General features of the pp interaction at 12 GeV/c

Simple inclusive cross sections for $\text{p}\text{p}$ interactions at 12 GeV/c are given. The data cover prong cross sections, V⁰ production and resonances. Separation has been made into annihilation and non-annihilation modes. Some implications of the data are discussed. It is pointed out that the ratios of cross sections for $\text{?}{}^0\text{π}{}^{\mathrm{?}}$ production are independent of incident antiproton momentum in $\text{p}\text{p}$ annihilation processes, and that data at the highest available pp energies (ISR) tend to the same value.     

Vector and tensor meson production in K−p interactions at 32 GeV/c

Inclusive production of vector and tensor mesons is studied in a K^?p experiment at 32 GeV/c in the MIRABELLE bubble chamber. The $\text{K}{}^{\mathrm{<mtext>1</mtext><mtext>0</mtext>}}\text{(890)}$, ?⁰ and ω cross sections are comparable, about 4 mb each. The $\text{K}{}^{\mathrm{<mtext>1</mtext><mtext>0</mtext>}}\text{(1420}$ and cross sections are also comparable, about 1 mb each. The $\text{K}{}^{\mathrm{<mtext>1</mtext><mtext>o</mtext><mtext>?</mtext><mtext>+</mtext>}}$(890), Φ, $\text{K}{}^{\mathrm{<mtext>1</mtext><mtext>o</mtext><mtext>?</mtext><mtext>?</mtext>}}$(1420) and f cross sections beam fragmentation; ? production is almost forward-backward symmetric in the c.m.s. The p_T production slopes of $\text{K}{}^{\mathrm{<mtext>1</mtext><mtext>o</mtext><mtext>?</mtext><mtext>?</mtext>}}\text{(890)}$ and ? are similar, the Φ slope is shallower. Vector and tensor mesons alone are responsible for ?50% (?60%) of final-state pions     

Comparison of the reaction pp → K0K0 at rest in hydrogen and deuterium. A test of S-state annihilation dominance

From the comparison of the frequency of antiproton annihilation at rest in two mesons in H₂ and D₂, the dominance of S-wave in $\text{p}\text{p}$ annihilation at rest is confirmed, the P-wave contribution being less than 6% at the 95% confidence level. The apparent discrepancy between the channels $\text{p}\text{p}\text{→}\text{K}{}^0\text{K}{}^0$ and $\text{p}\text{p}\text{→ππ}$ is due to the strong dependence of the annihilation dynamics from the angular momentum.     

Evidence for new meson resonances from the reaction pp → K−K+

The differential cross sections for $\text{p}\text{p}\text{→}\text{K}{}^{\mathrm{?}}\text{K}{}^{\mathrm{+}}$ provide new evidence for mesons with masses between 2.1 and 2.5 GeV/c². The zeros of the cross sections suggest the existence of J^P = 3^? states with both I = 1 and I = 0 at masses between 2.1 and 2.18 GeV/c². The results also support a J^P = 4⁺ state near 2.34 GeV and are consistent with 5^? states in both I = 1 and I = 0 close to 2.5 GeV. This analysis confirms the I = 1 3^?, 5^? and I = 0 4⁺ states seen previously in $\text{p}\text{p}\text{→ π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}$ and is in agreement with the existing data for the non-annihilation processes.     

The ϱ and A2 exchange amplitudes in meson-baryon scattering for ϱlab between 2.5 and 200 GeV/c

We present a parametrization of the ? and A₂ exchange amplitudes which fits all the available data on the reactions $\text{π}{}^{\mathrm{?}}\text{p}\text{→ π}{}^0\text{n}\text{, π}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^0\text{n}\text{,}\text{and K}{}^{\mathrm{+}}\text{n}\text{→}\text{K}{}^0\text{p}$ in the momentum range from 2.5 to 200 GeV/c and for momentum transfers up to t = ?2.0 (GeV/c)².     

A study of high transverse momentum π0's at ISR energies

We present a study of the transverse momentum spectrum of π⁰'s produced at c.m. angles θ = 90° and 53° in pp collisions at √s = 23.6, 30.8, 45.1, 53.2, and 62.9 GeV. The experiment was performed with a lead-glass detector. The data can be described with the usual parametrization $\text{p}{}_{\mathrm{<mtext>T</mtext>}}{}^{\mathrm{?n}}\text{?;(x}{}_{\mathrm{<mtext>T</mtext>}}\text{, θ)}$, with n = 7.2 ± 0.2. Comparison between the 90° and 53° data further indicates no appreciable dependence on θ, at least for x_T < 0.3. Two-particle inclusive cross sections for π⁰'s produced alongside are also presented. They are observed to have a dependence upon the transverse momentum of the dipion similar to that of single-particle cross sections and with the same value of n. Two-photon decays of η mesons are observed between 3 and 4 GeV/c transverse momentum with a production cross section half of that of π⁰.     

Search for non-strange exotic mesons produced via baryon exchange

Negative results on backward production, via baryon exchange, of exotic non-strange mesons are presented. The reactions π^?p→p_forwardX^?and π^?n→ p_forwardX^?? have been studied with a 12 GeV/cπ^? beam in the Omega spectrometer at CERN. No resonant peak in $\text{X}\text{→}\text{p}\text{p}\text{π}{}^{\mathrm{?}}\text{,}\text{p}\text{p}\text{π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{?}}\text{,}\text{p}\text{p}\text{π}{}^{\mathrm{?}}\text{π}{}^0\text{,π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{?}}\text{π}{}^0$ has been seen. The upper limits obtained on cross sections for exotic meson production $\text{X}\text{→}\text{N}\text{N}\text{π,}\text{N}\text{N}\text{π, 4π}$ are lower than the ?^? backward production cross section in the π^?p→p?^? reaction; this result seems to contradict the predictions of the two-component duality model. Compared to already published experiments in the search for exotics produced via baryon exchange, the sensitivity of this experiment is increased by an order of magnitude.     

Weak decays of the charmed baryon C0+ and the inclusive yield of Λ and p

We calculate the decay rates of the charmed baryon state C₀⁺(2.26) into 25 two body and quasi two body states involving baryons and mesons with $\text{J}{}^{\mathrm{P}}\text{=}\text{1}\text{2}{}^{\mathrm{+}}\text{,}\text{3}\text{2}{}^{\mathrm{+}}\text{, 0}{}^{\mathrm{?}}\text{and}\text{1}{}^{\mathrm{?}}$. These modes yield a width of Γ = 16.3 × 10¹²s^?1and an inclusive yield of $\text{Λ/}\text{p}\text{? 40\%}$.     

Neutral K1(890) and ρ0 meson production in e+e− annihilation at ;s=29GeV

The production of neutral K¹(890) and ρ⁰ mesons was studied in e⁺e^? annihilation at $\text{s}\text{=29}\text{GeV}$ using the High Resolution Spectrometer at PEP. Differential cross sections are presented as a function of the scaled energy variable z and compared to π⁰ and K⁰ production. The measured multiplicities are 0.84±0.08 ?⁰ mesons and $\text{0.57±0.09 K}{}^{10}\text{(890)}$ mesons per event for a meson momentum greater than 725 MeV/c. The ratios of vector meson to pseudoscalar meson production for (u,d), s and c quark are compared to predictions of the Lund model.     

The four-pion final state in pp annihilations at 5.7 GeV/c

577 events from $\text{p}\text{p}\text{→2π}{}^{\mathrm{+}}\text{2π}{}^{\mathrm{?}}$ annihilations at 5.7 GeV/c are analyzed. Single-particle spectra are studied and an effective matrix element in the form Π_i=1⁴ exp(?Bp_Ti²) is determined. The rates for production of ?° and f⁰ mesons are estimated and the influence of resonances on the angular distributions of pions and dipions is investigated. Transverse momenta correlations can be explained using peripheral phase space.     

Analysis of two-prong events in antiproton-proton interactions at 5.7 GeV/c

A study of elastic scattering, one-pion production and annihilation reactions in $\text{p}$p interactions at 5.7 GeV/c was carried out, from the two-prong events, obtained in the hydrogen bubble chamber exposed at CERN.Single particle distributions for the reactions $\text{pp}\text{→}\text{pp}\text{π}{}^0\text{,}\text{p}\text{p}\text{→}\text{p}\text{n}\text{π}{}^{\mathrm{+}}$ and $\text{p}\text{p}\text{→}\text{p}\text{n}\text{π}{}^{\mathrm{?}}$ are presented. The study of the squared momentum transfer distributions with and without charge exchange in the cross channel shows different behavior of the slope parameters versus the mass of the produced (Nπ) system. The cross sections for isobar production and for diffractive dissociation in the one-pion production reactions are obtained from a detailed Dalitz plot analysis. The results of the analysis of the decay angular distributions for the N(1510) and for the N(1680) produced in these reactions are in agreement with $\text{J =}\text{3}\text{2}\text{and}\text{J =}\text{5}\text{2}$ assignment, respectively. The cross sections of the annihilation reactions $\text{p}\text{p}\text{→ π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{and}\text{p}\text{p}\text{→ π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{π}{}^0$ are determined. Finally, we give some as aspects of the mass distributions for the last reaction.     

Inclusive π electroproduction in the deep inelastic region

Using 20.5 GeV electrons on protons, we measured inclusive π⁰'s (of transverse momentum, p_T, from 0 to 1.4 GeV/c) produced by virtual photons of energy, ν, from 4 to 16.5 GeV and four-momentum squared, q², from ?1.8 to ?8.5 (GeV/c)². Comparing with charged pion data, we find , supporting the quark model. Photon knockout of a quark is favored as the interpretation of these data because of scaling in z = E_π/ν and similarity in z-dependence of other pion production data. Consistent with this interpretation are the dependence of 〈p_T〉 on q², the azimuthal dependence, and fits to the constituent interchange model. We also observe a possible p_T^?4 dependence at large |q²| over a limited p_T range.     

The electronic spectrum of gaseous SnS

Observations of the spectrum of SnS excited in chemiluminescence have led to the characterization of two low-lying excited states of SnS, $\text{a}\text{Ω}\text{1(}{}^3\text{Σ}{}^{\mathrm{+}}\text{)}$, with T_e = 18 143.9 cm^?1, and $\text{A0}{}^{\mathrm{+}}\text{(}{}^3\text{Π}\text{)}$, with T_e = 22 021.3 cm^?1. Extended rotational analyses of the perturbed bands observed in the absorption spectrum enable assignments to be suggested for the components $\text{Ω}\text{0}{}^{\mathrm{+}}$ and 1 of ³Σ^? and $\text{Ω}\text{1}$ of ³Π.     

Results on the production cross sections π−p → neutrals and π− p→ χ↳2γ0n at 3.8, 6, 8 and 12 GeV/c

The ratio between the cross sections for the reactions $\text{π}{}^{\mathrm{?}}\text{p→}\text{χ}\text{?}{}_{\mathrm{2\gamma }}{}^0\text{n}$ and π^?p → η_→2γ n has been measured to be (2.4 ± 0.9) × 10^?2, (2.1 ± 0.6) × 10^?2 and (2.8 ± 1.3) × 10^?2 at 3.8,6,8 and 12 GeV/c incident momentum respectively.At the same momenta the cross section for π^t- p → neutrals is (1.48 ± 0.09) mb, (0.86 ± 0.05) mb, (0.64 ± 0.04) mb and (0.42±0.03) mb.     

Proton-antiproton annihilations at rest into π0ω, π0η, π0γ, π0π0, and π0η′

Proton-antiproton annihilations at rest in liquid hydrogen were investigated through the inclusive γ spectrum, related to the annihilation. The high-energy part of the spectrum was used to deduce branching ratios for the so far unobserved annihilation channels: $\text{R(}\text{p}\text{p}\text{→π}{}^0\text{ω) = (2.38 ± 0.65)\%}$, $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{η) = (0.82 ± 0.10\%}$, $\text{R}\text{p}\text{p}\text{→π}{}^{\mathrm{0\gamma )}}\text{= (0.015 ± 0.007)\%}$, and $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{π}{}^0\text{= (0.06 ± 0.04)\%}$. An upper limit for the π⁰η^′ channel was deduced to be $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{η}{}^{\mathrm{\prime }}\text{) < 1.1\%}$.     

Electromagnetic mass differences of the old and the charmed mesons

We predict for M_?⁺?M_?⁰ the values -3.4 ± 0.8 MeV using the ?-ω mixing and the quark model, respectively. The extracted parameters indicate the necessity of a relativistic treatment of the old mesons. The problem of extrapolating these parameters to the charmed mesons is discussed. Under conservative assumptions, we predict 1.7 ? M_D⁰ ? 2.2 MeV and .     

≡ Hypernuclei

We consider the possibility of forming doubly strange Ξ hypernuclei via the (K^?, K) reactions on various nuclear targets. Because of the high momentum transfer involved, even at 0°, the formation of high spin states is strongly favored. The available experimental information on the elementary processes K^?p → K⁺Ξ^? or K⁰Ξ⁰ is reviewed, leading to the determination of an optimum incident K^? momentum of about 1.9 GeV/c for the forward formation of discrete Ξ hypernuclear states. The cross section for the process ΞN → ΛΛ, responsible for the damping width of Ξ states in nuclei, is estimated theoretically and the very limited experimental data are also reviewed. The resulting Ξ hypernuclear widths are of order 5 MeV. Emulsion data which have been interpreted as due to the existence of ΛΛ and Ξ^? hypernuclei are discussed and used to obtain an approximate Ξ nuclear well-depth of 21–24 MeV. For this range of values, spectra of single particle Ξ^? states are obtained, and calculated angular distributions for the formation of simple Ξ^? particle-proton hole states in ⁴He, ¹²C and ²⁸Si targets are presented. The peak 0° lab cross section at p_lab = 1.9 GeV/c for such states ranges from tens of $\text{nb}\text{sr}$ to about 1 $\text{μ}\text{b}\text{sr}$. We briefly mention other methods for forming Ξ hypernuclei, such as the three body reaction K^?N → KπΞ (or $\text{K}{}^{\mathrm{?}}\text{p → K}{}^{\mathrm{+}}\text{K}{}^0\text{Ω}{}^{\mathrm{?}}$ for $\text{Ω}{}^{\mathrm{?}}$ hypernuclei).     

Neutral mesons with heavy quarks and mixing angles in the six-quark model

In the framework of the six-quark model, based on the gauge group SU(2)_L × U(1) we have obtained expressions for the amplitudes of $\text{K}{}^0\text{?}\text{K}{}^0\text{,}\text{D}{}^0\text{?}\text{D}{}^0\text{,}\text{B}{}^0\text{?}\text{B}\text{B}{}_{\mathrm{S}}{}^0\text{?}\text{B}{}_{\mathrm{S}}{}^0\text{,}\text{T}{}^0\text{?}\text{T}{}^0\text{and}\text{T}{}_{\mathrm{c}}{}^0\text{?}\text{T}{}_{\mathrm{C}}{}^0$ transitions at final 4-momenta of external lines Feynman box diagrams. We have estimated the correctness of using the approximation of extremely small 4-,omenta of valence quarks, composing K⁰-like mesons. The constraints for the parameters of the unitary matrix of weak charged currents have been found at arbitrary value of the t-quark mass. Estimates of numerical values for the mixing parameters and for the parameters of CP violation for neutral systems similar to $\text{K}{}^0\text{?}\text{K}{}^0$ are given.     

Temperature and pressure dependence of the elastic property of GeS2 glass

The sound velocities in GeS₂ glass have been measured by means of ultrasonic interferometry as a function of temperature or pressure up to 1.8 kbar. The bulk modulus K_s = 117.6 kbar and shear modulus G = 60.60 kbar were obtained for GeS₂ glass at 15°C and 1 atm. The temperature derivatives of both sound velocities and elastic moduli are negative :

$\text{(}\text{?ν}{}_1\text{?T}\text{)}$

_p =

$\text{?1.54 × 10}{}^{\mathrm{?4}}\text{km}\text{sec}$

°C,

$\text{(}\text{?ν}{}_1\text{?T}\text{)}$

_p =

$\text{?1.27× 10}{}^{\mathrm{?4}}\text{km}\text{sec}$

°C and

$\text{(}\text{?K}{}_{\mathrm{s}}\text{?T}\text{)}$

_p =

$\text{?1.27 × 10}{}^{\mathrm{?2}}\text{kbar}\text{°C}$

,

$\text{(}\text{?G}\text{?T}\text{)}$

_p = ?1.23 × 10^?2 kbar/°C,

$\text{(}\text{?Y}\text{?T}\text{)}$

_p = ?2.93 × 10^?2 their pressure derivatives are positive:

$\text{(}\text{?ν}{}_1\text{?P}\text{)}$

_T = 4.43× 10^?2km/kbar,

$\text{(}\text{?ν}{}_1\text{?P}\text{)}$

_T =

$\text{0.633 × 10}{}^{\mathrm{?2}}\text{km}\text{kbar}$

and (?K_s?P0)_T=6.81,

$\text{(}\text{?G}\text{?P)}{}_{\mathrm{T}}$

= 1.03, (?Y?T_T= 3.57. The Grüneisen parameter, γ_th= 0.298, and the second Grüneisen parameter, δ_s = 3.27, have also been calculated from these data. The elastic behavior of GeS₂ glass has proved to be normal despite the structural similarity among the tetrahedrally coordinated SiO₂, GeO₂ and GeS₂ glasses.     

On the λλ spectroscopy in e+e− annihilation

The properties of the radial excitations of the ?, ω and ? mesons are discussed. In particular it is proposed to identify the recently observed states at √s ? 1.5, 1.82 and 2.13 GeV in e⁺e^? annihilation with the $\text{?}{}_{\mathrm{<mtext>D</mtext>}}\text{≡}{}^3\text{D}{}_1\text{(λλ), ?″}\text{and}\text{?′″}$ mesons respectively. The ?′ meson is suggested to lie in the vicinity of 1.5 GeV and strongly coupled to the ?_D. The ?″(1.6) width is also suggested to be smaller than previously reported.