Neutrino oscillations induced by two-loop radiative mechanism

Two-loop radiative mechanism, when combined with an U(1)_L′ symmetry generated by L_e − L_μ − L_τ (=L′), is shown to provide an estimate of Δm²/Δm²_atm εm_e/m_τ, where ε measures the U(1)_L′-breaking. Since Δm²_atm 3.5×10⁻³ eV², we find that Δm² ε10⁻⁶ eV², which will fall into the allowed region of the LOW solution to the solar neutrino problem for ε 0.1.     

Measurement and analysis of the infrared reflection spectrum of semiconducting SnS

The infrared reflection spectrum of p-type SnS single crystals was measured between 2 and 25μ. The observed dispersion was ascribed to the combined effects of lattice vibrations and free holes. An analysis gave for the index of refraction n₀ = 3.6 ± 0.1, the dielectric constant = 19.5 ± 2, and the effective charge on the atoms e^* = 0.7e₀.

The effective mass of holes is isotropic in the plane perpendicular to the c-axis, with m^* = 0.20m₀; the effective mass parallel to the c-axis is much larger: m^* m₀.     

Considerations concerning the radiative corrections to muon decay in the Fermi and Standard theories

The FAC, PMS, and BLM optimization methods are applied to the QED corrections to the muon lifetime in the Fermi V-A theory. The FAC and PMS scales are close to m_e, while the BLM scale nearly coincides with the geometric average √m_em_μ. The optimized expressions are employed to estimate the third order coefficient in the (m_μ) expansion and the theoretical error of the perturbative series. Using arguments based on effective field theory and a simple examination of Feynman diagrams, it is shown that, if contributions of (m_μ²/M_W²) are neglected, the corrections to muon decay in the SM factorize into the QED correction of the Fermi V-A theory and the electroweak amplitude g²/(1 − Δr), both of which are strictly scale-independent. We use the results to clarify how the QED corrections to muon decay and the Fermi constant G_F should be used in the SM, and what is the natural choice of scales if running couplings are employed.     

Remarks on stochastic non-linear birth and death models

The first part of this paper is an attempt to formulate and motivate additional work on the important problem of obtaining global bounds applicable to the controlled truncation of the paper relates specifically to the linear birth, quadratic death model. Asymptotic results are given for the first finite difference ΔT_m where T_m is the exactly known mean time to extinction starting from state m (m= 0,1,…). These results are in terms of the environmental carrying capacity n^* taken to be large. For m near zero ΔT_me^n*/(n^*)²; whereas, for m near n^*ΔT_m ≈ (π/2)^1/2/(n^*)^3/2. This indicates the vastly different time scales in those two regions of state space - with considerably slower action near extinction than near n^*.     

NFX(X=-1,0,+1)分子离子基态的结构与势能函数

用密度泛函理论的B3LYP方法,分别以6-311++g(df,3pd),6-311g(3d,3p)和6-311++g(3df,3pd)为基函数对NF分子、NF⁺和NF^-离子基态进行几何优化和频率计算,并进行单点能扫描计算.用最小二乘法拟合得到NF^X(X=-1,0,+1)分子离子基态的Murrell-Sorbie势能函数.利用得到的解析势能函数计算出的NF分子和NF⁺离子基态光谱常数(B_e,α_e,ω_e,ω_eχ_e)与实验值符合很好.首次得到NF^-离子基态的光谱常数(B_e,α_e,ω_e,ω_eχ_e)和力常数(f₂,f₃,f₄),为NF-离子基态的后期研究提供理论参考.     

Continuous photoluminescence, time resolved photoluminescence and optically detected magnetic resonance measurements of PbI2 nanometer-sized particles, embedded in SiO2 films

The nanometer sized particles of PbI₂ were embedded in SiO₂ films. X-ray diffraction and the TEM pictures showed the preservation of the bulk layered structure and symmetry. The PL spectrum of the nano-particles exhibited a pronounced blue shift of the exciton band due to quantum size effect. The Lead Iodide represents an exceptionally small exciton Bohr radius (a_B = 19 Å) and a special case in which m_e m_h. The prepared samples contained particles with mean radii, a, in the range a_B < a < 3a_B. Within this limit (with m_e m_h), the experimental results suggest that the electron is localized nearly at the center of the particle, enabling the hole to move around it. Thus, the size confinement permits the creation of an acceptor-like exciton. The PL spectrum revealed additional states, associated with stoichiometric defects either at the interior or surface sites of the nano-particles. These defects act either as donor or acceptor states. The dynamics of the various recombination processes has been investigated by measuring the time resolved PL spectra. The results show a multiexponential behavior of the various recombination emission bands, indicating the occurrence of trapping and detrapping processes. Analysis of these results suggests that the existence of surface states give rise to these complex radiative decay processes. The correlation between donor-acceptor recombination emission bands in the aforementioned samples and lattice imperfections was examined, utilizing optically detected magnetic resonance (ODMR) spectroscopy. The results identified the following imperfection sites: an acceptor site associated with an isotropic Lead vacancy defect, [V⁻]_pb²⁺ and a donor site, associated with an anisotropic Iodine vacancy, [V⁰]_Iodine.     

Cyclotron resonance and effective mass renormalizations in Sr2RuO4

Using a microwave cavity perturbation technique, we have succeeded in observing cyclotron resonances in the layered Perovskite superconductor Sr₂RuO₄. Three cyclotron masses are deduced, corresponding to m_cγ=9.7m_e, m_cβ=5.8m_e and m_c=4.3 m_e. A comparison between these values and the effective masses deduced from other techniques provides us with a unique means of gauging the role of Coulomb correlations in the title compound.     

Projective and affine connections on S and integrable systems

It is known that the Korteweg–de Vries (KdV) equation is a geodesic flow of an L² metric on the Bott–Virasoro group. This can also be interpreted as a flow on the space of projective connections on S¹. The space of differential operators Δ⁽ⁿ⁾=∂ⁿ+u₂∂ⁿ⁻²++u_n form the space of extended or generalized projective connections. If a projective connection is factorizable Δ⁽ⁿ⁾=(∂−((n+1)/2−1)p₁)(∂+(n−1)/2p_n) with respect to quasi primary fields p_i’s, then these fields satisfy ∑_i=1ⁿ((n+1)/2−i)p_i=0. In this paper we discuss the factorization of projective connection in terms of affine connections. It is shown that the Burgers equation and derivative non-linear Schrödinger (DNLS) equation or the Kaup–Newell equation is the Euler–Arnold flow on the space of affine connections.     

Measurement of the slope parameter for the neutral pion spectrum in KL → πππ decay

The π⁰ spectrum in the K_L⁰ → 3π decay was measured using a wire chambers magnetic spectrometer. In the usual approximation, the matrix element can be expressed as: M² ≈ 1 + 2a₀(M_K/M_π²)(2T_π⁰−T_π⁰max) + a₁(M_K²/M_π⁴)(2T_π⁰−T_π⁰max)². We obtained a₀ = −0.282 ± 0.011 and a₁ consistent with zero.     

Perturbative QCD correction to the B → π transition form factor

We report on the perturbative O(_s) correction to the light-cone QCD sum rule for the B → π transition form factor f⁺. The correction to the product f_Bf⁺ in leading twist approximation is found to be about 30%, that is similar in magnitude to the corresponding O(_s) correction in the two-point sum rule for f_B. The resulting cancellation of large QCD corrections in f⁺ eliminates one important uncertainty in the sum-rule prediction for this form factor.     

Spectral intensities in the ν1 band of NH3

Intensities have been measured for individual transitions in the Q and R branches of the ν₁ band of NH₃ using a difference-frequency laser spectrometer. The data yield an integrated band strength of S⁰_v=219.36±1.03 cm^-2/MPa at 297 K, corresponding to a transition moment of μ_v = 8.535(20) × 10^-32 C·m, and a Herman-Wallis correction factor, (1 + _jm)², where _j = 0.0209(20). The intensities of a few lines for K 7 were noticeably perturbed by a perpendicular Coriolis interaction with 2ν₄ (E, L = 2), so were excluded from the fit. A small sample of ν₃ band lines occurring in the ν₁ band scans also yields a rough estimate of the ν₃ band intensity with evident irregular perturbations.     

The ΔNγ electromagnetic transition form factors GM(q) and GE(q)

A parameter-free, nonperturbative calculation of the ΔNγ electromagnetic transition amplitudes GM*(q2), GE*(q2), and the resonant multipole ratio REM(q2)≡E1+3/2(q2)/M1+3/2(q2) is performed in terms of the well-known nucleon isovector Sachs form factor GMV. Our methods are fully relativistic with conservation of the electromagnetic current guaranteed. We find that GM*(q2) decreases more rapidly than the nucleon dipole form factor when −q21 GeV2/c2 and that REM(q2) remains small even for very high four-momentum transfer implying that the perturbative QCD prediction REM(q2)→1 is purely asymptotic and is valid only for extremely high |q2|.     

Interactions of some peptides with sodium acetate and magnesium acetate in aqueous solutions at 298.15 K: A volumetric approach

The apparent molar volumes, V of diglycine, triglycine and glycyl-l-leucine have been determined in water and in aqueous sodium acetate (0.5, 1.0, 2.0, and 4.0 m_B) and magnesium acetate (0.5, 1.0, 1.5, and 2.0 m_B) solutions at 298.15 K by the measurement of densities using vibrating-tube digital densimeter. The partial molar volumes, V_2,m⁰ obtained from V have been used to calculate the partial molar volumes of transfer, Δ_trV_2,m⁰ for these peptides from water to aqueous solutions of sodium acetate (SA) and magnesium acetate (MA) solutions. The hydration numbers, n_H and volumetric interaction coefficients have also been calculated. The Δ_trV_2,m⁰ data suggest that ion-charged/or peptide group interactions of peptides are stronger with MA in comparison to SA.     

核磁共振碳谱研究:烷烃化学位移和(CSS)与分子路径指数矢量(VPM)

系统研究了核磁共振碳谱和化学位移规律及其定量构谱关系(QSSR).本文研究了一组十元素分子路径指数矢量VPM,并发现它与烷烃化学位移和CCS有良好线性相关性.采用多元线性回归进行准确估计与预测,结果优良.     

Spectral density analysis of the chiral transition in nf=4 finite temperature QCD

We apply the spectral density reweighting technique to the analysis of the chiral phase transition in finite-temperature lattice quantum chromodynamics (QCD) with four flavors of dynamical staggered fermions and m_qa=0.025. Our simulations were performed using the hybrid Monte Carlo method for L_tL³ lattices with L_t=4 and L=6, 8 and 10. We calculate partition function zeros, as well as the maxima of the specific heat and of the susceptibilities for the Polyakov loop and for the chiral condensate. A finite size scaling analysis of these data leads to preliminary results for the critical coupling β_c, for the critical exponent ν, for the latent heat, and for the jumps in the Polyakov loop and in the chiral condensate.     

Magnetic ordering in U4Cu4P7 single crystal

The magnetic ordering in the tetragonal ternary compound U₄Cu₄P₇ has been studied by neutron diffraction. It orders below T_N = 146 K with an antiferromagnetic structure of wave vector k = (001). The magnetic ordering corresponds to a stacking of ferromagnetic (001) uranium planes according to the sequences m₁, m₁, m₂, -m₂, -m₁, -m₁, -m₂, m₂ where m₁ and m₂ represent the magnetic moment, directed along the tetragonal axis of the two uranium sites U(1) (0,0,± z₁) and U(2) (0,0, ± z₂) respectively. The magnetic moments on these two sites have different temperature dependencies as well as well as they reach the different values of 1.1 and 2.2.μ_B for the U(1) and U(2) sites, respectively.     

Generalized Einstein manifolds

A Finslerian manifold is called a generalized Einstein manifold (GEM) if the Ricci directional curvature R(u,u) is independent of the direction. Let F⁰(M, g_t) be a deformation of a compact n-dimensional Finslerian manifold preserving the volume of the unitary fibre bundle W(M). We prove that the critical points g₀ F⁰(g_t) of the integral I(g_t) on W(M) of the Finslerian scalar curvature (and certain functions of the scalar curvature) define a GEM. We give an estimate of the eigenvalues of Laplacian Δ defined on W(M) operating on the functions coming from the base when (M, g) is of minima fibration with a constant scalar curvature H admitting a conformal infinitesimal deformation (CID). We obtain λ ≥ H/(n − 1) (Δf = λf). If M is simply connected and λ = H/(n − 1), then (M, g) is Riemannian and is isometric to an n-sphere. We first calculate, in the general case, the formula of the second variationals of the integral I (g_t) for G = g₀, then for a CID we show that for certain Finslerian manifolds, I″(g₀) > 0. Applications to the gravitation and electromagnetism in general relativity are given. We prove that the spaces characterizing Einstein-Maxwell equations are GEMs.     

N=2 6-dimensional supersymmetric E6 breaking

We study the N=2 supersymmetric E₆ models on the 6-dimensional space–time where the supersymmetry and gauge symmetry can be broken by the discrete symmetry. On the space–time M⁴×S¹/(Z₂×Z₂′)×S¹/(Z₂×Z₂′), for the zero modes, we obtain the 4-dimensional N=1 supersymmetric models with gauge groups SU(3)×SU(2)×SU(2)×U(1)², SU(4)×SU(2)×SU(2)×U(1), and SU(3)×SU(2)×U(1)³ with one extra pair of Higgs doublets from the vector multiplet. In addition, considering that the extra space manifold is the annulus A² and disc D², we list all the constraints on constructing the 4-dimensional N=1 supersymmetric SU(3)×SU(2)×U(1)³ models for the zero modes, and give the simplest model with Z₉ symmetry. We also comment on the extra gauge symmetry breaking and its generalization.     

Saturation and BFKL dynamics in the HERA data at small-x

We show that the HERA data for the inclusive structure function F₂(x,Q²) for x10⁻² and 0.045Q²45 GeV² can be well described within the color dipole picture, with a simple analytic expression for the dipole–proton scattering amplitude, which is an approximate solution to the non-linear evolution equations in QCD. For dipole sizes less than the inverse saturation momentum 1/Q_s(x), the scattering amplitude is the solution to the BFKL equation in the vicinity of the saturation line. It exhibits geometric scaling and scaling violations by the diffusion term. For dipole sizes larger than 1/Q_s(x), the scattering amplitude saturates to one. The fit involves three parameters: the proton radius R, the value x₀ of x at which the saturation scale Q_s equals 1 GeV, and the logarithmic derivative of the saturation momentum λ. The value of λ extracted from the fit turns out to be consistent with a recent calculation using the next-to-leading order BFKL formalism.