-extensive statistics have been formulated along the last few years, in particular the existence of a fractal structure in thermodynamic functions for hadronic systems. We investigate the properties of such fractal thermodynamical systems, in particular the fractal scale invariance is discussed in terms of the Callan-Symanzik~equation. Finally, we propose a diagrammatic method for calculations of relevant quantities.
↳ hep-phcond-mat.stat-mechnucl-thEPJ Web Conf.(2018)·0 citations
14
Chiral phase transition within the linear sigma model in the Tsallis nonextensive statistics based on density operator
Masamichi Ishihara🇯🇵
We studied the chiral phase transition for small $∣1 - q ∣$ within the Tsallis nonextensive statistics of the entropic parameter $q$ , where the quantity $∣1 - q ∣$ is the measure of the deviation from the Boltzmann-Gibbs statistics. We adopted the normalized $q$ -expectation value in this study. We applied the free particle approximation and the massless approximation in the calculations of the expectation values. We estimated the critical physical temperature, and obtained the chiral condensate, the sigma mass, and the pion mass, as functions of the physical temperature $T_{ph}$ for various $q$ . We found the following facts. The $q$ -dependence of the critical physical temperature is $1/ q$ . The chiral condensate at $q$ is smaller than that at $q^{'}$ for $q > q^{'}$ . The $q$ -dependence of the pion mass and that of the sigma mass reflect the $q$ -dependence of the condensate. The pion mass at $q$ is heavier than that at $q^{'}$ for $q > q^{'}$ . The sigma mass at $q$ is heavier than that at $q^{'}$ for $q > q^{'}$ at high physical temperature, while the sigma mass at $q$ is lighter than that at $q^{'}$ for $q > q^{'}$ at low physical temperature. The quantities which are functions of the physical temperature $T_{ph}$ and the entropic parameter $q$ are described by only the effective physical temperature defined as $q T_{ph}$ under the approximations.
↳ hep-phnucl-thIJMPE(2019)·2 citations

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