Evidence for high mass NN and NNπ enhancements observed in pd interactions at 5.55 GeV/c

Based on 4085 $\text{p}\text{n→Xπ}{}^{\mathrm{?}}$ events, X denoting a neutral $\text{N}$N or $\text{N}\text{Nπ}$ system, we present evidence for 5.1 and 3.1 standard deviation enhancements at the X mass of 2.85 and 3.05 GeV/c², respectively. The lower mass bump has a width of Λ ? 39 GeV/c² while the 3.05 GeV/c² is seen as a one bin accumulation (20 GeV/c² width). The relevance of these peaks is discussed.     

Determination of the one-pion exchange potential from pn and pp charge exchange scattering

The πNN vertex function is determined from $\text{d}\text{σ}\text{d}\text{t}$ for pn → np and $\text{p}\text{p →}\text{n}\text{n}$ at 8 GeV/c in the interval 0 < ? t < 0.1 GeV². A “regularor mass” of 3.5m_π=488 MeV is found, corresponding to an “extension” of 0.40 fm of the πNN vertex. The resulting OPE potential is discussed.     

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.     

Upper limits on D0-D0 mixing and BB production from muon-nucleon scattering

In deep inelastic interactions of 200 GeV muons with a carbon target, we have found 17 events of the type μ^±N→μ^±μ^?μ^?X (“wrong-sign” dimuons). We derive upper limits of 1.2% (90% CL) on $\text{D}{}^0\text{-}\text{D}{}^0$ transitions (mixing) or, alternatively, of 9 pb (90% CL) cross section for $\text{B}\text{B}$ pair production as possible sources of such events.     

Superconducting properties of ZnCr and ZnMn alloys

Measurements on the superconducting critical temperature T_c and critical field, H_c, of $\text{Zn}$Cr and $\text{Zn}$Mn alloys, down to 0.037°K are presented.The variation of T_c with increasing concentration depends strongly on T_cp/θ, with θ a characteristic temperature, while effects of H_c are similar to previously studied alloys.     

Final states with a neutral meson and a π+π− or pp pair in pp interactions at 7.2 GeV/c

Cross sections are reported for $\text{p}\text{p}$ interactions at 7.2 GeV/c beam momentum yielding one of the mesons ?⁰, ω, ?, η or η′; together with a gp⁺π^? pair or a $\text{p}\text{p}$ pair. Results are compared with data on similar $\text{p}\text{p}$ interactions at other beam momenta. The angular distributions for the final states with a ?⁰ or ω clearly show a peripheral behaviour. Our results may be understood within the framework of the quark model, but differ from the predictions of the quark rearrangement model. Deviations from ideal mixing of vector mesons are discussed. The energy dependence of ?⁰ and ω production is compared with that of analogous pp and π^±p interactions.     

Evidence for a narrow peak in Ksoπ±π+π- at 2.6 gev in 12 gev/cpp interactions

We report the evidence for a narrow charged peak (5.5 s.d.), which we suggest calling the I, in the 6-prong-V⁰ topology of $\text{p}$p interactions at 12 GeV/c. The mass, widht and the product of cross section σ_I times the branching ratio BR into the final state (K_s^oτ±τ⁺τ^? are found to be: $\text{M}{}_{\mathrm{I}}\text{=2.60 ±}\text{0.01}\text{GeV}\text{/}\text{c}{}^2$, $\text{Γ}{}_{\mathrm{I}}\text{?}\text{0.018}\text{GeV}\text{/}\text{c}{}^2$, σ_I·BR≈20 μbarn     

Structures in pp → ππ

A Barrelet-zero analysis is presented of data on $\text{p}\text{p}\text{→ π π}$ in the momentum range 1 to 2 GeV/c. With π^?π⁺ data alone, the slope for ambiguity is very large, but the addition of π⁰π⁰ information enables the number of solutions to be reduced to just a few. Although the alternative solutions differ considerably, they significant common features, in particular, with plausible extra assumptions, all solutions appear to be dominated by resonances in all spin states from J = 1 to 5.     

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.     

A comparison of direct photon, π0 in pp and pp interactions at the CERN ISR

We have measured the production of direct photons, π⁰'s, and η's in p$\text{p}$ and pp collisions at √s=53 GeV in the range 2≈p_T≈6 GeV/c for the central rapidity region |y| 0.4. No statistically significant difference between pp? and pp interactions is observed.     

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.     

In-out semi-classical gravity and 1N quantum gravity

Classical gravity with higher derivatives, when coupled to the in-out matrix element of T_μν: (a) appears to be free from instabilities of the in-in theory; (b) may be considered as the “underlying classical theory” to Tomboulis' $\text{1}\text{N}\text{-}\text{resummed}$ quantum gravity. I explain how these two facts may be adduced as evidence for the viability both of the former semi-classical approximation and of the latter approach to full quantum gravity.     

pp interactions at 303 GeVc: Analysis of diffraction excitation in the reaction pp → pX

The properties of the diffractively excited system observed at low missing mass in the inclusive pp → pX reaction at $\text{303}\text{GeV}\text{c}$ are presented. For diffraction excitation with |x| > 0.9, the cross section, σ_D=(5.6±0.8) mb, the mean charged multiplicity depends on the mass of the diffractive system approximately at 〈n_c〉 ≈ 0.6M_x + 2, and the slope of the momentum transfer distribution with |t| < 0.5 GeV² is 7.5±0.8 GeV^?2.     

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.     

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.     

Elastic pd scattering at 5.55 GeV/c incident momentum

Based on 150 000 photographs taken at the ZGS with the 30 inch deuterium-filled chamber we present an analysis of the elastic $\text{p}$d scattering reaction. Due to unrecoreded small deuteron recoils we were only able to measure the elastic cross section in the four-momentum region |t| > 0.03 (GeV/c)². Extrapolation towards small |t| by two different methods gave us two compatible estimates of the total elastic cross section. The differential cross section was analyzed by means of the Glauber formalism both with and without the effects due to the D-wave part of the deuteron wave function. The differential cross sections of np at 5.4 GeV/c and $\text{pn}$ deduced from our data were compared and exhibit a crossover phenomenon.     

Double inelastic interactions in pd collisions in the 1.6–4.3 GeV/c incident p momentum range

We present results on $\text{p}\text{d}$ multiplicity distributions at 3.9 and $\text{4.3}\text{GeV}\text{/c}\text{p}$ incident momenta obtained from a bubble chamber experiment. An excess is observed for the even-prong multiplicities as compared with $\text{p}$ collisions on free protons. This excess as well as that observed in other existing $\text{p}\text{d}$ data in the 1.6–2.9 GeV/c range was analysed in terms of double interaction processes inside the deuteron.     

D-state effects in (d, t) and (d, 3He) reactions

The influence of the deuteron and triton [³He] D-state on the form factor required in the DWBA analyses of the ($\text{d}$, t) [($\text{d}$, ³He)] reactions has been studied. The wave functions of Phillips are used for three-nucleon systems because they are designed to yield the correct asymptotic form for the (d, t) and (d, ³He) overlaps. The zero-range parameters D₀ and D₂ which enter into the calculation of the cross section and the tensor analysing power in the DWBA with the local energy approximation are calculated and found to yield values consistent with experimental data.     

Inclusive V0 production in pp interactions at 12 GeV/c

Results are presented on the inclusive reactions $\text{p}\text{p}\text{→}\text{K}{}^0\text{X}\text{,}\text{p}\text{p}\text{→ Λ}\text{X and}\text{p}\text{p}\text{→}\text{Λ}\text{X}$ at an incident antiproton momentum of 12 GeV/c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x, the rapidity, the transverse momentum of the V⁰ and the missing mass squared. The dependence of the Λ and $\text{Λ}$ polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/c are also made. Finally, events with two detected V⁰ are analyzed in order to study correlations arising from the production of two strange neutral particles.     

Peripheral pn production and decay angular distributions in the reaction π−p → (pn)p at 12 GeV/c incident momentum

The reaction $\text{π}{}^{\mathrm{?}}\text{p}\text{→ (}\text{p}\text{n}\text{)}\text{p}{}_{\mathrm{s}}$, where p_s is a slow proton, was measured at 12 GeV/c incident momentum with the CERN-OMEGA spectrometer. Both antiproton and proton were identified uniquely by electronics information. We obtained 1844 events with four-momentum Transfer squared in the range 0.13 ? |t| ? 0.33 GeV² and with invariant masses $\text{M(}\text{p}\text{n}\text{)}$ up to 2.5 GeV. The corresponding cross section in this t range is determined to be σ = 4 ± 0.4 μb. Extrapolating the differential cross section over the whole t range assuming dσ/dt ≈ exp(5.3t) we estimate a cross section of σ = 9.3 ± 2.0 μb. Comparison with data on $\text{π}{}^{\mathrm{?}}\text{p}\text{→ (}\text{p}\text{p}\text{)}\text{n}{}_{\mathrm{s}}$ (where n_s is a slow neutron) in the same t range shows that the $\text{(}\text{p}\text{n}\text{)}\text{p}{}_{\mathrm{s}}\text{and}\text{(}\text{p}\text{p}\text{)}\text{n}{}_{\mathrm{s}}$ cross sections have approximately the same magnitude.