Unitary representations of superconformal algebra

superconformal algebra is algebra with two Virasoro operators. The Kac determinant is calculated and the complete list of unitary representations is determined. Two types of extensions of algebra are discussed. A new approach to construction of algebras from rational conformal field theories is proposed.     

Calculations of Multipulse Sequence in NQR of Spins

The general formalism of the interaction representation with respect to an operator which is its own inverse is developed and applied to pure NQR of spins I = . Under the assumption of no relaxation and no dipolar coupling, it is shown that the calculation of the response to pure NQR multipulse sequences can be performed with the same concepts used in high field NMR, such as coherence pathways. All the tools and mathematical expressions to predict the time evolution of the signal created by a pure NQR multipulse sequence are presented explicitly. It takes into account the off-resonance irradiation as well as the angular dependence of the excitation and detection for every value of the electric field gradient asymmetry parameter. Particular attention is devoted to the powder average, which is performed via a probability function derived analytically for the first time, leading to a drastic reduction of simulation times. The theory is illustrated by the study of the optimization and excitation bandwidths of one- to three-pulse sequences and compared to experimental results on Chloranil. We show that the three-pulse “stimulated echo” sequence gives a more uniform excitation profile than the traditional two-pulse echo sequence for powder samples. Thus, the “stimulated echo” sequence could be useful to cover a large spectrum when the experiment duration, or the signal to noise ratio, are not critical parameters. Analytical expressions for the nutation spectra obtained by one or two-pulse sequences are also derived for the first time.     

Paramagnetic Proton Nuclear Spin Relaxation Theory of Low-Symmetry Complexes for Electron Spin Quantum NumberS=

A generalization of the modified Solomon–Bloembergen–Morgan (MSBM) equations has been derived in order to describe paramagnetic relaxation enhancement (PRE) of paramagnetic complexes characterized by both a transient (Δ^ZFS_t) and a static (Δ^ZFS_s) zero-field splitting (ZFS) interaction. The new theory includes the effects of static ZFS, hyperfine coupling, and angular dependence and is presented for the case of electron spin quantum numberS= , for example, Mn(II) and Fe(III) complexes. The model gives the difference from MSBM theory in terms of a correction term δ which is given in closed analytical form. The theory may be important in analyzing the PRE of proton spin–lattice relaxation dispersion measurements (NMRD profiles) of low-symmetry aqua–metal complexes which are likely to be formed upon transition metal ions associated with charged molecular surfaces of biomacromolecules. The theory has been implemented with a computer program which calculates solvent water protonT₁NMRD profiles using both MSBM and the new theory.     

High resolution images of Mo2C(0001)- structure by scanning tunneling microscopy

A C-terminated structure on Mo₂C(0001) was observed by scanning tunneling microscopy. The structure was observed as a honeycomb structure with dark depressions corresponding to C atoms which make up the lattice. High resolution imaging was possible at low tunneling resistance less than 1 MΩ. Each C atom appears as a shallow sombrero protrusion predicted by theoretical calculations of C atoms on a metal substrates. It is concluded that the C atoms occupied threefold hollow sites of the (1×1) Mo layer of the substrate and a model for the structure is proposed.     

Polarization phenomena for in collinear kinematics as a test of polarized strangeness

Polarization effects for the process are studied for the collinear Λ-production. Using the triplet channel dominance hypothesis for the -annihilation, we prove that the longitudinal polarization transfer coefficient from the initial proton to final Λ hyperon must be positive in this kinematical regime, independently of any model. The exact value of this coefficient, however, depends on the sign of the strange quark contribution to the proton spin, for relatively small momentum transfer.     

Search for charged Higgs bosons in ee collisions at = 181–184 GeV

Data collected at centre-of-mass energies of 181–184 GeV by ALEPH at LEP, corresponding to an integrated luminosity of 56.9 pb⁻¹, are analysed in a search for pair-produced charged Higgs bosons H^±. Three analyses are employed to select the , / and final states. No evidence for a signal is found. Mass limits are set as a function of the branching fraction B(H⁺→τ⁺ν_τ). Under the assumption that the decay modes considered cover the totality of the possible final states, charged Higgs bosons with masses below 59 GeV/c² are excluded at 95% C.L. independently of B(H⁺→τ⁺ν_τ).     

Internal dynamics of hydroxymethyl rotation from CH2 cross-correlated dipolar relaxation in methyl-β- -glucopyranoside

Conventional relaxation parameters (T₁⁻¹, T₂⁻¹, and NOE), obtained at different temperatures and magnetic fields, are reported for the hydroxymethyl (C6) carbon in methyl-β- -glucopyranoside in a D₂O/DMSO cryosolvent. These data are interpreted with the Lipari–Szabo model. In addition, two-field measurements of longitudinal and spin-locked relaxation rates related to the cross-correlated carbon–proton dipole–dipole interactions for the same carbon are reported. The complete data set consisting the conventional and cross-correlated relaxation parameters is interpreted using a new “hybrid” approach, in which the Lipari–Szabo model for the auto-correlated spectral densities is combined with the two-site jump model for the cross-correlated spectral densities, with the global correlation time as a common parameter. The two-site jump rates thus obtained are in reasonable agreement with the ultrasonic relaxation measurements, and have reasonable temperature dependence.     

C( ,pn) photon asymmetry for Eγ=180–340 MeV

The photon asymmetry (Σ) of the ¹²C( ,pn) reaction has been measured using linearly polarised tagged photons at the Mainz microtron MAMI for E_γ=180–340 MeV. The data have been analysed in separate missing energy (E_m) regions corresponding to the ejection of nucleons from (1p)² and (1p)(1s) shells. The measured Σ values for both E_m regions are smaller in magnitude than corresponding ²H data, but the (1p)² results have a similar E_γ dependence. Calculations of direct two-nucleon emission overestimate the magnitude of Σ at all photon energies.     

Flavor symmetry, K– mixing and new physics effects on CP violation in D and Ds decays

Flavor symmetry and symmetry breaking, K⁰– mixing and possible effects of new physics on CP violation in weak decay modes D^±→K_S,L+X^±, (K_S,L+π⁰)_K^*+X^± (for X=π,ρ,a₁) and D^±_s→K_S,L+X^±_s, (K_S,L+π⁰)_K^*+X^±_s (for X_s=K,K^*) are analyzed. Relations between D^± and D^±_s decay branching ratios are obtained from the ds subgroup of SU(3) and dominant symmetry-breaking mechanisms are investigated. A CP asymmetry of magnitude 3.3×10⁻³ is shown to result in the standard model from K⁰– mixing in the final-state. New physics affecting the doubly Cabibbo-suppressed channels might either cancel this asymmetry or enhance it up to the percent level. A comparison between the CP asymmetries in D^±_(s)→K_SX^±_(s) and D^±_(s)→K_LX^±_(s) can pin down effects of new physics.     

BOTTOM BARYONS(B=-1)∧_b~0=udb,≡_b~0=usb,≡_b~-=dsb,Ω_b~-=ssb

<正>~~     

BRANCHING FORMULAS FOR SO(n) SO(n－1) TENSOR AND SPINOR REPRESENTATIONS

Branching formulas for SO(n) SO(n－1) tensor representations are given from the branching rules for SO(n) SO(n－1) which described in F.D.Murnaghan's. Furthermore, these formulas are extended to the spinor representations by using the method of kronecker products. In this way a pair of complete branching formulas for SO(n) SO(n－1) is give in this paper.     

∧ BARYONS(S=-1,I=0)∧~0=uds

<正>~~     

关于B.W.Lee的公式ΓΓ=0的推广

本文将B.W.Lee的公式Γ*Γ=0推广为Γ^AF=0^[1,2], 只要命B.W.Lee公式中的dλ=ζ₁ζ₂ζ₀即可, 而不需要B.W.Lee式的二次变化变化等于零的限制. 从而, 该公式不仅包含了B.W.Lee的公式, 而且能直接解决其他一些问题.     

关于B.W.Lee的公式Г*Г=0的推广

本文将B.W.Lee的公式Г*Г=0推广为Г~(AF)＊Г~(AF)=0,只要命B.W.Lee公式中的dλ=ζ_1ζ_2ζ_0即可,而不需要B.W.Lee式的二次变化等于零的限制。从而,该公式不仅包含了B.W.Lee的公式,而且能直接解决其他一些问题。     

≡BARYONS(S=-2,I=1/2)≡~0=uss,≡~-=dss

<正>~~     

Is Bell-type inequality violated for K0-\bar K^0 , B0-\bar B^0 , . . . systems?

We extend the Clauser-Horne formulation of Bell-type inequality for the correlated pair of decaying and oscillating (neutral pseudo-scalar) meson-antimesons, using a few supplementary assumptions. The quantum-mechanical predictions for the B⁰- \(\bar B^0 \) system do lead to violations of this inequality under certain conditions. Further work is called for to investigate the possibility of dispensing with the supplementary assumptions.     

Search for new d0 half-metallic materials: theoretical investigation on KCaC1−xSix (x = 0; 0.25; 0.5; 0.75 and 1) compounds

In recent years, the investigations on d⁰ half-metallic materials have become the new trend in the search of novel materials for applications in spintronic devices. In this work, the structural, electronic and magnetic properties of KCaC${}_{1?x}$Si_x (x = 0; 0.25; 0.5; 0.75 and 1) compounds have been theoretically studied using the full-potential linearized augmented plane wave (FP-LAPW) method within framework of the density functional theory. The generalized gradient approximation scheme as proposed by Wu-Cohen (GGA-WC) and Tran-Blaha modified Becke-Johnson exchange potential with improved parameterization by Koller are adopted for the treatment of electron exchange-correlation. All considered materials show half-metallic characteristics with semiconducting majority spin channel and metallic minority one. The total spin magnetic moment is 1μ_B for ternary alloys and 4μ_B for quaternary compounds. Our obtained results suggest that these materials could be promising candidate for spintronic applications.