原子核质量中的奇偶性

原子核质量的描述和预言是原子核结构理论中的基础问题之一。相邻原子核质量存在奇偶性,这些奇偶性对于构造局域质量关系和研究核子对力相互作用有参考意义。本文回顾了我们在近年来注意到的相邻原子核质量之间的奇偶性方面研究的主要结果,包括最后一个质子与中子相互作用[标记为δV1p-1n]的奇偶性及其起源、δV1p-1n奇偶性导致的Garvey-Kelson质量关系的奇偶性、单核子分离能与原子核的质子和中子数奇偶相关性等。     

Garvey-Kelson relations for nuclear charge radii

The Garvey-Kelson relations (GKRs) are algebraic expressions originally developed to predict nuclear masses. In this paper we show that the GKRs provide a fruitful framework for the prediction of other physical observables that also display a slowly varying dynamics. Based on this concept, we extend the GKRs to the study of nuclear charge radii. The GKRs are tested on 455 out of the approximately 800 nuclei whose charge radius is experimentally known. We find a rms deviation of 0.01fm between the GK predictions and the experimental values. Predictions are provided for 116 nuclei whose charge radius is presently unknown.     

Masses of atomic nuclei far from stability

It is shown that a new way of applying a set of nuclear-mass relations among neighbouring nuclei, known as the Garvey–Kelson (GK) relations, holds exceptionally well for all currently measured masses. It is then demonstrated that these relationships are not adequately fulfilled for the best-known procedures to predict unknown masses. This suggests that these models may be optimized by constraining them to satisfy the (generalized) GK equations.     

Independent particle model approach to nuclear mass formula and mass relationships

A nuclear mass formula is derived using a few extremely reasonable assumptions within an independent particle model with residual interactions. The parameters in the mass formula are determined by a least square fit to the experimental energies. The mass formula is further used to study Garvey-Kelson and Franzini-Radicati mass relationships.     

Some new symmetric relations of quark masses and prediction of fourth-generation quark masses

In this study, we discover a mass space defined by generalized Koide relations, named here as k-relations, and achieve some new symmetric relations. These relations can be further used to predict the fourth-generation quark masses in terms of dilation magnitude and angular rotation ratios in the general mass space. Thus far, no theory has been proposed that can constrain the number of generations of quarks; this theory naturally limits the number of generations of quarks.     

The spectrum of the 4-generation Dirac–Kähler extension of the SM

We compute the mass spectrum of the fermionic sector of the Dirac–Kähler extension of the SM (DK-SM) by showing that there exists a Bogoliubov transformation that transforms the DK-SM into a flavor U(4)$U(4)$ extension of the SM (SM-4) with a particular choice of masses and mixing textures. Mass relations of the model allow determination of masses of the 4th generation. Tree level prediction for the mass of the 4th charged lepton is 370 GeV. The model selects the normal hierarchy for neutrino masses and reproduces naturally the near tri-bimaximal and quark mixing textures. The electron neutrino and the 4th neutrino masses are related via a see-saw-like mechanism.     

A search for leptoquarks and squarks at HERA

A search in the H1 experiment at HERA for scalar and vector leptoquarks, leptogluons and squarks coupling to first generation fermions is presented in a data sample corresponding to an integrated luminosity of 425 nb^–1. For masses ranging up to 275 GeV, no significant evidence for the direct production of such particles is found in various possible decay channels. At high masses and beyond the centre of mass energy of 296 GeV a contact interaction analysis is used to further constrain the couplings and masses of new vector leptoquarks and to set lower limits on compositeness scales.Supported by the Bundesministerium für Forschung und Technologie, FRG under contract numbers 6AC17P, 6AC47P, 6DO571, 6HH17P, 6HH271, 6HD171, 6HD271, 6KH7P, 6MP171, and 6WT87P     

Garvey-Kelson mass formula in the s-d shell

A literal interpretation of the Garvey-Kelson mass formula is used to relate deviations from the simple predictions for certain sextuplets of nuclei. The large discrepancies between prediction and experiment for ²⁵Ne, ²⁹Mg and ³³Si are, in this way, removed.     

O(3) flavor symmetry and an empirical neutrino mass matrix

Based on a new approach to quark and lepton masses, where the mass spectra originate in vacuum expectation values of O(3)-flavor 1+5$\mathbf{1}+\mathbf{5}$ (gauge singlet) scalars, a neutrino mass matrix of a new type is speculated. The mass matrix is described in terms of the up-quark and charged lepton masses, and, by assuming a special flavor basis, it can be accommodated to a nearly tribimaximal mixing without explicitly assuming a discrete symmetry. Quark mass relations are also discussed based on the new approach.     

A lagrangian model invariant under supergauge transformations

We study, in the one-loop approximation, a Lagrangian model invariant under supergauge transformations. The model involves a scalar, a pseudoscalar and a spinor field. Supergauge invariance gives rise to relations among the masses and the coupling of these fields and implies the existence of a conserved current. The renormalization procedure is discussed and the relations among masses and couplings are shown to be preserved by renormalization.     

The suppression of neutralino annihilation into Zh

The indirect detection of neutralino dark matter is most promising through annihilation channels producing a hard energy spectrum for the detected particles, such as neutralino annihilation into Zh. A cancellation however makes this particular annihilation channel generically subdominant in the huge parameter space of supersymmetric models. This cancellation requires non-trivial relations between neutralino mixings and masses, which we derive from gauge independence and unitarity of the MSSM. To show how the cancellation overshoots leaving only a subdominant result, we use a perturbative expansion in powers of the electroweak/supersymmetry breaking ratio m_Z/m_χ.     

Uncertainties from fermion masses ine^ + e^ - \to v\bar v\gamma

In the reaction \(e^ + e^ - \to v\bar v\gamma \) , the influence of the unknown masses of heavy fermions for three and four fermion generations is studied, which arises via virtual 1-loop corrections in the framework of the standard model. These masses are the top quark massm _t and in the case of 4 generations the lepton massm t, wherel ^? is theSU(2) partner of the fourth generation neutrino. Increasing the fermion masses from 50 GeV to 250 GeV, the maximum of the total cross section is found to decrease by a few percent.     

Mass of nonrelativistic meson from leading twist distribution amplitudes

In this paper distribution amplitudes of pseudoscalar and vector nonrelativistic mesons are considered. Using equations of motion for the distribution amplitudes, relations are derived which allow one to calculate the masses of nonrelativistic pseudoscalar and vector meson if the leading twist distribution amplitudes are known. These relations can be also rewritten as relations between the masses of nonrelativistic mesons and infinite series of QCD operators, what can be considered as an exact version of Gremm-Kapustin relation in NRQCD.     

Mass excesses of 79As, 81As,and 80Ge

Accurate mass measurements for the nuclides ⁷⁹As, ⁸¹As, and ⁸⁰Ge have been measured. Good agreement has been found for ⁷⁹As and ⁸¹As with the Garvey-Kelson transverse mass relation and with several mass model predictions. The agreement for ⁸⁰Ge is not as satisfactory and presents a challenge for understanding mass values far off the line of stability.     

Conversion electron measurements and determination of rotational parameters in 177Lu and 177Hf

We discuss the possibility whether superheavy elements can be produced in Nature by the astrophysical rapid neutron capture process. To this end we have performed fully dynamical network r-process calculations assuming an environment with neutron-to-seed ratio large enough to produce superheavy nuclei. Our calculations include two sets of nuclear masses and fission barriers and include all possible fission channels and the associated fission yield distributions. Our calculations produce superheavy nuclei with $\ensuremath A\approx 300$ that however decay on time scales of days.     

Sum rules for reduced matrix elements of the generalized momentum operator in III–V semiconductors

The band structure of III–V semiconductors near the Γ point is studied with full account of the spin-orbit interaction, which results not only in band splitting but also in spin-orbit mixing of wave functions of different spatial symmetry. In view of the last circumstance, a new version of the k·p method of perturbation theory is developed and strict symmetry relations are derived for the first time in which sums containing optical matrix elements and energy denominators are related to intrinsic electron characteristics (masses, g factors). These relations (sum rules) appear to be informative in analyzing the spatial symmetry of electronic states near the Γ point and are useful for quantitative estimation of the most important optical matrix elements.     

The multiplets of finite-width 0++ mesons and encounters with exotics

The complex-mass (finite-width) 0⁺⁺ nonet and decuplet are investigated by means of the exotic commutator method. The hypothesis of the vanishing of the exotic commutators leads to the system of master equations (ME). Solvability conditions of these equations define relations between the complex masses of the nonet and decuplet mesons which, in turn, determine relations between the real masses (mass formulae), as well as between the masses and widths of the mesons. Mass formulae are independent of the particle widths. The masses of the nonet and decuplet particles obey simple ordering rules. The nonet mixing angle and the mixing matrix of the isoscalar states of the decuplet are completely determined by solution of ME; they are real and do not depend on the widths. All known scalar mesons with the mass smaller than 2000 MeV (excluding σ(600)) and one with the mass belong to two multiplets: the nonet (a₀(980),K₀(1430),f₀(980),f₀(1710)) and the decuplet (a₀(1450),K₀(1950),f₀(1370),f₀(1500),f₀(2200)/f₀(2330)). It is shown that the famed anomalies of the f₀(980) and a₀(980) widths arise from an extra “kinematical” mechanism, suppressing decay, which is not conditioned by the flavor coupling constant. Therefore, they do not justify rejecting the qq̄ structure of them. A unitary singlet state (glueball) is included into the higher lying multiplet (decuplet) and is divided among the f₀(1370) and f₀(1500) mesons. The glueball contents of these particles are totally determined by the masses of decuplet particles. Mass ordering rules indicate that the meson σ(600) does not mix with the nonet particles.     

Pseudoscalar mesons and their radial excitations from the effective chiral Lagrangian

The effective chiral Lagrangian is derived from QCD in the framework of the field correlator method. It contains the effects of both confinement and chiral symmetry breaking due to a special structure of the resulting quark mass operator. It is shown that this Lagrangian describes light pseudoscalar mesons, and Gell-Mann-Oakes-Renner relations for pions, eta and K mesons are reproduced. The spectrum of radial excitations of pions and K mesons is found and compared to experimentally known masses.     

Violation of isotopic invariance in strong interactions and mass spectrum of the 1/2+ baryon octet

The ideas developed by Gell-Mann and Okubo in studying violation of unitary symmetry are used to describe violation of isototic invariance in strong interactions. The present consideration is performed for the example of the mass spectrum of the octet formed by baryons of spin-parity 1/2⁺: only for this family are the widths of its particles much less than the scale of the effects being investigated, their masses being known from experiments to a fairly high precision. The Gell-Mann-Okubo formula is generalized in such a way that relations both for the splitting between the isomultiplets of the octet and for the mass splitting within these isomultiplets follow from the new formula. Moreover, a relation between masses that describes their electromagnetic splitting and which coincides in form with the Coleman-Glashow relation also follows from this formula. The relations obtained for the masses of the baryons belonging to the octet in question are satisfied to a precision not poorer than 3%.     

The high frequency, transient response of a panel with attached masses

The general, high-frequency response of a panel with attached masses is approximated using a transient form of asymptotic modal analysis (AMA). This method is derived by applying asymptotic simplifications to classical solutions in both the time and frequency domains. These relations are applied to a panel with one or more attached masses that is excited by impulsive loads. Predictions are made of the mean-squared, transverse displacement histories as well as localized responses near the added masses. It is shown that the latter compare well with experimental data when the masses are separated by more than the mean wavelength of the frequency band. The approximate solutions are shown to require relatively little computational time and memory and are applicable to general forms of excitation.