Determining the KS→3π amplitude in pp(OR e+e−)→K0K0

The amplitude ratio 〈3π|T|K_S〉/〈3π|T|K_L〉 can be well determined in e⁺e^? (or low energy $\text{p}\text{p}\text{)→K}{}^{\mathrm{o}}\text{K}{}^{\mathrm{o}}$ from the decay time-distribution when each produced kaon→3π, other unknown parameters of the distribution being obtainable from corresponding observations involving known channels like ππ.     

Direct lepton production by soft virtual bremsstrahlung

Internal conversion of soft virtual bremsstrahlung, calculated in an essentially model independent infrared limit, yields numerous low mass-low energy lepton pairs. The resulting single lepton spectra rise sharply towards p_T = 0 for large angles θ_cm and towards x = 0 for θ_cm = 0°. The ratio $\text{e}\text{π}$ for p_T ? 400 MeV/c exhibits roughly the experimentally observed properties.     

Large-pT direct photon production and opposite-side photon-hadron correlations in QCD

Direct photon production in p-p, π-p and $\text{p}\text{-}\text{p}$ collisions at large transverse momenta (p_T) is studied in QCD and compared with existing data. Apart from the quark-gluon and quark-antiquark contributions, corrections due to bremsstrahlung of photons (q+q→q+q+γ) and to partons' intrinsic transverse momenta are taken into account. It is shown that p+p→γ+X provides one of the best determinations of the gluon distribution in the proton. Hadron production with an opposite-side large-p_T photon trigger is also studied. It is shown that the difference between the momentum sharing (x_e) distributions of π^?+p→γ+π^±+X and π⁺+p →γ+π^±+X (or of $\text{p}\text{+}\text{p}\text{→γ+π}{}^{\mathrm{\pm }}\text{+}\text{X}$ and p+p→γ+π^±+X) provides a good determinati on of the gluon fragmentation to a pion.     

Inclusive production of vector and tensor mesons in antiproton-proton annihilation and non-annihilation interactions at 9.1 GeV/c

Cross sections have been determined for the inclusive production of vector $\text{(?}{}^0\text{, ω,}\text{K}{}^1\text{)}$ and tensor (f, A₂^±) mesons in $\text{p}\text{p}$ reactions at 9.1 GeV/c for both annihilation and non-annihilation processes. Distributions in the Feynman variable x and transverse momentum squared, p_T², have been examined for the ?⁰, ω and f mesons. The slopes for p_T² appear to be exponential and decrease with increasing particle mass for both annihilation and non-annihilation reactions, furthermore the slopes have consistently higher values for non-annihilation reactions. Comparisons with other data indicate that the ratio ?⁰/π^? is independent of antiproton momentum in annihilation processes.     

Inclusive η production at high pT at the ISR

The inclusive η production cross section at the CERN ISR has been measured for p_T values of up to 11 GeV/c. We find that the $\text{η}\text{π}{}^0$ cross-section ratio has an average value of 0.55 ± 0.07 and varies little with p_T.     

The reaction pp→pπ−π+p at 25 and 40 GeV/c

The reaction $\text{p}\text{p}\text{→}\text{p}\text{π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}\text{p}$ has been studied at 25 and 40 GeV/c at the Serpukhov proton synchroton using the CERN-IHEP spectrometer. The differential cross section has been determined as a function of four-momentum transfer to the proton (0.05–0.30 (GeV/c)²) and $\text{p}\text{ππ}$ mass (up to 2.2 and 2.6 GeV/c²). At both energies there is a broad low-mass maximum with an enhancement at 1.6–1.8 GeV/c². The cross section in a given mass band falls rapidly with |t|, with an exponential slope that decreases with increasing mass. In both the background and the 1.7 GeV/c² peak there is a strong $\text{Δ}{}^{\mathrm{??}}\text{π}{}^{\mathrm{+}}$ component. Possible spin-parity (J^P) contributions to it are discussed. Throughout the range 1.5–2.2 GeV there is at least one state of $\text{J ?}\text{3}\text{2}$ and there is interference between states of opposite P, |ΔJ| ? 1. At the peak there is a $\text{J ?}\text{5}\text{2}$ component. There are striking parallels between this reaction and the boson reactions π^?p→π^?π^?π⁺p and K^? → K^?π^?π⁺p.     

Pressure effects on the quadrupole coupling constant of 7Li in first stage lithium graphite

The pressure dependence of the experimental ⁷Li NMR spectra is reported for first stage lithium graphite (LiC₆) intercalation compound at temperatures T = 232 and 293 K. This experiment together with the presented point charge model calculation of the ⁷Li quadrupole coupling constant $\text{(}\text{e}{}^2\text{qQ}\text{h}\text{)}$ allows an unambiguous determination of the sign of e²qQ/h which is negative: $\text{e}{}^2\text{qQ}\text{h=-52 kHz}$ at p = 1 bar and T = 232 K. The averaged location of the electrons transferred from the Li intercalant to the graphite layers, as estimated in this study, is in excellent agreement with earlier theoretical energy-band calculations. The compressibility of LiC₆ in the c-direction is predicted to be k_c = 1.7 × 10^-12cm²dyn^-1, it agrees with estimates derived from the available phonon dispersion relations.     

An isospin analysis of the reaction pN→NNπ from threshold to 2.90 GeV/c

We have performed an isospin analysis of single-pion production processes in antiproton-nucleon scattering from threshold to 2.90 GeV/c. Reactions used are $\text{p}\text{p}\text{→}\text{p}\text{p}\text{π}{}^0\text{,}\text{n}\text{p}\text{π}{}^{\mathrm{?}}\text{and}\text{p}\text{p}\text{→}\text{p}\text{p}\text{π}{}^{\mathrm{?}}$. Results show that σ₁, the total I=1 cross section, rises rapidly from threshold to reach a broad maximum around 2.5 GeV/c and σ₀, the I=0 cross section, rises from threshold and continues on a linearly rising trend at least up to 2.90 GeV/c. In the region of 2.9 GeV/c, σ₁ and σ₀ have comparable values, thus suggesting that considerable amount of $\text{I=}\text{1}\text{2}\text{N}\text{π}$ and $\text{N}\text{π}$ states is produced even in this low momentum region. We further determine that single pion production processes are not the source of the π₀ (2375,190) enhancement observed in the $\text{p}\text{p}$ and $\text{p}\text{d}$ total cross sections and may account for as much as 25±8% of the π₁ (2350,140) enhancement.     

A t-channel isospin analysis of the chew-low plot for NN → N(Nπ) interactions at 5.7 GeV/c

A new approach to the t-channel isospin analysis of ZN → Z′(Nπ) reactions is presented. This approach, useful for $\text{Z = N,}\text{N}\text{, K}{}^{\mathrm{?}}$ when only five independent sets of data are availables, is used to analyse data of $\text{N}\text{N →}\text{N}\text{(Nπ)}$ reactions obtained in a $\text{p}\text{p →}\text{N}\text{N}\text{π}$ experiment at $\text{5.7}\text{GeV}\text{/c}\text{and a}\text{p}\text{d →}\text{N}\text{Nπp}{}_{\mathrm{s}}$ experiment at 5.5 GeV/c. the t behaviour of the different isospin exchange amplitudes, suggests their exchange mechanism production. The mass spectrum, M_πN, of the contributions produced by exchanged isospin I_ex = 1, shows enhancements corresponding to N(1490) N(1670) and Δ(1230) isobars, while the mass spectrum for I_ex = 0 presents only a large bump at ～1350 MeV commonly identified as N¹(1400).     

Diffraction dissociation of neutrons in the reaction dp → pppπ− at 25 GeV/c

We observe the reaction dp → p_spec (pπ^?)p in a bubble chamber exposure at 25 GeV/c incident deuteron momentum. The (pπ^?) system with invariant mass below 2.0 GeV is interpreted as neutron diffraction dissociation. The (pπ^?) mass spectra show little if any direct evidence of N¹ production. The decay angular distributions and the momentum transfer distributions of the (pπ^?) system suggest a smooth increase in contributions from higher partial waves $\text{(J ?}\text{3}\text{2}\text{)}$ with increased mass or momentum transfer. A simple partial-wave analysis shows a P₁₁ contribution below 1.3 GeV for small ?t′ and a dominant D₁₃ contribution elsewhere. Both the P₁₁ and D₁₃ amplitudes peak far below the N¹(1470) and N¹(1520) resonances. We also find evidence for the charge-exchange reaction np → p(pπ^?). In this process the (pπ^?) system shows evidence for Δ^o(1236) and N¹(1520) production.     

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.     

Comparison of direct photon production in pp collisions at s= 30.6 GeV and 53.2 GeV

We present data obtained at the ISR, on the determination of the ratio $\text{R =}\text{γ}\text{π}{}^0\text{at}\text{s}\text{= 30.6}$ GeV and we compare the results with our previous measurement at $\text{s}\text{= 53.2}$ GeV. The ratio $\text{R =}\text{γ}\text{π}{}^0$ integrated over the interval 0.1 ? χ_T ? 0.2 is (1.6 ± 0.5) × 10^?2 and we obtain an indication of a universal χ_T dependence.     

Charged particle multiplicity distributions for 32 GeV/c K±p and pp interactions and for 50 GeV/c π±p interactions

Topological cross sections are presented for K⁺p, K^?p and $\text{p}\text{p}$ interations at 32 GeV/c and for π⁺p and π^?p interactions at 50 GeV/c observed in the 4.5 m Mirabelle hydrogen bubble chamber at Serpukhov. Parameters characterizing the behaviour of the multiplicity distributions, namely 〈n_c〉, D and f₂ and the normalized moments are given. The dependence of these parameters on the energy and the nature of the beam particle is discussed. The multiplicity distributions obtained cannot be described by a single function in the KNO variables.     

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.     

Search for a Ks0π±π+π− resonance near 2.6 GeV in 14.75 GeV/ c pp interactions

We present the results of a search for a resonance at 2.6 GeV decaying into K_S⁰π^±π⁺π^? in the six-prong plus K_S⁰ final state in 14.75 GeV/c$\text{p}\text{p}$ interactions. We do not find confirming evidence, and with 95% confidence we quote an upper limit of σ·BR < 21 ub.     

A monte-carlo/molecular dynamics study of the diffusional recombination kinetics of C(a) + O(a) → CO(g) on Pt(111)

The diffusion constants for C and O adsorbates on Pt(111) surfaces have been calculated with Monte-Carlo/Molecular Dynamics techniques. The diffusion constants are determined to be D_C(T)=(3.4 × 10^?3e^{$\text{?13156}\text{T}$})cm²s^?1 for carbon and D_O(T) = (1.5×10^?3 e^{$\text{?9089}\text{T}$}) cm² s^?1 for oxygen. Using a recently developed diffusion model for surface recombination kinetics an approximate upper bound to the recombination rate constant of C and O on Pt(111) to produce CO_(g) is found to be (9.4×10^?3 e^{$\text{?9089}\text{T}$}) cm² s^?1.     

Neutral heavy lepton candidate in e+e− interactions

An event of the form e⁺e^? → μ⁺μ^? + (2 jets) recently observed at √s = 43.45 GeV is interpreted as production of a pair of neutral heavy leptons N, each with mass 20.5 ± 1.0 Gev/c². Two possibilities are explored: (i) the lepton is a wak isodoublet neutrino, produced in pairs by virtual Z⁰ decay. In this case, one expects $\text{B(}\text{Z}{}^0\text{→}\text{N}\text{N}\text{) ≈ 5\%}$; (ii) the lepton is a “right-handed neutrino”, produced in pairs via a new vector boson Z_χ. In this case, in one model, the Z_χ must lie between about 50 and 67 GeV/c². More generally, it must be very weakly coupled to ordinary quarks and leptons in order not to conflict with low-q² neutral-current data. Suggestions are made for further observation of N$\text{N}$ pairs and other effects of Z_χ in forthcoming e⁺e^? and p$\text{p}$ collisions.     

Molecular constants for the I1Πg and J1Δg states of the 3d complex in H2, HD,and D2

The experimental rovibronic energies of the 3dπI¹Π_g^? and 3dδJ¹Δ_g^? states of H₂ and D₂ (v = 0–4 and N = 1–11) have been fitted by rovibronic constants, including L-uncoupling through constants B_v^ΠΔ and D_v^ΠΔ. Comparison of the constants obtained for H₂ and D₂ yields information on the Born-Oppenheimer and adiabatic electronic energies T_e^BO and T_e^AD, and on the diagonal corrections for nuclear motion. T_e^BO derived from experiment for the I¹Π_g state lies 2 cm^?1 below the ab initio calculation of Ko?os and Rychlewski (J. Mol. Spectrosc., 66, 428–440 (1977). The nuclear mass dependence of the ω_e and B_e values in H₂ and D₂ deviates from simple isotope relationships but agrees with expectations based on the R-dependence of the diagonal corrections for nuclear motion through the term $\text{〈L}{}^2\text{?2}\text{Λ}{}^2\text{〉}\text{2μR}{}^2$, i.e., $\text{+2}\text{μR}{}^2$ for 3dπ and $\text{?1}\text{μR}{}^2$ for 3dδ.     

Radiative decays of the Jψ and evidence for a new heavy resonance

The three photon final state produced in e⁺e^? collisions has been measured at the mass of the $\text{J}\text{ψ}$ resonance using the nonmagnetic part of the double arm spectrometer DASP. The decays $\text{J}\text{ψ}\text{→ ηγ, η'γ}$ and π^oγ were observed and their branching ratios are given. A four standard deviation signal was observed in the γγ mass spectrum at a mass of (2.83 ± 0.03) GeV. An upper limit is given for the direct decay $\text{J}\text{ψ}\text{→ 3γ}$.     

A study of charge symmetry breaking effects in elastic π±d scattering

We computed external and internal Coulomb distortions as well as strong charge symmetry breaking (CSB) effects in π^±d→ π^±d. Available data for T_π = 143 MeV indicate the presence of CSB on the level of observed and deduced parameters for different Δ-isobars and the pn mass difference. Data for $\text{T}{}_{\mathrm{\pi }}\text{1}\text{?}\text{80}\text{MeV}$ are predicted to better suit the extraction of a measure of charge symmetry breaking. This note also contains a critical analysis of a previous study of CSB effects on σ_πd^tot.