Does the enhancement mechanism work in non-leptonic decays of heavy pseudoscalar mesons with new flavors (b and t)?

We show that the enhancement mechanism proposed for non-leptonic decays of charmed mesons (D⁰, F⁺) is still important for decays of pseudoscalar mesons with b flavor, while its effect is small for mesons with t flavor. For the semi-leptonic branching ratios of B^? (b$\text{u}$), B⁰(b$\text{d}$) and B_S⁰(b$\text{s}$) we predict BR (B^? → evX ～' 9%, BR(B⁰ → evX) ～' BR(B_s⁰ → evX) ～' 5%. We can also derive the enhancement of the branching ratios of uncharmed final states in B decays, i.e. $\text{BR}\text{(}\text{B}{}^{\mathrm{?}}\text{→}\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>u</mtext>}}\text{)}$ ～' 20 %, $\text{BR}\text{(}\text{B}{}^0\text{→}\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>d</mtext>}}\text{)}$ ≈ 10%, where $\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>u</mtext><mtext>(</mtext><mtext>s</mtext><mtext>d</mtext><mtext>)</mtext>}}$ = $\text{K}$π + ... + $\text{K}$K$\text{K}$ + ... .     

Axial contraction in toroidal pinches with non-circular plasma cross-sections

The axial contraction of linear pinches with racetrack-shaped and elliptic cross sections is studied byδW-analysis near the equilibrium shape. A surface current profile and a fixed plasma cross-section area are assumed. It is shown for the corresponding special perturbation thatδW is given by the variation of the surface energy(δW=δW _s =1/8B _p ² ξ _b ² ), and thatδW is nearly independent of the shape of the plasma (racetrack or ellipse). The axial oscillation frequency is found to beΩ _ax=1/2√CB _p /√ρ_l with a constantC<1. The model correctly predicts theB _p and ρ_l-dependences of the experimental belt-pinch results and yields theoreticalΩ _ax-values a factor of 2 above the experimental ones.     

Multipole mixing ratios of transitions in Te

Gamma-gamma directional correlation measurements were made on nine transitions in ¹²⁴Te with a NaI(Tl)-Ge(Li) detector arrangement and multichannel analysis. The multipole mixing ratios obtained were δ(646) = 0.000±0.001, δ(714) = 1.5_−0.3^+0.6, δ(723) = −3.3±0.2, δ(1437) = 3.7_−2.0^+2.7, δ(1489) = −3.4_−1.5^+0.9, δ(968) = −0.03_−0.05^+0.06, δ(1368) = −0.045±0.090, δ(1045) = 0.041_−0.041^+0.047, δ(1691) = −0.02±0.01, and δ(2091) = 0.00_−0.03^+0.02. The first δ is M3/E2, the next three are E2/M1, and the last five are M2/E1. The retardation (a factor of approximately 50) of the crossover to cascade transitions from the 2039 keV, third 2⁺ level to the second and first 2⁺ levels is essentially the same for both the M1 and E2 components. In addition, spin and parity assignments of 2⁺ were made for the 2039 and 2092 keV levels.     

Pion-pion phase shift and K2π decay

We remark that, using the Cabibbo transformation properties for the weak Hamiltonian we can obtain Δ₀ = δ₀⁽⁰⁾ (s = M_K⁽²⁾ (s = M_K²) from the experimental decay rates for K_s → 2π, K⁺ → π⁰π⁺, obtaining δ₀ = 58.0° ± 4.6°. This result implies in particular a value of ≈ 0.6 for the S-wave isospin zero scattering length, in accordance with K_e4 results but in violent disagreement with Weinberg's calculation.     

Experimente und Berechnungen zur Hyperfeinstruktur der 3d 9 5g-Konfiguration im Kupfer II-Spektrum

The 3d ⁹ 5g-configuration in the Cu II-spectrum is an example for extreme(j _d l _g )K-coupling. It is shown how under these circumstances experimental hyperfinestructure separations can be explained and calculated by means of the concept of intermediate coupling between two basic coupling schemes. The basic schemes used are built on the vectorK coupled either to the spins of the outer 5g-electron or to the nuclear spinI. The value of the experimental magnetic separation factorya _j (3d) can be understood as the consequence of the core polarization of the inners-electrons by the spin of the unfilled 3d-shell. — The measured effective spin-orbit-constantζ _5g is three times larger than the theoretical result. Reasons for this discrepancy will be discussed.     

Mirror supersymmetry in the space of (super) extended Poincaré algebras p(p,q)

We classify extended Poincaré Lie superalgebras and Lie algebras of any signature (p, q), i.e. Lie superalgebras and ₂-graded Lie algebras g = g₀ + g₁, where g₀ = s₀(V) + V is the (generalized) Poincaré Lie algebra of the pseudo Euclidean vector space V = ^{p, q} of signature (p, q) and g₁ is a spin 1/2 s₀(V)-module extended to a s₀-module with kernel V.As a result of the classification, we obtain, if g₁ = S is the spinor module, the numbers L ⁺(n, s) (resp. L ^–(n, s)) of independent such Lie super algebras (resp. Lie algebras), which are periodic functions of the dimension n=p+q (mod 8) and the signature s=p–q (mod 8) and satisfy: L ⁺(–n, s)=L ^– (n, s).Supported by Max-Planck-Institut für Mathematik (Bonn).Supported by the Alexander von Humboldt Foundation, MSRI (Berkeley) and SFB 256 (Bonn University).     

Observation of πo mesons with large transverse momentum in high-energy proton-proton collisions

Invariant cross-sections are presented for the inclusive reaction p + p → π^o + anything, Measurements of large transverse momentum π^o's (2.5 GeV/c<p_⊥<9 GeV/c) were made near 90° at the CERN ISR at five centre-of-mass energies (√s = 23.5, 30.6, 44.8, 52.7 and 62.4 GeV. At large p_⊥, the invariant cross-sections are seem to vary with s and p_⊥, in good agreement with a fit of the form Ap_⊥^?nF(p_⊥/√s), with n≈8 and F(p_⊥/√s)≈exp(?26p_⊥/√s).     

The half-life of the 1437 keV 11/2− state in97Mo

Using the (,n) reaction, the half-life of the first 11/2^– level in⁹⁷Mo has been determined as T_1/2(1437.0 keV)=2.5±0.3 ns by means of the pulsed beam method. The experimentally obtainedB(M2) value between theh _11/2 andg _7/2 configurations in⁹⁷Mo has been satisfactorily described within the quasiparticle-phonon model usingg _s ^eff =0.6g _s ^free . Similar calculations and comparisons with experminental data have been performed also for^95,99Mo as well as for⁹⁹Ru and¹⁰¹Pd.This work is partly supported by the Bulgarian National Research Foundation     

Discharged generator of singlet oxygen for oxygen-iodine laser. Transport kinetics of O2(a 1δg) and O2(b 1σ g + ) molecules and O(3 P) atoms in Ar:O2 and He:O2 flows excited by a 13.56-MHz discharge

To understand and reveal the basic physical factors providing the possibility of scaling of a discharged singlet oxygen generator (DSOG) in an oxygen-iodine laser, the production, and transport kinetics of metastable O₂(a ¹δ_g) and O₂(b ¹σ _g ⁺ ) molecules, as well as O(³ P) atoms, were investigated in Ar:O₂ and He:O₂ gas flows excited by a 13.56-MHz discharge in a wide range of pressures (4–40 Torr) and oxygen percentages. It is shown that the densities and transport kinetics of O₂(a ¹δ_g), O₂(b ¹σ _g ⁺ ), and O(³ P) appear similar for oxygen mixtures with argon and helium in the same conditions independent of discharge mode. Compared to pure O₂, the dilution of oxygen with an inert gas allows higher energy inputs per an oxygen molecule to achieved, especially under conditions of the homogeneous discharge mode (α-mode), which gives a higher efficiency of O₂(a ¹δ_g) excitation in Ar:O₂ and He:O₂ mixtures. But the maximum attainable yield of singlet oxygen in Ar:O₂ and He:O₂ at fixed partial O₂ pressure is found to be comparable with the O₂(a ¹δ_g) yield in pure oxygen at the same pressure. The reason for this is the increased three-body deactivation of O₂(a ¹δ_g) by atomic oxygen in the mixtures because of the greater total pressure. The estimation of the rate constant of O₂(a ¹δ_g) three-body quenching by O(³ P) in Ar:O₂ and He:O₂ mixtures as (1.5 ± 0.5) × 10^?32 cm⁶/s was carried out from the analysis of transport kinetics of singlet and atomic oxygen in the discharge afterglow at high pressures exceeding ～10 Torr. A similar analysis for the lower pressures has revealed that losses both of metastable O₂(a ¹δ_g) and O₂(b ¹σ _g ⁺ ) molecules, and of O(³ P) atoms on the surface of the discharge tube, are determined by the density of each of the components. The obtained loss probabilities of O₂(a ¹δ_g), O₂(b ¹σ _g ⁺ ), and O(³ P) on the silica surface show that the surface loss probabilities of all the species can increase noticeably under the discharge exposure. Thus, the key parameters determining the maximal O₂(a ¹δ_g) yield in the DSOG are a homogeneous volumetric mode of the discharge, energy input per oxygen molecule in this mode, and a low rate of O₂(a ¹δ_g) quenching. Just three-body quenching of O₂(a ¹δ_g) by O(³ P) limits the singlet oxygen yield with increasing pressure. The fast removal of atomic oxygen both in discharge and in the earlier afterglow could provide DSOG scaling with pressure.     

Spin-dependent parton distributions in polarized deep inelastic lepton nucleon scattering

We analyze the recently measured first moment Г ^p (Q ²) of the structure functiong ₁ ^p (x,Q ²) obtained in deep inelastic scattering of polarized electrons from polarized protons. It is shown that the recent experimental result Г ^p (〈Q ²〉?10 GeV²)? 0.113 implies a polarized strange quark sea whose total polarization Δs(μ²)??0.22 is comparable to Δμ(μ²)?0.74 and Δd(μ²)??0.50 already at a typically hadronic scale μ=0(1 GeV). Most remarkably, the total polarization due to quark distributions Δμ(μ²)+Δd(μ²)+Δs(μ²) practically vanishes which implies that the spin of the proton is carried by the gluons, ΔG(μ²), and/or the angular momentum of the partons. This surprising conjecture can be experimentally tested with heavy quark production in longitudinally polarized lepton-nucleon scattering. In particular the (real) photon-gluon fusion process γg→Q \(\bar Q\) provides a rather unique measure of ΔG(x,Q ²).     

Laser-rf double-resonance hyperfine structure measurements of the metastable 3d 4s 1 D 2 state of43Ca

The hyperfine structure of the (3(d 4s)¹ D ₂metastable state of⁴³Ca has been measured using theABMR-LIRF method (atomic beam magnetic resonance, detected by laser induced resonance fluorescence). The measurements yielded for the magnetic dipole and electric quadrupole constantsA=?17.650(2) MHz andB=?4.642(12) MHz, respectively. From the measuredB factor the spectroscopic electric quadrupole moment (uncorrected for shielding effects) has been calculated to beQ(⁴³Ca)=?0.062(12) barn. In addition, isotope shifts in the lines (3d 4s)¹ D ₂(3d 4p)¹ F ₃ ⁰ and (3d 4s)¹ D ₂(4s 5p)¹ p ₁ ⁰ for the stable calcium isotopes have been obtained by high resolution laser spectroscopy.     

ππ Scattering Amplitudes that Satisfy Inelastic Unitarity Constraints

We construct amplitudes which are represented by a Mandelstam representation with a finite number of subtractions and that satisfy ππ crossing symmetry and the unitarity constraints Im f_l^I(s) ≧|f_l^I (s)|², l=0, 1, 2,…, for all energies above threshold s > 4, in the three isospin channels I=0, 1, 2. The following types of solutions are derived.

• 1 The amplitudes have a positive double spectral function ϱ(s, t) ≧ 0. The total cross section decreases like σ_T(s) ∼ (log s)^-δ for arbitrary δ ≧ 1, including the limiting case δ=1.
• 2 The amplitudes are dominated by Regge poles, the total cross section can reach a constant asymptotic value, σ_T(s) → const.
• 3 The amplitudes are dominated by Regge cuts, the total cross section can increase logarithmically σ_T(s) → log s.

     

Inverse Laplace transforms of osculatory and hyperosculatory interpolation polynomials

In the numerical calculation of f(t), the inverse Laplace transform of F(p), where f(′) = (1/2πi) °_c−i∞^c+i∞ e^pt F(p)dp, sufficient accuracy is usually obtainable when p³F(p), s > 0, is replaced by an interpolating polynomial in 1/p. From the values of F(p) with F′(p), or with F′(p) and F″(p), for p at points equally spaced on the real axis, an osculatory or hyperosculatory interpolation polynomial for p⁸F(p), namely L_2n−1(x) or L_3n−1(x), where x = 1/p, is obtained in barycentric form. Then f(t) is calculated by a Gaussian-type quadrature formula employing complex values of L_2n−1 or L_3n−1 and instead of p^sF(p) which may be unknown or more difficult to compute. For calculating L_2n−1 and L_3n−1, auxiliary coefficients, suitable for economical storage in the program, are given exactly for n = 2(1)11 and n = 2(1)7, furnishing up to 21st and 20th degree accuracy, respectively.     

Applications of photoelectron spectroscopy to molecular propertles: XVIII. The vertlcal ionization potentials of diphosphene as calculated by perturbation corrections to koopmans' theorem

The vertlcal ionization potentials (VIP's) of dimethyl diphosphene have been computed using perturbation corrections to Koopmans' theorem. These corrections allow an estimate of the effects of polarization and correlation, and show for this molecule an important contribution of the specific correlation of the ion for the ²A_g and ²B_u states. The results predict for the first three VIP's the ordering ²A_g, ²A_u, ²B_u, in agreement with our previous assignment.     

Investigation of the φ-meson resonance by electron-positron colliding beams

Using the colliding beam machine, VEPP-2, the excitation curve of the ø-meson resonance was investigated in the three main decay modes. The resonance parameters obtained are the width, the total cross-section and the branching ratios. Namely: Γ = (4.67 ± 0.42) MevB(K⁺K⁻) = (54.0 ± 3,4) %σ_o = (3.96 ± 0.35) μBB(K^o_sK^O_L) = (25.7 ±3,0) %B(e⁺e⁻ = (2,81 ± 0.25) × 10⁻⁴B(π⁺π⁻π^o) = (20.3 ± 4,2) %     

Effect of a heavy atom in the S 1(ππ*) ↝ T 1(ππ*) nonradiative transition. 9,10-Dichloroanthracene

The rate constant K _ST for the nonradiative intersystem crossing transition S ₁(¹ B _1u ) ? T ₁(³ B _1u ) (I) in 9,10-dichloroanthracene (DClA) is calculated in terms of the model of vibronic-induced spin-orbit (VISO) interactions. The magnitude fluorescence quantum yield ?_fl is estimated. Comparison of K _ST(I) and ?_fl for DClA with the corresponding values obtained earlier for anthracene (AC), where K _ST is governed by the conversion channels (I) and S ₁(¹ B _1u ) ? T ₂(³ B _3g ) (II), shows that the theoretical estimates reflect the anomalous heavyatom effect in these molecules in accordance with the experimental (literature) data. The cause for this effect is revealed. The influence of different factors on the K _ST(I) constant and on the ratio of its components K _ST ^s (where s denotes the z and y spin-sublevels) is established for DClA. These factors are the magnitude of the spin-orbit coupling parameter in a chlorine atom, the change, as compared to AC (in the same conversion channel (I)) of the distribution of electrons in the carbon core of the DClA molecule, and the change in the form of out-of-plane vibrational modes involved in VISO interactions.     

The polarization of protons from the 2H(d, p)3H reaction for deuteron energies below 1 MeV

The angular distribution of proton polarization P^γ' (θ) from the ${}^2\text{H}\text{(}\text{d,}\text{p}\text{)}{}^3\text{H}$ reaction has been measured at 975 keV deuteron energy. Moreover, the energy dependence of P^γ′(E_d) was measured at 45°(lab) for deuteron energies between 250 and 975 keV. The values of σ₀(θ)P^γ' (θ) were fitted in terms of an associated Legendre polynomial expansion. The measured energy dependence of P^γ' (E_d) has been analyzed in terms of barrier-penetration parameters.     

Structure of even-even actinides in the interacting boson model and the N = 152 subshell closure

We show that a wide range of deformed actinides can be described in terms of an interacting boson model hamiltonian with three parameters, two of them [including the coefficient of the only SU(3) symmetry breaking term] remaining almost constant over the whole region. In addition to ground γ₁ and β₁ spectra, B(E2:0_g⁺ → 2_g⁺) values are well reproduced with no extra adjustable parameters for nuclei with 136⩽N⩽146, while for nuclei beyond N = 146 an effective boson number has to be considered in order to fit the observed in the B(E2:0⁺_g → 2⁺_g) values, which is due to the presensce of a subshell closure at N = 152. The sensitive dependence of the B(E2:0_g⁺→2_g⁺) values on the effective boson numbers is emphasized. β₁ → ground and β₁ → ground transitions are fitted by breaking the SU(3) symmetry of the E2 transition operator.     

Extracting d-orbital occupancy from magnetic Compton scattering in bilayer manganites

We consider the shape of the magnetic Compton profile (MCP), J_mag(p_z), in La_1.2Sr_1.8Mn₂O₇ for momentum transfer p_z along the [110] direction and the associated reciprocal form factor B(r) defined by taking the one-dimensional Fourier transform of J_mag(p_z). B(r) is shown to contain a prominent dip at r≈1 Å, where the minimum value B_min of B(r) can be related to the occupancies of the e_g orbitals of dx²−y² and d3z²−r² symmetry in the system. We illustrate our procedure in detail by analyzing the measured MCP at 5 K and the MCP computed within the framework of the local spin density approximation (LSDA) and comment on the differences between the measured and computed e_g occupancies as a reflection of the limitations of the LSDA in treating electron correlation effects.