Subjects: Physics >> Nuclear Physics submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
Abstract： The nuclear dynamical deformation, the fusion probability and the evaporation residue (ER) cross sections for the synthesis of superheavy nuclei are studied with the di-nuclear system model and the related dynamical potential energy surface. The intrinsic energy and the maximum dynamical deformations for 48Ca+248Cm are calculated. The effect of dynamical deformation on the potential energy surface and fusion is investigated. It is found that the dynamical deformation influences the potential energy surface and fusion probability significantly. The dependence of the fusion probability on the angular momentum is investigated. The ER cross sections for some superheavy nuclei in 48Ca induced reactions are calculated and it is found that the theoretical results are in good agreement with the experimental results.
Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： In this contribution we present some recent results about neutron halos in deformed nuclei. A deformed relativistic Hartree-Bogoliubov theory in continuum has been developed and the halo phenomenon in deformed weakly bound nuclei is investigated. These weakly bound quantum systems present interesting examples for the study of the interdependence between the deformation of the core and the particles in the halo. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nuclei 42Mg. The core of this nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the existence of halos in deformed nuclei and for the occurrence of this decoupling effect are discussed.
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Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： Multi-dimensional constrained covariant density functional theories were developed recently. In these theories, all shape degrees of freedom βλμ deformations with even μ are allowed, e.g., β20, β22, β30, β32, β40, β42, β44, and so on and the CDFT functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the non-linear or density-dependent couplings. In this contri- bution, some applications of these theories are presented. The potential energy surfaces of actinide nuclei in the (β20 , β22 , β30 ) deformation space are investigated. It is found that besides the octupole deformation, the triaxiality also plays an important role upon the second fission barriers. The non-axial reflection-asymmetric β32 shape in some transfermium nuclei with N = 150, namely 246Cm, 248Cf, 250Fm, and 252No are studied.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： We have developed multi-dimensional constrained covariant density functional theories (MDC-CDFT) for finite nuclei in which the shape degrees of freedom βλμ with even μ, e.g., β20, β22, β30, β32, β40, etc., can be described simultaneously. The functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the non-linear or density-dependent couplings. For the pp channel, either the BCS approach or the Bogoliubov transformation is implemented. The MDC-CDFTs with the BCS approach for the pairing (in the following labelled as MDC-RMF models with RMF standing for “relativistic mean field”) have been applied to investigate multi-dimensional potential energy surfaces and the non-axial octupole Y32-correlations in N = 150 isotones. In this contribution we present briefly the formalism of MDC-RMF models and some results from these models. The potential energy surfaces with and without triaxial deformations are compared and it is found that the triaxiality plays an important role upon the second fission barriers of actinide nuclei. In the study of Y32-correlations in N = 150 isotones, it is found that, for 248Cf and 250Fm, β32 > 0.03 and the energy is lowered by the β32 distortion by more than 300 keV; while for 246Cm and 252No, the pocket with respect to β32 is quite shallow.
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Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： AdeformedrelativisticHartree-Bogoliubovtheoryincontinuumhasbeendevelopedfor the study of neutron halos in deformed nuclei and the halo phenomenon in deformed weakly bound nuclei is investigated. Magnesium and neon isotopes are studied and some results are presented for the deformed neutron-rich and weakly bound nuclei 44Mg and 36Ne. The core of the former nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the existence of halos in deformed nuclei and for the occurrence of this decoupling effect are discussed.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： The effects of nuclear superfluidity on antimagnetic rotation bands in 105Cd and 106Cd are in- vestigated by the cranked shell model with the pairing correlations and the blocking effects treated by a particle-number conserving method. The experimental moments of inertia and the reduced B(E2) transition values are excellently reproduced. The nuclear superfluidity is essential to repro- duce the experimental moments of inertia. 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, and its sensitive dependence on the nuclear superfluidity is revealed.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： Background: The pseudospin symmetry (PSS) has been studied extensively for bound states. Recently we justified rigorously that the PSS in single particle resonant states is exactly conserved when the attractive scalar and repulsive vector potentials of the Dirac Hamiltonian have the same magnitude but opposite sign [Phys. Rev. Lett. 109, 072501 (2012)]. Purpose: To understand more deeply the PSS in single particle resonant states, we focus on several issues related to the exact conservation and breaking mechanism of the PSS in single particle resonances. In particular, we are interested in how the energy and width splittings of PS partners depend on the depth of the scalar and vector potentials. Methods: We investigate the asymptotic behaviors of radial Dirac wave functions. Spherical square well poten- tials are employed in which the PSS breaking part in the Jost function can be well isolated. By examining the zeros of Jost functions corresponding to small components of the radial Dirac wave functions, general properties of the PSS are analyzed. Results: By examining the Jost function, the occurrence of intruder orbitals is explained and it is possible to trace continuously the PSS partners from the PSS limit to the case with a finite potential depth. The dependence of the PSS in resonances as well as in bound states on the potential depth is investigated systematically. We find a threshold effect in the energy splitting and an anomaly in the width splitting of pseudospin partners when the depth of the single particle potential varies from zero to a finite value. Conclusions: The conservation and the breaking of the PSS in resonant states and bound states share some similar properties. The appearance of intruder states can be explained by examining the zeros of Jost functions. Origins of the threshold effect in the energy splitting and the anomaly in the width splitting of PS partners, together with many other problems, are still open and should be further investigated.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： The pseudospin symmetry (PSS) is a relativistic dynamical symmetry directly connected with the small component of the nucleon Dirac wave function. Much effort has been made to study this symmetry in bound states. Recently, a rigorous justification of the PSS in single particle resonant states was achieved by examining the asymptotic behaviors of the radial Dirac wave functions: The PSS in single particle resonant states in nuclei is conserved exactly when the attractive scalar and repulsive vector potentials have the same magnitude but opposite sign. Several issues related to the exact conservation and breaking mechanism of the PSS in single particle resonances were investigated by employing spherical square well potentials in which the PSS breaking part can be well isolated in the Jost function. A threshold effect in the energy splitting and an anomaly in the width splitting of pseudospin partners were found when the depth of the square well potential varies from zero to a finite value.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： Symmetry plays a fundamental role in physics. The quasi-degeneracy between single-particle orbitals (n, l, j = l + 1/2) and (n − 1, l + 2, j = l + 3/2) indicates a hidden symmetry in atomic nuclei, the so-called pseudospin symmetry (PSS). Since the introduction of the concept of PSS in atomic nuclei, there have been comprehensive efforts to understand its origin. Both splittings of spin doublets and pseudospin doublets play critical roles in the evolution of magic numbers in exotic nuclei discovered by modern spectroscopic studies with radioactive ion beam facilities. Since the PSS was recognized as a relativistic symmetry in 1990s, many special features, including the spin symmetry (SS) for anti-nucleon, and many new concepts have been introduced. In the present Review, we focus on the recent progress on the PSS and SS in various systems and potentials, including extensions of the PSS study from stable to exotic nuclei, from non-confining to confining potentials, from local to non-local potentials, from central to tensor potentials, from bound to resonant states, from nucleon to anti-nucleon spectra, from nucleon to hyperon spectra, and from spherical to deformed nuclei. Open issues in this field are also discussed in detail, including the perturbative nature, the supersymmetric representation with similarity renormalization group, and the puzzle of intruder states.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2017-07-30
Abstract： The covariant density functional theory with a few number of parameters has been widely used to describe the ground-state and excited-state properties for the nuclei all over the nuclear chart. In order to describe exotic properties of unstable nuclei, the contribution of the continuum and its coupling with bound states should be treated properly. In this Topical Review, the development of the covariant density functional theory in continuum will be introduced, including the relativistic continuum Hartree-Bogoliubov theory, the relativistic Hartree-Fock-Bogoliubov theory in continuum, and the deformed relativistic Hartree-Bogoliubov theory in continuum. Then the descriptions and predictions of the neutron halo phenomena in both spherical and deformed nuclei will be reviewed. The diffuseness of the nuclear potentials, nuclear shapes and density distributions, and the impact of the pairing correlations on nuclear size will be discussed.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-18
Abstract： A foremost task in understanding the nature of the燲(3872)爄nvolves the discrimination of the two-quark and multiquark configurations. In this work, we propose a method to probe the short-distance component of the燲(3872)燽y measuring the ratio between the燘c爏emileptonic and nonleptonic decays into the燲(3872). We demonstrate that if the燲(3872)爌roduction mechanism is through the燾痗燾omponent, the ratios would be universal and could be reliably predicted in theory. Measurements of these ratios at LHC and the next-generation electron-positron colliders are capable of validating/invalidating this production mechanism and providing deeper insights into the nature of the燲(3872).
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-14
Abstract： Recent progress in holographic approach makes it more transparent that each conductivity can be decomposed into the coherent contribution due to momentum relaxation and the incoherent contribution due to intrinsic current relaxation. In this paper we investigate this decomposition in the framework of Einstein-Maxwell-Dilaton theory. We derive the perturbation equations which are decoupled for a large class of background solutions, and then obtain the analytic results of conductivity with slow momentum relaxation in low frequency approximation, which is consistent with the known results from memory matrix techniques.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-14
Abstract： We calculate the next-to-next-to-leading-order (NNLO) perturbative corrections to P-wave quarkonia annihilation decay to two photons, in the framework of nonrelativistic QCD (NRQCD) factorization. The order-α2s short-distance coefficients associated with each helicity amplitude are presented in a semi-analytic form, including the "light-by-light" contributions. With substantial NNLO corrections, we find disquieting discrepancy when confronting our state-of-the-art predictions with the latest \textsf{BESIII} measurements, especially fail to account for the measured χc2→γγwidth. Incorporating the effects of spin-dependent forces would even exacerbate the situation, since it lifts the degeneracy between the nonperturbative NRQCD matrix elements of χc0 and χc2 toward the wrong direction. We also present the order-α2s predictions to χb0,2→γγ, which await the future experimental test.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-14
Abstract： We construct a bulk geometry with Q-lattice structure, which is implemented by two gauge fields and a coupling between the lattice and the Maxwell field. This gravity dual model can describe a novel insulator which exhibits some key features analogous to Mott insulator. In particular, a hard gap in insulating phase as well as vanishing DC conductivity can be simultaneously achieved. In addition, we discuss the non-Drude behavior of the optical conductivity in low frequency region in insulating phase, which exhibits some novel characteristics different from ordinary Mott insulator.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-14
Abstract： We establish the factorization formula for scalar Glueball production through radiative decays of vector states of heavy quarkonia, e.g. J/ψ, ψ(2S) and Υ(nS), where the Glueball mass is much less than the parent heavy quarkonium mass. The factorization is demonstrated explicitly at one-loop level through the next-to-leading order (NLO) corrections to the hard kernel, the non-relativistic QCD (NRQCD) long-distance matrix element (LDMEs) of the heavy quarkonium, and the light-cone distribution amplitude (LCDA) of scalar Glueball. The factorization provides a comprehensive theoretical approach to investigate Glueball production in the radiative decays of vector states of heavy quarkonia and to determine the physic nature of Glueball. We discuss the scale evolution equation of LCDA for scalar Glueball. In the end, we extract the value of the decay constant of Scalar Glueball from Lattice QCD calculation and analyze the mixing effect among f0(1370), f0(1500) and f0(1710).
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-14
Abstract： In this paper, we study double charmonia production in Upsilon peaks, especially, a S-wave charmonium ηc and a P-wave charmonium hc(1P1), or a S-wave charmonium J/ψ and the X(3940) and X(4160) within the nonrelativistic QCD (NRQCD) approach which is a powerful tool to realize the factorization of double charmonia production in electron-positron annihilation. The JPC=1−− state Υ(nS) can provide an ideal laboratory for studying the properties of double-heavy quarkonium and also can separate the perturbative and nonperturbative parts due to the large heavy quark mass compared with the typical hadron scale ΛQCD. Explanation of the X(3940) and X(4160) as the 31S0 and 41S0 states, respectively, are compatible with the observed upper limits for the branching fractions of Υ(1S,2S)→J/ψ+X, where X=X(3940), X(4160) by the Belle Collaboration. The branching fractions of Υ(1S,2S,3S)→ηc+hc(1P1) are predicted to be around 10−6, which shall be tested in Belle-II experiments.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-14
Abstract： In quantum gravity, a foamy structure of space-time leads to Lorentz invariance violation (LIV). As the most energetic astrophysical processes in the Universe, gamma-ray bursts (GRBs) provide an effective way to probe quantum gravity effects. We use continuous spectra of 20 short GRBs detected by the Swift satellite to give a conservative lower limit of quantum gravity energy scale燤QG. Due to the LIV effect, photons with different energy have different velocities. This will lead to the delayed arrival of high energy photons relative to the low energy ones. Based on the fact that the LIV-induced time delay can't be longer than the duration of a GRB, we present the most conservative estimation of the quantum gravity energy scales from 20 short GRBs. The most strict constraint,燤QG>5.05�014燝eV, is from GRB 140622A.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
Abstract： We calculate the tree and penguin amplitudes in the B0→π+π− decay channel employing the perturbative QCD factorization approach. Using the amplitudes as input with the theoretical uncertainties sufficiently considered, we constrain the UT angle γ to 53∘≤γ≤70∘, from the measurements of the CP violation parameters Cπ+π− and Sπ+π− in B0→π+π−. The U-spin breaking effect between B0→π+π− and B0s→K+K− is estimated to be around 30\%.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
Abstract： We report on a theoretical study of the π−p→D−D0p reaction near threshold within an effective Lagrangian approach. The production process is described by t channel D∗0 meson exchange, s-channel nucleon pole, and u channel Σ++c exchange. In our work, the final D0p results from the ground Λ+c(2286) state and also dominantly from the excited Λ+c(2940) state which is assumed as a D∗0p molecular state with spin parity JP=12+ or 12−. We calculate the total cross section of the π−p→D−D0p reaction. It is shown that the spin parity assignment of 12− for Λ+c(2940) gives a sizable enhancement for the total cross section in comparison with a choice of Jp=12+. However, our theoretical result of the total cross section is sensitive to the value of the cutoff parameter involved in the form factor of the exchanged off-shell particles. Moreover, we also calculate the second order differential cross section and find it can be used to determine the parity of the Λ+c(2940). It is expected that our model calculations can be tested by future experiments at J-PARC in Japan.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
Abstract： By assuming that the scalar meson K∗0(1430) belongs to the first excited states or the lowest lying ground states, we study the pure annihilation-type decays B→K∗±0(1430)K(∗)∓ in the QCD factorization approach. Within the standard model, the branching fractions are at the order of 10−8−10−7, which is possible to be measured in the ongoing LHCb experiment or forthcoming Belle-II experiment. We also study these decays in the family non-universal Z′ model. The results show that if mZ′≈600GeV (ζ=0.02), both the branching fractions and CPasymmetries of B¯¯¯¯0→K∗+0(1430)K− could be changed remarkably, which provides us a place for probing the effect of new physics. These results could be used to constrain the parameters of Z′ model.
Peer Review Status:Awaiting Review
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