A strong negative transverse polarization P z is found for forward produced lambdas observed in 10 and 16 GeV/ c K − p interactions. This indicates that exchanges of natural spin-parity are dominant in the production process. Using the polarization results, the d σ d u′ distributions for natural and unnatural spin-parity exchanges are derived. For unnatural exchanges, a dip is observed at u ′≅0.3 GeV 2 , which can be explained as a nonsense-wrong-signature zero of the N β trajectory. The value of P z for forward producted lambdas is constant with energy. This is in agreement with the triple-Regge model prediction, as is the fact that P z is constant as a function of M 2 s . The two non-transverse polarization components, P x and P y , have been measured and are found to be consistent with zero for all x values, unlike P z .
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The inclusive production of K̄ ∗ (890) and K̄ ∗ (1420) is studied in K̄ − p interactions at 10 and 16 GeV/ c . At 10 GeV/ c an enhancement in the ( K ̄ 0 π − ) mass distribution is found at 1.74 GeV, but no clear signal is seen at 16 GeV/ c . The fraction of K 0 ' s coming from decay of the K ∗ (890) or K ∗ (1420) is large, being (50 ± 6)% and (45 ± 5)% at 10 and 16 GeV/ c , respectively. The inclusive cross sections for K ∗− (890) and K ∗0 (890) production are almost constant with energy from 8 to 32 GeV/ c with values of 3.5 and 3.3 mb, respectively. The K ∗ (890) production cross section is studied as a function of transverse and longitudinal variables and found to derive mainly from fragmentation of the incident K − meson. The spectra of K 0 ' s resulting from the decay of K ∗ (890) are studied.
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Inclusive production of Λ and Λ in K + p interactions is studied at incident momenta of 8.2 and 16.0 GeV/ c . Cross sections and single-particle distributions are presented, the correlation between longitudinal and transverse momentum is investigated, and the dependence of average charge multiplicity on missing mass measured. For Λ production, early scaling is observed in the target fragmentation region when the data are presented in terms of ( M 2 - M th 2 )/ s and t , where M th is the threshold value of the missing mass M . Furthermore, a triple-Regge analysis in these variable yields an effective exchange trajectory which passes through the K, Q and L mesons. There is evidence for beam fragmentation in Λ and Λ production, but the contributions seem not to be dominant in the fragmentation region. Nevertheless, the parameter values in a triple-Regge description are estimated, and together with those for target fragmentation in Λ production, provide a complete description of the fragmentation contributions to the two reactions. Integration of the resultant distribution functions over the complete Chew-Low plot yields fragmentation cross sections increasing approximately as log s ; in addition the observed features of the x , p L and p T 2 projections and of the p L - p T correlation are well-described in the fragmentation regions. Central production contributions are isolated by subtracting the calculated fragmentation distributions
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We report measurements of the invariant cross section in the forward hemisphere for inclusive photoproduction of π±, K±, p, and p¯ from hydrogen and deuterium with an incident photon energy of 18 GeV. A small amount of data was also taken at incident energies of 9 and 13 GeV. The measurements were made using the SLAC 20-GeV/c spectrometer, and a bremsstrahlung-subtraction technique was used to obtain the cross sections at the specified incident energy. The data are compared with those from lower-energy experiments and interpreted within the context of the Mueller-Regge model and the constituent-interchange model.
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Measurements of inclusive scattering in the target-fragmentation region are extended to higher incident energy. The combined data set shows departures from an approach to the asymptotic scaling limit as A+Bs−12 that are significant even at the highest energies. When these departures are taken into account, the data approach a limit that is consistent with equal cross sections induced by particles and antiparticles and with Pomeron factorization. The corrections to A+Bs−12 are so large that detailed tests of Mueller-Regge relationships are not conclusive.
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The inclusive reaction K + p → K 0 + X is studied at 5, 8.2 and 16 GeV/ c . The energy dependence and the shapes of inclusive spectra in the central region are found to be consistent with double-Regge expansion. With the values obtained for the parameters of the Regge expansion, prediction are made for the behaviour of the cross section at higher energies.
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We present a systematic analysis of the production of K ∗+ (892) and Δ ++ (1236) resonances in the K + p → K 0 p π + reaction at 5, 8.25 and 16 GeV/ c . We have measured total cross sections, differential cross sections, density matrix elements and examined resonance production mechanisms in terms of the exchange of states with definite naturality. Some results on the reaction K + p → K ∗+ (1420) p are also given.
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The energy dependence of the modulus and phase of the K L 0 -K S 0 regeneration amplitude on hydrogen in the range of 14–50 GeV has been investigated at the Serpukhov 70 GeV accelerator. It has been established that the modulus of the modified regeneration amplitude decreases with increasing momentum as 2|ƒ 21 0 (p)|/k = (0.84 ± 0.42) · p −0.50±0.15 mb . The amplitude phase is energy-independent and its mean value is ϕ 21 0 = −132° ± 5°. The results obtained are compared with other experiments and with predictions of different theoretical models.
TABLE ALSO CALCULATES FORWARD DIFFERENTIAL CROSS SECTION AND SIG(AK0 P) - SIG(K0 P) TOTAL CROSS SECTION DIFFERENCES.
In a single-arm spectrometer experiment, high-precision measurements of dσdt for π−p, K−p, and p¯p elastic scattering have been made at 8 and 16 GeV/c. The π−p data show rich structure at 8 GeV/c, indicative of strong non-Pomeron contributions, while the 16-GeV/c data are much smoother. For −t≳1 (GeV/c)2 there is a strong s dependence while there is very little for −t<1 (GeV/c)2. For p¯p scattering the forward region is smoothly diffractive for −t<0.4 (GeV/c)2 and shows antishrinkage. The exponential slope parameter b is measured to be 12.36 ± 0.04 (GeV/c)−2 at 8 GeV/c and 11.40 ± 0.04 (GeV/c)−2 at 16 GeV/c. The structure near −t=0.6 (GeV/c)2 seen at lower energies is still obvious at 16 GeV/c. The K−p data show some structure at 8 GeV/c, but can be represented adequately by a quadratic exponential form. At 16 GeV/c the K−p angular distribution shows antishrinkage and lies above the 8-GeV/c cross section for 0.11<−t<0.8 (GeV/c)2.
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The reactions K + p → K ∗+ (890) p , K + p → K ∗+ (1420) p and K + p → K 0 Δ ++ have been systematically studied for eleven incident momenta between 3.0 and 16.0 GeV/ c . Cross sections, differential cross sections and density matrix elements are presented. For K ∗ (890) production the contributions from natural and unnatural parity exchanges have also been separated into I = 0 and I = 1 components. Effective trajectories have been extracted in the case of natural parity exchange, and also for Δ ++ production.
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DATA AT NEIGHBOURING MOMENTA ARE GROUPED TOGETHER. THE RESONANCE PRODUCTION TOTAL CROSS SECTIONS ARE FITTED BY P**-N. THIS TABLE GIVES THE VALUES FOR EACH GROUP OF MOMENTA OF THE FITTED TOTAL CROSS SECTIONS WHICH ARE USED TO NORMALIZE THE DIFFERENTIAL CROSS SECTIONS.
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