Gyromagnetic ratios of 4+ and 6+ states in156Gd and158Gd

The followingg-factors have been derived from time integral measurements of γ-γ angular correlations in the static magnetic hyperfine field of magnetized gadolinium metal probes:¹⁵⁶Gd:g(4 ₁ ⁺ )=+0.310(19)g(6 ₁ ⁺ )=+0.25(21)g(4 ₃ ⁺ , 1511 keV)=+0.809(27)¹⁵⁸Gd:g(4 ₁ ⁺ )=+0.409(15). The 5.35d ¹⁵⁶Tb sources were produced by the reaction¹⁵⁶Gd(d, 2n)¹⁵⁶Tb in our cyclotron. A carrier-free 150y ¹⁵⁸Tb source was obtained from ISOLDE/CERN. In comparison with the precisely knowng-factors of the 2 ₁ ⁺ states,g(2 ₁ ^su+ ,¹⁵⁶Gd) =+0.386(4) andg(2 ₁ ⁺ ,¹⁵⁸Gd)=0.381(4), we observe a large reduction for the¹⁵⁶Gd 4 ₁ ⁺ state whereasg increases slightly for¹⁵⁸Gd. The half-life of the 4 ₁ ⁺ state of¹⁵⁸Gd was remeasured as¹⁵⁸Gd:T _1/2(4 ₁ ⁺ )=148(2) ps. A measurement of the rotation in the 4 ₃ ⁺ state of¹⁵⁶Gd in external magnetic fields of various strengths up toB _ext=9.5 T did not confirm the anomalous dependence of the magnetic hyperfine field in gadolinium metal on the external field, which has been reported by Persson et al. [29].     

Inclusive production ofK s 0 , K s 0 K s 0 andK *±(892) in\bar pp interactions at 3.0, 3.5, 4.0 and 4.5 GeV/c

InclusiveK _s ⁰ andK _s ⁰ K _s ⁰ production in \(\bar pp\) interactions at 3.0, 3.5, 4.0 and 4.5 GeV/c are studied. Cross sections ofK _s ⁰ , K _s ⁰ K _s ⁰ andK ^*±(892) are presented for each incident momentum. The production ofK _s ⁰ andK ^*±(892) through annihilation process is investigated. It is found that the annihilation process is dominant but decreases with incident momentum. The annihilation process is compared withe ⁺ e ^? interactions. Remarkable similarity between them is found in the \({{x_0 = 2E(K_s^0 )} \mathord{\left/ {\vphantom {{x_0 = 2E(K_s^0 )} {\sqrt s }}} \right. \kern-0em} {\sqrt s }}\) distribution. Events with two detectedK _s ⁰ 's are analyzed. The result shows theK _s ⁰ K _s ⁰ pairs are produced in the central region of c.m. system and there is a clearS ^* signal in theK _s ⁰ K _s ⁰ effective mass distribution.     

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.     

Correlation femtoscopy of Kaons in the SELEX experiment

Preliminary results from the correlation femtoscopy of identical kaons in the SELEX experiment (Fermilab E781) are presented. Kaons are selected in inclusive reactions of Σ^?C(Cu) interactions at an initial energy of 610 GeV. Kaon pairs are studied in all possible charged states: K _s ⁰ K _s ⁰ , K _s ⁰ K⁺, K _s ⁰ K^?, K⁺K⁺, K⁺K^? and K^?K^?. The source sizes of the hadronization region of neutral and charged kaon pairs are measured.     

π-phase magnetism in ferromagnet-superconductor superlattices

New 0π and ππ Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states with antiferromagnetic orientation of magnetizations in the neighboring layers of a ferromagnetic metal (FM) are predicted for FM/superconductor (FM/S) superlattices. Under certain conditions, the critical temperature T _c of these states is higher than for the known 00 and π0 LOFF states with ferromagnetic ordering of the FM layers. It is shown that the nonmonotonic behavior of T _c in the FM/S superlattices with S-layer thickness d _s less than the threshold value d _s ^π is due to the phase transition cascade 0π-ππ-0π At d _s >d _s ^π , the T _c oscillations are caused by the 00-π0-00 transitions. New logic elements based on the FM/S structures and combining the advantages of the superconducting and magnetic data-record channels in a single sample are proposed.     

Hyperfine structure of the atomic osmium spectrum: Superposition of configurations and the effect of nucleus volume

The contributions of the superposition of configurations ns ²5d ⁷6s+ns5d ⁷6sn′s+ns5d ⁷6s ² (n=1–5, n′=7–10) to the parameters of the hyperfine structure a _5d ⁰¹ , a _5d ¹² , a _5d ¹⁰ , a _6s ¹⁰ in the spectrum of the osmium atom Os I are calculated. Nonzero contributions are shown to be made only to the parameters a _5d ¹⁰ and a _6s ¹⁰ . This fact justifies the inclusion of the parameter a _5d ¹⁰ in the semiempirical analysis of experimental values of magnetic dipole constants of the hyperfine structure of the 5d ⁷ s configuration in the spectrum of the osmium atom. The effect of nucleus volume on the parameters of the hyperfine structure in the spectra of osmium isotopes ¹⁸⁷Os and ¹⁸⁹Os is estimated.     

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.     

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.     

Nonfactorization and the decaysD s +→φπ +,φρ + andφl + ν l

Using the experimentally measured values ofx=A ₂(0)/A ₁(0) andy=V(0)/A ₁(0) and the measured ratiosR _st=Γ(D _s ⁺ →φl ⁺ ν _l)/Γ(D _ins ⁺ →φπ ⁺) andR _h=Γ(D _s ⁺ →φρ ⁺)/Γ(D _s ⁺ →φπ ⁺), we present evidence for significant nonfactorization contribution in the decay amplitude forD _s ⁺ →φπ ⁺. We analyze the role of nonfactorization inD _s ⁺ →φρ ⁺ and conclude that present data onR _h are consistent with factorization inD _s ⁺ →φρ ⁺. A measurement of polarization inD _s ⁺ →φρ ⁺ would greatly assist our analysis.     

An analysis of Cabibbo-favored two-body decays of charmed mesons withη orη′ in the final state

We have carried out a study of Cabbibbo-favored two-body decays ofD ⁰ andD _s ⁺ involving η and η′ in the final state, $D^0 \to (\eta ,\eta ')\bar K^0 , D^0 \to (\eta ,\eta ')\bar K*^0 $ andD _s ⁺ →(η,η′)π ⁺,D _s ⁺ →(η,η′)ρ ⁺. We have introduced an annihilation term wherever admissible, and investigated its size if it were to bridge the gap between theory and experiment in each case. We have also related the semileptonic rates forD _s ⁺ →(η,η′)e ⁺ v to those of the hadronic rates forD _s ⁺ →(η,η′)π ⁺ and unveiled a puzzle. We offer a possible solution.     

Decay of 0 2 + states in88,92,94Zr andE0 systematics of Zr isotopes

Branching ratios ofE0 andE2 transitions depopulating the 0 ₂ ⁺ states of^{88, 92, 94}Zr have been determined using conversion-electron and γ-ray spectroscopy. Two different lifetime-measurement methods were applied in the remeasurement of the half-lives of the 0 ₂ ⁺ states in^{92, 94}Zr, yielding consistent results ofT _1/2(0 ₂ ⁺ ,⁹²Zr)=85(15) ps andT _1/2(0 ₂ ⁺ ,⁹⁴Zr)=280(40) ps. The monopole strengths extracted areρ ²(⁹²Zr)=8.4(17) ×10^?3 andρ ²(⁹⁴Zr)=11.9(20)×10^?3. The proton configurations of the 0 ₂ ⁺ states are discussed in view of these values and proton transfer data.     

Evidence for a 3.6 minute isomeric 12− state of the πh 11 2/−1 vi 13 2/−1 configuration in206Tl and effective two-particle interactions

Using the²⁰⁴Hg(α, pn)-reaction andα-particles of energies 39–55 MeV, we have found an isomeric 3.6 min 12^? state in²⁰⁶Tl at 2,642.9 keV which has the two-hole configurationπh ₁₁ ^2/?1 vi ₁₃ ^2/?1 The 12^? state decays mainly by anE5 transition of energy 1,021.4 keV to a 7⁺ state at 1,621.5 keV whose main configuration isπs ₁ ^2/?1 vi ₁₃ ^2/?1 There is, in addition, evidence for a weak 565 keVM 4 branch to an 8⁺ state at 2,078 keV whose main configuration should beπh ₁₁ ^2/?1 vf ₅ ^2/?1 . The 7⁺ state decays by a stretched cascade ofγ-rays to states of the following values ofJ ^π and excitation energy: 5 _? ⁺ , 1,405.4 keV; 4^?, 952.1 keV; 2^?, 265.8 keV and 0^?, 0 keV. The main configurations of these states areπh ₁₁ ^2/?1 vp ₁ ^2/?1 ,πd ₃ ^2/?1 vf ₅ ^2/?1 ,πd ₃ ^2/?1 vp ₁ ^2/?1 andπs ₁ ^2/?1 vp ₁ ^2/?1 respectively. From the nuclear masses of²⁰⁸Pb,²⁰⁷Pb,²⁰⁷Tl, and²⁰⁶Tl and the experimental excitation energies it is possible to obtain the proton hole-neutron hole interaction in²⁰⁶Tl. This interaction is compared with the calculations of Kuo and Herling and the discrepancies are discussed. The 12^?→8⁺ M4 transition rate is reduced because of destructive interference between the protonh _11/2→d _3/2 and the neutroni _13/2→f _5/2 contributions. The magnitude of the reduction is accurately reproduced by the wave functions of Kuo and Herling. The 12^?→7⁺ E5 transition rate is about twice as large as the single-holeπh ₁₁ ^2/?1 πs ₁ ^2/?1 transition rate. This deviation is fully explained by the configuration admixtures in the 7⁺ state, given by Kuo and Herling.     

Study of B s 0 → µ+µ− and B d 0 → µ+µ− decays in flavor-changing Z′ models

Recently, the first evidence for the decay B _s ⁰ → μ ⁺ μ ^? has been announced by the LHCb Collaboration and the measured branching ratio B( _s ⁰ → μ ⁺) = (3.2 _?1.2 ^+1.5 ) × 10^?9 is in good agreement with the standard model (SM) expectation. It has also reported an upper limit for B(B _d ⁰ → μ ⁺ μ ^?) < 9.4 × 10^?10 at 95% confidence level. In this paper, we study the B _s ⁰ → μ ⁺ μ ^? and B _d ⁰ → μ ⁺ μ ^? rare decays in flavor-changing Z′ model. Our estimated branching ratios are enhanced from their SM values and provide signals for new physics.     

Description of the properties of the low-lying energy states in 100Mo with IBM2

The properties of the low-lying energy states for the 100Mo isotope is investigated within the framework of the proton-neutron interacting model IBM2.By considering the relative energy of the d proton boson to be diferent from that of the neutron boson and taking into account the dipole interacting among like-boson LπLπand LνLν,the low-lying energy spectrum is reproduced well.Particularly,the relative position of the energies for 2+1,0+2,2+2 and 4+1states shifted correctly fit the experimental data.The electromagnetic properties,including the key observable B(E2)reduced transition branching ratios and the E2 reduced matrix elements of the experimental data,are well described.Our calculations show possible shape coexistence in the 100Mo nucleus.     

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.     

g-factor of the second 4+ state in24Mg

The transient field technique has been used to determine theg-factor of the 4 ₂ ⁺ state at 6.010MeV excitation in²⁴Mg. The deduced value ofg=+0.5(4) is consistent with collective model expectations. Further, the equality within experimental accuracies, of the g-factors of the 2 ₁ ⁺ , 2 ₂ ⁺ , 4 ₁ ⁺ and 4 ₂ ⁺ states agrees with theoretical predictions for thisT=0 self-conjugate nucleus, in contrast to the results for²⁰Ne.     

Neutral strange particle production inK + p interactions at 32 GeV/c

The production properties ofK _s ⁰ , \(\bar \Lambda\) andK ⁺ p interactions at 32 GeV/c are investigated using the final statistics of the experiment. We present total and semi-inclusive cross sections and aver-age multiplicities. Estimates are given of the diffractive dissociation contributions to total and differential cross sections. Thex-,p _T ^?, and transverse mass dependence of inclusive and semi-inclusive distributions is discussed as well as properties of “prompt”K _s ⁰ 's. The ratio of “prompt”K ₈₉₀ ⁺ (K ₈₉₀ ⁰ ) to “prompt”K ⁰ cross sections is measured to be 1.03±0.12 (0.98±0.17). From a comparison of \(\bar \Lambda\) production inK ^± p interactions at 32 GeV/c, we estimate a strange sea-quark suppression of 0.26 ±0.02. The double differential cross sections ofK _s ⁰ 's is studied as a function of Feynman-x andp _T ² , and a Triple-Regge fit performed. The data are compared in detail to versions of the Lund-model for low-p _T hadronic collisions.     

Hot gluon matter in a constantA 0 background

We compute the effective action of finiteT SU(3) gauge theory in a constant diagonal background fieldA ₀(t,x)=B ₀ ³ T₃+B ₀ ⁸ T₈ in the general covariant background gauge up to terms of orderg ³.B ₀ ^3,8 shield the infrared singularities and the aim is to study whether the minimum of the effective action would determine their values dynamically. We find that the orderg ² term depends explicitly on the gauge fixing parameter ξ. Since the background field screens already at the tree diagram level the interactions of the six non-diagonal gluon fields they do not contribute to the plasmon-likeg ³ term. The two diagonal fieldsA ₀ ³ ,A ₀ ⁸ do, but the electric mass squared they develop will become negative if the background fields are larger than aboutT/g. Hence large background fields make the system unstable.     

Determination of the CP violating phase γ by a sum over common decay modes toB s and\bar B_s

To help the difficult determination of the angle γ of the unitarity triangle, Aleksan, Dunietz and Kayser have proposed the modes of the typeK ^? D _s ⁺ , common toB _s and $\bar B_s $ . We point out that it is possible to gain in statistics by a sum over all modes with ground state mesons in the final state, i.e.K ^? D _s ⁺ ,K ^*? D _s ⁺ ,K ^? D _s ^*+ ,K ^* D _s ^* . The delicate point is the relative phase of these different contributions to the dilution factorD of the time dependent asymmetry. Each contribution toD is proportional to a product $F^{cb} F^{ub} f_{D_s } f_K $ whereF denotes form factors andf decay constants. Within a definite phase convention (i.e. for example the one defined by the heavy quark symmetry in the limit of heavy quarks), lattice calculations do not show any change in sign when extrapolating to light quarks the form factors and decay constants. Then, we can show that all modes contribute constructively to the dilution factor, except theP-waveK ^* D _s ^*+ , which is small. Quark model arguments based on wave function overlaps also confirm this stability in sign. By summing over all these models we find a gain of a factor 6 in statistics relatively toK ^? D _s ⁺ . The dilution factor for the sumD _tot is remarkably stable for theoretical schemes that are not in very strong conflict with data onB→ψK(K ^*) or extrapolated from semileptonic charm form factors, givingD _tot≥0.6, always close toD(K ^? D _s ⁺ ).     

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.