Short-range Nuclear Force Research Articles

The structure of low-lying 1− states in 90,94Zr from (α,α′γ) and (p,p′γ) reactions

The low-lying dipole strength was investigated in 90,94 Zr via the (p,p′γ) reaction at 80 MeV and via the (α,α′γ) reaction at 130 MeV. These experiments were performed at the Research Center for Nuclear Physics (Osaka University) and made combined use of the high-resolution magnetic spectrometer Grand Raiden and the CAGRA HPGe gamma array. The comparison of our results with existing (γ,γ′) reaction data shows differences in the excitation patterns. In the present experimental conditions, in fact, both α and p probes are exciting the investigated 1− states mainly through the short-range nuclear force, expected to favour the population of surface excitations. Distorted Wave Born Approximation (DWBA) calculations were made using form factors built assuming specific transition densities, characterized by a strong neutron component at the nuclear surface and based on Random Phase Approximation (RPA). A combined analysis of the (α,α′γ) and (p,p′γ) data was performed to investigate the isoscalar character of the 1− states in 90,94Zr. Although an overall general consistency was obtained in the studied energy intervals, not all (p,p′γ) cross sections were well reproduced using the isoscalar strength deduced from (α,α′γ) data. This might suggest that the mixing of isoscalar and isovector components and the degree of collectivity are not the same for all the 1− states studied.

Weinberg operator contribution to the CP -odd nuclear force in the quark model

The contribution of the CP violating three-gluon interaction, proposed by Weinberg, to the short-range CP-odd nuclear force is evaluated in the nonrelativistic quark model. We first show that the naive leading contribution generated by the quark exchange process vanishes at sufficiently short distance within the resonating group method, by considering the one-loop level gluon exchange CP-odd interquark potential induced by the Weinberg operator with massive quarks and gluons. We then estimate the true leading contribution by evaluating the gluonic correction to the CP-odd interquark potential in the closure approximation. It is found that the resulting irreducible CP-odd nuclear force is comparable to that generated by the chiral rotation of the CP-even short-range nuclear force, where the CP-odd mass calculated with QCD sum rules is used as input. The explicit calculation of the electric dipole moment (EDM) of the $^3$He nucleus yields $d_{^3{\rm He}}^{\rm (irr)} (w) = - 1.5 \, w\, e $ MeV. The total $^3$He EDM, accounting for the intrinsic nucleon EDM, the pion-exchange and the short-range CP-odd nuclear force, is $d_{^3{\rm He}}^{\rm (tot)} (w) = 20_{-11}^{+14} \, w\, e $ MeV, with the dominant effect coming from the intrinsic nucleon EDM.

Application of Information and Complexity Measures to Neutron Stars Structure

We apply several information and statistical complexity measures to neutron stars structure. Neutron stars is a classical example where the gravitational field and quantum behaviour are combined and produce a macroscopic dense object. We concentrate our study on the connection between complexity and neutron star properties, like maximum mass and the corresponding radius, applying a specific set of realistic equation of states. Moreover, the effect of the strength of the gravitational field on the neutron star structure and consequently on the complexity measure is also investigated. It is seen that neutron stars, consistent with astronomical observations so far, are ordered systems (low complexity), which cannot grow in complexity as their mass increases. This is a result of the interplay of gravity, the short-range nuclear force and the very short-range weak interaction.

Field Coupling-Based Image Filter for Sand Painting Stylization

Sand painting is a very new and popular performance art technique, and it has important meaning for the artistic creation. Computer-aided sand painting is now in the ascendant, whose fully automated mechanism is still an attractive challenge. Image data field, inspired from short-range nuclear force in physics, is introduced into sand painting stylization. With preserving edges and features, a fully automatic image filter pipeline based on image field coupling is proposed, which consists of three main steps, including image data field generating, multiscale field coupling, and additional details optimizing. The visual comparisons indicate that the proposed pipeline and image filter are feasible and effective, and sand painting-like artistic images can be produced by using multiscale field coupling. The qualities of various rendering images are also investigated from the perspective of feature similarity measures. The quantitative and qualitative results suggest that the field coupling-based filter is appropriate for sand painting stylization, and the time cost is satisfied for practice applications. Generally, the proposed method provides a reference for automatic creation of computer-aided sand painting art.

Short Range Gravity Potential Self Energy and Nonlinear Potential Dependent Lorentz Transformation

Using Poisson equation beside Maxwell distribution law for very hot star core consisting of elementary particles one can find new Poisson equation. This equation predicts existence of short range gravity force. This short force may have a link with short range nuclear force, thus raises a hope in unifying gravity and nuclear force. This short range field beside long range field secures singular finite self-energy. This central role of potential in unifying self-energy for high relativistic particles at star cores requires seeking Lorentz transformation that accounts for effect of fields. This work derived new Lorentz transformation for accelerated frame. This transformation is potential dependent and reduces to SR and explains time dilation and gravitational red shift.

Dibaryon Concept for Short-Range 2N and 3N Forces: Consequences for Hadronic and Nuclear Physics

The short-range aspects of 2N and 3N nuclear interactions are considered in light of numerous novel experimental data obtained in JLab, BNL, Mainz, etc. Many of these new experimental results contradict strongly to the traditional models for short-range (or high-momentum) components of nuclear forces and therefore require a novel understanding within new models alternative to the traditional (one-boson-exchange) ones. At the NN distances r N N < 1 fm the nucleon quark cores get overlapped with each other and thus the generation of the common six-quark bag is very likely. So, the dibaryon concept considers the generation of the intermediate six-quark bag dressed with meson (predominantly the scalar-isoscalar σ-meson) clouds as a driving mechanism for short-range nuclear force. Numerous predictions of the above dibaryon model are considered in the paper.

The GEM Unification Theory of the Vacuum: Did Dimensional Collapse Trigger the Big Bang

The GEM (Gravity EM) unification theory builds on the Sakharov and Kaluza-Klein approaches to unify all four force fields of nature: Gravity, EM, Strong, and Weak using Feynman Path integral formalism. The model is rudimentary, and can be called a “Bohr Model” of unification. It is basically found that Gravity and the other forces can be understood as quantum electrodynamics. In particular the proton emerges as a fundamental particle despite being composed of quarks and is the principle interaction vertex of the Higgs boson, which is seen here as direct consequence of a hidden 5th dimension, where the Higgs mass is due to 5th dimensional compactification. Collapse and compactification of a 5th dimension is argued as the triggering event for the Big Bang. A particle mass formula based on Feynman Path Integrals including paths across the hidden 5th dimension gives the proton and electron masses to high accuracy and finds the charged bosons responsible for the short range nuclear forces. The masses calculated for the particles are as follows: the charged pion m = 2 me / 140.0 MeV and W boson: mw =2 mp = 80.4 GeV. The c meson m =2985 GeV is identified with the 5th dimension compactification force mediated by the Radion field. The Higgs boson associated with this mass inducing field is the most general EM+Radion scattering quanta off the hidden dimension size with a mass mp/α  127.7 GeV. This results in a structural resonance Higgs = rp where Higgs is the Compton radius of the Higgs boson and Higgs =c/mHiggsc2 the rp electro-dynamic length of the proton rp=e2/mpc2. Vacuum decay results from this value of the Higgs boson mass, which is a key parameter in a mass system that creates the proton-electron mass system and thus hydrogen in the Big Bang. The vacuum is found to decay into proton-electron pairs and to give an “eternally inflating” cosmos of Hubble Time TH  ( 9/ )1/3 /2 e2 /(4oGmemp ) re/c = 1.2 x1010 years. The predicted value of the CBR(Cosmic Background Radiation) temperature from this vacuum decay is TCBR  (4cGme2/(3Th2Stefan-Boltz.)1/3 = 2.65K Support for this consists of observation of the failure of the Sunaeyev-Zeldovich effect, where distant galaxies are not observed to cast shadows in the CBR indicating a source for the CBR in the vacuum itself in the line of sight to more distant galaxies.

Nuclear Structure of the Heaviest Elements – Investigated at SHIP-GSI

The quest for the heaviest nuclei that can exist is a basic topic in natural science as their stability is characterized by a delicate interplay of short range nuclear forces acting between the nucleons (protons and neutrons) and long-range Coulomb forces acting solely between charged particles, i.e. the protons. As the stability of a nucleus is strongly correlated to its structure, understanding the nuclear structure of heaviest nuclei is presently a main challenge of experimental and theoretical investigations concerning the field of Superheavy Elements. At the velocity filter SHIP at GSI Darmstadt an extensive program on nuclear structure investigations has been started about a decade ago. The project covered both as well systematic investigations of single particle levels in odd-mass isotopes populated by α-decay as investigation of two- or fourquasi-particle states forming K isomers and was supplemented by direct mass measurements at SHIPTRAP and investigation of spontaneous fission properties. Recent experimental studies allowed to extend the systematics of low lying levels in N = 151 and N = 153 up to 255Rf and 259Sg, investigation of possible relations between nuclear structure and fission properties of odd-mass nuclei and investigation of shell strengths at N = 152 and towards N = 162.

Short-range components of nuclear forces: Experiment versus mythology

The present-day situation around the description of various (central, spin-orbit, and tensor) components of short-range nuclear forces is discussed. A traditional picture of these interactions based on the idea of one-meson exchange is contrasted against numerous results of recent experiments. As is shown in the present study, these results often deviate strongly from the predictions of traditional models. One can therefore state that such models are inapplicable to describing short-range nuclear forces and that it is necessary to go over from a traditional description to some alternative QCD-based (or QCD-motivated) picture. This means that, despite the widespread popularity of traditional concepts of short-range nuclear forces and their applicability in many particular cases, these concepts are not more than scientific myths that show their inconsistency when analyzed from the viewpoint of the modern experiment.

Short-range nuclear forces in singlet channels

Continuing our effort to build a consistent power counting for chiral nuclear effective field theory (EFT), we discuss the subleading contact interactions, or counterterms, in the singlet channels of nucleon-nucleon scattering, with renormalization group invariance as the constraint. We argue that the rather large cutoff error of the leading amplitude requires $\mathcal{O}(Q)$ of the EFT expansion to be nonvanishing, contrary to Weinberg's original power counting. This, together with the ultraviolet divergences of two-pion exchanges in the distorted-wave expansion, leads to enhancement of the ${}^{1}{S}_{0}$ counterterms and results in a pionless-theory-like power counting for the singlet channels.

Image data field for homogeneous region based segmentation

Some innovative methods for image segmentation inspired by physical world are presented in recent years. Aiming to find homogeneous regions and latent semantic information, the paper presents a novel image segmentation method based on image data field. Image data field, developed by simulating the short-range nuclear forces field theory in the physical world, can effectively represent the spatial interactions of neighborhood pixels. Then, the homogeneous regions are characterized by maximum tolerance classes, which induced by homogeneous attraction relation comparing the contributions of potential values in image data field. More specifically, the proposed method mainly focuses on the images with uneven lighting conditions. Compared with the existing relative methods on a variety of images, the experimental results suggest that the presented method is efficient and effective.

Neutron halo isomers in stable nuclei and their possible application for the production of low energy, pulsed, polarized neutron beams of high intensity and high brilliance

We propose to search for neutron halo isomers populated via γ-capture in stable nuclei with mass numbers of about A=140–180 or A=40–60, where the 4s 1/2 or 3s 1/2 neutron shell model state reaches zero binding energy. These halo nuclei can be produced for the first time with new γ-beams of high intensity and small band width (≤0.1%) achievable via Compton back-scattering off brilliant electron beams, thus offering a promising perspective to selectively populate these isomers with small separation energies of 1 eV to a few keV. Similar to single-neutron halo states for very light, extremely neutron-rich, radioactive nuclei (Hansen et al. in Annu. Rev. Nucl. Part. Sci. 45:591–634, 1995; Tanihata in J. Phys. G., Nucl. Part. Phys. 22:158–198, 1996; Aumann et al. in Phys. Rev. Lett. 84:35, 2000), the low neutron separation energy and short-range nuclear force allow the neutron to tunnel far out into free space much beyond the nuclear core radius. This results in prolonged half-lives of the isomers for the γ-decay back to the ground state in the 100 ps-μs range. Similar to the treatment of photodisintegration of the deuteron, the neutron release from the neutron halo isomer via a second, low-energy, intense photon beam has a known much larger cross section with a typical energy threshold behavior. In the second step, the neutrons can be released as a low-energy, pulsed, polarized neutron beam of high intensity and high brilliance, possibly being much superior to presently existing beams from reactors or spallation neutron sources.

Convergence of Density-Matrix Expansions for Nuclear Interactions

We extend density-matrix expansions in nuclei to higher orders in derivatives of densities and test their convergence properties. The expansions allow for converting the interaction energies characteristic to finite- and short-range nuclear effective forces into quasilocal density functionals. We also propose a new type of expansion that has excellent convergence properties when benchmarked against the binding energies obtained for the Gogny interaction.

Complexity and neutron star structure

We apply the statistical measure of complexity introduced by López-Ruiz, Mancini and Calbet (1995) [1] to neutron star structure. We continue the recent application of Sañudo and Pacheco (2009) [2] to white dwarfs. The interplay of gravity, the short-range nuclear force and the very short-range weak interaction shows that neutron stars, under the current theoretical framework, are ordered (low complexity) systems.

3 Why is gravity so weak?

Why is gravity weak? Gravity is plagued with this and many other questions. After decades of exhausting work we do not have a clear answer. In view of this fact it will be shown in the following pages that there are reasons for thinking that gravity is just a composite force consisting of the long-range manifestations of short range nuclear forces that are too tiny to be measured at intermediate or long ranges by particle colliders. This is consistent with Einstein's proposal in 1919.

Dibaryons as Carriers of Strong Internucleon Interactions and a Basis for Nuclear Physics Based on QCD

New concept of intermediate- and short-range nuclear force proposed by the authors a few years ago is discussed briefly. The general concept is based on an assumption on generation of the dressed dibaryon in intermediate state in NN interaction. This new mechanism has been shown to lead not only to numerous new predictions in hadronic physics but also should be responsible for a large portion of nuclear binding energy and properties of nuclear wavefunctions at high momenta.

Barrier for cold-fusion production of superheavy elements

We estimate the fusion-barrier height ${B}_{\mathrm{fu}}^{\text{(two-body)}}$ for approaching ions in cold-fusion reactions in a model where the projectile deformation and quadrupole zero-point vibrational energy are taken into account. This barrier height is defined as the barrier energy at the target and projectile separation distance where an original oblate deformation of projectile and/or target caused by a repulsive Coulomb force turns into a large prolate deformation caused by the attractive nuclear force as the target and projectile come closer. The instability develops before touching because the attractive short-range nuclear force overcomes the repulsive Coulomb force and the shape-stabilizing effect of shell structure. The shell structure of the doubly magic $^{208}\mathrm{Pb}$ target is sufficiently strong that its shape remains very close to spherical in all cases studied here. The fusion potential for approaching ions in the two-body channel is calculated in the macroscopic-microscopic model with the quadrupole vibrational zero-point energy obtained in the WKB approximation. We compare our results with data from 10 experimental cold-fusion reactions and with the Bass barriers. Differences and similarities between the Yukawa-plus-exponential model and the Bass model are discussed. We also calculate five-dimensional potential-energy surfaces for the single compound system and show that well-established fission and fusion valleys are both present. For heavy systems, ${B}_{\mathrm{fu}}^{\text{(two-body)}}$ becomes lower than the fission barrier just beyond the ground state of the compound system. In the vicinity of this transition, the optimum collision energy for formation of evaporation residues can be expected to depend in a delicate fashion on the interplay among ${B}_{\mathrm{fu}}^{\text{(two-body)}}$, the fusion valley, the fission barrier of the compound system, and the one- and two-neutron separation energies ${S}_{1n}$ and ${S}_{2n}$. We discuss these issues in detail and calculate fission-barrier heights. Except for reactions in which the projectile is doubly magic or near doubly magic, the calculated quantities are consistent with the observed optimal energies for evaporation-residue formation.

Microscopic Basis of the Interacting Boson Model

The microscopic basis of the IBM is discussed in this paper, presenting a derivation of the IBM system from the multi-nucleon system. Although there could be different approaches to this goal as stated in the preface of this supplement, we focus on two approaches. One is the Otsuka-Arima-Iachello mapping, which works for the spherical and near-spherical nuclei. The other is a mapping for deformed nuclei. In this paper, we discuss mapping methods for deriving the Interacting Boson Model (IBM). l) We first present a mapping method for spherical and near-spherical nuclei, usually referred to as the Otsuka-Arima-Iachello (OAI) mapping. 2 ), 3 ) The OAI mapping is based on the seniority scheme as will be discussed in detail. This mapping has been developed so that realistic calculations can be carried out as presented in a subsequent paper. In this paper, the basic concepts of the mapping are discussed rather in detail. Furthermore, the proton-neutron Interacting Boson Model (IBM-2) is discussed as a natural consequence of this mapping. 2 ), 3 ) In the second half of this paper, a mapping method for strongly deformed nuclei 8 ) will be reviewed. Although this mapping is for deformed nuclei, it is somewhat related to the OAI mapping. The work on deformed nuclei is much before any sort of completion, and considerable effort should be made in the future. For this purpose, the Quantum Monte Carlo Diagonalization method proposed recently 4 )- 7 ) may be useful. When the IBM was proposed from the phenomenological viewpoint by Arima and Iachello, the microscopic picture of bosons of this model was not known as pointed out in the preface of this supplement. The microscopic theory has made a crucial contribution even to phenomenological studies by the IBM, also as mentioned in the preface. Before starting rather detailed discussions, it may be useful to overview relevant properties of the effective nucleon-nucleon interactions. The short-range nuclear force favors two nucleons lying close to each other. This means that, if the wave functions of the two neutrons have large spatial overlap, the matrix element of this interaction becomes larger. On the other hand, two identical fermions cannot occupy the same quantum state, and this is the case for two neutrons. The next optimum case for gaining energy is that the two neutrons are moving on the same orbital but in opposite directions. Because the direction is opposite, the quantum states of the two neutrons are different. In this case, the total angular momentum of the two-neutron system is zero, because the rotation is completely cancelled. In fact, the

Possible soft-core effect in heavy-ion collisions

We study the nuclear equation of state by simulating Nb+Nb heavy-ion collisions from 100 to 1000 MeV/nucleon and solving the Liouville equation with a classical interaction. Sensitivity to the nuclear equation of state is investigated by changing the short-range input nuclear force. A stiffer short-range potential is shown to result in greater transverse momentum transfer and collective flow angle. We provide a qualitative explanation of recent LBL/GSI plastic ball data, which show a saturation of the flow, in terms of the classical many-body model with internucleon potentialV(r=0) finite.

The Reykjavík Summit and European Security

THE REYKJAVIK SUMMIT_ AND EUROPEAN SECURITY David S. Yost ML my West Europeans have agreed in retrospect that the most disturbing feature of the Reykjavik summit was the apparent "indifference or quasi-indifference" of the United States regarding European security interests .1 This judgment is based on the specific arms-control arrangements that President Reagan and General Secretary Gorbachev discussed in Iceland in October 1986, plus the subsequent explanations of the U.S. administration. The Reykjavik summit also provided fresh evidence of the Soviet Union's more imaginative diplomatic style under Gorbachev and, more substantively, ofenduring Soviet preferences regarding security in Europe. Although West Europeans have expressed concerns about Soviet motives and about U.S. competence and long-term reliability, they have reached little consensus about practical steps that governments should take. In public declarations the West Europeans have generally professed to be pleased with the arms-control measures discussed at Reykjavik. The Nuclear Planning Group (NPG), which includes all the allies except France and Iceland, asserted in October 1986: "We extended our warm appreciation to the President on his conduct of the talks and fully endorsed his bold attempt to seek far-reaching arms control agreements 1. Valéry Giscard d'Estaing, "Pour une expression de solidarité européenne," Le Monde, 8 November 1986, 4. David S. Yost is an associate professor at the Naval Postgraduate School, Monterey, California, and a 1986-87 visiting scholar at SAIS. Dr. Yost worked in the Department of Defense, primarily in the Office of Net Assessment, in 1984-86 under the auspices of fellowships from NATO and the Council on Foreign Relations. He would like to express his appreciation to the Earhart Foundation for research support. The views expressed are his alone and should not be construed to represent those of the Department of the Navy or any U.S. government agency. 1 2 SAIS REVIEW with the Soviet Union. We fully endorsed the President's programme presented in Iceland and stressed that this programme provides the opportunity for historic progress."2 Subsequent reports and Alliance deliberations have made it clear, however, that this communiqué language overstated West European support for the U.S. positions. According to Robert O'Neill, the director of the International Institute for Strategic Studies in London, "We have got into an absurd situation, where everyone in the alliance is saying exactly the opposite of what he thinks."3 West European misgivings concern four main topics: the tentative agreement on intermediate-range nuclear forces (INF); the proposals for strategic force limitations, especially the U.S. plan to eliminate all ballistic missiles in ten years; the goal of complete nuclear disarmament; and conflicting views on future limitations on ballistic missile defense (BMD). Intermediate-Range Nuclear Forces According to a standard Western definition, there are two basic categories of INF missiles: shorter-range INF(SRINF) with ranges between 150 and 1,000 kilometers, such as the Soviet SS- 12/22 and SS-23 and longer-range INF (LRINF), with ranges between 1,000 and 5,500 kilometers, such as the Soviet SS-20 and SS-4 and U.S. Pershing II and ground-launched cruise missiles. Missiles with ranges below 150 kilometers, such as the U.S. Lance and Soviet FROG/SS-21 systems, are not SRINF but simply short-range nuclear forces (SNF). At Reykjavik the United States accepted a Soviet offer to endorse a version of the global zero option for U.S. and Soviet LRINF missiles that was first proposed by the United States in 1981. The Soviet-proposed zero option called for the elimination of all U.S. and Soviet LRINF missiles on European soil. The Soviet Union would retain no more than 100 warheads on LRINF missile launchers in Asia, the United States no more than the same total on U.S. soil. Despite their presummit indications, the Soviets announced at Reykjavik that no LRINF agreement could be firmly concluded unless the United States and the Soviet Union had also come to terms on a package of limits on strategic forces and space and defense systems, including new constraints on U.S. Strategic Defense Initiative (SDI) research. Soviet spokesmen added that the Soviet Union could not...