Gauge boson masses and lepton mixing inO(4)⊗U(1) gauge model

The Cabibbo angle is introduced as a mixing angle of the gauge bosonsW ^± andX ^± in anO(4)?U(1) gauge model. Masses of gauge bosons are calculated to beM _W=82 (input), \(M_z = \sqrt 2 M_W s\gamma = 130\) (γ is mixing angle, sin² γ=0.21),M _x=666, andM _Y=660, in units GeV. TheW _μ ^± andZ _μ ⁰ couple to the familiar charged and neutral currents, respectively. The effective neutrino oscillation angle is found to be the Cabibbo angle.     

Mößbauereffekt in157Gd und155Gd

Using the Mössbauer technique electric hyperfine interactions of the first excited non-rotational states at 64 keV in¹⁵⁷Gd and at 86.5 keV in¹⁵⁵Gd have been determined in GdF₃ and GdCl₃· 6H₂O. For the ratio of quadrupolmoments the ratiosQ ₆₄ ¹⁵⁷ /Q _g ¹⁵⁷ =1.74±0.04,Q _86.5 ¹⁵⁵ /Q _g ¹⁵⁷ =?0.07 ± 0.21 andQ _g ¹⁵⁵ /Q _g ¹⁵⁷ =0.78 ± 0.06 were found. In addition isomer shifts were observed from which a ratio δ〈r²〉 ₆₄ ¹⁵⁷ /δ〈r²〉 _86.5 ¹⁵⁵ =?2.6±0.15 can be inferred.     

Gyromagnetic ratios of excited states in186W

The gyromagnetic ratios of the 4 ₁ ⁺ , 6 ₁ ⁺ , and 2 ₂ ⁺ states in¹⁸⁶W were measured relative to that of the 2 ₁ ⁺ level by means of the transient field implantation perturbedγ-ray angular distribution technique. The nuclei in the states of interest were Coulomb excited using a beam of 220-MeV⁶³Cu projectiles and recoiled swiftly through a thin, polarized Fe foil. The present measurements yielded ratiosg(4 ₁ ⁺ )/g(2 ₁ ⁺ )=1.04±0.07,g(6 ₁ ⁺ )/g(2 ₁ ⁺ )=1.03 ±0.20 andg(2 ₂ ⁺ )/g(2 ₁ ⁺ )=0.63±0.13. The sizable disparity between the measuredg-factors of the ground- and excited-band is examined within the context of the interacting boson approximation model.     

Simultaneous electrochemical and electron paramagnetic resonance studies of fullerene anion radicals C 60 1− and C 60 3−

Simultaneous electrochemical and electron paramagnetic resonance experiments have been carried out on the reduced C₆₀ fullerene to examine theg-factor assignment of the radical species. C ₆₀ ^1? and C ₆₀ ^3? show the following EPR characteristics at room temperature: C ₆₀ ^1? :g _1?=2.0002±0.0001, 2ΔB _1s=0.17 mT, and C ₆₀ ^3? :g _{3?=2.0008±0.0002}, 2ΔB _1s=0.07 mT. EPR linewidths are apparently narrower compared to those in most of the spectra previously reported. Variable temperature EPR study on solution containing C ₆₀ ^1? has shown thatg _1? value is not while the linewidth is only slightly temperature dependent.     

Analysis of experiments on the measurement of the pion electromagnetic formfactor

We analyse the experiments [1–3] on the measurement of the pion electromagnetic formfactor in the time-like and space-like region using an expression with correct analytical properties and with the asymptotics predicted by QCD. The best fit values for the physical quantities (1) electromagnetic radius of the pion:r _π ² =0.466±0.002 fm², (2) the mass and width of the ρ (770) and the ρ′ (1600) meson:m _ρ=768±1 MeV,Г _ρ=138±1 MeV,m _ρ′=1546±26 MeV,Г _ρ'=620±60 MeV; (3) the residuesg _ρ m _ρ ² =0.676±0.003,g _ρ′ m _ρ′ ² =?(0.644±0.009); (4) the ππ-scattering lengtha ₁ ¹ =(0.1±0.01)m _π ^?3 .     

Electroweak parameters from a high statistics neutrino nucleon scattering experiment

The final results from the WA 1/2 neutrino experiment in the 1984 CERN 160 GeV narrow band beam are presented. The ratiosR _ν and \(R_{\bar v} \) of neutral to charged current interaction rates of neutrinos and antineutrinos in iron are measured to beR _ν=0.3072±0.0033 and \(R_{\bar v} \) =0.382±0.016. A value of the electroweak parameter sin² θ _w = 1 ?m _W ² /m _Z ² is extracted fromR _ν. The result is sin² θ _w =0.228+0.013(m _c ?1.5)±0.0003 (theor.) wherem _c is the mass of the charmed quark in GeV form _t =60 GeV,M _H =100 GeV, ρ=1. CombiningR _ν and \(R_{\bar v} \) one obtains a value for ρ=0.991+0.023(m _c ?1.5)±0.020(exp.). Alternatively,R _ν and \(R_{\bar v} \) yield a precise value of the ratio of intermediate vector boson massesm _W /m _Z =0.880?0.007(m _c ?1.5)±0.002(exp.)±0.002(theor.). Comparison of these results with those from direct measurements of the vector boson masses are presented. In a model-independent analysis the left- and right-handed neutral current coupling constants,g _L ² andg _R ² , are determined.     

MeanM-subshell fluorescence yields atZ=88, 90, 92, and 94

M x-ray —L x-ray coincidence measurements with high resolution, cooled Si(Li) x-ray detectors were made on transitions following the alpha decays of²²⁸Th,²³²U,²³⁸Pu, and²⁴⁴Cm, in order to determine the meanM-subshell fluorescence yields. The values obtained are:v ₄ ^M =0.032±0.002, andv ₅ ^M =0.024±0.002 atZ=88;v ₁ ^M =0.038±0.003,v ₄ ^M =0.042±0.002, andv ₅ ^M =0.038±0.002 atZ=90;v ₁ ^M =0.047±0.002,v ₄ ^M =0.048±0.002, andv ₅ ^M =0.044±0.002 atZ=92;v ₁ ^M =0.066±0.002,v ₄ ^M =0.062±0.002, andv ₅ ^M =0.063±0.002 atZ=94. The quantityΩ ₁ ^M +f ₁₂ ^MΩ ₂ ^M was measured as (56±10)×10^?4, (62±12)×10^?4, (99±18) ×10^?4, and (93±15)×10^?4 forZ=88, 90, 92, and 94, respectively, which agree well with the calculations of McGuire. The radiativeL ₁-L ₃ transition intensity was measured for the four atomic numbers and found to be consistently less than the calculations of Scofield by about 45 percent.     

Electronic properties of charged fullerenes characterized by EPR and Vis-NIR spectroscopy

EPR and Vis-NIR absorption spectra have both been measured for clarification of contradictory statements about the para-and diamagnetic states of fullerenes. Thereby identification of one sharp EPR signal in solution at room temperature to C ₆₀ ^? (g=2.000±4.0001; ΔB=0.07±0.01 mT) could be made upon using different fullerene sources (TechnoCarbo, Hoechst) and methods of anion generation (chemically, electrochemically, and photochemically). This fact is also supported by the similar observation for a monosubstituted derivative (g=1.9999; ΔB=0.10 mT), in which a small broadening of this sharp signal is found originating from additional¹H hyperfine interactions. Furthermore theg-values of the radical anions of C₆₀ increase with charge (g(C ₆₀ ^? <g(C ₆₀ ^2? ) < <g(C ₆₀ ^3? ) <g(C ₆₀ ^5? )) indicating largest contributions from spin-orbit coupling for the monoanion. No diamagnetic states for the dianions of [60]- and [70]- fullerenes could be found so far but biradical species with largest zero field splittingsD=2.7 mT (C ₆₀ ^2? ), andD=3.1 mT (C ₇₀ ^2? ), respectively. The cation formation of C₆₀ (g=2.0023-2.0029; ΔB=0.15-0.20 mT) with antimony pentachloride was controlled by mass spectrometry. Stable cations were found only in methylenechloride. In other solvents like toluene addition reactions seem to occur.     

EPR investigations of SiC and SiOC nanometric powders

EPR investigations are performed in SiC and SiOC nanometric powders annealed between 1200 and 1800°C. By using different EPR frequency bands and a suitable spectra analysis, three quite different paramagnetic defects with well defined $\tilde g_i $ (i=1, 2, 3) and hyperfine $\tilde A_i $ (i=1, 2) tensors account for the EPR signal in these materials. The defects are characterized by $\tilde g_1 $ (g ₁ ^‖ =2.0046(3), g ₁ ^? =2.0023(3)), $\tilde g_2 $ (g ₂ ^‖ =2.0037(3), g ₂ ^? =2.0028(3)) and isotropic $\tilde g_3 $ (2.0030(3)) tensors. In SiC powders, the defects assignment is discussed with respect to the different SiC forms, namely α-SiC and β-SiC polytypes as well as amorphous SiC and carbon present in minor concentration in the network. In SiOC powders, the above defects are evidenced only at high annealing temperature (T _a≥1200°C) when the oxygen contained is highly reduced.     

Magnetic moments of the 2 1 + states in102, 104Mo

Theg factors of the first excited 2⁺ levels in the neutron-rich nuclei¹⁰²Mo and¹⁰⁴Mo have been studied through the measurement of the perturbed angular correlations for theγ-γ cascades between the 0 ₂ ⁺ -2 ₁ ⁺ -0 ₁ ⁺ level sequences. The results of g=0.42±0.07 for¹⁰²Mo and ofg= _?0.11 ^+0.12 for¹⁰⁴Mo agree with the prediction of the vibrational-rotational model. In terms of IBA, with the assumption ofN _π=3 for the Mo isotopes which takes into consideration a two particle, two-hole excitation across the Z=40 subshell, the proton-bosong factor is deduced to beg _π=1.00±0.23. It is shown that this value provides evidence for subshell effects in¹⁰⁰Zr.     

Phenomenology of composite colored weak bosons

In composite models of quarks, leptons and weak bosons whereW-constituents are colored objects, color octet partners ofW ^± andZ ⁰ are predicted. We study in detail the phenomenology of these particles. Independent of the specific model one expects a color octet isotriplet of vector bosons (W ₈ ^± ,Z ₈ ⁰ ) with mass in the range of 100–200 GeV, and a color octet isosinglet vector bosonV ₈ ⁰ with substantially larger mass, due to mixing with the gluon. Moreover, relatively light color octet excitations of the leptons appear, while the existence of “color exotic” partners of the quarks is model dependent. These particles decay mainly into a lepton (quark) and a gluon. We construct the couplings ofW ₈ ^± ,Z ₈ ⁰ andV ₈ ⁰ to ordinary and “color exotic” fermions. The signals of color octet weak bosons in low energy weak reactions are explored in detail. The production cross section ofW ₈ ^± (Z ₈ ⁰ ) in hadron-hadron collisions is calculated for \(0.54TeV \leqq \sqrt s \leqq 20TeV\) . Various decay modes of colored weak bosons are studied. The most prominent decay signatures ofW ₈ ^± andZ ₈ ⁰ are events of the type (l ^+-: charged lepton;j: hadronic jet; : missing transverse momentum). The present CERN \(p\bar p\) collider data on such events are discussed in the light ofW ₈ ^± andZ ₈ ⁰ decays. If colored weak bosons are not found with a mass less than ～250 GeV composite model building will be strongly restricted.     

Investigation of the two quasiparticle rotational band at 1172 keV in172Yb and determination of theg R -factor of the 3+ 3 band head

Investigations of the rotational band based on the 3⁺ 3 two quasiparticle state in¹⁷²Yb have shown that some of its properties can be well described by the collective model of Bohr and Mottelson. As a result of these investigations we have derived the ratio (g _k – g _R )/Q _o =? (0.0136 ± 0.0007). The magneticg-factor of the band head has also been determined by an integral angular correlation measurement perturbed by an external magnetic field. As a result we foundg=0.201 ± 0.030. Using this value and our result of (g _k – g _R )/Q _o we have calculated theg _R -factor of the two quasiparticle state asg _R =0.283 ± 0.018 which is out of the errors smaller than theg _R -factor of the ground state rotational band. An analysis of our angular correlation experiments gave for the mixing parameter δ of theK-forbidden 1094 keV intraband transition: δ=? (3.63 _?0.06 ^+0.14 ) in agreement with the results of other authors.     

Hadronic contributions to (g−2) of the leptons and to the effective fine structure constant α(M Z 2 )

The new experiment planned at Brookhaven to measure the anomalous magnetic moment of the muona _μ≡(g _μ?2)/2 will improve the present accuracy of 7 ppm by about a factor of 20. This requires a careful reconsideration of the theoretical uncertainties of theg?2 predictions, which are dominated by the error of the contribution from the light quarks to the photon vacuum polarization. This issue is cruicial also for the precise determination of the running fine structure constant at theZ-peak as LEP/SLC experiments continue to increase their precision. In this paper we present an updated analysis of the hadronic vacuum polarization using all presently availablee ⁺e^? data. This seems to be justified because previous work on the subject was based to some extent on preliminary or incomplete experimental data. Contributions from different energy ranges are presented separately forg?2 of the muon and the τ-lepton and for α(M _Z ² ). We obtain the resultsa _μ ^had* =(725±16)×10^?10 anda _τ ^had* =(351±10)×10^?8, where the asterisk indicates the dressed (renormalization group improved) value. For the effective fine structure constant atM _Z=91.1888 GeV we obtainΔα _had ⁽⁵⁾ =0.0280±0.0007 and α(M _Z ² )^?1=128.896±0.090. Further improvement in the accuracy of theoretical predictions which depend on the hadronic vacuum polarization requires more precise measurements ofe ⁺e^? cross-sections at energies below about 12 GeV in future experiments.     

Observation of perturbations in the rovibronic transition probabilities for the (4d)r 3Π g − , (4d) s 3 Δ g − → (2p) c 3Π u ± band systems of the H2 molecule

The ratios of the radiative transition probabilities for the lines of the P, Q, and R branches of the (4d)r ³Π _g ^? , (4d)s ³Δ _g ^? → (2p) c ³Π _u ^± band systems of the H₂ molecule have been measured for the first time. Significant (to two orders of magnitudes) differences are found between the experimental values and the adiabatic theory predictions. It is established that the results of the nonadiabatic calculation performed by us in the pure-precession approximation taking into account the electronic-rotational interaction of the 4d ³Π_g and 4d ³Δ_g states are in agreement with the experimental data. The optimal energies of rovibronic levels of the r ³Π _g ^? , s ³Δ _g ^? , c ³Π _u ^? , and c ³Π _u ⁺ states have been found and reidentification of 11 from 54 spectral lines, assigned previously to the (0-0) and (1-1) bands, was performed.     

Lebensdauer- und Hyperfeinstrukturmessungen an einigen angeregten Zuständen der Konfiguration 4d 9 5p im Pd I-Spektrum mit der Level-crossing-Methode

Lifetimes and hfs coupling constants of some excited states of the 4d ⁹ 5p configuration of Pd I have been determined in a level crossing experiment by observing the field dependence of the polarization of the fluorescence radiation in a magnetic field. From the halfwidths of the measured zero field level crossing signals one obtains the mean lifetimes of the following fine structure states:τ(³P ₁ ⁰ )=(7.46±0.32)nsec;τ(³ P ₂ ⁰ )=(6.9±0.76)nsecτ(³P ₁ ⁰ )=(4.99±0.35)nsec;τ(³ D ₁ ⁰ )=(4.89±0.40)nsecτ((³D ₃ ⁰ )=(6.99±0.49)nsec;τ(³ F ₄ ⁰ )=(7.09±0.46)nsec.Δm=2 crossing signals were detected in the³ P ₁ ⁰ ,³D ₃ ⁰ and³F ₄ ⁰ -states of the odd isotope¹⁰⁵Pd. A detailed analysis of the experimental curves yields the hfs coupling constantsA andB of these states:A(³P ₁ ⁰ )=?(133±2) Mc/sec;B(³ P ₁ ⁰ )=(140±30) Mc/secA(³D ₃ ⁰ )=?(120±10) Mc/sec;B(³ D ₃ ⁰ )=?(660±100) Mc/secA(³F ₄ ⁰ )=?(87±2) Mc/sec;B(³ F ₄ ⁰ )=?(330±30) Mc/sec. A theoretical calculation of the hfs constants is given on the basis of reduced matrix elements. Within the limit of the errors these values agree with the experimental ones. The nuclear electric quadrupole moment deduced from the measuredB values isQ (¹⁰⁵Pd)=(0.8±0.3)·10^?24 cm² (without corrections).     

An ESR study of NH 3 + , al center and HO2 · radical in alkali feldspars

Paramagnetic centers of NH ₃ ⁺ , Al, and HO₂ · have been observed in alkali feldspars from Aichi prefecture, Japan. The quartet signal has been tentatively ascribed to NH ₃ ⁺ rather than to ·CH₃, although the hyperfine splitting by¹⁴N (I=1) was not observed. The averageg- andA-valuesg _av=2.0033 andA _av ^H =2.45 mT, respectively, were attributed to hydrogen. The powder spectra of Al centers stable up to 400 K were simulated by the anisotropicg factors ofg _zz =2.060,g _xx =2.0014,g _yy=2.0021 andA=0.9 mT. Newly discovered HO₂ · is stable up to 570 K. The intensities of the spectra from NH ₃ ⁺ and Al centers were enhanced by gamma-ray irradiation, while that of HO₂ · was not enhanced. Production efficiency,G-value (radical/100 eV) of NH ₃ ⁺ has been obtained to beG=0.01. These results suggest that ESR dating of feldspars is possible.     

Jahn-Teller effect in low-spin Ni3+ in the LaAlO3 ceramic

This paper reports on an EPR study of LaAl_1?x Ni_xO₃ solid solutions with x≤0.12 made in the 4.2-to 300-K temperature range. In the X range, the broadening of the single EPR line with g _eff=2.148 was observed at temperatures below ～40 K. In the Q range, a slightly anisotropic EPR line with g _⊥ ^′ =2.145±0.002 and g _‖ ^′ =2.154±0.002 transforms to a rhombic-symmetry spectrum with g ₁=2.183±0.002, g ₂=2.143±0.002, and g ₃=2.118±0.002. It is shown that the observed low-temperature effects are due to the lowered symmetry of the complex under the combined action of the tetragonal Jahn-Teller distortions and of the trigonal component of the crystal field.     

Pulse ENDOR studies on the radical pair P 700 +· A 1 ·− and the photoaccumulated quinone acceptor A 1 ·− of photosystem I

The secondary acceptor A₁ of the electron transport chain(s) of photosystem (PS) I is a phylloquinone (vitamin K₁, VK₁). Pulse electron paramagnetic resonance and electron nuclear double resonance (ENDOR) experiments at X-band frequencies were performed on the photoaccumulated acceptor radical A ₁ ^·? and the radical pair state P ₇₀₀ ^·+ A ₁ ^·? in PS I ofThermosynechococcus elongatus. The data obtained were compared with data from the respective radical anion of VK₁ in organic solvents. The unusualg tensor magnitude of A ₁ ^·? is explained by the hydrophobic binding pocket of this radical. The hyperfine couplings and the spin (and charge) density distribution is very different for A ₁ ^.? in PS I and VK ₁ ^·? in frozen alcoholic solution. This is attributed to a rather strong one-sided hydrogen bond to A ₁ ^·? . The presence of a hydrogen bond to A ₁ ^·? has only a minor effect ong. The hyperfine coupling constants of A ₁ ^·? determined from the radical pair spectra deviate only slightly from those derived from photoaccumulated A ₁ ^·? in PS I treated with dithionite at high pH. ENDOR resonances of the proton in a H bond were detected and an estimate of the strength and geometry of this bond to A ₁ ^·? was obtained. The significance of the hydrogen bond and other (hydrophobic) interactions of A₁ with the surrounding are briefly discussed.     

Temperature dependence of Mn2+ EPR in Sn2P2S6 near the phase transition

The X-band EPR spectrum of Mn²⁺ in Sn₂P₂S₆ was studied in the temperature rangeT=223–363 K. At room temperature the spin-Hamiltonian constants areg=2.00±0.01,B ₂ ⁰ =(163±3)·10^?4 cm^?1,B ₂ ² =(159±3)·10^?4 cm^?1,A=?(75±1)·10^?4 cm^?1. The effect of the invariance in temperature of the resonance magnetic fields in the narrow temperature rangeT=337–340 K and the model of the paramagnetic centre are discussed. According to EPR data a phase transition occurs atT=337 K. This transition from the paraelectric phase to the ferroelectric one is accompanied by a dramatic change in value of the spin-Hamiltonian constantB ₂ ⁰ .