Perpendicularev mass fromW decay

We point out properties of the “perpendicularev mass”, defined in terms of transverse momentap _t byM _T ² (ev)=2|p _eT | |p _vT |?2p _eT ·p _vT , that make it particularly well suited toW mass and width determinations. We give an analytic expression for its distribution inW production and subsequentW→ev decay a \(\bar pp\) colliders, accurate to order 〈p _WT ² /M _W ² 〉≈1%. A maximum likelihood fit of this formula to the five UA1 events givesM _W=80.3 _?3 ⁺⁶ GeV.     

Behavior of Nitroxide Biradicals with Acetylene Bridges in Organic Solvents and Ionic Liquids

Intramolecular electron spin exchange (IESE) in two nitroxide biradicals, R₆–C≡C–C≡C–R₆ (1) and R₆–C≡C–p-C₆H₄–C≡C–R₆ (2), is studied as a function of temperature and solvent properties. The effect of molecular solvents and ionic liquids (ILs, [1-methyl-3-butylimidazolium]⁺[PF₆]^?, bmimPF₆, and [1-methyl-3-octylimidazolium]⁺[BF₄]^?, omimBF₄) on the IESE in magnetically diluted solutions is investigated. Changes in electron paramagnetic resonance spectra are analyzed and the thermodynamic parameters of these changes are calculated. Geometry optimization and D-tensor calculations of biradicals 1 and 2 were carried out on the DFT/UB3LYP/cc-pVdz and DFT/ROPBE/N07D levels of theory. The probable differences in biradical behavior are discussed.     

T-odd correlation in the K_{13_\gamma } decay

The dependence of the K ⁺ → π ⁰ l ⁺ ν _lγ decay rate on the T-odd kinematical variable ξ = q · [p _l × p _π]/m _K ³ is investigated in the tree and one-loop approximations of the Standard Model (SM). It is shown that the partial width of the decay on the tree level is an even function of the variable ξ, whereas the odd component is generated by the electromagnetic final-state interaction and determined by the imaginary parts of one-loop diagrams. The ξ-odd components of the partial widths of the K ⁺ → π ⁰e⁺ ν _e γ and K ⁺ → μ ⁰μ⁺ ν _μ γ decays calculated in the one-loop approximation are smaller by four orders of magnitude than the even components evaluated from the tree-level SM diagrams.     

Two-particle production inK + p interactions at 32 GeV/c

Results are presented on two-particle inclusive production inK ⁺ p interactions at 32 GeV/c. We study thex _1,2=x ₁+x ₂ dependence of invariant structure functions of (ππ)-pairs and compare them to single particle inclusive distributions in the fragmentation regions. Distributions of particles observed at Feynmanx ₂ in association with various “trigger” particles or systems atx ₁ in the same hemisphere are dicussed in terms of the reduced variable \(\tilde x_2 = x_2 /(1 - |x_1 |)\) . We further present absolute production rates and production ratios of π⁺'s and π^?'s associated with π^±,K _s ⁰ , Λ, \(\bar \Lambda \) ,K ^*+ (890), (K _s ⁰ π⁺), and (π⁺ π^?)-triggers, and compare them with qualitative predictions of the quark recombination model. Forwardbackward correlations between (K _s ⁰ π^±), (K _s ⁰ ,p), (Λ, π^?), \((\bar \Lambda \pi ^ \pm )\) , and (p, π^?) pairs are also discussed.     

Inclusive cross section ratios in highp T proton-proton scattering at ISR energies

Ratios of inclusive cross sections σ(π⁺)/σ(π⁺+K ⁺+p) and \(\sigma (\pi ^ - )/\sigma (\pi ^ - + K^ - + \bar p)\) were measured for proton-proton interactions with a highp _T hadron in the final state around c.m.s. scattering angles θ?20°, 20° and 45° at two ISR energies \(\sqrt s = 31\) Gev and 62 GeV. Results are shown as functions of transverse and longitudinal momentum and are compared with parton model predictions. The different dependences of positive and negative pion fractions atp _T ?2–3 GeV/c on longitudinal momenta is similar to that observed in soft hadronic interactions at low values ofp _T where the leading proton effect (diquark fragmentation) is known to contribute. The quantitative agreement of the data with diquark model predictions indicates the presence of diquark fragmentation also in highp _T jets.     

Spatial representation of groups of automorphisms of von Neumann algebras with properly infinite commutant

Theorem. Let a topological groupG be represented (a→φ _a ) by *-automorphisms of a von Neumann algebraR acting on a separable Hilbert spaceH. Suppose that

1. G is locally compact and separable,
2. R′ is properly infinite,
3. for anyT∈R,x,y∈H the function

$$a \to \left\langle {\phi _a (T)x,y} \right\rangle _H $$ is measurable onG. Then there exists a strongly continuous unitary representation ofG onH,a→U _a , such that forT∈R,a∈G, $$\phi _\alpha (T) = U_a TU_a *.$$ .     

Bloch electron dynamics

New equations of motion for a Bloch electron [momentum p=h k,energy ε _n(p),zone number n, charge -e]: $$m_j \frac{{dv_j }}{{dt}} = - e(E + v \times B)_j $$ are proposed, where v≡?ε_n(p)/?p is the velocity, and {m_j}are the principal masses m _j ^? 1=?²ε_n/?p _j ² along the normal and the two principal axes of curvatures at each point of the constant-energy surface represented by ε=ε_n(p).Their advantages over the prevalent equations of motion where the left-hand-side is replaced by hk _j are demonstrated by examining de Haas-van Alphen oscillations and orientation-dependent cyclotron resonance peaks.     

A microscopic investigation of gR and band cut-off effects

An in-beam study of excited states in¹⁴⁰Ce revealed 16 new levels of positive and negative parity on top of the 6⁺ isomer. The excitation energies of these states are well reproduced by diagonalizing the same Hamiltonian in two model spaces, aπ=+1 shell-model basis and aπ=?1 particle-core coupling basis.     

Systematics of exclusive diffraction dissociation modes inK ± p interactions at 32 GeV/c

We present results of an investigation of diffraction dissociation in exclusive channels inK ^± p interactions at 32 GeV/c. Total cross sections are determined forK ^±→K ^±π⁺π^?,K ^±2π⁺2π^?,K ⁰π^±π^± K ^±2π⁺π^?,K ^± K ⁺ K ^?,K ^±p \(\bar p\) , \(\bar \Lambda \) p, andp→pπ ⁺π^?,p2π⁺2π^?,pK ⁺K^?,ΛK ⁺,ΛK ⁺π⁺π^? dissociation modes, ranging from a high of ? 300 μb to ～ 3 μb. Thedσ/dt′ differential cross sections of most of the systems studied exhibit structure, with breaks of slope att′ ～ 0.2 to 0.5 GeV²; some modes have a sharp forward spike with a slope exceeding 10 GeV^?2. A systematic investigation of two-body dissociation modesK→A+B andp→A′+B′ shows that these cross sections decrease with increasing threshold massM _A+M _B, that they are comparable for kaon and proton dissociations at similar diffractive excitation masses and are systematically suppressed by a factor 3–4 for dissociations requiring an \(s\bar s\) quark pair creation when compared to \(u\bar u\) pair creation indicating a breakdown ofSU ₃ symmetry for the \(q\bar q\) sea.     

Vibronic-spin-orbit coupling in 1,3,6,8-tetrachlorodibenzo-p-dioxin

The squared dipole moments (P _0R )² of vibronic transitions caused by vibronic-spin-orbit coupling along the coordinates of out-of-plane vibration modes R were calculated for the triplet ππ* electronic states (with u and g types of orbital symmetry) in a 1,3,6,8-tetrachlorodibenzo-p-dioxin (αβTCDD) molecule. Special features of distribution (P _0R )² over R related to transitions from various sublevels of triplet states are ascertained. The obtained data made it possible to infer that the observed fine-structure phosphorescence spectrum of an αβTCDD solid solution corresponded to the ³ A _g →S ₀ and to eliminate a certain ambiguity in interpreting the vibronic structure of this spectrum.     

Theoretical studies of ground and excited states in a series of Zn(II) complexes,derived from thiourea and thiosemicarbazide

Theoretical studies for a series of mono- and binuclear zinc (II) complexes Zn(CH₃COO)₂(H₂L)₂ [H₂L = N-2-propenyl-N ^′-2-pyridinylthiourea] (A), Zn₂(CH₃COO)₂(H₃L-a)₂ [H₃L-a = 2-[(2-hydroxy phenyl)methylene]hydrazine-N-phenylcarbothioamide] (B), and Zn(H₃L-b)₂ [H₃L-b = 2-[(2-hydroxy phenyl)methylene]hydrazine-N-(2-propenyl)carbothioamide] (C) have been performed on their structures and excited-state absorption spectra. The singlet ground-state geometries are fully optimised at three DFT levels, i.e., B3LYP, B3PW91, and M06. Different geometries, i.e., strongly distorted tetrahedral coordination environment in complex A, distorted square-pyramidal environment in complex B, and irregular octahedral mode in complex C are identified. Consequently, the spectroscopic properties are calculated by means of time-dependent density functional theory (TDDFT) with the Polarisable Continuum Model (PCM) based on the optimised gas-phase geometries. Three absorption peaks are identified for every complex, which are in good agreement with the experimental ones. For complex A, all three absorption peaks centered at 280.33 nm, 268.09 nm, and 250.87 nm, respectively, are ascribed to the (p,π) → π* transition with a mixed intraligand charge-transfer (ILCT)/ligand-ligand charge-transfer (LLCT) character. The composition of frontier orbitals involved in major absorption bands for the three complexes shows similarities, which results in the almost homologous transition attributions and characteristics. A remarkable bathochromic shift in the lowest-lying absorption band is observed for complexes B and C as compared with complex A, which is attributed to the decreased H (HOMO)-L (LUMO) energy gap (ΔE |HOMO-LUMO|) by the formation of conjugate metallocycles in complexes B and C.     

Measurement of the analyzing power of high-transverse-momentum charged hadrons in proton-nucleus collisions at an energy of 40 GeV

The transverse single-spin asymmetry was measured for charged hadrons (π ^±, K ^±, p, $\bar p$ ) produced in proton-nucleus collisions. The measurements were performed at the FODS-2 spectrometer by using a polarized proton beam that was accelerated to an energy of 40 GeV at the accelerator of the Institute for High Energy Physics (IHEP, Protvino) and which was made to hit carbon and copper nuclear targets. The data in question were obtained in the range of c.m. angles between 73° and 94° near the central region (?0.01 < x _F < 0.27, 0.7 < p _T < 3.6 GeV/c). The single-spin asymmetry for π ⁺ and K ⁺ mesons is significant at high values of p _T and moderately small positive values of x _F. The analyzing power for other hadrons (π ^?, K ^?, p, $\bar p$ ) is compatible with zero in the p _T range studied here. The dependence of the analyzing power on the mass number of the target nucleus is insignificant.     

Confrontation between the quasiparticle-phonon nuclear model and the interacting boson model for deformed nuclei

TheK ^π=0⁺, 2⁺ and 4⁺ states are considered in doubly even deformed nuclei. It is shown that in the quasiparticle-phonon nuclear model (QPNM) and in the interacting boson model (IBM) a vibrational state has one dominating component. The states withK _n ^π =0 ₃ ⁺ , 0 ₄ ⁺ 0 ₅ ⁺ 2 ₂ ⁺ , 2 ₃ ⁺ , 4 ₁ ⁺ and 4 ₂ ⁺ have a dominating one-phonon component within the QPNM and a two- or three-boson component within the IBM. According to the QPNM the contribution of two-phonon components to the wave functions of these states is less than 10%, i.e. there is a qualitative discrepancy in describing the structure of these states within the QPNM and the IBM. The experimental data indicate the existence in these states of one-phonon or two-quasiparticle components. They are rather well described within the QPNM. These states cannot be described within the IBM. This is due to the fact that the IBM takes into account only a small part of the space of two-quasiparticle states, just the one entering intoΒ- andγ-vibrational states.     

Electric properties of levels of 156Dy rotational bands

The nonadiabaticity of E0 transitions from 0 ₂ ⁺ states and 2 ₁ ⁺ bands in ¹⁵⁶Dy is examined within a phenomenological model that takes into account the mixing of K ^π = 0 ₁ ⁺ , 0 ₂ ⁺ , 0 ₃ ⁺ , 2 ₁ ⁺ states and 1⁺-bands. It is shown that the nonadiabaticity of E0 transitions is due primarily to the mixing of 0 ₂ ⁺ and 0 ₃ ⁺ bands.     

Vibronic-spin-orbit coupling in octachlorodibenzo-p-dioxin

The dipole moments of vibronic transitions P _0R caused by vibronic-spin-orbit coupling along the coordinates of out-of-plane vibration modes R (to which the most intense vibronic lines of the fine-structure phosphorescence spectrum correspond) were calculated for the ³ B _1u (π π*) → S ₀ electronic transition in an octachlorodibenzo-p-dioxin molecule. The dependence of distribution (P _0R )² over R on the constant of spin-orbit coupling ?_A in different atomic groups (A = C, O, α-Cl, and β-Cl) of the molecule is ascertained. The contribution of these atomic groups (related to ?_A) to the value of P _0R ⁱ for the transitions from various triplet i-sublevels of the electronic state is determined. The obtained results about the different effect of the α-Cl and β-Cl atoms on the vibronic P _0R ⁱ and pure electronic transition dipole moments are discussed in connection with experimental data on the weak influence of the amount of chlorine atoms in polychlorinated dioxins on the phosphorescence decay time.     

Effect of renormalization of magnetic fluctuations on the kinetic coefficients of high-T c superconductors

Temperature dependences of resistivity, ρ(T), and Hall coefficient, R _H (T), in a 2D doped antiferromagnet are studied for various forms of the dynamic spin susceptibility X(q, θ) (in the mean-field approximation, taking into account attenuation and renormalization of the magnetic excitation spectrum θ_q, and for so-called strongly overdamped magnons). Doped CuO₂ planes in cuprates are considered in the one-band model of the Kondo lattice. Charge carrier scattering anisotropy, which strongly depends on temperature, is taken into account using the density matrix formalism and seven-moment approximation for the nonequilibrium distribution function. It is shown that the behavior of ρ(T) and R _H (T) is completely determined by the renormalization θ_q → $\omega _q \to \tilde \omega _q $ of the spin wave spectrum (the renormalization is essentially controlled by the fulfillment of the sum rule for X(q, θ) and by the strong temperature dependence of the gap δ(T). The resultant ρ(T) and R _H (T) dependences match the experimental data for optimally doped high-T _c superconductors.     

Aging effect in CaLaBa{Cu1???xFex}3O7???�� with 0 �� x �� 0.07 studied by M?ssbauer spectroscopy

In this work, we study the long-term aging effect caused by Fe atoms in the superconductor CaLaBa{Cu_1???xFe_x}₃O_7????? with 0 ?? x ?? 0.07. XRD confirms that this system has a YBCO-like structure. The critical temperature (T_c) is strongly affected by aging and depends on the amount of Fe in the structure. Room temperature Mössbauer spectroscopy reveals the presence of the typical species A, B?CB ??, C and new species E ?? and F. Interestingly; A, which corresponds to the Fe^3?+? atom located in the Cu(1) of the chains with spin S _z = 3/2, shows a drastic reduction which means migration to the species B, B ?? and C. Species B and B ?? correspond to the Fe^3?+? in the Cu(2) site forming planar quasi-octahedral and planar square pyramidal, while the C specie is a square pyramidal with O(5) respectively (spin S_z = 3/2 in all these cases). Aging causes loss of superconductivity in the samples with 5 and 7% of iron content.     

Leading role pseudovector and vector mesons in quasielastic pion electroproduction on a nucleon by longitudinal photons at comparatively high virtual momenta in the range 0.4 ≤ |k| ≤ 1 GeV/c

It is shown that, under kinematical conditions of quasielastic knockout, the differential cross section for the exclusive process p(e, e′π ⁺)n induced by longitudinal virtual photons γ* _L changes its physical nature as the recoil momentum |k| of the spectator nucleon grows from values in the range |k| ～ 0.1–0.4 GeV/c, which are typical in studying the pion cloud of the nucleon, to values around |k| ～ 1 GeV/c. Calculations within the ³ P ₀ quark microscopic model reveal that the amplitudes for the deexcitation of vector and pseudovector mesons via the processes ρ ⁺ + γ* _L → π ⁺ and b ₁ ⁺ + γ* _L → π ⁺ become dominant here. Concurrently, the effective momentum distributions develop a substantial angular anisotropy of about 50% with respect to the angle between the momentum of the photon γ* _L and the recoil momentum of the spectator nucleon, the longitudinal differential cross sections undergoing respective changes. In this region, the energy of knock-on pions is expected to be about 5 GeV under conditions of quasilastic kinematics.