Inclusive strange particle production in π+p interactions at 16 GeV/c

The production of $\text{K}{}_{\mathrm{S}}{}^0\text{, Λ}\text{and}\text{Λ}$ is measured in π⁺p reactions at 16 GeV/c. The total strange particle cross section is found to be 4.0 ± 0.3 mb, about 20% of the inelastic cross section. Cross sections for single strange particles and for strange particle pairs are determined, both inclusively and as functions of the charged multiplicity. Relative production rates for different strange particle combinations are compared with the prediction of the isospin statistical model. Inclusive spectra for single particles are studied and it is found the K_S⁰ are produced mostly in the forward hemisphere, most probably by fragmentation of the incident pion into $\text{K}\text{K}\text{π}$. The Λ are mostly backwards, probably deriving from fragmentation of the proton into ΛK pairs. The $\text{Λ}$ tend to be produced forwards, but evidence is found for central $\text{Λ}\text{Λ}$ production. Distributions in rapidity of the Λ particles from π⁺p interactions are compared in terms of the factorisation hypothesis. Results are given on the Λ transversal polarisation.     

Production of strange particles in antineutrino interactions at the CERN PS

We have studied neutral strange particle production in the bubble chamber Gargamelle filled with propane and exposed to antineutrinos from the CERN PS. Cross sections are presented for Λ, Σ⁰ and K⁰ production. Associated production reactions (ΔS = 0) have been observed in the charged and the neutral current channels. From 45 candidates for the quasi-elastic reaction $\text{ν}\text{p}\text{→ μ}{}^{\mathrm{+}}\text{Λ}$, on bound and free protons, estimates of the axial transition form factor M_A have been made using the total cross section and the t distribution. The weighted average from the two methods is M_A = 862 ± 190 MeV. From a subsample of 15 candidates for $\text{ν}$ interactions on free protons in propane, with (28±6)% background from $\text{ν}$ interactions on bound protons, we obtain M_A = 883 ± 243 MeV. The polarization of the Λ hyperons has been studied for the quasi-elastic reaction. We observe a significant Λ polarization in the production plane, normal to the Λ line of flight. The observed polarizations agree well with the predicted theoretical polarizations without any contribution from second-class axial coupling.     

Λ and Λ production in K+p interactions at 32 GeV/c

A study of the inclusive and semi-inclusive Λ and $\text{Λ}$ production in K⁺p interactions at 32 GeV/c is presented. The inclusive cross sections for Λ and $\text{Λ}$ amount to 0.78 ± 0.05 and 0.42 ± 0.04 mb thus showing a remarkable growth between 16 and 32 GeV/c with a factor of 1.7 for Λ and 2.8 for $\text{Λ}$. Target and beam fragmentation processes are found to be dominant for Λ and $\text{Λ}$ production respectively with the following lower limits for the corresponding cross sections: $\text{σ(p}\text{→}\text{K}{}^{\mathrm{+}}\text{?) > 0.5}\text{mb}$ and $\text{σ(K}{}^{\mathrm{+}}\text{→}\text{p}\text{?}\text{) > 0.3}\text{mb}$. Although the early scaling conditions are fulfilled for the Λ production in the target fragmentation region, and $\text{Λ}$ production in the beam fragmentation region, scaling is not observed between 16 and 32 GeV/c in the x and p_T² Feynman variables. The Λ production is found to be very similar in the K⁺p inclusive reaction at 32 GeV/c and in the semi-inclusive reaction $\text{K}{}^{\mathrm{?}}\text{p}\text{→ Λ}\text{K}\text{K}\text{X}$ at the same energy. The $\text{Λ}\text{Λ}$ pair production cross section increases significantly in K⁺p interactions from 16 to 32 GeV/c where it reaches the value $\text{σ}{}_{\mathrm{<mtext>\Lambda </mtext><mtext>\Lambda </mtext>}}\text{= 47 ± 11 μ}\text{b}$. The cross sections for Λ or $\text{Λ}$ produced in association with an identified proton are also given and discussed.     

Statistical chain decay of fireballs with quantum numbers

The effects of internal quantum number consevation are considered in the statistical chain decay of fireballs. A simple model containing I = 1, G = ?1, S = 0 mesons (ground state and excited pions) and $\text{I =}\text{1}\text{2}\text{, S = 0}$ baryons (ground state and excited nucleons) is investigated in detail: inclusive distributions, multiplicity distributions and semi-inclusive distributions are determined. The methods are completely general and can be used in more general models with any set of states. As examples, a model with ? and π mesons, and nucleons and another one with π and K mesons, and N and Λ baryons are considered.     

On the presence of the S4z-term in Fe(HCOO)2 · 2H2O

The magnetic specific heat of ferrous formate dihydrate is analysed on the basis of a model, $\text{S}{}_{\mathrm{A}}\text{=}\text{1}\text{2}$ and S_B = 2. The experimental result turns out to be well explained by the introduction of a large S⁴_z-term for B site ions.     

Properties of K0 and Λ inclusive production in charged-current antineutrino-nucleon interactions

In this paper we discuss inclusive spectra of K⁰'s and Λ's produced in charged in charged-current $\text{ν}{}_{\mathrm{\mu }}\text{N}$ interactions in the Fermilab 15 ft bubble chamber filled with a 64% Ne-H₂ mixture. Data presented in terms of the invariant cross section show, when compared with results from experiments with other incident beams, that the behavior of these distributions is approximately the same. The K⁰ and Λ fragmentation functions are presented and the shape of the K⁰ fragmentation function is found to be consistent with the parametrization of Field and Feynman.The average K⁰ and Λ transverse momentum squared as a function of Q², W², x and z is presented. Comparisons for the K⁰'s produced in the current fragmentation region are in qualitative agreement with QCD predictions. The value of the Λ polarization is measured and a positive normal polarization P_N = 0.34±0.18 is found.     

The uv spectrum of 18OD

The combined high-resolution ultraviolet (uv) absorption spectrum of ¹⁶OD and ¹⁸OD was obtained. State selective measurements of the transitions from the electronic ground state to the first excited electronic state, $\text{A}\text{?}{}^2\text{Σ}{}^{\mathrm{+}}\text{←}\text{X}\text{?}{}^2\text{Π}$, in the 0-0 vibronic band were performed by means of a narrow bandwidth dye laser system. Evaluation of these transition frequencies in wave-numbers yielded molecular constants as well as rotational term values for each of the isotopic species. A computer program based on a linearized least-squares procedure was used to determine the molecular constants and term values. The term value formulas which were employed for this purpose, take into account the Λ splitting and the centrifugal distortion of the diatomic species. The transitions, recalculated from the semiempirically determined term values agree with the measured absorption lines to better than 0.1 cm^?1. The following molecular constants are reported: B, D, H, the rotational constants of the ²Π and ²Σ⁺ states; O₀, P₀, Q₀, the constants of the Λ splitting of the ²Π state; A and A₁; the constants of the spin-orbit coupling of the ²Π state; and γ₀, the constant of the p doubling of the ²Σ⁺ state. Futhermore, term values up to J″ and J′ of 25.5 and the corresponding uv transitions are given.     

Strange particle production in three- and four-body final states of 16 GeV/cπ±p reactions

Three- and four-body final states with strange particles are studied in π⁺p and π^?p interactions at 16 GeV/c. We present cross sections and investigate their energy dependence. Production mechanism, resonance production and quantum number transfer are discussed. Strong Y¹(1385) production is found in the reaction π⁺p → ΛK⁺π⁺, while the corresponding π^?p reaction is dominated by production of K¹(890). In the $\text{NK}\text{K}\text{π}$ channels, the K and $\text{K}$ are produced mainly at the same vertex, i.e. non-strangeness exchange ΔS = 0 is dominant (about 75% of the cases), whereas in the ΛKππ channels, the Λ and K are more frequently produced at opposite vertices, i.e. |ΔS| = 1 exchange is important (about 60% of the cases). Results on the polarization of the lambdas produced in the π⁺p reactions are given.     

Renormalizable asymptotically free quantum theory of gravity

We prove that higher derivative quantum gravity is asymptotically free in all essential coupling constants by the calculation of one-loop counterterms (correcting the previous result of Julve and Tonin) and the solution of the corresponding renormalization group (RG) equations. Strong arguments are presented in favour of the possibility that renormalizable asymptotically free gravity establishes asymptotic freedom for the effective mass parameters and non-gauge couplings in grand unified gauge theories. We also analyse the RG equations in the Einstein theory with Λ term and in the higher derivative conformal invariant theories. Among other topics discussed are the algorithm for the divergences of the determinant of the fourth-order differential operator, the consistent renormalization of the boundary terms in the action, the one-loop β-function in the fourth derivative vector gauge theory and the RG equations in the $\text{“gφ}{}^4\text{+ ηRφ}{}^2\text{”}$ theory.     

A classification of compactifying solutions for d =11 supergravity

Supergravity in eleven dimensions is known to have classical solutions of the type (anti-de Sitter space-time) × (7-dimensional Einstein space). We give a list of all homogeneous 7-manifolds which admit an Einstein metric. Known solutions are reviewed, with some emphasis on the SU(3) × SU(2) × U(1) compactifications. Their topology is discussed in detail.The list includes three new solutions, with symmetry groups SU(3) × SU(2), SO(5) and SO(5) × U(1). The first solution has no supersymmetry, while the second and third yield respectively N = 1 and N = 2 supersymmetry in four dimensions. The last two solutions may be extended to solutions with nonzero internal photon curl, breaking all supersymmetry.The existence of a spin structure on homogeneous manifolds $\text{G}\text{H}$ is discussed and related to topological properties of $\text{G}\text{H}$. As an illustration, we treat the coset spaces SU(m + 1) × SU(n + 1)/SU(m) × SU(n) × U(1), which include the spaces with SU(3) × SU(2) × U(1) symmetry.     

Long-lived non-equilibrium population of Fe3+ electronic states after the K-capture of 57Co

Mössbauer emission spectra of a frozen aqueous solution of ⁵⁷CoCl₂ show contributions from the $\text{S}{}_{\mathrm{z}}\text{= +}\text{5}\text{2}$ and the $\text{S}{}_{\mathrm{z}}\text{= +}\text{3}\text{2}$ Zeeman levels of Fe³⁺ ions at T = 4.2 K in H ? 30 kG. The K-capture results in a non-equilibrium state of relaxation time comparable to the lifetime of the nuclear excited state (～ 10^?7 s).     

Temperature dependence of the ESR spectra of Mn2+ in iron pyrite (FeS2)

The first observation of the ESR spectra of Mn²⁺, entering substitutionally for Fe²⁺ in the Van Vleck paramagnet FeS₂ (polycrystals), is reported. The data from 5 to 295 K fits the spin-Hamiltonian $\text{h}{}_{\mathrm{s}}\text{= gβ}\text{H}\text{·}\text{S}$ + $\text{[S}{}^{\mathrm{<mtext>2</mtext>}}{}_{\mathrm{z}}\text{?}\text{1}\text{3}\text{S(S + 1)] + A}\text{S}\text{·}\text{I}$, with g = 2.000 ± 0.001, A/β = ?95.0 ± 0.5 Oe and D/β varying from 50 Oe (5K) to 59 Oe (295 K). The temperature dependence of D can be described in terms of a single phonon-mode with frequency ? 145 cm^?1.     

Mean lifetimes of excited levels of Ar II. I. Time correlation measurements

Mean Lifetimes of excited levels of Ar II have been measured using the method of time-correlated photons in cascade. The following results were obtained: for 4p⁴S^°_{$\text{3}\text{2}$}, τ = 7·2±0·3ns; for 4p′²F^°_{$\text{7}\text{2}$}, τ = 8·8±0·2 ns; for 4p′²F^°_{$\text{5}\text{2}$}, τ = 8·0±0·2 ns. These results are compared with experimental and theoretical values.     

Unitary operators with discrete spectrum induced by measure preserving transformations

The purpose of this paper is to prove the following theorem.Theorem. Given a countable subset Λ on the circle K and an integer-valued function n(λ) on Λ, there exists a dynamical system with discrete spectrum (X,$\text{F}$,μ,T) such that Λ is the set of all eigenvalues of T and n(λ) is the multiplicity function of T if and only if there exist two systems of subgroups {G_i}_i∈N and $\text{{S}{}_{\mathrm{j}}\text{}}{}_{\mathrm{j\in M}}\text{(}\text{N}\text{??}{}_0\text{,}\text{M}\text{??}{}_0\text{)}$ of the circle such that Λ = G ∪ S and

$\text{n(λ)=}\text{∞}\text{for}\text{λ∈S,}\text{{i∈N; λ∈G}{}_{\mathrm{i}}\text{}}\text{for}\text{λ∈G?S,}$

where $\text{G =}\text{?}\text{i∈N}\text{G}{}_{\mathrm{i}}\text{, S =}\text{?}\text{j∈M}\text{S}{}_{\mathrm{j}}$.     

On the luminescence and absence of luminescence of F centers

A model, proposed originally by Dexter, Klick and Russell, is used to explain the occurence or non-occurence of F-center luminescence in ionic crystals, in terms of a simple two-state configuration coordinate diagram. In this model, which works for all known cases, luminescence is quenched by a competing non-radiative process whenever the intersection of the ground and excited state curves lies below the energy reached in absorption in a vertical (Franck-Condon) transition. The criterion for the occurence of luminescence is expressed as $\text{Λ <}\text{1}\text{4}$, where Λ (=excited-state lattice-relaxation energy/optical-absorption energy) is a parameter, related to the relative displacement of the two curves, which can be inferred from data on the temperature dependence of the F-band line width. Thus the possibility of observing luminescence can be predicted from optical absorption data alone. It is found emperically that Λ for alkali halides with rocksalt structure is independent of lattice parameter, and the observed dependence of Λ on the ratio of ionic radii in terms of ion-size effects. Values of Λ range from 0.009 for CsF to 0.831 for LiI; NaCl with Λ = 0.260 is a marginal case for luminescence.     

Massless composites with massive constituents

We construct model field theories in which a confining gauge interaction binds massive elementary fermions into massless composite particles. The massless composites are either Goldstone bosons or $\text{spin}\text{-}\text{1}\text{2}$ fermions. In these models, the manner in which exact chiral symmetries are realized changes at a critical value of the elementary fermion mass of order (e²/16π²)Λ, where Λ is the confinement scale and e is a weak gauge coupling.     

Accurate determination of the 17O16O + n coupling constant and spectroscopic factor

We have measured ¹⁶O¹⁷O elastic cross sections at 22 MeV between 65°–140° to ± 1 %. The observed oscillatory interference between Coulomb scattering and the neutron transfer process is analyzed using exact finite-range DWBA. A model-independent value of $\text{C}\text{?}{}^2\text{= 0.82 ± 0.07}$ is obtained for the coupling constant of the 1d_{$\text{5}\text{2}$} neutron in ¹⁷O. We also present an analysis of data on magnetic electron scattering from ¹⁷O, which yields precise information on the magnitude and the radial shape of the $\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ neutron bound-state wave function. With this we relate the coupling constant to the spectroscopic factor and find S = 1.04 ± 0.11. We show that the magnetic electron scattering data alone yield S = 1.04 ± 0.10. Combining these results with earlier work we recommend $\text{C}\text{?}{}^2\text{= 0.79 ± 0.04}$ and S = 1.03 ± 0.07 as best values. This spectroscopic strength corresponds to (91 ± 7) % of the full single-particle value.     

Absence of the second-order phase transitions in the dimerized Ising chains with spin larger than 12

A general spin S Ising chain interacting with a single phonon mode of the harmonic lattice is studied. The thermodynamics of the spin system is calculated exactly for S = 1, $\text{1}\text{2}$ and $\text{3}\text{2}$, while self-consistent equations for the induced lattice distortions are derived. It is demonstrated that for S >$\text{1}\text{2}$ there is no second-order phase transition, in contrast to the case S = $\text{1}\text{2}$ which was proved to have a tricritical point. This is found to cohere with the previous studies of the dimerized magnetic model chains.     

Quantum Hall effect in higher dimensions

Following recent work on the quantum Hall effect on S⁴, we solve the Landau problem on the complex projective spaces $\text{C}\text{P}{}^{\mathrm{k}}$ and discuss quantum Hall states for such spaces. Unlike the case of S⁴, a finite spatial density can be obtained with a finite number of internal states for each particle. We treat the case of $\text{C}\text{P}{}^2$ in some detail considering both Abelian and nonAbelian background fields. The wavefunctions are obtained and incompressibility of the Hall states is shown. The case of $\text{C}\text{P}{}^3$ is related to the case of S⁴.