Excited strange mesons and their decays in a chiral U(3)×U(3) Lagrangian

We bosonize the Nambu-Jona-Lasinio quark model with separable nonlocal interactions in order to derive a chiral U(3)×U(3) Lagrangian, containing, besides the usual meson fields, their first radial excitations. The spontaneous breaking of chiral symmetry is governed by the Nambu-Jona-Lasinio gap equation. The first radial excitations of the kaon, K*, and ? are described with the help of two form factors. The decays K*′ → ρK, K*′ → K*π, K*′ → Kπ, ?′ → K*K, ?′ → $\bar KK$ K, K′ → Kρ, K′ → K*π, and K′ → K2π are considered, and a qualitative agreement of our results with the experimental data is found.     

QCD corrections to charmlessb→s processes

QCD corrections to the penguin induced charmless inclusiveB decays are performed to an improved leading-log approximation. For processb→sqq (q=uds) andbb→ss, four previous missed 4-quark operators are included to make a complete leading log QCD corrected result. Furthermore, part of the next-leading log effect was also given for the above processes and processb→sg. In comparison to previous QCD corrected calculations by Grigjanis et al., the inclusive decay rates for processb→sqq (q=ud),b→ssq andbq→sq are suppressed 10%, 14% and 18% respectively. The branching ratio of processb→sg is enhanced by 2–3 orders, the result for this process is in agreement with the result of Ciuchini et al.     

Pseudoscalars and vector mesons in a unitary and self-consistently broken SU(6) W scheme

We estimate hadronic self-energy effects to “bare” pseudoscalar (P) and vector (V) meson states due to theP→PV→P, P→VV→P, V→ PP→V, V→PV→V andV→VV→V loops. We simulate higher order diagrams by consistently requiring external and internal particles to have the same mass. We find good agreement with all the experimental masses (exceptm _π), widths and mixing angles. The “bare”P andV states are heavy (≈1.26 GeV) and degenerate up to a smallm _s?m_u quark mass difference term. The “bare” coupling constants for thePPV, PVV andVVV vertices obey exact OZI rule and almost exact SU(6) _W symmetry. We use a common cut-off ofk _cm?0.7 GeV/c corresponding to a harmonic oscillator radius of ?0.7 fm for all SU(6) _W related thresholds except for the pion.     

Large charmless yield inB decays and inclusiveB decay puzzles

In recent studies of inclusiveB decays, it has been suggested that eitherB mesons decay much more copiously to final states with no open charm than currently assumed, orB(D ⁰ → K^?π⁺) has to be reduced significantly. This note takes the experimentalB(D ⁰ → K^?π⁺) at its face value and estimatesB(b → no open charm) using complementary methods: one accounts for thec quark inb → c transitions, the other accounts for the c quark inb → ccs transitions. Through cancellation of errors, the average gives our best estimate ofB(b → no open charm), and the difference measures the consistency. The results of the methods are consistent with each other, strongly suggesting a much enhancedB(b → no open charm). This observation indicates that non-perturbative QCD effects are probably causing a sizable fraction of theb → ccs transitions to be seen as charmlessb → s processes, contrary to smaller traditional expectations. This mechanism has generally been overlooked and may explain the existing experimental data within the framework of the standard model. We then briefly discuss implications on baryon production governed byb → ccs processes, rare hadronicB decays and CP violation studies.     

Possible mechanisms of fragmentation of 16O nuclei with a momentum of 4.5 GeV/c per nucleon in track emulsions

The angular distributions of doubly charged fragments of ¹⁶O nuclei having a momentum of 4.5 GeV/c per nucleon and interacting with track-emulsion nuclei were studied. The experimental angular distributions of doubly charged fragments of a ¹⁶O nucleus are not described by the statistical model of the fragmentation of nuclei. The possible channels of fragmentation of ¹⁶O nuclei may include ¹⁶O → 2⁸Be → 4α, ¹⁶O → ⁸Be +⁸ Be* → 4α, ¹⁶O → 2⁸Be* → 4α, ¹⁶O → α+¹²C, ¹⁶O → α +¹²C* → α + 3α, ¹⁶O → α +¹²C* → α + pα ⁷Li, ¹⁶O → α +¹²C* → α + 2⁶Li, ¹⁶O → α +¹²C* → α + pt2α, ¹⁶O → Li + B, and ¹⁶O → Li* + B*.     

Electroproduction final states as ω → 1

The successful model of Barbour and Moorhouse for pion photoproduction is extended to electroproduction and combined with recent ideas on configuration mixing or SU(6) breaking in deep inelastic electroproduction as ω → 1. We find that two consequences obtain in the current fragmentation region as ω → 1: (a) the missing mass spectrum in ep → eπ^?X and en → eπ⁺X will be featureless (phase space); (b) in ep → eM^+,0X and en → eM^0,?X for any non-strange meson M the missing hadron system will contain only octets. Hence, in particular, ep → eπΔ will vanish relative to ep → eπ⁺n as ω → 1. For K production only Λ and no Σ final states will be produced.     

A quark model of mesons based on chiral symmetry

We construct a model of mesons as q$\text{q}$ pairs in the infinite momentum frame. The basic symmetry is spontaneously broken chiral SU₂ × SU₂. We compute the rates for the decays ? → 2π, σ → 2π, A₁ → ?π, A₁ → σπ, A₂ → ηπ, π_N → ηπ, D → ηπ, f → 2π and the coupling constant, g²_?ωπ. We find qualitative agreement with the experimental values. The theory is similar to that of Gilman and Harari.     

Effect of reactive stresses on the heat of martensitic transformations in titanium nickelide

Calorimetric studies of titanium nickelide show that thermally reversible prestraining does not affect the heat of the B2 → R and R → B2 martensitic transformations. At the same time, reactive stresses induced by straining under constrained conditions are found to decrease the heat of the B19′ → B2, R → B19′, B2 → R, and R → B2 transformations by a factor of 1.16–1.40. A formula describing this effect is proposed.     

A “unified” phenomenological approach to the non-leptonic decays of hyperons

In analogy with the pole model for the non-leptonic hyperon decays, a new model is proposed, and which gives satisfactory results for all the non-leptonic decays of the hyperons (B→B′π,B→B′γ andB→B′πγ).     

Near-threshold ω-and φ-meson production in pn → dM reactions and OZI-rule violation

The reactions pn → dω and pn → dφ are investigated near the corresponding thresholds. The S-wave amplitudes are calculated within the two-step model described by a triangle graph with π, ρ, and ω mesons in the intermediate state. The cross sections for the reactions pn → dω and pn → dφ are predicted to be significantly larger than the cross sections for the corresponding reactions pp → ppω and pp → ppφ at the same values of the c.m. excess energy Q. The phi-to-omega yield ratio is found to be (34±10)×10^?3.     

Momentum dependent vertices σγγ, σργ and σρρ the NJL scalar hidden by chiral symmetry

We calculate the momentum dependence of three particle verticesσγγ, σργ andσρρ in the context of a Nambu Jona Lasinio type model. We show how they influence the processesγγ→σ→ππ, ρ→γσ andγγ→ρρ and how chiral symmetry shadows the presence of theσ.     

On Z → γγ decay and cancellation of axial anomaly in Z → γγ transition amplitude for massive fermions

Z → γγ decay amplitude is considered and proven to be zero due to properties of polarization vectors and Bose statistics. Triangular diagrams for a pseudoscalar → γγ and Z → γγ processes with massive fermions in the loop are explicitely calculated. In the Standard Model axial anomaly vanishes in the sum of these diagrams as Z boson is mixed with one of the Goldstone bosons.     

The Z → c \bar c → γγ*, Z → b \bar b → γγ* triangle diagrams and the Z → γψ, Z → γϒ decays

The approach to the Z → γψ and Z → γ? decay study is presented in detail, based on the sum rules for the Z → c $ \bar c $ → γγ* and Z → b $ \bar b $ → γγ* amplitudes and their derivatives. The branching ratios of the Z → γψ and Z → γ? decays are calculated for different hypotheses on saturation of the sum rules. The lower bounds of Σ _ψ BR(Z → γψ) = 1.95 × 10^?7 and Σ_υ BR(Z → γ?) = 7.23 × 10^?7 are found. Deviations from the lower bounds are discussed, including the possibility of BR(Z → γJ/ψ(1S)) ～ BR(Z → γ?(1S)) ～ 10^?6, that could be probably measured in LHC. The angular distributions in the Z → γψ and Z → γ? decays are also calculated.     

Large-pTπ0 production with pion beams and dominance of the subprocess quark + quark → baryon + antiquark

We compare the predictions of the subprocesses M + q → M + q, q + $\text{q}$ → M + M, q + q → B + q?, for large-p_Tπ⁰ inclusive production in π^?p collisions, with the data. Calculations performed with various models show, in a model independent way, that q + q → B + q? is dominant in pp collisions.     

Spectral characteristics of a broadband exciplex spontaneous emission source upon mixtures of the cadmium dibromide vapor with gases

The spectral characteristics of radiation from atmospheric-pressure gas-discharge plasma in mixtures of cadmium dibromide vapor with gases (Ne, Ar, Kr, Xe, and N₂), as well as the temporal characteristics of the voltage and current, have been investigated. A barrier discharge at the repetition frequency of sine voltage pulses up to 140 kHz has been used to create the gas-discharge plasma and excite the components of the working mixture. The discharge radiation has been analyzed in the spectral range 200–900 nm with a high resolution (0.05 nm). In the spectra, we have revealed radiation from exciplex molecules CdBr(B → X) and CdBr(C → X), atomic lines of cadmium and inert gases, and, in mixtures with xenon, radiation of exciplex molecules XeBr(B → X, B → A). The XeBr(B → X) radiation prevailed in the spectra at mixture temperatures up to 200°C. The further increase of the temperature resulted in the prevalence of the CdBr(B → X) radiation. The most intense CdBr(B → X) radiation was observed in mixtures of CdBr₂/Xe. When the temperature of the mixture was higher than 250°C, the discharge radiation had a silvery-white color. Regularities in the spectral characteristics of the radiation from the gas-discharge plasma are discussed. The high-frequency atmospheric-pressure barrier discharge in mixtures of cadmium dibromide with gases, excited by sine voltage pulses, can be used in multiwave and broadband excilamps, operating in the UV and visible regions.     

Baryon duality solutions with the harmonic-oscillator spectrum and the amplitude signs in πN→πΔ

By constructing exact exchange-degenerate solutions of baryons with the harmonic-oscillator spectrum for a set of reactions MB→M′B′, MB → M′D′ and MD → M′D′, we investigate the duality constraints on the amplitude signs in MB → M′D′. It is shown that the amplitude signs determined by duality are consistent with those predicted by the extended version of SU(6)_W symmetry with the universal dominance of the ΔL_Z = 0 or ΔL_Z = ±1 amplitude in the mesonic transitions of the baryons.     

To search for four-quark states in γγ-collisions

It is shown that the reactions γγ into hadrons is a rather effective means of searching for fourquark states. We predict the suppression ofS ^*(980,0⁺) and δ(980,0⁺) in γγ→ππ and γγ→π⁰ η respectively, if they are four-quark states from (9.0⁺). The well-known anomaly in γγ→ρ ⁰ ρ ⁰ is interpreted as the production of the tensor four-quark resonances with the isospin 0 and 2. We predict the absence of similar enhancement in γγ→ρ ⁺ ρ ^?. The bright anomalies are predicted near thresholds of γγ→ρ ⁰ ω and γγ→ρ ⁰ ?     

A search for K−p → Λγ and K−p → Σ0γ at rest

A search has been made for photons from the reactions K^?p → Λγ and K^?p → Σ⁰γ produced by K^? stopping in a liquid hydrogen target. No signal from these reactions was found; upper limits on the branching ratios are K^?p → Λγ/K^?p → anything ? 4 × 10^?4, K^?p → Σ⁰γ/K^?p → anything ? 4 × 10^?3. The first of these is in conflict with a theoretical prediction using recent values for coupling constants and scattering amplitudes. This may reflect the influence of the Λ(1405) on the radiative capture.