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2017 Vol. 34, No. 1

2016 Dalian International Workshop on Nuclear Physics(2016DIWNP)
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Proceedings of the 2016 Dalian International Workshop on Nuclear Physics(2016DIWNP)
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2017, 34(1): .
Abstract:
Progress in the Study of Multi-quark States
WANG Fan, PING Jialun, HUANG Hongxia
2017, 34(1): 1-7. doi: 10.11804/NuclPhysRev.34.01.001
Abstract(1551) PDF (206KB)(195)
Abstract:
The progress in the study of multi-quark states for the last half century is reviewed schematically and the dibaryon sector is emphasized. By employing the dynamical symmetry, the Gursey-Radicati mass formula, which can give a reasonable description of the masses of multi-quark states, can be reproduced. The dibaryons in bag model and realistic quark model, quark delocalization color screening model, are discussed.
Skyrmion Properties in an Uniform Magnetic Field
HE Bingran
2017, 34(1): 8-12. doi: 10.11804/NuclPhysRev.34.01.008
Abstract(1800) PDF (244KB)(148)
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The mass and shape of skyrmion in an uniform magnetic field are investigated. Base on the symmetry of the system, an axially symmetric ansatz of the soliton is proposed to perform the study. The baryon number is shown to be always conserved even in a nonzero magnetic background. It is found that with the increase of the strength of magnetic field, the static mass of skyrmion first decreases then increases, as the dominant role shift from the linear term of magnetic field to the quadratic term of magnetic field, while the soliton size first increase then decrease. Finally, in the core part of magnetar, the equation of state have strong dependence of magnetic field, which also modifies the mass limit for magnetar.
Several Controversial Issues of QED3
FENG Hongtao
2017, 34(1): 13-15. doi: 10.11804/NuclPhysRev.34.01.013
Abstract(1609) PDF (132KB)(119)
Abstract:
Quantum electrodynamics in (2+1) dimensions (QED3) is an important nonperturbative system. This seems relatively simple Abel system, there are several issues that need to be clarified: whether or not the partition function of the system depends on chemical potential; whether or not there exists dynamical chiral symmetric breaking; whether or not the boson can acquires nonzero mass. In this paper, we give an in sight of the traits of QED3 from the dependence of density, temperature and massive boson to discuss those problems.
Effect of Fermion Velocity on Fermion Chiral Condensate in QED3 at Finite Temperature
LI Jianfeng
2017, 34(1): 16-19. doi: 10.11804/NuclPhysRev.34.01.016
Abstract(1489) PDF (168KB)(115)
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Analogous to Quantum QCD, QED3 has two interesting features: dynamical chiral symmetry breaking (DCSB) and confinement. By adopting the rainbow approximation, we numerically solve the fermion self-energy equation at finite temperature in the framework of Dyson-Schwinger equations and discuss the relation between chiral condensate and fermion flavor for several fermion velocities in the finite temperature QED3. It is found that the fermion chiral condensate decreases monotonically with the fermion velocity increasing for a fixed N at finite temperature.
Symmetry Energy in Nucleon and Quark Matter
CHEN Liewen
2017, 34(1): 20-28. doi: 10.11804/NuclPhysRev.34.01.020
Abstract(2087) PDF (480KB)(276)
Abstract:
The symmetry energy characterizes the isospin dependent part of the equation of state of isospin asymmetric strong interaction matter and it plays a critical role in many issues of nuclear physics and astrophysics. In this talk, we briefly review the current status on the determination of the symmetry energy in nucleon (nuclear) and quark matter. For nuclear matter, while the subsaturation density behaviors of the symmetry energy are relatively well-determined and significant progress has been made on the symmetry energy around saturation density, the determination of the suprasaturation density behaviors of the symmetry energy remains a big challenge. For quark matter, which is expected to appear in dense matter at high baryon densities, we briefly review the recent work about the effects of quark matter symmetry energy on the properties of quark stars and the constraint of possible existence of heavy quark stars on quark matter symmetry energy. The results indicate that the u and d quarks could feel very different interactions in isospin asymmetric quark matter, which may have important implications on the isospin effects of partonic dynamics in relativistic heavy-ion collisions.
Nuclear Fragmentation and Particle Production Induced by Antiprotons
FENG Zhaoqing
2017, 34(1): 29-34. doi: 10.11804/NuclPhysRev.34.01.029
Abstract(1621) PDF (433KB)(166)
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Within the framework of the Lanzhou quantum molecular dynamics (LQMD) transport model, the nuclear fragmentation and particle production induced by low-energy antiprotons have been investigated thoroughly. Production of strange particles in the antiproton induced nuclear reactions is modeled within the LQMD model, in which all possible reaction channels such as elastic scattering, annihilation, charge exchange and inelastic scattering in antibaryon-baryon, baryon-baryon and mesonbaryon collisions have been included. A coalescence approach is developed for constructing the primary fragments in phase space. The secondary decay process of the fragments is described by the well-known statistical code. It is found that the strangeness exchange reactions dominate the hyperon production. A bump structure in the domain of intermediate mass for heavy targets appears owing to the contribution of fission fragments. It has advantage to produce heavier hyperfragments and hypernuclides with strangeness s = -2 (double-Λ fragments) and s = 1 (Λ-fragments) in antiproton induced reactions. The production cross sections are evaluated.
Dibaryons without Strangeness
DAI Lianrong, SU Hang, LI Bing, SHAO Sijia, SUN Yueling
2017, 34(1): 35-40. doi: 10.11804/NuclPhysRev.34.01.035
Abstract(1138) PDF (256KB)(174)
Abstract:
In the present work we discuss three dibaryons without strangeness in the chiral SU(3) quark model by solving the resonating group method (RGM) equation. In the calculation, the model parameters are taken from our previous work in which the nucleon-nucleon (NN) scattering phase shifts are fitted quite well. Firstly, the structure of deuteron is discussed, which is very important since it is the first dibaryon confirmed by experiment in the past many years. Deuteron belongs to NN system with spin S =1 and isospin T =0, the binding energy, scattering length and the relative wave functions of deuteron are discussed. The results show that the chiral SU(3) quark model describes the properties of deuteron quite well and tensor interaction is important in forming the deuteron loosely bound. Secondly, the predicted results of ΔΔ dibaryon with S =3 and T =0 are shown, the resultant binding energy and size of root-mean-square (RMS) of six quarks are calculated by including the L coupling and hidden color channel (CC) coupling. The results show that the CC coupling effect is much larger than the L mixing effect, which means that CC coupling plays an important role in forming the spin S =3 ΔΔ dibayon state. Our predicted binding energy is several tens MeV, it is lower than the threshold of the ΔΔ channel and higher than the mass of NΔπ. Unexpectedly, our predicted mass is quite close to the recent confirmation by WASA experiments in 2014. Thirdly, we present our new results of ΔΔ dibaryon with S = 0 and T =3, obtained recently by extending the single-channel calculation to including the CC coupling. It is seen that the CC coupling also has a relatively large effect on (ΔΔ)ST=03 state. However, its mass is still lower than the threshold of the ΔΔ channel and higher than the mass of NΔπ, similar as that of (ΔΔ)ST=30 state. Finally, we further make some comparisons between S = 3 and S = 0 ΔΔ states to show the difference of the two dibaryons. The results show that the attractive interactions from σ' meson and OGE exchanges are dominantly important for S =0 and S =3 states, respectively, so their binding energies all become larger in coupled-channel calculation.
Skyrme Tensor Force in 16O+16O Fusion Dynamics
SHI Long, GUO Lu
2017, 34(1): 41-45. doi: 10.11804/NuclPhysRev.34.01.041
Abstract(1279) PDF (221KB)(167)
Abstract:
The fusion dynamics of 16O+16O around Coulomb barrier has been studied in the timedependent Hartree-Fock (TDHF) theory with the full Skyrme effective interaction. The calculations have been carried out in three-dimensional Cartesian basis without any symmetry restrictions. We have included the full tensor force and all the time-odd terms in Skyrme energy density functional (EDF). The Coulomb barrier obtained from the dynamical TDHF calculations and EDF with frozen density approximation has been compared with the available experimental data. The isoscalar tensor terms and the rearrangement of other terms are found to decrease the barrier height in the spin-saturated system 16O+16O, while the energy of Coulomb barrier tends to decrease as the isovector coupling constant decreases. The fusion cross section for 16O+16O collision has been calculated with and without the tensor force. We found that the tensor force has minor effect on the fusion dynamics of 16O+16O at the energies around Coulomb barrier.
Nuclear Symmetry Energy Constrained by Nuclear Radioactivities
XU Chang
2017, 34(1): 46-50. doi: 10.11804/NuclPhysRev.34.01.046
Abstract(1255) PDF (291KB)(149)
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The density-dependence of symmetry energy is of particular importance to many problems in nuclear physics and astrophysics. Exotic cluster radioactivity is proposed to constrain the density slope of symmetry energy L(ρ0) by using the density-dependent cluster model (DDCM) where the cluster radioactivity serves as a link between the neutron skin thickness of 208Pb and the density slope L(ρ0). The isovector part of cluster-208Pb potential constructed from the M3Y nucleon-nucleon interaction is found to be very important in determining the density slope parameter L(ρ0). The correlation between the neutron skin thickness of 208Pb and the density slope parameter are obtained from cluster radioactivities around 208Pb with measured data. The constraint of L(ρ0) from proton radioactivity is also discussed.
New Magicity within the Relativistic Hartree-Fock-Bogoliubov Approach
LI Jiajie, LONG Wenhui
2017, 34(1): 51-56. doi: 10.11804/NuclPhysRev.34.01.051
Abstract(1873) PDF (392KB)(193)
Abstract:
Recent applications of the relativistic Hartree-Fock-Bogoliubov (RHFB) approach in exploring the new magicities under extreme conditions are presented for the superheavy elements with the limits of mass and charge and for the exotic nuclei with extreme neutron-to-proton ratios. It is found that the emergence of new magic shells in superheavy region is tightly related to the restoration and violation of pseudo-spin symmetry, respectively for the neutron and proton ones, in which the model deviations are indicated and discussed. In medium-heavy exotic nuclei, the occurrence of new magicity N = 32, 34 in Ca isotopes is well reproduced by the RHFB approach, in which the isovector Lorentz tensor couplings are found to play an essential role. The results exemplify that the RHFB approach, which considers the exchange (Fock) terms explicitly, furnishes a new theoretical instrument for advancing relativistic nuclear mean-field approaches.
Decay Out of Superdeformed Bands in 190,192Pb
GU Jianzhong, PENG Bangbao, LI Zhenyu, YU Guoliang
2017, 34(1): 57-61. doi: 10.11804/NuclPhysRev.34.01.057
Abstract(1425) PDF (376KB)(107)
Abstract:
The combined method is applied to calculate the angular momentum projected potential energy surfaces (AMPPES) of 190,192Pb. The Supper-deformed(SD) rotational bands of the two nuclei are studied with the AMPPES computed with the Gogny D1S and Skyrme SkP and SLy4 interactions. It is found that there is no pronounced SD band in 190Pb in the case of the Gogny interaction, which is consistent with the experimental observation. A well developed SD band with the Gogny interaction is found in 192Pb. The tunneling width of 192Pb is comparable to that given by the GW approach (Nucl. Phys. A 660 (1999)197) and orders of magnitude larger than that given by the SB approach (Phys. Rev. C 60 (1999) 051305). The influence of the angular momentum projection on the potential energy surfaces is examined in the case of the Gogny interaction for 190,192Pb. It is shown that the angular momentum projection suppresses the barrier separating the SD and ND rotational bands. Higher barriers of the AMPPESs for the two nuclei computed with the Skyrme SkP and SLy4 interactions are obtained compared with those given by the Gogny force. The tunneling width of 192Pb is also big for the Skyrme interactions. We put the SB approach into question which gives only an extremely small spreading width.
Correlations of the SO(8) Pairing and SU(3) Quadrupole Bases in the Algebraic Shell Model
Ana Ivanova Georgieva, Kalin Pavlov Drumev
2017, 34(1): 62-72. doi: 10.11804/NuclPhysRev.34.01.062
Abstract(1287) PDF (492KB)(104)
Abstract:
We establish a correspondence between the SO(8) isoscalar, isovector and total pairing bases and the Elliott's SU(3) basis in the algebraic structure of the spatial part of the microscopic shell model. It is derived from the complementarity of these algebras to the same T, S, (S,T) irreducible representations (irreps) of the Wigners supermultiplets, contained in the shell-model number-conserving algebra U(4Ω). This important result allows for the evaluation of the content of SU(3) irreps into the different types of pairing bases which leads to an investigation of the complementarity and competitive effects of pairing and the quadrupole-quadrupole interactions on the energy spectra of the nuclear systems. The theory is valid for any shell and for a number of shells as well, but we illustrate it with the results for a single ds-shell.
Goodness of Generalized Seniority in Semi-magic Nuclei
Ashok Kumar Jain, Bhoomika Maheshwari
2017, 34(1): 73-81. doi: 10.11804/NuclPhysRev.34.01.073
Abstract(1381) PDF (554KB)(137)
Abstract:
Symmetry plays an important role in understanding the nuclear structure properties from the rotation of a nucleus to the spin, parity and isospin of nuclear states. This simplifies the complexity of the nuclear problems in one way or the other. Seniority is also a well known quantum number which arises due to the symmetry in the pairing interaction of nuclei. We present empirical as well as theoretical evidences based on decay rates which support the goodness of seniority at higher spins as well as in nrich or, n-deficient nuclei. We find that the generalized seniority governs the identical trends of high-spin isomers in different semi-magic chains, where different set of nucleon orbitals from different valence spaces are involved.
Neutrino Potential for Neutrinoless Double Beta Decay
Yoritaka Iwata
2017, 34(1): 82-86. doi: 10.11804/NuclPhysRev.34.01.082
Abstract(2056) PDF (336KB)(126)
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Nuclear matrix element in double beta decay under the closure approximation is outlined, in which neutrino potential for neutrinoless double beta decay is studied with focusing on its statistical property. It is shown from the analysis that Fermi and Gamow-Teller parts provide almost the same positive values with the Fermi part slightly larger than the Gamow-Teller part in general, while the tensor part includes small but non-negligible positive and negative values. Positive correlation of the values between Fermi, Gamow-Teller, and tensor parts has been clarified. The statistics provides a gross view of understanding amplitude of constitutional components of the nuclear matrix element.
Towards Microscopic Descriptions of Thermal Fission Rates
PEI Junchen, ZHU Yi
2017, 34(1): 87-91. doi: 10.11804/NuclPhysRev.34.01.087
Abstract(1583) PDF (283KB)(133)
Abstract:
The studies of thermal fission rates are relevant to novel reactors, astrophysical environments, and survival probabilities of compound superheavy nuclei. This has been conventionally studied by the Bohr-Wheeler statistical model that depends on phenomenological level densities and fission barriers. In this context, we propose to study the thermal fission rates based on microscopic temperature dependent nuclear energy density functional theory. The microscopic temperature dependent fission barrier heights and curvatures, and collective mass parameters can be self-consistently obtained. The fission lifetimes from low to high temperatures can be given by the imaginary free energy method in a consistent framework. Microscopic temperature dependent fission barriers play an essential role in fission studies.
Medium-heavy Superdeformed Hypernuclei in Skyme Hartree-Fock Model
ZHOU Xianrong, E. Hiyama, H. Sagawa
2017, 34(1): 92-97. doi: 10.11804/NuclPhysRev.34.01.092
Abstract(1023) PDF (368KB)(131)
Abstract:
The superdeformed (SD) states in medium heavy hypernuclei with core nuclei of Ar isotopes and 40Ca are studied in the frame of Skyrme Hartree-Fock (SHF)+ BCS model together with a microscopic ΛN interaction. The calculation indicates that the Λ separation energy SΛ of ground state is larger than that of SD state. The result is consistent with the antisymmetrized molecular dynamics (AMD) calculation, but inconsistent with that of relativistic mean field (RMF). The difference comes from the different interaction and density distribution in the core nuclei and the corresponding hypernuclei.
Nuclear Shape Phase Transitions in SD-pair Shell Model
DING Xiaoxue, ZHANG Yu, LI Lei, LUO Yanany, PAN Feng, Jerry P. Draayer
2017, 34(1): 98-104. doi: 10.11804/NuclPhysRev.34.01.098
Abstract(1296) PDF (386KB)(117)
Abstract:
The nuclear shape phase transitional patterns were studied in the SD-pair shell model. The results show that the transitional patterns similar to the U(5)-SU(3) and U(5)-SO(6) transitions in the interacting boson model can be produced. The signatures of the critical point symmetry in the interacting boson model are also produced approximately. It is also found that the shape phase transitional pattern between vibration and rotation can also be produced by changing the interactional strength.
Beyond the 2-body Interaction Paradigm in Modeling Nuclear Structure
Vesselin G. Gueorguiev
2017, 34(1): 105-109. doi: 10.11804/NuclPhysRev.34.01.105
Abstract(1136) PDF (256KB)(104)
Abstract:
We discuss modeling of nuclear structure beyond the 2-body interaction paradigm. Our first example is related to the need of three nucleon contact interaction terms suggested by chiral perturbation theory. The relationship of the two low-energy effective coupling parameters for the relevant three nucleon contact interaction terms cD and cE that reproduce the binding energy of 3H and 3He has been emphasized and the physically relevant parameter region has been ilustrated using the binding energy of 4He. Further justification of A-body interaction terms is outlined based on the Okubo-Lee-Suzuki effective interaction method used in solving the nuclear many-body problem within a finite model space. The third example we use is an exactly solvable A-body extended paring interaction applied to heavy nuclei with a long isotopic chain; in particular using 132Sn as closed core system illustrates a remarkable relationship between the extended pairing strength G(A) and the size of the valence space dim(A) for the members of the Sn-isotope chain: G(A)=αdim(A)-β with α=259.436 and β =0.9985 which is actually a one parameter expression since β is practically 1. These three cases present evidence for the need of better understanding of the NNN-, NNNN-, and A-body interactions in nuclei either derived from ChPT or from a phenomenological considerations.
Which Nuclei are Well Described by Liquid Drop Model: A Statistical Study Based on Uncertainty Decomposition Method
YUAN Cenxi
2017, 34(1): 110-115. doi: 10.11804/NuclPhysRev.34.01.110
Abstract(1183) PDF (311KB)(127)
Abstract:
Which data are well described by a theoretical model? Such questions can be answered through the physical origin of the model. For example, the liquid drop model (LDM) well describes the heavy and far from shell nuclei. Because the liquid-drop assumption is more suitable for nuclei with more nucleons and LDM does not include the shell effect. Such answer is qualitative and needs a clear view on the physical origin of the model. Is it possible to give an semi-quantitatively answer only from the mathematical form of the model and the observed data. In the present work, the recently suggested uncertainty decomposition method (UDM) is used to answer which nuclei are well described by LDM. The residues between LDM and the observed data can be decomposed through UDM to systematic and statistical uncertainties, which represent the uncertainty of the deficiency of the model and the indeterminate parameters, respectively. Based on UDM, the chart of nuclides are semi-quantitatively divided into three parts, areas dominated by the systematic and statistical uncertainties, and the cross area. Contrary to the common sense, the well described nuclei by LDM are not the nuclei with small residues, but actually the nuclei of which the residues are dominated by the statistical uncertainty. These nuclei are indeed the heavy and far from shell nuclei, which agrees with the physical consideration of LDM. But only the mathematical form of the model and the experimental data are needed during the use of UDM. The nuclides dominated by the statistical uncertainty can be well described by LDM (standard deviation less than 0.7 MeV) with parameters fitting to these nuclei.
Effects of Pairing Correlations on the Antimagnetic Rotation
ZHANG Zhenhua
2017, 34(1): 116-120. doi: 10.11804/NuclPhysRev.34.01.116
Abstract(1048) PDF (302KB)(125)
Abstract:
The antimagnetic rotation bands in 105;106Cd are investigated by the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia, I-Ω relation and the reduced B(E2) transition probabilities are well reproduced. The two-shears-like mechanism for the antimagnetic rotation is investigated by examining the shears angle, i.e., the closing of the two proton hole angular momenta. The sensitive dependence of the shears angle on the nuclear pairing correlations is revealed.
Ground-state Properties of Er, Yb and Hf Isotopes
GUAN Xin, PAN Feng
2017, 34(1): 121-127. doi: 10.11804/NuclPhysRev.34.01.121
Abstract(1394) PDF (414KB)(138)
Abstract:
The Nilsson mean-field plus extended-pairing model for deformed nuclei is applied to describe the ground-state properties of selected rare-earth nuclei. Binding energies, even-odd mass differences, moments of inertia for the ground-state band of 152-164Er, 154-166Yb, and 156-168Hf are calculated systematically in the model employing both proton-proton and neutron-neutron pairing interactions. In comparison with the corresponding experimental data, it is shown that for these rare-earth nuclei, pairing interaction is crucial in elucidating the properties of the ground state. With model parameters determined by fitting the energies of these states, ground-state occupation probabilities of valence nucleon pairs with angular momentum J =0,1, …,12 for even-even 156-162Yb are calculated. It is inferred that the occupation probabilities of valence nucleon pairs with even angular momenta are much higher than those of valence nucleon pairs with odd angular momenta. The results clearly indicate that S, D, and G valence nucleon pairs dominate in the ground state of these nuclei.