Strangeness and baryon number flow in K−p interactions at 8.25 GeV/c

The behaviour of the flow of the strangeness and baryon quantum numbers between initial and final state particles is investigated for K^?p reactions at 8.25 GeV/c. Channels where the final state strange particle is $\text{K}{}^0\text{,}\text{K}{}^{\mathrm{?}}\text{and}\text{Λ}{}^0$ are studied, for total particle multiplicities from 3 to 8. The data are analysed in terms of a link-correlated model and are compared with predictions of this model.     

The spectrum of HeNe+

Discharges through mixtures of helium and neon show two band groups near 4250 and 4100 Å as first observed by Druyvesteyn. These bands, assigned to the HeNe⁺ ion by Tanaka, Yoshino, and Freeman, have been studied under high resolution and have been fairly completely analyzed. The upper state of the transition is a very weakly bound state resulting from $\text{He}{}^{\mathrm{+}}\text{(}{}^2\text{S) +}\text{Ne}\text{(}{}^1\text{S}{}_0\text{)}$. There are two lower states resulting from the two components of $\text{Ne}{}^{\mathrm{+}}\text{(}{}^2\text{P) +}\text{He}\text{(}{}^1\text{S}{}_0\text{)}$. The upper of these two (${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$) is also very weakly bound while the lower of the two, the ²Σ⁺ ground state, has a dissociation energy of 0.69 eV and an r_e value of 1.30 Å. All bands in both band groups show four branches designated R_ff, Q_ef, Q_fe, and P_ee. From their analysis the rotational constants in the various vibrational levels of the three electronic states have been determined. While no spin splitting in the B²Σ⁺ state has been found the ground state X²Σ shows a very large spin splitting and the $\text{A}{}_2{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ state a very large $\text{Ω-type}$ doubling. The vibrational numberings in all these states were established by the study of the spectrum of ³HeNe⁺. At the same time the hyperfine structure observed in all lines of ³HeNe⁺ confirmed the nature of the upper state B²Σ⁺ as resulting from He⁺ + Ne, i.e., by charge exchange from the ground state. The ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ component of the ²Π state has not been observed, presumably because of low intensity.     

Derivation of the dielectric loss formula (a theory of dielectric relaxation in glassy systems)

The derivation is given of the empirical formula tan $\text{σ = A(ω)[}\text{1}\text{B}\text{(T?T}{}_{\mathrm{c}}\text{)]}{}^2\text{sech}{}^2\text{[}\text{1}\text{B}\text{(T?T}{}_{\mathrm{c}}\text{)]}$, where A (ω), B and T_c are constants of the dipolar material at constant applied frequency ω, which has been shown to be in excellent agreement with experimental dielectric loss data on polymers and other amorphous glasses. The derivation is based on the dynamics of a two-level model. The energy splitting, Δ, of the system is derived and determined experimentally for polymers.     

Some three-body final states in K−p reactions at 14.3 GeV/c

We present experimental results on a number of K^?p reactions at 14.3 GeV/c that have three bodies in the final state. The final states are $\text{K}{}^{\mathrm{?}}\text{ω}\text{p}\text{,}\text{K}{}^{\mathrm{?}}\text{π}\text{p}\text{, Λπ}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{, Λ}\text{K}{}^{\mathrm{+}}\text{K}{}^{\mathrm{?}}\text{, Λp}\text{p}\text{,}\text{K}{}^1{}^{\mathrm{?}}\text{ω}\text{p}\text{, Λ(1520)}\text{K}{}^{\mathrm{+}}\text{K}{}^{\mathrm{?}}\text{and}\text{Λ(1520)}\text{p}\text{p}$. Whenever, with one exception explained by the Zweig rule, there is a K^? or a proton in the final state, there is a diffractive-like threshold enhancement in the mass spectrum of the two recoiling particles. These enhancements account for a large fraction of the events in all but the Λπ⁺π^? final state, where they cannot occur, and which is dominated by resonance production. We find evidence for the Q₁(1300) decaying into K^?ω.     

Predissociation and Λ-doubling in the even-parity Rydberg states of the nitrogen molecule

Predissociations in the y¹Π_g and $\text{x}{}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{?}}$ Rydberg states of N₂ (configurations $\text{1π}{}_{\mathrm{u}}{}^{\mathrm{?1}}\text{4pσ}$ and $\text{1π}{}_{\mathrm{u}}{}^{\mathrm{?1}}\text{3pπ}$, respectively) and their likely causes, are discussed. Peaking of rotational intensity at unusually low J values, without sharp breaking off, is interpreted as due to case c^? or case cⁱ predissociation. Λ doubling in the y state, attributed to interactions with the $\text{x}{}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{?}}$ state and with another, ¹Σ⁺, state of the same electron configuration as x, is analyzed. From this analysis the location of the (unobserved) ${}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}$ state, here labeled x′, is obtained. It is concluded that the predissociation in the Π⁺ levels of the y state is an indirect one mediated by the interaction with x′ coupled with predissociation of x′ by a ${}^3\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{?}}$ state dissociating to ${}^4\text{S +}{}^2\text{P}$ atoms: combined, however, with perturbation of the y state by the k¹Π_g Rydberg state (configuration $\text{3σ}{}_{\mathrm{g}}{}^{\mathrm{?1}}\text{4dπ}$), whose Π⁺ levels are completely predissociated.     

On a least upper bound Tc of superconductors with paramagnetic impurities

We have obtained a least upper bound, $\text{k}{}_{\mathrm{B}}\text{T}{}_{\mathrm{c}}\text{? c(μ}{}^1\text{, t)A}$, on the critical temperature T_c of an isotropic superconductor with paramagnetic impurities described by the scattering matrix t for fixed values of μ¹. We have also obtained the corresponding optimal spectrum $\text{α}{}^2\text{F(m) = Aδ[ω?d(μ}{}^1\text{, A]}$. The numerical results for the functions $\text{c(μ}{}^1\text{, t)}\text{and}\text{d(μ}{}^1\text{, t)}$ are presented for $\text{α}{}^1\text{= 0.1}$ and 0.16 in the form of universal curves representing $\text{c(μ}{}^1\text{, t)}\text{and}\text{d(μ}{}^1\text{, t)}$ as functions of the reduced impurity concentration $\text{t}\text{= t/A}$. We have also established an upper limit to the reduced critical concentration $\text{t}{}_{\mathrm{crit}}$ for an arbitrary shape of α²F(ω)1.     

The spectrum of HeAr+

Two band groups near 1450 Å, first observed by Tanaka, Yoshino, and Freeman (J. Chem. Phys.62, 4484–4496 (1975)) in discharges through mixtures of helium and argon and assigned by them to the HeAr⁺ ion, were studied under high resolution. Like the similar spectrum of HeNe⁺ previously investigated, the spectrum of HeAr⁺ is a charge transfer spectrum. The upper state B²Σ⁺ of both band groups is derived from $\text{He}{}^{\mathrm{+}}\text{(}{}^2\text{S) +}\text{Ar}\text{(}{}^1\text{S)}$ while the two lower states $\text{A}{}_2{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and X²Σ⁺ are derived from $\text{He}\text{(}{}^1\text{S) +}\text{Ar}{}^{\mathrm{+}}\text{(}{}^2\text{P)}$. All three states are very weakly bound, the two lower states even more weakly than the upper state. Unlike HeNe⁺ most of the HeAr⁺ bands are violet shaded. In the longward band group each band shows only three branches while in the shortward group there are four. The former observation shows that the $\text{A}{}_2{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ state behaves like a ²Σ^? state with γ_v ≈ 0. The B, D, γ, p, and ΔG values of all states were evaluated. While the B_v values of upper and lower states are nearly equal, the D_v values are quite different and this difference accounts for the violet shading of most of the bands even when B′_v is slightly smaller than B″_v; it also accounts for some of the extraheads and linelike features in the rotational structure. As in HeNe⁺ the ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ component of ²Π was not observed.     

Study of the production of a strange (S = −1) dibaryon in the interactions of K− and π+ on deuterium below 1.5GeV/c

The production of a strange dibaryonic system called H⁺₁ (M = 2.13 GeV/c², S = ?1), has been studied with a missing mass spectrometer, at the CERN Proton Synchrotron, in the reaction K^?d → π^?H⁺₁ and in the line-reversed reaction π⁺d → K⁺H⁺₁ between 0.9 and 1.4 GeV/c.The reactions

$\text{K}{}^{\mathrm{?}}\text{d}\text{→ π}{}^{\mathrm{?}}\text{X}{}^{\mathrm{+}}$

,

$\text{π}{}^{\mathrm{<mtext>d</mtext>}}\text{→}\text{K}{}^{\mathrm{+}}\text{X}{}^{\mathrm{+}}$

,have been studied in a missing mass spectrometer at CERN. The experiment (PS159) is well adapted to search for a signal in the missing mass X⁺ (B = 2, S = ?1) produced in the backward c.m.s. direction, between 2.0 and 2.3 GeV/c². The two reactions have been analysed at three different beam settings: 1.4, 1.06 and 0.92 GeV/c for reaction (1) and 1.4, 1.2 and 1.06 GeV/c for reaction (2).     

A least upper bound on the superconducting transition temperature

It is rigorously shown that the superconducting transition temperature of any material for which the Eliashberg theory is valid must satisfy k_BT_c ? 0.2309 A, where A is the area under its electron-phonon spectral function α²F(ω). This relation is a least upper bound, not just an upper bound, in the sense that there is an optimal situation in which the equality holds. This occurs when the Coulomb pseudopotential parameter $\text{μ}{}^1$ is zero and the spectral function is the Einstein spectrum Aδ(ω ? 1.750 A). These results are generalized in an approximate, but sufficiently accurate, way to the case $\text{μ}{}^1\text{≠ 0}$ to obtain the more useful least upper bound $\text{k}{}_{\mathrm{<mtext>B</mtext>}}\text{T}{}_{\mathrm{<mtext>c</mtext>}}\text{? c(μ}{}^1\text{) A}$ and the corresponding optimal spectrum $\text{Aδ[ω ? d(μ}{}^1\text{)A]}$. Numerical results for the functions $\text{c(μ}{}^1\text{)}$ and d(μ¹) are presented for $\text{0 ? μ}{}^1\text{? 0.20}$. It is shown that the T_c's of many materials (including Nb₃Sn), for which experimental values of A and $\text{μ}{}^1$ are available, do not lie very far below the upper bound.     

Study of the reactions K−p → K+K−Λ and K−p → ppΛ, at 10 and 16 GeV/c

The reactions (1) K^?p → K⁺K^?Λ and (2) $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{p}\text{p}\text{Λ}$ have been studied on samples of 109 and 64 events, respectively, at 10 GeV/c and 125 and 69 events at 16 GeV/c, reasonably free from contaminations. The investigation of the first reaction uses also 84 events of the $\text{K}{}^0\text{K}{}^0\text{Λ}$ final state at 10 GeV/c. Analysis of the Van Hove plots indicates that the K⁺K^?Λ and $\text{p}\text{p}\text{Λ}$ final states are produced by two main mechanisms: (i) a ΔQ = 0 process, with a strong diffractive component near threshold, involving the dissociations p → K⁺Λ in reaction (1) and $\text{K}{}^{\mathrm{?}}\text{→}\text{p}\text{Λ}$ in reaction (2) and (ii) a ΔQ = 1 process involving hypercharge exchange, and producing K⁺K^? and $\text{p}\text{p}$ systems in reactions (1) and (2), respectively, recoiling off the Λ. With increasing energy, this hypercharge exchange process decreases slowly when K⁺K^? is produced, but fast where the production of $\text{p}\text{p}$, violating the Zweig rule, occurs.     

Diffraction dissociation of neutrons into (pπ−) on protons in the momentum range 35 to 65 GeV/c

The diffraction dissociation reaction n + p → (pπ^?) + p was studied at the Serpukhov accelerator neutron beam in the momentum range 35–65 GeV/c in an electronics experiment. The differential cross sections of the reaction are analysed and presented in the five-dimensional phase space $\text{(p}{}_{\mathrm{<mtext>n</mtext>}}\text{, m}{}^1\text{, t,}\text{cos}\text{θ}{}^1\text{, φ}{}^1\text{)}$. The backward peak observed in the distribution over if cosθin GJ ¹ in the Gottfried-Jackson frame of if(pπ) is interpreted as a baryon-exchange effect. The angular distribution of the (pπ^?) system is compared with Deck-type models.     

Peripheral behaviour of pp → K1±K∓ between 1 and 2.5 GeV/c

The reaction $\text{p}\text{p}\text{→}\text{K}{}^1\text{K}$ does not exhibit any s-channel resonance effect between 1 and 2.5 GeV/c. On the contrary, the data on $\text{p}\text{p}\text{→}\text{K}{}^{\mathrm{1?}}\text{K}{}^{\mathrm{\pm }}$ are compatible with an exchange mechanism in the t- and u-channels above 1.5 GeV/c. Strong similarities are found with $\text{p}\text{p}\text{→}\text{K}{}^{\mathrm{?}}\text{K}{}^{\mathrm{+}}\text{and}\text{K}{}^{\mathrm{1?}}\text{K}{}^{\mathrm{1+}}$. The polarisation of K^1± is given. The reaction $\text{p}\text{p}\text{→}\text{K}{}^{10}\text{K}{}^0$ vanishes above 1.5 GeV/c     

A new electronic band system of PbO

The chemiluminescence spectrum of atomic Pb reacting with O₃ under single-collision conditions includes a series of 55 bands in the regions 450–850 nm. A vibrational analysis is obtained which shows emission is to the ground state of PbO from excited electronic states not previously analyzed. Forty-nine of the bands are assigned to the a(1)-X(0⁺) transition and the remaining six are tentatively identified as the forbidden b(0^?)-X(0⁺) transition. Both the a and b states are believed to be Hund's case (c) components of the ³Σ⁺ states arising from the configuration $\text{σ}{}^2\text{π}{}^3\text{π}{}^1$. The vibrational parameters of the a state are ν₄ = 16 029 ± 8, ω_e′ = 478.7 ± 1.9, and ω_ex_e′ = 2.292 ± 0.128 cm^?1, where the uncertainties represent two standard deviations of the least-squares fit. Emission is also observed from the PbO B state produced in the reaction of metastable Pb atoms with O₃. Using pulsed laser excitation, an attempt is made to determine radiative lifetimes. We find for the PbO A(0⁺) state τ = 3.74 ± 0.3 μsec, and for the PbO B(1) state τ = 2.58 ± 0.3 μsec, while for the a(1) state τ is estimated to be greater than 10 μsec. From the vibrational analysis, energy conservation arguments place a lower limits to the ground state dissociation energy of $\text{D}{}_0{}^0\text{(}\text{PbO}\text{) ≥ 3.74 ± 0.03}\text{eV}$ (86.2 ± 0.7 kcal/mole). For the Pb + O₃ reaction we find less than 1% of the products are PbO¹ molecules that emit in the visible. Correlations are made with the low-lying states of other Group IV chalconides based on the assignment of the PbO $\text{a}{}^3\text{Σ}{}^{\mathrm{+}}\text{(1)}$ state and the correspondence between the low-lying triplet states of PbO and CO.     

Dielectric susceptibility and correlation length of one-dimensional CDW with impurties. II. weak disorder

Dependence of static dielectric susceptibility and correlation length of charge density waves (CDW) with weak defects on parameter of incommensurability with lattice is investigated. In almost commensurate phase (h?h_ch_c), $\text{χ ～ (h?h}{}_{\mathrm{c}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{In}{}^{\mathrm{<mtext>-4</mtext><mtext>3</mtext>}}\text{h}{}_{\mathrm{c}}\text{/h?h}{}_{\mathrm{c}}$ and R_c ～ (h ? h_c)^{$\text{2}\text{3}$}. In${}^{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{h}{}_{\mathrm{c}}\text{/h ? h}{}_{\mathrm{c}}$. Far from commensurability $\text{(h?h}{}_{\mathrm{c}}\text{) χ～ (a+h}{}^2{}_{\mathrm{c}}\text{/h}{}^2\text{)}{}^{\mathrm{<mtext>-2</mtext><mtext>3</mtext>}}$, $\text{R}{}_{\mathrm{c}}\text{～ (a + h}{}^2{}_{\mathrm{c}}\text{/h}{}^2\text{)}{}^{\mathrm{<mtext>-2</mtext><mtext>3</mtext>}}$, where a is the dimensionless ratio of random potential intensities, corresponding to backward and forward scattering impurities.     

Microwave optical double resonance and continuous wave dye laser excitation spectroscopy of NO2: Rotational assignment of the K = 0−4 subbands of the 593 nm band

A rotational assignment of approximately 80 lines with K_a′ = 0, 1, 2, 3, and 4 has been made of the 593 nm ${}^2\text{A}{}_1\text{→}{}^2\text{B}{}_2$ band of NO₂ using cw dye laser excitation and microwave optical double-resonance spectroscopy. Rotational constants for the ²B₂ state were obtained as A = 8.52 cm^?1, B = 0.458 cm^?1, and C = 0.388 cm^?1. Spin splittings for the K_a′ = 0 excited state levels fit a simple symmetric top formula and give $\text{(?}{}_{\mathrm{bb}}\text{+ ?}{}_{\mathrm{cc}}\text{)}\text{2}\text{= ?0.0483}\text{cm}{}^{\mathrm{?1}}$. Spin splittings for K_a′ = 1 (N′ even) are irregular and are shown to change sign between N′ = 6 and 8. Assuming that the large inertial defect of 4.66 amu Ų arises solely from A, a structure for the ²B₂ state is obtained which gives $\text{r}\text{(NO) = 1.35}\text{A}\text{?}$ and an ONO angle of 105°. Alternatively, weighting the three rotational constants equally gives $\text{r = 1.29}\text{A}\text{?}$ and θ = 118°.     

Laser magnetic resonance spectrum of BrO (2Π12 ← 2Π32)

Magnetic dipole transitions between the ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ components of the ground electronic state of BrO have been detected using the technique of laser magnetic resonance on three CO₂ laser lines between 964 and 970 cm^?1. This is the first direct observation of the ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ state in BrO. The spin-orbit splitting parameter, A, is determined to be ?967.9831(2) cm^?1 for ⁷⁹Br¹⁶O and ?967.9981(2) cm^?1 for ⁸¹Br¹⁶O. Accurate values for the rotational constant $\text{B}{}^{\mathrm{<mtext>eff</mtext>}}\text{(}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}$, the hyperfine parameters ($\text{b}{}_{\mathrm{F}}\text{+}\text{2c}\text{3}$) and d, the Λ-doubling parameter p, and the Zeeman parameter g| are also determined from an analysis of the measured spectra.     

Ab initio study of the photodissociation of ammonia

An ab initio SCF and CI treatment of the electronic spectrum of ammonia in both the pyramidal and planar conformation is reported which employs an [8, 6, $\text{1}\text{4}$, 1] AO basis of near Hartree-Fock quality; the ground state CI energy obtained for the equilibrium conformation is ?56.4241 a.u. In addition, further calculations have been carried out at the SCF level to study various photodissociation reactions of NH₃. The calculated CI transition energies are seen to agree with corresponding experimental values to within 0.0–0.3 eV, usually in the 0.1-eV range. Photodissociation to the $\text{NH}{}_2\text{(}{}^2\text{B}\text{?}{}_1\text{) +}\text{H}\text{(}{}^2\text{S)}$ products is confirmed thereby to proceed via the $\text{A}\text{?}\text{1a″}{}_2\text{→ 3s}$ state of ammonia, but contrary to earlier speculation it is found that the transformation between reactant and products is already satisfactorily described at the SCF or orbital level, i.e., a Rydberg 3s of NH₃ is seen to be gradually converted into a pure hydrogenic 1s species as dissociation proceeds. In addition the photolysis of NH₃ to NH₂$\text{(}{}^2\text{A}{}_1\text{) +}\text{H}\text{(}{}^2\text{S)}$ is argued to occur via the $\text{C}\text{?}\text{1a″}{}_2\text{→ 3pz}{}^1\text{A′}{}_1$ state and as such is seen to be a symmetry allowed process, in contrast to the previous assignment involving the $\text{B}\text{?}\text{1a″}{}_2\text{→ 3px}$, $\text{y}{}^1\text{E″}$ species. Finally an attempt is made to analyze the mechanisms of various NH + H₂ photodissociation processes with the help of SCF calculations and symmetry arguments for various higher-lying excited states of ammonia.     

On some recent results concerning the superconducting transition temperature

The Eliashberg gap equations relate the transition temperature T_c of an isotropic superconductor to its electron-phonon spectral function α²F(ω) and Coulomb pseudopotential parameter $\text{μ}{}^1$. Recently the Eliashberg theory has been used to derive some supposedly rigorous results bearing on the problem of attaining higher superconducting transition temperatures: Bergmann and Rainer derived an expression for the functional derivative $\text{δT}{}_{\mathrm{c}}\text{δα}{}^2\text{F(ω)}$; Allen and Dynes showed that in the asymptotic limit of very large $\text{λ(λ?10)k}{}_{\mathrm{B}}\text{T}{}_{\mathrm{c}}\text{=f(μ}{}^1\text{)(λ〈ω}{}^2\text{〉)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and Leavens proved that for any isotropic superconductor k_BT_c ?0.2309A, where A is the area under its electron-phonon spectral function. In this letter we show that the result of Allen and Dynes is not compatible with the other results and is, in fact, incorrect.