Elastic pp scattering in the cern sps energy region

The pronounced dip-bump structure with a sharp minimum at |t| = 1.5 (GeV/c)², recently observed in elastic $\text{p}$p scattering at P_L = 50 GeV/c at the CERN SPS, is explained by the quark multiple scattering model with a realistic wavefunction for the proton and the antiproton. It is predicted that a second dip will appear around |t| = 7 (GeV/c)² at P_L = 50 GeV/ c and at higher energies.     

Possible heavy lepton signals at pp colliders

If a new sequential heavy lepton L exists with mass below that of the W boson, it will give rise to the following decay chains: W → Lν_Lwith $\text{L}\text{→}\text{e}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{ν}{}_{\mathrm{<mtext>L</mtext>}}$ or $\text{L}\text{→}\text{Q}\text{qν}{}_{\mathrm{<mtext>L</mtext>}}$. We critically study, and quantify, the possibility of identifying this heavy lepton signal against the various backgrounds in high energy p?p collision. We find that the leptonic decay signal is plagued by serious b?b, W → eν, and W → τν backgrounds, whereas the hadronic decay mode leads to a distinctive signature, after selected cuts are applied. We discuss how the mass of such a lepton may be determined.     

Observation of a narrow resonance near the pp threshold

Annihilation and elastic cross-sections of $\text{p}$p have been measured between 400 and 850 MeV/c. In both cross-sections a resonance is observed at a mass of 1939 ± 3 MeV. For its natural width τ ? 4 MeV is obtained.     

K−p and pp elastic scattering at 10.1 GeV/c

The differential cross sections for K^?p and $\text{p}$p elastic scattering have been measured over the range of four-momentum transfer squared 0.18<?t<3.3 (GeV/c)². The K^?p data decrease smoothly as a function of ?t, whereas, the $\text{p}\text{p}$ data shows a break at ?t = 0.6 (GeV/c)² followed by a fast drop to ?t ? 1.6 (GeV/c)² where the differential cross section levels off and stays constant out to ?t = 3 (GeV/c)².     

Remarks on multiplicity fluctuations and KNO scaling in pp collider experiments

It is suggested that a major source of the recently observed large multiplicity fluctuation satisfying KNO scaling in $\text{p}$p collider experiments is the fluctuation of the impact parameter b. Conssequences of the association of the KNO variable z with b are discussed.     

Diffractive dissociation of the beam particle in pp interactions at 32.1 GeVc

We report the results of a study of the reaction $\text{p}\text{p}\text{→}\text{p}\text{+}\text{x}\text{at}\text{32.1}\text{GeV}\text{c}$, where the recoiling proton has a small laboratory momentum. The reaction is studied in the 4.5 m Mirabelle bubble chamber at Serpukhov. We compare the diffractive dissociation of the incident antiproton to other incident particles.     

pp and pp forward elastic scattering between 4 and 10 GeV/c

Differential cross sections have been measured in the region of small forward angles (between 0 and ～40 mrad) for the elastic scattering reactions $\text{pp}\text{→}\text{pp at}\text{4.2, 7.0}\text{and}\text{10.0}\text{GeV}\text{/c}\text{and}\text{p}\text{p}\text{→}\text{p}\text{p at}\text{4.2, 6.0, 8.0}\text{and}\text{10.0}\text{GeV}\text{/c}$. The maximum momentum transfer is ～0.025 GeV² at the lowest and ～0.10 GeV/c at the highest incident momentum. Values of the slope and the real part of the forward scattering amplitude of the above reactions have been derived; the values obtained are in good agreement with dispersion relations.     

Strange particle production in pp annihilations at 8.8 GeV/c

Results are presented from an experiment at the SLAC 40″ hybrid facility (SHF) using an 8.8 GeV/c antiproton beam. Using external detectors and an on-line trigger, a sample of events enriched in $\text{p}$p annihilations was obtained. pp interactions taken under the same conditions enabled the annihilations to be identified. Cross sections and distributions for the inclusive production of K_s⁰ and K^1±(890), and cross sections for exclusive channels with a pair of strange particles are presented.     

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.     

Diffractive processes in pp interactions at 5.1 GeV/c

We have investigated the interaction $\text{p}\text{p}\text{→}\text{p}\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}$ at 5.1 GeV/c using the prism plot method. In addition to the $\text{Δ}{}^{\mathrm{++}}\text{Δ}{}^{\mathrm{??}}$ final state, we isolate the three particle diffractive dissociation of the proton and antiproton into (pπ⁺π^?) and $\text{(}\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{)}$ respectively. We estimate this process accounts for 30% of the final state.     

Optical model analysis of p-atoms

We examine how different types of form factors for $\text{p}$-nucleus optical potential affect the analysis of X-ray data in $\text{p}$-atoms. We also study the effect of L·S force due to strong interaction in $\text{p}$-atoms.     

Jets in pp collisions: Radiation zeroes and the electric charges of colored quarks

Measurements involving more than one photon (e.g., γγ → hadrons, e⁺e^- → q$\text{q}$γ) can determine the electric charge of colored quarks rather than the color-averaged value measured, for example, by the R-value in e⁺e^- → hadrons. We draw attention to the fact that this measurement of the absolute quark charges can be performed in hadron collisions via the process qq → qqγ. The charge signature is dramatic due to the appearance of radiation zeroes whose position depends on the values of the electric charges. This can be exploited to perform such measurements with a detector lacking γ/π⁰ separation capability. Such experiments also study the interface of color and electromagnetic amplitudes and can further elucidate the QCD origin of jets.     

Mechanisms in pp annihilation

We consider the annihilation mechanism in the antiproton momentum range 2.5 to 9.1 GeV/c. Techniques for identifying a “leading pion” are discussed. The annihilation is examined as a quasi two-body process, and the properties of the “leading pion” and the remaining multi-pion “cluster” are presented. A simple parametrization is found to reproduce satisfactorily several features of the data.     

A pθ, pz dependent equilibrium solution for the cylindrical pinch

We have obtained a solution of the cylindrical pinch equilibrium equation with both a poloidal and a longitudinal current. The β poloidal is typically between 0.1 and 0.5. The ratio of poloidal and toroidal currents is estimated.     

Search for substructure in pp total cross section in the 2200 MeV mass region

The $\text{p}$p total cross section was measured from 2130 to 2250 MeV with mass resolution 2.25 MeV (FW). No fine structure was found with σΓ above the statistical limit of 7 MeV mb. A spin J particle coupled to the $\text{p}$p system must have partial width less than $\text{1.8}\text{(2J+1)}$ MeV.     

QCD predictions for beauty production in π p and pp collisions

The total cross sections for beauty production in πp, pp and $\text{p}$p collisions are calculated within perturbative QCD. It turns out that the cross sections are around several nanobarns at presently available energies. For the future $\text{p}$p colliders, the total cross section reaches several millibarns.     

Charged particle multiplicities in 100 GeV/cpp interactions

Results are presented on the topological cross sections obtained for antiproton-proton interactions from an exposure of the Fermilab 30-inch bubble chamber to a 100 GeV/c negative beam enriched in $\text{p}$'s. The $\text{p}$p inelastic cross section is found to be σ_inel = 34.6 ± 0.4 mb, and the average inelastic charged particle multiplicity to be 〈n〉 = 6.74 ± 0.05.     

Nonrelativistic distorted wave born approximation predictions for 500 MeV (p, p') spin-rotation observables

We discuss couplings of scalar gluonium σ on the basis of the low energy theorems of broken chiral symmetry and the anomalous trace of the energy—momentum tensor, implemented using a phenomenological lagrangian. Taking the ITEP value of the gluon consensate as input, we find $\text{Γ(σ → ππ) ? 0.6}\text{GeV}\text{× (}\text{m}{}_{\mathrm{\sigma }}\text{1}\text{GeV}\text{)}{}^5$ and $\text{Γ(σ → γγ) ? 90}\text{eV}\text{× (}\text{m}{}_{\mathrm{\sigma }}\text{1}\text{GeV}\text{)}{}^5$, while m_σ is undetermined. These results suggest that if the scalar gluonium mass is above 1 GeV, it is probably unobservably wide, while production in γγ collisions is probably too small to be detectable if m_σ < 1.5 GeV. We comment on the observability of J/ψ → σ + γ and on the relevance of our results to other gluonia.     

Squark production at the pp collider

The recently observed $\text{p}\text{p}$ collider events with large missing P_T are analysed in terms of a supersymmetric model with a light photino and scalar quarks with mass in the range 20 to 35 GeV. A lower bound of O(60 GeV) on the gluino mass in this scenario is found.     

Deviation from Matthiessen rule in Mg-Cd and Cd-Mg

The interference term between electron-phonon and electron impurity scattering has been evaluated for $\text{Mg}$Cd and $\text{Cd}$Mg and found to be negative, in agreement with experiment. It is shown that measurements on single crystal should give valuable information.