Glueball masses and symmetry restoration inSU(3) lattice gauge theory: A high statistics Monte Carlo study

We calculate 0⁺⁺, 2⁺⁺ and 1^?+ correlation functions for a wide range of momenta in a high statisticsSU(3) study on an 8⁴ lattice: 28,000 sweeps at β=5.7 and 18,000 at β=5.9. We obtain an accurate confirmation of the restoration of the continuum relativistic dispersion relation,E ²=p ²+m ², and of rotational invariance. We obtain accurate 2⁺⁺ mass estimates up to two lattice spacings, and confirm consistency with asymptotic scaling. For the 1^?+ the results are much poorer and we can only present some very crude mass estimates. We compare our 0⁺⁺ data to our previous calculations with a source, and make some statements about the relative efficiencies of source and variational calculations in this range of couplings.     

Calculation of the glueball mass spectrum ofSU (2) andSU (3) non-abelian lattice gauge theories II:SU (3)

We calculate the glueball mass spectrum in theSU (3) lattice regularized gauge theory. We find fourlight glueballs: the 0⁺⁺, 2⁺⁺, 0^?+ and, most interestingly from the experimental point of view, the oddball 1^?+. We calculate the 0⁺⁺ and 2⁺⁺ masses over a range of β values and find thatboth states conform to continuum renormalization group behaviour to a very significant degree. The question of metastable states and temperature is addressed in detail. Finally we discuss and resolve contrary claims in the recent literature.     

Scaling in lattice QCD: Glueball masses and string tension

We study the scaling behaviour of lattice quantum chromodynamics by comparing the β dependence of the string tension and the 0⁺⁺ glueball mass. We use a source method at β=5.7, β=5.9 and β=6.1, on lattices from 9³· 24 to 16³· 32. Assuming a string tension of about (420 MeV)², the lattice spacing ranges from 0.16 to 0.08 fm. In order to separate finite volume from scaling violation effects we have compared data from lattices having approximately the same overall physical size at the different values of β. We find deviations from scaling to be very small.     

Strong-coupling expansions for the off-axis glueball masses

Strong-coupling expansions, up to order g^?4, for the off-axis glueball masses are developed in four-dimensional spacetime for lattice gauge theories with gauge groups SU(2), SU(3), Z₂, Z₃. Glueball mass spectra for the states 0⁺⁺, 2⁺⁺, 1^+? are obtained. Restoration of Lorentz invariance is discussed.     

String tension,gluebal masses and finite size effects in lattice SU(3)

We estimate the string tension by looking at Wilson loops and measuring the correlation between Wilson lines at g² = 1.0 for lattice SU(3). The bound $\text{Λ}{}_{\mathrm{<mtext>L</mtext>}}\text{σ}\text{?0.0087 ± 0.0011}$ is larger than the previous results. The mass of the 0⁺⁺ glueball is also estimated. The finite size effects on these quantities are shown to be large by comparing results on a 6³ × 10 lattice with those on 9⁴ lattice.     

In-situ NMR study of dislocation motion in Ca-doped NaCl crystals

Using a fast multi-window NMR technique, we have measured in-situ the mean jump width x of mobile dislocations during plastic deformation in a series of NaCl single crystals with varying Ca⁺⁺ content. Aside from immobile forest dislocations, the Ca⁺⁺ impurities form additional obstacles for the moving dislocations thus lowering x. We found that the Ca⁺⁺-related obstacles exhibit a pronounced non-random distribution which results in a corresponding broad distribution of x. We show that the data can be evaluated by means of an appropriate distribution function g(1/x) with an uncommon dependence of the observed fitting parameters on the Ca⁺⁺ content. As expected, quenching of a sample leads to a more uniform distribution of the Ca⁺⁺-related obstacles resulting in a corresponding narrowing of g(1/x).     

Inclusive Δ++ production in K+p interactions at 8.2 and 16 GeV/c

The reaction K⁺p→Δ⁺⁺(1236)+ anything is studied at beam momenta 8.2 and 16 GeV/c and compared with other Δ⁺⁺ producing reactions. We find that the low-mass Δ⁺⁺π^? enhancement affects the shapes of Δ⁺⁺ inclusive distributions. The triple-Regge formula is found to be consistent with the data. Dual properties of this formula are successfully tested.     

Glueball spectroscopy in 4d SU(3) lattice gauge theory (II)

We report on a Monte Carlo variational calculation of the SU(3) glueball mass spectrum on a 5³ · 8 lattice. This investigation relies on Wilson loops up to length 8. Within finite-size effects and statistical fluctuations our previous results from a 4³ · 8 lattice are confirmed: we find a scaling window for the 0⁺⁺ state, but no scaling for 15 other states considered.     

On the nature of the isoscalar resonances in theK\bar K\pi system below 1.6GeV

Implications of the recent discovery of the resonanceD′(1526)IJ ^PC=01⁺⁺ are discussed. We consider possibilities of a mistakenJ ^PC assignment forE(1420) orD′(1526). It is also pointed out that the theoretical prediction excluding low lying 1⁺⁺ glueball is based on the assumption of the valence gluon which is not necessarily true. A possibility of theE(1420) meson being 1⁺⁺ gluonium quarkonium mixture is investigated.     

Surface states due to deposited alkaline earth cations on ZnO

Surface states due to Be, Mg, Ca, Sr, and Ba ions deposited on ZnO as salts with varying anions have been examined, to make available a selection of nonvolatile surface states for later study, and to provide a relatively simple group of substitutional surface states that could be used to compare theories with experiment. The results indicate that Be⁺⁺ and Ba⁺⁺ additions lead to shallow acceptor levels, near or above the ZnO conduction band, while deeper acceptor levels (as low as 0.9 eV below the conduction band) are associated with Mg⁺⁺, Ca⁺⁺, and Sr⁺⁺ additions. The energy of the resulting surface state depends somewhat on whether the alkaline earth species is added as the hydroxide or the fluoride. There is evidence of a high density donor level at 1.1 eV below the conduction band perhaps associated with surface lattice oxygen or with OH^? groups. Arguments arepresented suggesting that the surface state is associated with the alkaline earth ions at lattice sites at the ZnO/additive interface, and some of the factors are discussed that must be considered in a theoretical model.     

Interference between Δ++ and Q− production in K−p → K−π−π+p at 4.25 GeV/c

Evidence is found for overlap and interference between Δ⁺⁺ and Q^? production in K^?p → K^?π^?π⁺p at 4.25 GeV/c. The strong forward asymmetry observed in the Δ⁺⁺ decay is such that it cannot be explained by the contribution of pπ⁺ S- and P-waves only. It finds a natural interpretation in terms of overlap between Δ⁺⁺ ar Q^? production. The interference between Δ⁺⁺ and Q^? production is constructive over essentially the whole Δ⁺⁺ region.     

Photoproduction of πΔ(1.232) from hydrogen in the energy range 2.4–4.8 GeV

We present differential cross sections andΔ ⁺⁺ spin density matrix elements for the photoproduction processγp→π ^? Δ ⁺⁺ and differential cross sections for the processγp→π ⁺ Δ ⁰. The incident photon energy dependence is studied and a comparison is made with previous experiments and with the predictions of a theoretical model.     

A variational source method for numerical studies of field theory

A common method of measuring mass gaps in numerical studies of lattice field theories is to calculate the spatial dependence of the expectation value of test operators in the presence of a source. A novel source method is described which is variational: the mass extracted from expectation values measured at any separation is always an upper bound to the true mass. The method is illustrated with an example, the 0⁺⁺ glueball mass is computed in SU(3) lattice gauge theory at β = 5.7.     

Spectral function sum rules for gluonic currents

We determine the masses and the decay amplitudes of the 2⁺⁺, 0^?+ and 0⁺⁺ gluonia in anSU(3) _c Yang-Mills theory. We estimate the so-called topological susceptibility of theU(1) sector. We discuss theSU(3) _F breaking effects to the η′(896) massrelation from current algebra and predict the η′ parameter values.     

A transverse gluonium potential model with Breit-fermi hyperfine effects

We introduce a potential model of bound transverse gluons with a fictitious constitutent mass. The gluonic Breit hamiltonian due to one gluon exchange is derived, and its effect on thegg spectrum is estimated; hyperfine corrections are large, but not nonperturbatively so. We find a degenerate (0⁺⁺, 0^?+) ground state and a first 2⁺⁺ excitation at ～1.2M ₀. Our list ofgg states disagrees with some sources, due to the absence of unphysical longitudinal degrees of freedom in the model.     

SU(3) lattice Monte Carlo calculation of the glueball mass spectrum

We have calculated the glueball masses of various spins and parities in SU(3) gauge theory. Our first results give m_M(0⁺⁺)=(3.6±0.2)Λ_mom, m_E(0⁺⁺)=(4.3±0.3)Λ_mom, m(0^?+)=(7.2_?0.9^+1.6)Λ_mom, m_M(2⁺⁺)=(8.1±1.1)Λ_mom and m_E(2⁺⁺)=(8.3_?1.0^+1.6)Λ_mom as well as information on the glueball wave functions.     

Effect of AlGaAs barrier layer on the characteristics of InGaP/InGaAs/Ge triple junction solar cells

As an effort to improve the conversion efficiency of InGaP/InGaAs/Ge triple junction solar cells, we investigated the effect of AlGaAs barrier layer on the cell performance under concentrated light condition. Three different solar cells having upper tunnel junctions (TJs) as n⁺⁺-GaAs/p⁺⁺-AlGaAs layers, n⁺⁺-GaAs/p⁺⁺-GaAs layers and n⁺⁺-GaAs/p⁺⁺-GaAs/p⁺⁺-AlGaAs layers were prepared. Under concentrated light condition, open-circuit voltage (V_OC), fill factor (FF) and conversion efficiencies were higher for the sample with an AlGaAs barrier layer than the samples without an AlGaAs barrier layer. For the sample with an AlGaAs barrier layer, external quantum efficiency was higher than other two samples. Most of all, the sample with a TJ as n⁺⁺-GaAs/p⁺⁺-GaAs layers showed a very poor electrical performance, which was associated with an imperfect crystalline quality of the InGaP top cell layers.     

Variational computation of glueball masses in continuum QCD

We apply a field-theoretic Rayleigh-Ritz method to compute masses of the low-lying glueballs, with allowance for non-perturbative effects via condensate contributions to the gluon propagator. Since the gluon propagator is non-covariant, condensates of the form 〈TrAA〉 are allowed and must be introduced. Fitting the coupling constant and condensate parameter from the glueball candidates ι(1440) and θ(1690), we predict that mass (0⁺⁺) = 1320 ± 20 MeV, mass (2⁻⁺) = 1760 ± 40 MeV, at α_s = 0.46 ± 0.05 (with an error estimated by using a variety of trial wavepackets). Our result has the 0⁺⁺ glueball mass close to that of the isoscalar 0⁺⁺ states ε(1300) and g_s(1240), suggesting that at least one of these states (presumably he g_s(1240)) has a large-valence glue component.     

InclusiveΔ ++ (1232) and∑ ± (1385) production inK − p interactions at 32 GeV/c

We have studied inclusiveΔ ⁺⁺ (1232),∑ ⁺ (1385), and∑ ^? (1385) baryon resonance production inK ^? p interactions at 32 GeV/c. The inclusive and topological cross sections are estimated and compared with published results at lower energies. No energy variation of the cross section is observed forΔ ⁺⁺ (1232) and only a slight decrease is seen in case of∑ ^± (1385). The production properties are investigated through longitudinal and transverse momentum distributions. TheΔ ⁺⁺ (1232) is dominantly produced in the target fragmentation region. The∑ ⁺ (1385) is produced both in the target fragmentation region and in the central region, while the∑ ^? (1385) is predominantly produced in the central region. About 20% of the final state protons are produced via aΔ ⁺⁺ (1232) decay and about 25% of the Λ produced come from the decay of∑ ⁺ (1385) and∑ ^? (1385).