K−p elastic scattering at 14.3 GeV/c

Results are presented of a bubble chamber experiment on K^?p elastic scattering at 14.3 GeV/c, in four-momentum transfer range 0.04 < |t| < 2.74 GeV² using an initial set of 40 000 events. The total elastic cross section is (2.96 ± 0.10) mb. The results are compared with K⁺p elastic scattering data at 13.8 GeV/c, and the effective Regge trajectory is calculated using K^?p data from 5 to 100 GeV/c.     

Measurement of polarization in K−p elastic scattering between 0.955 GeV/c and 1.272 GeV/c

The polarization parameter has been measured for K^?p elastic scattering at nine incident beam momenta between 0.955 and 1.272 GeV/c covering the c.m. angular range $\text{?0.9 < cos θ}{}^1\text{< + 0.9}$. Experimental results and coefficients of Legendre polynomial fits to the data are presented and compared with other measurements and a partial-wave analysis.     

Differential cross sections for K+n elastic scattering between 0.64 and 1.51 GeV/c

We present experimental results on the K⁺n → K⁺n differential cross sections measured in deuterium at 13 momenta between 0.64 and 1.51 GeV/c.     

Inclusive production cross sections of resonances in 32 GeV/c K+p interactions

The inclusive production of resonances is systematically studied in K⁺p interactions at 32 GeV/c. Total production cross sections are given for three baryon resonances, five vector and three 2⁺ tensor mesons. We also compare the central and fragmentation components of the total production cross sections with quark model predictions.     

Dispersion-relation analysis of K+p scattering below 2 GeV/c

We have obtained K⁺p scattering amplitudes that fit a large body of data below 2 GeV/c, satisfy phenomenological partial-wave backward dispersion relations, and are consistent with forward dispersion relations for the spin-non-flip amplitude, and forward dispersion-relation sum rules for the K⁺p P-wave scattering lengths. This has been achieved by firstly making an energy-dependent phase-shift analysis of 1 660 pieces of K⁺p data below 2 GeV/c, using parameterised partial-wave dispersion relations, with the additional constraints of forward dispersion relations and P-wave scattering lengths obtained from forward dispersion-relation sum rules, and then checking the resulting solutions for consistency with backward K⁺p dispersion relations.     

K+P elastic scattering at 32 GeV/c

Elastic scattering of 32.1 GeV/c K⁺ on protons has been measured in a bubble chamber experiment. Results are presented in the momentum transfer interval 0.06–1.40 GeV² and compared with data at different energies. An effective Regge trajectory is calculated using K⁺p elastic data from 10 to 175 GeV/c.     

A measurement of π+p backward elastic differential cross sections from 1.282 to 2.472 GeV/c

New high-statistics measurements of π⁺p elastic scattering differential cross sections are presented at 30 momentum points between 1.282 and 2.472 GeV/c, covering most of the angular distribution outside the forward diffractive peak. These data show significant disagreements at some momenta with previous high-statistics experiments and with current partial wave analyses.     

K−π− elastic scattering cross section measured in 14.3 GeV/c K−p interactions

Results are presented on a measurement of the I = 3/2 Kπ elastic scattering cross section by applying the Chew-Low extrapolation method in the reaction K^?p → K^?π^?Δ⁺⁺at14.3GeV/c. The magnitude of σ(K^?π^? → K^?π^?) is found to be about 3 mb at threshold and slowly falling with energy to about 1.5 mb at 2.8 GeV. The off-mass-shell moments of the differential elastic cross section are given. The absolute value of δ₃⁰ is found to be increasing slowly from 0° to 20° between threshold and 1.2 GeV.     

Channel cross sections and two-body reactions in K−p interactions at 32 GeV/c

We present a systematic investigation of channel cross sections in K^?p interactions at 32 GeV/c. The energy dependence of these cross sections is discussed. We also investigate a few non-diffractive two-body reactions. The total cross sections of the two reactions $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^{\mathrm{1?}}\text{(890)}\text{p}\text{and}\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^{\mathrm{1?}}\text{(1420)}\text{p}$ have a markedly different energy behaviour. There is clear evidence for the reaction $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^{10}\text{(890)}\text{N}{}^0\text{(1688)}$; its differnttial cross section exhibits a sharp forward slope of 24 ± 3 GeV^?2.     

The K−p charge exchange and elastic scattering reactions at 4.2 GeV/c

In this letter results are presented on the reactions $\text{K}{}^{\mathrm{?}}\text{p →}\text{K}{}^0\text{n and K}{}^{\mathrm{?}}\text{p → K}{}^{\mathrm{?}}\text{p}$ from a high statistics CERN 2-metre hydrogen bubble chamber exposure at 4.15 GeV/c. The behaviour of the differential cross section as a function of four-momentum transfer shows remarkable similarities between the two reactions studied. From a comparison of our data with K⁺p elastic scattering at 4.27 GeV/c we draw some conclusions concerning the magnitude of the contributing amplitudes.     

Measurement of the real part of the forward scattering amplitude in K±p elastic scattering between 0.9 and 2.6 GeV/c

The differential cross section for K^±p elastic scattering has been measured in the forward meson direction (0.0008 < t < 0.1 GeV²) in an electronics experiment at incident momenta between 0.9 and 2.06 GeV/c. The high statistics and absolute normalisation of the data allow a good determination of the real part of the forward nuclear scattering amplitude by means of the Coulomb-nuclear interference effect.     

Neutral kaon production in K+p interactions at 32 GeV/c

The production of neutral kaons in the reaction K⁺p → Kⁿ + X is studied at the incident momentum of 32 GeV/c. Inclusive cross sections and single-particle distributions are presented and compared with the data at lower energies. The total inclusive cross section amounts to 7.9 ± 0.3 mb at 32 GeV/c and is significantly higher than at lower energies due to the rapid rise of multikaon production. The fraction of Kⁿ's coming from the decay of the K¹ resonances stays roughly constant with energy between 8.2 and 32 GeV/c. In the central and beam fragmentation regions the single-particle distributions reveal no energy dependence between the 16 and 32 GeV/c data in contrast with the behaviour at lower energies, while in the proton fragmentation region the data are compatible with the trend observed at lower energies and with theoretical expectations.     

Measurement of the polarization parameter in π−p elastic scattering at 40 GeV/c

We report our first measurements of the polarization in the elastic scattering of negative pions from polarized protons at an incident pion momentum of 40 GeV/c. The momentum-transfer region covered was 0.08 < |t| < 1.3 (GeV/c)². The angular distribution of the polarization exhibits a first minimum of ～ ? 5% and the well-known zero around t ≈ ? 0.6 (GeV/c)². The energy variation of the first minimum (at around t = ? 0.2) may be expressed in a simple form, $\text{P}{}_{\mathrm{<mtext>avr</mtext>}}\text{= ?(0.48±0.06) s}{}^{\mathrm{?0.52\pm 0.05}}$.     

The K+π- elastic scattering cross section as observed in K+p→K+π-Δ++ from 3 to 13 GeV/c

The four-body reaction K⁺p→K⁺π^-Δ⁺⁺ is analysed in a sample of 77 300 bubble chamber events of K⁺p→K⁺π^-π⁺p for beam momenta from 2.5 to 12.6 GeV/c to study the K⁺π^- elastic scattering cross section. The relative merits of several analytic continuations to the pion pole are discussed. Maximum likelihood method is used and, for each experiment fits are performed simultaneously over the whole range of the M(pπ⁺), m(K⁺π^-) and t variables. The K⁺π^- cross section is parametrized in terms of the down solution for the s-wave, a p-wave resonating at the K¹(890) and a d-wave resonating at the K¹(1420). Fitted values are obtained for the four-body cross section, the s-wave contribution to the K⁺π^- cross section, and the masses and widths of the K¹(890) and K¹(1420).     

Λ production in K−p interactions at 32 GeV/c

Lambda production is studied in K^?p interactions at 32 GeV/c. The total Λ cross section is 2.31±0.03 mb. Using the measured Λγ combinations we find that (31±4)% of all Λ's are produced via the Σ⁰→Λγ decay. About 60% of the Λ's are associated with either a $\text{N}\text{N}\text{or K}\text{K}$ pair; about 40% of the Λ's are produced through the hypercharge annihiltion reaction K^?p→Λ+π'a. The two-peak structure of the invariant x distribution can be related to fragmentation processes. The Λ is found to be unpolarized in the target fragmentation region, whereas a transverse polarization is observed for forward produced Λ's. As a function of p⊥, a polarization effect is measured at medium p⊥.     

Measurement of the reactions K+d → K+d and K+d → p+pn and an investigation of elastic K+-nucleon scattering at 4.6 GeV/c

The coherent elastic reaction K⁺d → K⁺d and the break-up reaction K⁺d → K⁺pn are studied in a K⁺d experiment at 4.6 GeV/c which the CERN 2 m bubble chamber. Partial and differential cross sections are given and the slopes of the differential cross sections are determined. The results for the reaction K⁺d → K⁺p(n_s), where n_s denotes the spectator neutron, are compared with those of the reaction K⁺p → K⁺p on free protons. Combining our data with existing data on the reactions K⁺d → K⁰pp and K⁺p → K⁺p, parameters of the elastic K⁺-nucleon scattering at 4.6 GeV/c are determined in the framework of the Glauber model. The D-wave of the deuteron and spin-flip effects are taken into account.