Effects of the scale-dependent vacuum expectation values in the renormalisation group analysis of neutrino masses

The contribution of scale-dependent vacuum expectation values (VEVs) of Higgs scalars, which gives significant effects in the evolution of the fundamental fermion masses in the minimal supersymmetric standard model (MSSM), is now considered in the derivation of the analytic one-loop expression for the evolution of the left-handed Majorana neutrino masses with energies. The inclusion of such an effect of the running VEV increases the stability of the neutrino masses under quantum corrections even for the low values of at the scale GeV, and leads to a mild decrease of the neutrino masses with higher energies. Such a trend is common with that of other fundamental fermion masses. Received: 18 September 2000 / Published online: 23 February 2001     

Isospin dependence in the odd-even staggering of nuclear binding energies

The FRS-ESR facility at GSI provides unique conditions for precision measurements of large areas on the nuclear mass surface in a single experiment. Values for masses of 604 neutron-deficient nuclides (30 < or = Z < or = 92) were obtained with a typical uncertainty of 30 microu. The masses of 114 nuclides were determined for the first time. The odd-even staggering (OES) of nuclear masses was systematically investigated for isotopic chains between the proton shell closures at Z = 50 and Z = 82. The results were compared with predictions of modern nuclear models. The comparison revealed that the measured trend of OES is not reproduced by the theories fitted to masses only. The spectral pairing gaps extracted from models adjusted to both masses, and density related observables of nuclei agree better with the experimental data.     

Phenomenology of non-universal gaugino masses and implications for the Higgs boson decay

Grand unified theories (GUTs) can lead to non-universal gaugino masses at the unification scale. We study the implications of such non-universal gaugino masses for the composition of the lightest neutralino in supersymmetric (SUSY) theories based on SU(5) gauge group. We also consider the phenomenological implications of non-universal gaugino masses for the phenomenology of Higgs bosons in the context of large hadron collider.      

On the cosmological effects of thermal masses in the era 1011K⩾T⩾5xl09K

The cosmological effects of thermal masses of particles (masses induced via interactions at nonzero temperature) as well as ordinary masses are studied. These effects are shown to be negligible for photons. For electrons, however, they modify the dependence of the universe's radiusR and the timet on temperature.     

Flavour democracy calls for the fourth generation

It is argued with the help of an illustrative model, that the inter species hierarchy among the fermion masses and the quark mixing angles can be accommodated naturally in the standard model with (approximate) flavor democracy provided there are three exactly massless neutrinos and four families of sequential quark-leptons with all members of the fourth family having roughly equal masses. The special problem of light neutrino masses (if any) and possible solutions are also discussed.     

Neutrino masses and the dark energy equation of state: relaxing the cosmological neutrino mass bound

At present, cosmology provides the nominally strongest constraint on the masses of standard model neutrinos. However, this constraint is extremely dependent on the nature of the dark energy component of the Universe. When the dark energy equation of state parameter is taken as a free (but constant) parameter, the neutrino mass bound is sigma m(v) < or = 1.48 eV (95% C.L.), compared with sigma m(v) < or = 0.65 eV (95% C.L.) in the standard model where the dark energy is in the form of a cosmological constant. This has important consequences for future experiments aimed at the direct measurement of neutrino masses. We also discuss prospects for future cosmological measurements of neutrino masses.     

Dynamical Running Mass of Quark in the Dyson-Schwinger Equation Approach

Based on the Dyson-Schwinger equations of QCD in the "rainbow" approximation, the fully dressed quarkpropagator Sf(p) is investigated, and then an algebraic parametrization form of the propagator is obtained as a solutionof the equations. The dressed quark amplitudes Af and Bf built up the fully dressed quark propagator and the dynamicalrunning masses Mf defined by Af and Bf for light quarks u, d and s are calculated, respectively. Using the predictedrunning masses Mf, quark condensates <0|q(0)q(0)|0> = -(0.255 GeV)a for u, d quarks, and <0|s s|0> = 0.8<0|q(0)q(0)]0)for s quark, and experimental pion decay constant fπ = 0.093 GeV, the masses of Goldstone bosons K, π, and η are alsoevaluated. The numerical results show that the masses of quarks are dependent on their momentum p2. The fully dressedquark amplitudes Af and Bf have correct behaviors which can be used for many purposes in our future researches onnonperturbative QCD.     

Complete one-loop corrections to the mass spectrum of charginos and neutralinos in the MSSM

The mass spectrum of the chargino–neutralino sector in the minimal supersymmetric standard model (MSSM) is calculated at the one-loop level, based on the complete set of one-loop diagrams. On-shell renormalization conditions are applied to determine the counterterms for the gaugino-mass-parameters and the Higgsino-mass parameter . The input is fixed in terms of three pole masses (two charginos and one neutralino); the other pole masses receive a shift with respect to the tree-level masses, which can amount to several GeV. The detailed evaluation shows that both the fermionic/sfermionic loop contributions and the non-(s)fermionic loop contributions are of the same order of magnitude and are thus relevant for precision studies at future colliders. Received: 26 April 2002 / Published online: 21 June 2002     

Predictions of SUSY masses in the minimal supersymmetric grand unified theory

The Minimal Supersymmetric Standard Model (MSSM) distinguishes itself from other GUT's by a successful prediction of many unrelated phenomena with a minimum number of parameters. Among them: a) Unification of the gauge couplings constants; b) Unification of the b-quark and τ-lepton masses; c) Proton stability; d) Electroweak symmetry breaking at a scale far below the unification scale and the corresponding relation between the gauge boson masses and the top quark mass. A combined fit of the free parameters in the MSSM to these low energy constraints shows that the MSSM model can satisfy these constraints simultaneously. From the fitted parameters the masses of the as yet unobserved superpartners of the SM particles are predicted, the top mass is constrained to a range between 140 and 200 GeV, and the second order QCD coupling constant is required to be between 0.108 and 0.132. The complete second order renormalization group equations for the gauge and Yukawa couplings are used and analytical solutions for the neutral gauge boson, the Higgs masses and the sparticle masses are derived, taking into account the one-loop corrections to the Higgs potential.     

Evolution of the N=50 shell gap energy towards 78Ni

Atomic masses of the neutron-rich isotopes (76-80)Zn, (78-83)Ga, (80-85)Ge, (81-87)As, and (84-89)Se have been measured with high precision using the Penning trap mass spectrometer JYFLTRAP at the IGISOL facility. The masses of (82,83)Ga, (83-85)Ge, (84-87)As, and 89Se were measured for the first time. These new data represent a major improvement in the knowledge of the masses in this neutron-rich region. Two-neutron separation energies provide evidence for the reduction of the N=50 shell gap energy towards germanium (Z=32) and a subsequent increase at gallium (Z=31). The data are compared with a number of theoretical models. An indication of the persistent rigidity of the shell gap towards nickel (Z=28) is obtained.     

Ability of the radial basis function approach to extrapolate nuclear mass

The ability of the radial basis function(RBF) approach to extrapolate the masses of nuclei in neutron-rich and superheavy regions is investigated in combination with the Duflo-Zuker(DZ31), Hartree–Fock-Bogoliubov(HFB27), finite-range droplet model(FRDM12) and Weizs?cker-Skyrme(WS4) mass models. It is found that when the RBF approach is employed with a simple linear basis function, different mass models have different performances in extrapolating nuclear masses in the same region, and a single mass model may have different performances when it is used to extrapolate nuclear masses in different regions. The WS4 and FRDM12 models(two macroscopic–microscopic mass models), combined with the RBF approach, may perform better when extrapolating the nuclear mass in the neutron-rich and superheavy regions.     

Baryon masses in the SU(4) skyrme model

We consider the SU(4) Skyrme model with explicit chiral and flavour symmetry-breaking terms. Using the masses of the 15-plet pseudoscalar mesons as the input, we calculate the masses of the 20-plet baryons. The baryon masses predicted by this model agree with results based on quark model to about 15%. We find that the generalized Gell-Mann Okubo mass relation is very well satisfied.     

Axial vector current divergences and the pseudoscalar meson spectrum

The strong anomaly in the axial vector current divergence is simply related to the mass of the ninth pseudoscalar meson in an SU (3) × SU (3) quark model. A discussion is given of the dependence of the pseudoscalar meson masses upon quark masses as well as upon the strong coupling; the SU (3) character of the states is also treated.     

Chromomagnetic stability of the three flavor Larkin–Ovchinnikov–Fulde–Ferrell phase of QCD

We compute in the Ginzburg–Landau approximation the gluon Meissner masses for the Larkin–Ovchinnikov–Fulde–Ferrell (LOFF) phase of QCD with three flavors in the kinematical range where it is energetically favored. We find real Meissner masses and therefore chromomagnetic stability.     

非线性超声射频信号熵对乳腺结节良恶性的定征

本文提出了一种基于非线性超声射频(radio frequency, RF)信号熵对乳腺结节良恶性进行定征的方法.对306例乳腺结节样本(良性158例,恶性148例)提取了基于超声RF信号二次谐波的熵和加权熵,以及常规超声参数(图像灰度、纵横比、不规则度、乳腺结节大小、深度);采用t检验和线性分类器检测参数对乳腺结节良恶性的区分度;进一步将有效参数组合输入支持向量机对乳腺结节良恶性进行分类.结果表明:除图像灰度外,其余参数均在乳腺结节的良性与恶性间有显著差异.多参数结合输入支持向量机的良恶性分类的准确率、敏感性和特异性分别为81.4%, 78.4%和84.2%.本文工作表明非线性超声RF信号的熵可有效地定征乳腺结节的良恶性,有望成为乳腺结节良恶性定征新参量.     

Mass measurements and implications for the energy of the high-spin isomer in 94Ag

Nuclides in the vicinity of 94Ag have been studied with the Penning trap mass spectrometer JYFLTRAP at the Ion-Guide Isotope Separator On-Line. The masses of the two-proton-decay daughter 92Rh and the beta-decay daughter 94Pd of the high-spin isomer in 94Ag have been measured, and the masses of 93Pd and 94Ag have been deduced. When combined with the data from the one-proton- or two-proton-decay experiments, the results lead to contradictory mass excess values for the high-spin isomer in 94Ag, -46 370(170) or -44 970(100) keV, corresponding to excitation energies of 6960(400) or 8360(370) keV, respectively.     

Enhanced electric dipole moment of the muon in the presence of large neutrino mixing

The electric dipole moment (edm) of the muon ( d(e)(&mgr;)) is evaluated in supersymmetric models with nonzero neutrino masses and large neutrino mixing arising from the seesaw mechanism. It is found that if the seesaw mechanism is embedded in the framework of a left-right symmetric gauge structure, the interactions responsible for the right-handed neutrino Majorana masses lead to an enhancement in d(e)(&mgr;) to values as large as 5x10(-23)e cm, with a correlated value of (g-2)(&mgr;) approximately 13x10(-10). This should provide a strong motivation for improving the edm of the muon to the level of 10(-24)e cm as has recently been proposed.     

Mass of the Higgs boson in the standard model with four generations

We study the functional behavior of the quartic scalar coupling in the standard model with four generations. From the assumed boundedness of its ratio to theU(1) gauge coupling and the stability of the Higgs potential under radiative corrections, we derive upper and lower bounds on the Higgs-boson mass as functions of the fourth-generation fermion masses. We also obtain a solution in which the Higgs-boson mass is determined as a function of the other masses of the model.     

High-precision determination of the pi, K, D, and Ds decay constants from lattice QCD

We determine D and D(s) decay constants from lattice QCD with 2% errors, 4 times better than experiment and previous theory: f(D(s))=241(3) MeV, f(D)=207(4) MeV, and fD(s))/f(D)=1.164(11). We also obtain f(K)/f(pi)=1.189(7) and (f(D(s))/f(D))/(f(K)/f(pi))=0.979(11). Combining with experiment gives V(us)=0.2262(14) and V(cs)/V(cd) of 4.43(41). We use a highly improved quark discretization on MILC gluon fields that include realistic sea quarks, fixing the u/d, s, and c masses from the pi, K, and eta(c) meson masses. This allows a stringent test against experiment for D and D(s) masses for the first time (to within 7 MeV).     

Transition temperature of a magnetic semiconductor with angular momentum j

We employ dynamical mean-field theory to identify the materials properties that optimize T(c) for a generalized double-exchange model. We reach the surprising conclusion that T(c) achieves a maximum when the band angular momentum j equals 3/2 and when the masses in the m(j) = +/- 1/2 and +/-3/2 and subbands are equal. However, we also find that T(c) is significantly reduced as the ratio of the masses decreases from one. Consequently, the search for dilute-magnetic semiconductor materials with high T(c) should proceed on two fronts. In semiconductors with p bands, such as the currently studied Mn-doped Ge and GaAs semiconductors, T(c) may be optimized by tuning the band masses through strain engineering or artificial nanostructures. On the other hand, semiconductors with s or d bands with nearly equal effective masses might prove to have higher T(c)'s than p-band materials with disparate effective masses.